Centuro 600 Bandsaw _ Bearings

[andrew whicker]

Howdy,

I removed both wheels last night. The bearings are indeed trashed. I think I'll remove the dust covers and clean up / re-grease. However, these bearings were Shielded (Top wheel was SKF, Bottom wheel was Fanfir / Temkin). Reading about Shielded vs Sealed makes me believe that I want Sealed bearings instead. Which is quite the upgrade ($$), but is cheap in the long term of the machine. Hopefully my forever machine, so a few hundred dollars isn't bad.

Is there a reason why Shielded might be preferred over Sealed for this bandsaw (heat, load, speed)?

Thanks much,

[andrew whicker]

So the more I go down this rabbit hole, the more questions I have. The Centuro parts list doesn't give any mfg P/N's, only their own P/N. Does anyone have the mfg recommended bearings?

The upper wheel on mine has SKF 6207-2Z / C3GJN. The lower wheel: Fafnir 207KDD Z3 FS50000.

SKF nomenclature means the bearing: Shielded w/ C3 clearances. C3 clearance is "larger than normal clearances" on diameters.

Fafnir / Temkin nomenclature means the bearing: Shielded w/ ?? clearances.

Anyway, the reason for taking this stuff apart is the blade flutter so I'm not wanting to order expensive bearings w/ too big of a clearance by copying these exact bearings. Or maybe these bearings are correct?

[Andrew Hughes]

I’m not a expert of bandsaw bearings so take this for what it’s worth. My Aggazani B20/20 has a expensive German made bearing on the lower wheel and inexpensive bearings on the upper wheel.
I don’t remember if they were sealed or shield. I just remember discussing it with Jesses bandsaw tech when I first bought my saw.
Good Luck

[andrew whicker]

Hmm, both SKF and Timken are good brands as far as I can tell. I'm more wondering if they got replaced with the wrong clearances.

It also seems that 72 mm OD / 35 mm ID / 17 mm thickness is a standard size for radial bearings, so if anyone has a bandsaw in the same size range (600 mm / 24 inch) and has the mfg bearings PN's I could probably use that to help me as well.

[mike stenson]

Timken lists it as a Radial/Deep Groove Ball Bearing - Straight Bore, 35 mm ID, 13.2500 in OD, 0.6693 in Width, Double Shielded. Which would also be 6207-2Z

Edit: SKF, FAG, NSK, NTN, Timken etc.. all good choices for bearings IMO.

[andrew whicker]

Grizzly manual shows a 2RS bearing which is a double sealed bearing (vs shielded) of a slightly different size.

I'm going to try to clean up the ones I have and see f I find any runout in the shafts by rolling them on flat top?

Hmm... I don't think I felt any play in the wheels when they were installed... but I'd hate to take everything apart again.

[mike stenson]

If they're working, I trust the bearings in my hand. I'd also do a 2RS bearing on woodworking tools. I generally don't care much about mfg's purchasing choices for bearing manufacturers, most of the time they're looking to save money. (repacking a bearing that already feels notchy is a short-term fix IME).

[Mike Cutler]

Howdy,

Is there a reason why Shielded might be preferred over Sealed for this bandsaw (heat, load, speed)?

Thanks much,

They're typically much cheaper than a sealed bearing.If a manufacturer can save $$$$, by spec'g lower cost components, that's direct profit.

Take the bearings you have to a bearing distributor. They'll cross reference the part number and should be able to come up with a selection of new bearings to replace the old.

[Chris Parks]

Buying bearings is best done at a specialist bearing supplier in person as it can be a complicated process. Doing it in person will ensure you get quality bearings and not some no name low quality bearing.

[Bill Dufour]

Go with rubber sealed for anything under 5,000 RPM in a dusty wood shop. Motor grade or better is fine for bearings. So class three or higher. Do not use better then class 5 or you will have problems.
Modern synthetic rubber is much better then real rubber was.
Shielded is 1950's tech. maybe still used if the machine has a few hundred bearings and the extra friction adds up. Like a conveyer belt system.
NTN Used to have. good bearing look up search function from the three dimensions. Hope it still works.
BilL D

https://bearingfinder.ntnamericas.com/advanced/ball-bearings

[Bill Dufour]

Timken lists it as a Radial/Deep Groove Ball Bearing - Straight Bore, 35 mm ID, 13.2500 in OD, 0.6693 in Width, Double Shielded. Which would also be 6207-2Z

Those sizes make no sense. ID must be smaller then OD. I doubt it is 13.25 inches diameter.
I assume all dimensions should be metric no inch at all. Unless this was made in usa before 1950 or so.
Very possible someone replaced only top or bottom bearings at some time.
Bill D

[Chris Parks]

The quickest and safest way to get what you need is take the bearings to a bearing supplier.

[mike stenson]

Those sizes make no sense. ID must be smaller then OD. I doubt it is 13.25 inches diameter.
I assume all dimensions should be metric no inch at all. Unless this was made in usa before 1950 or so.
Very possible someone replaced only top or bottom bearings at some time.
Bill D

It's a one-liner at the top of the page I copied, pasted and missed that because I was looking at the specs below. Here's the specs from that section

OD 72.00mm
Width 17mm


I hate mixed measurements. I suspect prior replacement is highly likely. While I'm thinking about it, I hate bearings that are labelled other than series, bore diameter, shield code, clearance code, etc..

[Bill Dufour]

looks to be a 6207 bearing. About $15 each for Nachi on the bay. NTN, FAG, SKF, Nachi, Timken. are all good. I use VXB with good results.
A bearing that big and expensive you will not find a tube of ten for a excellent price.
BilL D

[Erik Loza]

Agree with Bill on this: No need to overthink, here. Just get some good quality sealed bearings of the brands mentioned and move on. I can 100% guarantee that there is no “science” in bearing selection for bandsaws. The last new Centauro I worked on had Korean-made bearings and you know the track record of the MM16/S400P. Good luck with it.

Erik

[John TenEyck]

I doubt the blade flutter you mentioned was due to worn bearings. Most likely the tension you had on it resulted in a harmonic.

John

[Andrew Hughes]

I just looked at the bearing on my lower wheel and it’s just a cheap Chinese bearing. Unless there’s another behind it it must of been changed when I had the saw in for service. So I retract yesterday’s post
My experience with bandsaws is the blade and tires make the most difference.
Good Luck

[Tom Trees]

I doubt the blade flutter you mentioned was due to worn bearings. Most likely the tension you had on it resulted in a harmonic.

John
I've often read of this, and watched various flutter methods before, and I can't say that I'm convinced of this being a thing with a properly set up machine.
Having experienced this, mainly plonking away dressing tires with inconsistent results years before, it seemed I was getting a better impression of how the machine would
run, whilst not being tensioned fully.

Eager to do some experiments regarding this, so I'll be keeping that in mind.

As it happens, I can't recall what the general consensus is, in regards to this phenomenon being most apparent...
I guess some sort'a rule of thumb being the wider the more apparent?

Not sure I can recall this discussion with carbide blades, but that's possibly more understandable, as the suggestion is to use thereabouts around 25000 PSI tension.
Also worth noting if you look at Andrew's other video, you can see the blade on this machine being fairly cranked up.

[andrew whicker]

Cranked up enough that I could hardly move the wheel anymore.

[andrew whicker]

Alright, I ordered some SKF branded 6207-2RS's from Zoro.

Grainger prices are always crazy to me. Zoro is so much cheaper.

[John TenEyck]

I've often read of this, and watched various flutter methods before, and I can't say that I'm convinced of this being a thing with a properly set up machine.
Having experienced this, mainly plonking away dressing tires with inconsistent results years before, it seemed I was getting a better impression of how the machine would
run, whilst not being tensioned fully.

Eager to do some experiments regarding this, so I'll be keeping that in mind.

As it happens, I can't recall what the general consensus is, in regards to this phenomenon being most apparent...
I guess some sort'a rule of thumb being the wider the more apparent?

Not sure I can recall this discussion with carbide blades, but that's possibly more understandable, as the suggestion is to use thereabouts around 25000 PSI tension.
Also worth noting if you look at Andrew's other video, you can see the blade on this machine being fairly cranked up.


I'm not sure what you mean by a properly set up machine, Tom. If it includes adjusting blade tension to eliminate any flutter that occurs when the blade is rough tensioned, then, yeah, that's a properly set up machine.

Narrow blades tend to flutter more easily because they will resonate at more frequencies than wider (stiffer) blades. In any case, if you follow the blade installation instructions, at least those with my Grizzly bandsaw, you rough tension the blade with the guides away from the blade, turn on the saw and look for flutter, and increase tension if any is observed, until it is eliminated. Pretty simple stuff.

John

[Tom Trees]

I'm not sure what you mean by a properly set up machine, Tom. If it includes adjusting blade tension to eliminate any flutter that occurs when the blade is rough tensioned, then, yeah, that's a properly set up machine.

Narrow blades tend to flutter more easily because they will resonate at more frequencies than wider (stiffer) blades. In any case, if you follow the blade installation instructions, at least those with my Grizzly bandsaw, you rough tension the blade with the guides away from the blade, turn on the saw and look for flutter, and increase tension if any is observed, until it is eliminated. Pretty simple stuff.

John

It'll be interesting to see if I can achieve any flutter going from rough tensioned to apt, is what I meant.
I'm just a bit sceptical of this being a frequency thing, and more partial to believe this, as a sign of mis-alignment, or tire issues,
as I've eliminated that before under the actual unchanged blade tension whilst dressing tires, (note the blood smear on the chassis waist :))
way back when I didn't know anything about bandsaws,
I've went back and fourth on that, as you probably know, and can mention I experienced eliminating flutter more than once during that time,
whilst being especially curious regarding how things might tip the upper wheel, so left the tension unchanged,
as I was getting the impression of mad variables, and being too thick to question if the faces of the wheels were actually true,
so spent way too much time going back and fourth, as the beam is very sensitive.

Be interesting to see how things go, and surely a test also for my tire dressing job, which I just about got away with...for the umpteenth time, that is...
as silly me believed there were such a thing as true flat tires, and went on a bit of a quest for a red herring on that one ! :rolleyes:

Seemingly there might be others who might think the same, as in..I wouldn't attempt cutting if I seen flutter, as the set would compress,
although some videos exist of this seemingly not being an issue...
(Not reckoning fluttering is blade tension related, that is?..)
Take that Stockroom supply's bandsaw sled guy for instance,
slicing veneers using a wee saw, with a blade intentionally woefully inadequately tensioned, yet he still ends up with results!.
I must watch again to see if he actually does mention this.

My take on why that/those sleds work so well is, they might well be splitting the difference between wheels out of alignment.
Not that that'll be a problem for those with a foot mounted motor like the CO, but for others without such adjustments available,
I'd guess you just got a good one, and someone has gotta have a lemon seeing as most anything else out ain't built as such,
and whoever got the worst one, found an correlation with such a phenomenon, and coined that whole flutter = blade resonance thing.
I'd take a pot shot it, was a lot less hefty than your extra thick welded steel framed machine too.

Though I could be just talking out my hat, I'll find that one out fairly quickly,
In my defence, crowned tires are a bit new to me, as in lots of experiments I can do yet,
as when I had flat tires, hand turning the wheels whilst blade at least half or more tensioned, wasn't allowed, (blade dives hard into thrust guide)
so perhaps that might explain so, and it'll be interesting to see how much less tension I need for the above, not to happen.

Good to have two reasons to have a wee narrow blade, use for occasional curves and for testing the flutter.
I spent waay too much time on my machine, and I haven't used it since but for an emergency bird house, so more experiments can wait for me.

Cheers
Tom







509085509086

[Brian Runau]

Nachi makes a great bearing. C3 is the internal clearance between the races of the bearing, 2NSE is their double rubber sealed version. Brian

[Brian Runau]

Alright, I ordered some SKF branded 6207-2RS's from Zoro.

Grainger prices are always crazy to me. Zoro is so much cheaper.

Zoro is grainger. Grainger is industrial discounted per account, zoro retail discount. Brian

[andrew whicker]

Zoro is grainger. Grainger is industrial discounted per account, zoro retail discount. Brian

I understand, but you'd have to have one heck of an account to make Grainger prices work out when they start out at 2x to 3x their "retail brand" prices.

[Jay Houghton]

A number of years ago I bought a band saw blade tension meter from a guy on eBay. He milled the body out of aluminum and then you installed your own dial indicator. Cost was about $100. I use it most of the time when I put a new blade on and it's amazing how much more it takes to get to 22,000 psi than you think. But if your machine can get you there then the blade is rock solid and will cut like a table saw. I have a Meber 600 which is probably the same machine as the Centauro 600 and can get a 1" Lenox Tri-Master tensioned to 22,000 psi. I just did a bunch of resawing with it and the blade with that tension looks like it's not moving. I can also peel off .080 veneer from 12" stock with little variation top to bottom. My personal experience is that most people under tension the blade either because the machine can't get there or they are afraid of breaking the blade. But be aware that metal band saws that ride with no rubber tires are tensioned to 40,000psi and the blades can take it.
Jay

[Brian Runau]

I understand, but you'd have to have one heck of an account to make Grainger prices work out when they start out at 2x to 3x their "retail brand" prices.

Agreed. Brian

[John TenEyck]

It'll be interesting to see if I can achieve any flutter going from rough tensioned to apt, is what I meant.
I'm just a bit sceptical of this being a frequency thing, and more partial to believe this, as a sign of mis-alignment, or tire issues,
as I've eliminated that before under the actual unchanged blade tension whilst dressing tires, (note the blood smear on the chassis waist :))
way back when I didn't know anything about bandsaws,
I've went back and fourth on that, as you probably know, and can mention I experienced eliminating flutter more than once during that time,
whilst being especially curious regarding how things might tip the upper wheel, so left the tension unchanged,
as I was getting the impression of mad variables, and being too thick to question if the faces of the wheels were actually true,
so spent way too much time going back and fourth, as the beam is very sensitive.

Be interesting to see how things go, and surely a test also for my tire dressing job, which I just about got away with...for the umpteenth time, that is...
as silly me believed there were such a thing as true flat tires, and went on a bit of a quest for a red herring on that one ! :rolleyes:

Seemingly there might be others who might think the same, as in..I wouldn't attempt cutting if I seen flutter, as the set would compress,
although some videos exist of this seemingly not being an issue...
(Not reckoning fluttering is blade tension related, that is?..)
Take that Stockroom supply's bandsaw sled guy for instance,
slicing veneers using a wee saw, with a blade intentionally woefully inadequately tensioned, yet he still ends up with results!.
I must watch again to see if he actually does mention this.

My take on why that/those sleds work so well is, they might well be splitting the difference between wheels out of alignment.
Not that that'll be a problem for those with a foot mounted motor like the CO, but for others without such adjustments available,
I'd guess you just got a good one, and someone has gotta have a lemon seeing as most anything else out ain't built as such,
and whoever got the worst one, found an correlation with such a phenomenon, and coined that whole flutter = blade resonance thing.
I'd take a pot shot it, was a lot less hefty than your extra thick welded steel framed machine too.

Though I could be just talking out my hat, I'll find that one out fairly quickly,
In my defence, crowned tires are a bit new to me, as in lots of experiments I can do yet,
as when I had flat tires, hand turning the wheels whilst blade at least half or more tensioned, wasn't allowed, (blade dives hard into thrust guide)
so perhaps that might explain so, and it'll be interesting to see how much less tension I need for the above, not to happen.

Good to have two reasons to have a wee narrow blade, use for occasional curves and for testing the flutter.
I spent waay too much time on my machine, and I haven't used it since but for an emergency bird house, so more experiments can wait for me.

Cheers
Tom







509085509086


I spent a lot of my engineering career challenging what some folks espoused as true. Never along the way, however, did I challenge basic, proven, engineering principles. It's not a matter of belief or disbelief. Engineering is pretty black or white. That's a lead in to say bandsaw blades flutter due to resonate frequencies induced in them as a result of the applied tension. Different blades will resonant at different frequencies, but the concept is the same. Solving flutter takes nothing more than adjusting the tension, higher or lower, to move the frequency out of the resonant zone. The saw itself is irrelevant to the problem.

John

[andrew whicker]

I spent a lot of my engineering career challenging what some folks espoused as true. Never along the way, however, did I challenge basic, proven, engineering principles. It's not a matter of belief or disbelief. Engineering is pretty black or white. That's a lead in to say bandsaw blades flutter due to resonate frequencies induced in them as a result of the applied tension. Different blades will resonant at different frequencies, but the concept is the same. Solving flutter takes nothing more than adjusting the tension, higher or lower, to move the frequency out of the resonant zone. The saw itself is irrelevant to the problem.

John

It didn't matter what force I put on the blade. It was fluttering. One inch blade.

The only way I could go tighter would be to use a lever arm on the wheel.

My tension measure on the bandsaw doesn't seem accurate. But I was tightening until I couldn't anymore while the machine was on and thy flutter never went away. Maybe it passed thru a few frequencies getting better or worse but never became normal

[Tom Trees]

This makes for some very interesting reading, as I haven't experienced this atall, even when the wheels were likely still out of alignment,
differing blades and all.


The saw itself is irrelevant to the problem
Not as far as someone without a class blade tension indicator! :D

Not being sure what the dimensions are of my ACME tension screw,nor the screw on your machine, but one could suggest that being quite relevant,
though for the curious, anything is better than nuffin....
It's a very vague question, I understand, but I'll ask it none the less.

Unsure of what your might deem a minimum amount of PSI might be starting at, guessing around 15Kpsi (say, for edging shingles, something thin)
By say turning the screw 90 degrees, or a quarter turn, how many times can one expect to experience this flutter?

A ping or deflection "white finger test" would have been good Andrew,
https://www.youtube.com/watch?v=HTWi9O13zu8
I'd guess the machine should be good in ballpark tension, that's if Andrew's...
A. Not been living under a rock, and actually looked some stuff to get some sort of idea, (note the smaller bandsaw at the back)
B. He's not too weak to turn the screw, doesn't seem the case to me either,
C .The blade being good, and not having a stress crack in the gullet, and is giving warning signs.
D. add to whatever other speculation their might be in regards to something not being mis-alignment.

That's if those tires are good, should be a no-brainer if they were the replaceable type with the offset groove.
I see paint on the upper one, so it's not new.
Erik has mentioned some of the CO's being vulcanized real rubber tires, and the thickness of them & the paint job would suggest it's an old one also,
so I'm guessing it likely needs a wee lick.


All the best
Tom

[John TenEyck]

It didn't matter what force I put on the blade. It was fluttering. One inch blade.

The only way I could go tighter would be to use a lever arm on the wheel.

My tension measure on the bandsaw doesn't seem accurate. But I was tightening until I couldn't anymore while the machine was on and thy flutter never went away. Maybe it passed thru a few frequencies getting better or worse but never became normal

Just to make sure we are all using the word flutter for the same phenomenon, here's a link to a YouTube video where the guy demonstrates it. Skip the first 3 minutes.

https://www.bing.com/videos/riverview/relatedvideo?q=bandsaw+blade+flutter&mid=7C142708C6CFBE6373E27C142708C6CFBE6373E2&FORM=VIRE

I don't agree with his statement on proper tension, but the video is good for showing what flutter looks like.

FWIW, I've never seen a 1" blade flutter on my saw, maybe because I've never had less than 20K psi on it. But I'm sure one would if the span were long enough (mine is 16+" with the guides loose) and the tension low enough for it to go into a resonant frequency. But I'm wondering if you are really seeing the blade flutter or something else related to the bearings being bad. It makes no sense to me that the flutter you described did not change as you increased blade tension. Are you sure the spring and tensioning mechanism are working properly? This is where a tension meter is an excellent tool in helping diagnose a problem.

John

[Tom Trees]

Just seems like another misaligned saw to me, which I guess likely has quite a crown on tires.
I've not even experienced this with another 315mm wheeled machine at the folks.
What could well be the reason for this though, is my 24" had a flat profile to the wheels, so not much leeway in regards to low tension, (tracking would be required to do so)
and the other machine, the old rubber like compound tires, are soft and squishy, so once again, not necessarily a camber.

Is there a correlation between more pronounced tire crown profile, kinda seeming possibly so...
That makes it doubly interesting to me, since I've dressed my tires with such a pronounced profile.

Cheers
Tom

[Erik Loza]

No dog in this fight but doesn’t the OP’s machine have flat tires? If so, then “wheel alignment” isn’t a thing. I’ve rebuilt/adjusted lots of Centauros and never needed to make any adjustment to wheel alignment, aside from the usual tracking adjustment, in order to get good results.

Erik

[Tom Trees]

One possible reason there's no reason to need adjust a Centauro could be because, they may have some clever method
of using the groove for such alignment?

One could speculate the... flange mounted motor? got a knock sometime, and someone adjusted the motor or wheel/both
to attempt a fix, compounded with some tire profile like the state in which my mistreated saw came in.
Thus rendering some methods of alignment, take the Rikon guide, or what's in the Laguna manual for instance, likely not successful.
509133509134

No doubt, regarding anyone's opinion, something to spot would be some original witness marks from the motor, should it be shunted,
and another thing to look for is marring of the bolt heads for the jacking screws.

ps WARNING this could be dodgy, and clicking it could mean instant download,
I know nothing about computers, and running with a Linux boot program, so perhaps I'm safe...
Nothing mentioned about that if so, on the UK forum, if a woodworking forum is to go by, but these things could change, ?

It's for the SP series, but the best I've read so far.

I can't get the link to work, but here's the forum page link instead

I see in the thread, a video of when I had flat tires, and a blade with no set, likely from mis-alignment,
and clear to see the saw refusing to cut anymore,
which when re-profiled ala Centauro's 1mm apex being closer to the front, but a bit more pronounced,
was just able to do the job.
That was crystal clear proof to me, regarding of the importance of the crown,
which is exactly what's in the manual, i.e
Here's an interesting snippet which I cannot screenshot....
" MAIN TROUBLE AND RELATIVE REMEDIES "


The blade moves very far back when it receives the cutting force
- Insufficient flywheel seal convexity, notify the technical service of the area dealer.

https://www.ukworkshop.co.uk/threads/centauro-400-ssp-bandsaw-does-anyone-have-a-manual.141846/

[Erik Loza]

One possible reason there's no reason to need adjust a Centauro could be because, they may have some clever method
of using the groove for such alignment?…

No… In my experience, hobbyists worry way more about “setting up their bandsaws” than Italian manufacturers do. In Italy’s mind, the bandsaw is a very basic machine, to which they dedicate the barest level of engineering. I mean, we’re talking about a steel frame and two rotating wheels. That’s it. Historically speaking, every bell or whistle has come about due to AMERICAN market demand. Fancy blue guides, micro-adjustable fences, etc. The machine remains very basic and, assuming it wasn’t dropped off the back of a truck, should not require any sophisticated level of engineering or adjusting to get it to cut the way the owner wants. Like I would always tell customers, “You’re paying several thousand dollars specifically to have machine that DOESN’T require any special fussing”. Just my 2-cents.

Erik

[Tom Trees]

Agreed, blade guides aside, and upper wheel carriage & depth adjustment as per the premium Italian machines...
Centauro are still making machines with flange mounted motors, and that along with the wheels, is a good amount of extra expense, compared to the competitors,
but a worthwhile one, to ensure the best amount of success in regards to getting honestly good running machines out the door.
BTDT going with the budget resawing bandsaw.

I've got tales of woe, regarding a new belt which might have been too short, combined with lower wheel misalignment,
should one think the chassis behind the wheel is some sort of ballpark datum, (that was new motor bearings for me)

The foot mount motor is a foolproof design in that regards, it might even be self aligning?
Perhaps not the case with an old machine like Andrew's, should he find dents all over the mounting plate.

Tom

[Chris Parks]

Such a simple machine complicated by a lot of misunderstandings and the need to complicate things for no good reason.

[Tom Trees]

Aye, indeed.;)

Tom

[Tony Shea]

Alright, I ordered some SKF branded 6207-2RS's from Zoro.

Grainger prices are always crazy to me. Zoro is so much cheaper.

I know we are past the bearing discussion but wanted to reassure the OP that his bearing choice of SKF 6207-2RS bearings is a great choice. I personally try to buy NTN bearings through my local bearing supplier but SKF makes high quality bearings as well. The reason for using my local supplier is due to the massive amount of counterfeit bearings in the wild. Who would have thought that bearings would be something that's wildly counterfeited. There are guides out there by these manufacturers on how to tell your name branded bearings are actually real.

99% of bearings for woodworking machines benefit from sealed bearings as the rpm is plenty low to not cause issues with heat. The fine wood dust in a woodworking shop is much more of an issue than seals causing heat due to friction. Manufacturers will almost always use shielded bearings instead of sealed purely based on price.

[andrew whicker]

Finally got the new bearings installed (forgot to purchase a ratcheting snap plier so took a few more days).

Still runs like crap. I heard a pop and think I broke a blade trying to tension it. I looked inside and saw the lead screw was completely butted up against the stop. So no more tension possible.

My only other scary thought is the bottom shaft is misaligned. Not sure how to go about checking that.

The belts are fairly tight, motor seemed tight. Blade is running in the right spot on the tires.

[Tom Trees]

The scary part is over, should the job done be sound...if yer Centauro CO is one with a foot mounted motor.:cool:

?...


i.e, is the motor fastened onto a mounting plate, like on this one has...
509504

[Tom Trees]

Just incase you wish to keep troubleshooting without taking the table off...
You might wish to know that it's a good idea to keep those old belts installed, as better a stretchy belt than one with no give atall,
and should you happen to get new ones.... the ones installed may not be the original length spec!
as I guess was the case with mine, as a replacement (of the same brand/size) turned out to be much tighter, though not apparent by eye or feel,
(well, I didn't go giving it the Stretch Armstrong)
509506

That meant a trip to the bearing shop for me, and was a hard lesson learned, incase anyone was thinking one could simply align the lower wheel
with the chassis, at least for a troubleshooting starting point ala Rikon or Laguna manuals, then you need to have a very loose belt(s).
(and good tires)

And if that warning isn't heeded, and the motor bearings get toasted, before pressing on the second motor bearing, and is a similar motor as mine...
Remember that disc goes on beforehand!
509505

All the best.
Tom

[Erik Loza]

Andrew, when you say the bandsaw “still runs like crap”, what exactly does that mean? I still believe your blades are too long, BTW. The blade ought to snap long before you run out of thread on the tensioning screw. At least on every Centauro I’ve worked on. There is some large piece to this puzzle missing. No bandsaw should require this much work just to run right.

Erik

[Jim Becker]

I was just going to suggest what Erik did...sounds like the band(s) you have are too long if the tension adjustment is bottoming out.

[John TenEyck]

Finally got the new bearings installed (forgot to purchase a ratcheting snap plier so took a few more days).

Still runs like crap. I heard a pop and think I broke a blade trying to tension it. I looked inside and saw the lead screw was completely butted up against the stop. So no more tension possible.

My only other scary thought is the bottom shaft is misaligned. Not sure how to go about checking that.

The belts are fairly tight, motor seemed tight. Blade is running in the right spot on the tires.


I wonder if that pop you heard was the spring breaking?

John

[andrew whicker]

The blades are still fluttering is what I mean.

It does sound better though. I did measure everything at one point to find the rough blade length tolerance. Here they are (found them in my last thread about this machine):

The blades are 14 ft 11.5 inches (179.5 inches / 4559 mm). I did some rough measurements and my min blade length is around 176.5 inches and max is around 183.25 inches. So good there

[andrew whicker]

I should note, I didn't physically measure the blade length, I went off the box they came in. I'll physically measure one today. I personally feel like the blades are stretching. ?

[andrew whicker]

My motor is mounted like that.

I'll have to check on the spring... the one thing I'm not enjoying about this machine is getting inside certain areas is actually impossible. Just a metal welded box, no door, etc.

[andrew whicker]

My upper wheel has side to side alignment bolts. The bottom shaft as X and Y alignment at the rear of the machine. Two of those alignment nuts and bolts are wired in their position... as if it was done at the factory.

I can also check the shaft runout with some simple vee blocks... maybe that's the issue?

My top wheel is pushed all the way to the right. When I lined up a laser level to be level with the table, my upper wheel needed to go right about a 1/4". However, I didn't think that was too much of a big deal. I assumed I just need to tilt the table to make it square. Haven't looked any final adjustments yet since my problem at this point is so basic.

[Tom Trees]

I wonder if that pop you heard was the spring breaking?

John

Could be, Erik or Van Huskey (wherever he's gone) would know,
On the older CO's with spoked wheels, it certainly appears possible the wheel would "bottom out" on the chassis, so if the blade is not long enough for concern
then that might explain.
Can you hear anything without a blade installed, feel or magnet on a stick catch anything through the screwhole?
509508509509

Here's another Italian saw, just to see the force that screw can apply, could pop a tack weld I guess...
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I'd imagine this would be very apparent.
But it also could have been the hardened washers for the thrust bearing, very likely if like my machine, mine was in about 6 fragments,
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the Bowden cable somewhere, or possibly just a little roller in the thrust washer for smooth turning,
I'm missing one or two of those.

If the sound was seemingly not that, and was a silent enough odd knock, with slight creaking that's what I was experiencing, before the wheels came to a halt.
then it's either alignment or tire profile.
One could have just crowned the tires I suppose, and not bother going down rabbit holes speculating something broken regarding the carriage assembly.
I went there and added quite a bit of meat, bit too much actually, made no difference apart from being a lot smoother to tension a blade.


Tom

[Tom Trees]

My upper wheel has side to side alignment bolts. The bottom shaft as X and Y alignment at the rear of the machine. Two of those alignment nuts and bolts are wired in their position... as if it was done at the factory.

I can also check the shaft runout with some simple vee blocks... maybe that's the issue?

My top wheel is pushed all the way to the right. When I lined up a laser level to be level with the table, my upper wheel needed to go right about a 1/4". However, I didn't think that was too much of a big deal. I assumed I just need to tilt the table to make it square. Haven't looked any final adjustments yet since my problem at this point is so basic.

None of the carriage adjustments made any difference to me, as in wheel depth, nor scooting the carriage assembly,
and if you might note many a bandsaw have smaller lower wheels like on this Centauro, but found on from all sorts of manufacturers.
Those are for matching to the guidepost.
Same can be said for the 30mm shaft on my machine, I rotated it a few times thinking it may have been bent slightly,.
Red herring if that's what your thinking.
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[andrew whicker]

I measured one at 179.625. So right on length essentially

[andrew whicker]

Okay. I just saw a sticker on my machine that says the blades have to be btwn 4580 mm and 4440 mm. I'm pretty close to the upper limit.

I will buy some new blades at the half way point and try those...

Sound good?

[Tom Trees]

I suggest a half inch or three quarter for alignment purposes, 3TPI would be good, i.e not too jagged to catch yourself on.
I suspect others could give you their measurements for vendors, but that would depend on TPI.


In the meantime..... you could tram those wheels without needing a blade,
if wanting to do a good sure job of things, and keep your bearings (and wheel bores more importantly) in good nick,

I haven't seen any guide of sorts for alignment thereafter, well not regarding the motor...
should the machine have much vibration without a blade installed (and belts not new with a lump on the joints,)
Sighting down them would be another good idea, but you'd need to remove the table to get a good look, once again if the foot mounted motor got shunted,

Difficult to get a clear photo of this, as I need a lamp to get a proper look at depth adjustment of the pulley,
but also worth noting might be just out of alignment either, either way, something to spot.

i.e you can see the pulley would like to be seated closer to the wheel here, if you can make out the belt favouring one side of the groove.
509537

And the belts in-line with the wheel now, don't let the joints in the belt fool ya
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That would keep you tied over, or the alternative approach...

or the gett'r done as fast as possible route, without heed in regards to either wheel or motor bearings...
Inspect the tires to see if there is a crown on them, as Centauro specify.
If doing so on the machine,
You'd likely need a blade installed to stop that upper wheel from tilting....well if rigging up some kind of setup what's under the wheel anyway.


Wheel depth might just matter here, as I was doing a lot of experiments with my wrongly assumed idea of these machines having flat tires,
but I reckon that's a red herring, which is easily proven either way using a plumbline, well with the table removed it is.

Note to get the lamp and have a good look at those four jacking screws (the hub at the back of the lower wheel)
Can you see any signs of a wrench having gone near them?
(I've read of paint used to denote both factory set axis screws (bolts, with nuts set)
I'd not be very keen to keep running it, or winging it re-crowning the tires, if you do see some signs of them been touched.

All the best
Tom

[John TenEyck]

My motor is mounted like that.

I'll have to check on the spring... the one thing I'm not enjoying about this machine is getting inside certain areas is actually impossible. Just a metal welded box, no door, etc.


Whatever is not accessible probably doesn't need to be.

John

[John Lanciani]

I'm going to jump into the fray here. I have mentioned it before but I had to replace the spring in a then brand new mm20 that I bought in 2005 or so due to it fully collapsing and not being able to tension a 1" blade. These saws are nice but they are not always perfect. (Though Tom's should probably just be put in the dumpster) They are not nearly as complicated as some want to believe though, you just need to work through them logically. Focus on the basics, resist the temptation to get dragged out into the weeds.

[Tom Trees]

Nonsense, my Griggio is Centaurolized now, cuts great runs smooth.
No flutter, nor pulsating fore and aft, no spelching, of the underside of the cut, nor burning, loads'a beam tension , couldn't be happier...
( Edit, what I should've said... now that my Griggio is Centaurolized....) :)

t'was only a bit of alignment and a crown on the tires needed, just took me some figuring how to do.
I suspect Andrew's saw is pretty much the same deal.

Tom

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[Tom Trees]

I shoulda mentioned this whilst I was posting the carriage assembly yesterday,
but should one suspect the spring snapped, or washers, and disassembly is required,
then one should be very very careful of those roll pins, holding on the handle, which needs removal if wanting to get at those parts.

I think someone intended for mine never to come out, and they nearly succeeded, took grinding half of that pin to remove,
(in absence of a few die grinder bits, perhaps.... I've not got the wallet to find out how expensive of a job it coulda been)

Amazing and infuriating the grip mine had, it was like it was welded in.
Tread carefully if it's the case, make or buy decent punch with hardened steel and not some easy solution,
should one not show any signs of budging.

That was a good test of the Italian cast iron I tell'ya, as I really, really didn't want to cut the handle off,
and am not short of a hammer or two.
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Good luck
Tom

[andrew whicker]

509704

Top wheel is unbalanced... not sure if enough to matter?

I'm marking low spots

[andrew whicker]

Also found some play in the upper carriage... not sure if it matters as the tension is so high when this is running..

Thoughts?

https://youtu.be/2QE-Fpo2e8M?si=RCsyT2P8O89ChulD

[Tom Trees]

I don't think that carriage assembly would be an issue, you'd probably be able to tell by grasping the wheel, with blade installed.
Its mentioned regarding a few budget machines out there, where this is actually the case, yet the machines are said to run well.
(I've seen large saws what one might call a real janky design by comparison, and seen the same machine cutting tall stuff)

Not had a balance problem with my wheels, upper wheel might turn back slightly for a half second before halting.
Likely only noticeable with some tape, never noticed until that.

I did note some discrepancy of the width of the flat (real estate for alignment)
which correlated with the high spots when I faced my wheels.
Here's a thread of a bad case regarding that, in which I suggested the face could have a much larger error than my wheels,
That alone wouldn't cut the mustard in this case, but perhaps for a wonky wheel, might do the job.
There was weights involved, and seemingly that done the trick, unfortunately no gloating shot of the cutting though.
https://owwm.org/viewtopic.php?f=1&t=241172&p=1755429&hilit=felder+wheels#p1755429

You'll have to excuse my numptyness regarding believing a flat tire would run on a saw like so,
and totally getting hints here that those tires need attention.
A flat profile and a crown won't run well together...well not for me anyway before I could align my wheels,
and even with wheels aligned now, would still reckon that flutter and pulsating would be apparent.
Most would agree on speculating on that first off.

(should you not feel a broken spring somehow without dissasembly)

Good luck

Tom

[Erik Loza]

Also found some play in the upper carriage... not sure if it matters as the tension is so high when this is running..

Thoughts?..

That looks normal to me. On modern Centauros, you can grab the upper wheel and rock it back and forth a lot more freely than your video.

Did your new length blades arrive yet?

Erik

[andrew whicker]

Hmm.. Both of the tires seem flat to me unless the crown is so small after install that you can hardly tell?

I haven't received my new blades yet.. that's the next step. I really don't have anything to do other than that for the moment. I can order a lower wheel tire I guess. But it looks fine and I'm tired of spending money on the machine for the moment.

[Tom Trees]

Vulcanized tires are made of real rubber, and not synthetic rubber like butyl compound, like featured in Sam Blasco's Minimax MM16 video,where he demonstrates getting a finger nail under, as those aren't glued on...
so if those wheels take the vulcanized flavour, then dressing is the done thing, or for the well heeled, sent away presumably to Italy?

If you look on the likes of the OWWM forum, you can get an idea of the longevity of real rubber, and that's likely counting wonky saws and all, which says a lot, in addition to mentioning from personal experience, you've got a lot of chances of dressing tires, heck I must've dressed my tires a dozen times,
trying out various methods, improving my techniques,
before finally coming to the conclusion flat tires don't work, and back to putting a crown on the rubber again,
and more experimentation afterwards with that. :rolleyes:

Worth noting many articles on bad running saws of this type, there will generally be evidence of indeed a flat profiled tire, or even worse, a concave profile,
like what was on mine before I started.
Obviously narrow blades the culprit, but the omission of the apex mentioned, @17.5mm in from the front, well on the newer CO,
which I presume ACM being the same,
combined with many the mention of narrow blades being somewhat more troublesome to run,
leads me to speculate that some might have been unknowingly removing what is likely a very slight crown on the tires, (say from a previously owned saw,
with a new owner who actually looked at the machine)
by running fine tooth blades with gullets dead on centre.

Also worth noting not all real rubber created equal, the tire on my lower wheel is softer than the upper one,
could even be intentional for all I know, might make sense since the upper wheel tilts.
Age could be another thing, compression factor or whatnot, hence why I dressed my tires with a more pronounced profile than the Centauro CO replacement tire,
whilst keeping the apex and curvature as similar as I could (i.e a slightly flatter profile at the back)
and it done no harm atall, well with a 3/4" blade anyway, that's all I've been testing with, since my other old blades have been through the thick of it.

All the best
Tom

[Erik Loza]

Hmm.. Both of the tires seem flat to me unless the crown is so small after install that you can hardly tell?…

The only Italian bandsaw I’ve ever seen that had anything vaguely resembling a crowned tire were some of the Mebers. In those cases, it was more of a slight roundover at the edge of the tire but still 100% flat where the blade would track on the tire. Of all the bandsaws I’ve ever monkeyed with, “tires” (unless obviously damaged) are not really anything that’s caused a performance issue. Andrew, I think that you are on the right track with getting a shorter blade on there.

Erik

[Tom Trees]

I guess the crown on my Centauro tire is much less apparent when stretched on the wheel.
Another thing worth noting, is what happens when a blade or indeed a tire behaves, when shaped to a circumference,
as seen here on this clip taken from the Cooks sawmills channel.
Which might explain things better.
https://youtu.be/Y-pyJr7EMTw?si=9PpUrRbbLanlpKAX&t=137

All the best

Tom

[andrew whicker]

Got the new blades installed. So am I tensioning until the blade is fluttering around a 1/16" with no guides and then installing the guides to remove the rest of the fluttering?

Or am I still going to have to chase this further?

[John TenEyck]

Got the new blades installed. So am I tensioning until the blade is fluttering around a 1/16" with no guides and then installing the guides to remove the rest of the fluttering?

Or am I still going to have to chase this further?


If you have no tension meter, which is easy to make so you should have one, then first tension it to the nominal mark on the saw's tension indicator. Then turn it on. If there's no flutter, you're done. If there is flutter, then adjust the tension up/down until it stops. All of this is done with no guides.

John

[andrew whicker]

I didn't have time to make one today, but I have a dial indicator. Can make one later this week.

[Tom Trees]

If you have no tension meter, which is easy to make so you should have one, then first tension it to the nominal mark on the saw's tension indicator. Then turn it on. If there's no flutter, you're done. If there is flutter, then adjust the tension up/down until it stops. All of this is done with no guides.

John

That's what the company technician from UK and the retailer tried, with a hefty 1 inch blade, as a last ditch attempt to fob me off
on that 20" Far eastern machine I had briefly, (the model mentioned wasn't on the market for long)
and even I had to cough up for a 3/4" blade previously, to come across as at least reasonable,
even though they were not, and scolded me like a child for using a competitors blades (which are highly reputed)
going anywhere near the jacking screws (which weren't even close to being snug with the shaft)
and asking for advice on forums, and receiving a response as "the blind leading the blind"

But we'll be nice to you and send you a replacement upper guide (which the thread wasn't stripped on)
Nuffin wrong with that saw they were sayin...whilst demonstrating some firewood techniques ,
which was all the machine could do, since the blade was fluttering more than the thickness of veneers I wanted to cut! :eek:
Got my money back, and nearly not my mobile base which I rolled the machine into the shop with.
The last sting left he had, was to mention "you'll not get another machine with the spec your looking for" (most of us have single phase in Eire) :rolleyes:
Luckily, around just that time, I'd just gleaned some valuable info regarding VFD's what could tame a much more capable machine, to run from my puny supply.
Kudos to Bob Minchin and his induction motor volume 3 document. :cool: ( download freely available to download on the woodhaven2.)

Sorry, just a little warning there regarding the gamble on a machine, what's not a fully adjustable Centauro CO (one with foot mounted motor, that is)
Back on topic again

Going back to the flutter and the elimination of such, it wasn't possible to get rid of it with the Rikon lower wheel guide,
so I can only presume the wheels had some large variance, in which the tires were bonded to the edge,
and thus creating different paths for the blade.
I tried loads of stuff with that machine to get it running sweet, but nothing worked.
On the phone prior to bringing the machine back, (said technician who confirmed was to call by along the way, never showed)
and got some cock and bull story about the machines being built around the wheels, so my misalignment of the wheels was technically impossible.
Though I mentioned other wonky stuff, like the lower guide assembly not being drilled in anywhere near the ballpark location, and completely different to
another helpful forum member which got sent a blade for his troubles.
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I contest that you'd be expecting miracles if you reckon going from a fairly adequately tensioned blade, to a Starrett certified 2500kpsi will eliminate flutter.
That amount of flutter on the video is something I've always associated with something wrong with the machine.
Not saying that frequency thing might not occur whatsoever, but something which you'd need to go to effort to "tune in" and not something like what's in that
"flutter method" where things are quite the opposite.

Tom

[andrew whicker]

I feel like I've gone thru every tension possible and never saw a point where the blade was steady.

When I get the tension really high the blade starts coming off the front of the upper wheel even though it was steady there for the rest of the tension.

I'm about to throw it in the ocean.

[Tom Trees]

Tires will be next, even for the folks who've had it easy.

If you've seen my efforts on the three part tire dressing series, where I actually dressed my tires flat (cuz of the misinformation)
you wouldn't be assuming your tires were in good nick... ala the Centauro SP manual
" MAIN TROUBLE AND RELATIVE REMEDIES "


The blade moves very far back when it receives the cutting force
- Insufficient flywheel seal convexity, notify the technical service of the area dealer.


with the caveat, If you choose to dress'em on the machine, then the edges of the wheels need be trustworthy,
as you need have a suitable blade installed to keep the upper wheel from tipping back,

and as such, need to actually be sure the upper wheel is co-planar ...and not what might be 4mm out if the upper wheel has 0.5mm discrepancy.
as you can wipe out the crown you've just dressed very easily otherwise.

It's all very simple really, if your willing to remove the table....but seems like it's not in the books of old bandsaws,
and there hasn't been one for Centauro since. (one of the only foolproof machine designs out there)

MP4 is a coming (Published), should you not like reading threads, nothing new (by now) as the beans are spilled already ;)
Unless perhaps some others have some rabbit hole suggestions for to spend more money on.
Wheel balancing if not attention paid to the vulcanized tires.

My last post it seems, didn't emphasise enough how good of a machine you have, much nicer to go through some troubleshooting
than to have a battle on your hands, on brand new machine what's not adjustable at the end of the day.
Well...everything is adjustable if you wish, though not getting the impression you'd like to do this either,
should you have went with a non adjustable new machine.
509979


I'll look forward to the scrutiny from doing the above, as I'm the king bandsaw troll, and I got a bag of unanswerable questions,
well, unanswerable only to those who haven't been paying attention, that is. :rolleyes:

All the best
Tom

[Erik Loza]

Andrew, what width blades are these? Tension level should never cause a blade to walk off a wheel. That’s a tracking issue.

Erik

[John TenEyck]

I feel like I've gone thru every tension possible and never saw a point where the blade was steady.

When I get the tension really high the blade starts coming off the front of the upper wheel even though it was steady there for the rest of the tension.

I'm about to throw it in the ocean.

The blade is moving forward as you add more tension because that's what blades do in response to the machine bending (cantilevered wheels on a C shaped frame), which is normal up to whatever the design limit of the machine is. The wheels tip towards each other and the upper wheel moves to the right. You'll know where that limit is if the side of the blade is no longer perpendicular to the table. The guides will be out of vertical alignment at that point, too. But unless you have a blade tension meter you are flying blind. Once you know what the actual tension is vs. the on-board tension indicator for the blade you're using you won't need the meter anymore. You'll also know something about the tension limit for your machine.

To get the blade recentered on the upper wheel tilt the upper wheel backwards.

John

[Tom Trees]

Time for school now folks! :)

[John TenEyck]

Time for school now folks! :)

Things usually go better when you understand how things work. Ignorance may be bliss, but rarely solves problems.

John

[Tom Trees]

Here's a link to a load of differing brochures for this machine, perhaps it's of some interest.

Tom
https://wtp.hoechsmann.com/en/lexikon/3465/co_600