Centauro 600 _ axial blade movement

[andrew whicker]

Hi all,

New blades, new tires (flat), new bearings.

I moved the bottom wheel (made a new spacer. They were out 3 mm) so that the bottom and top wheel are co planar.

I see the blade moving axially back and forth. Do the wheels need to be slightly out of plane to ensure the blade doesn't move like this?

Anything else?

I'm seriously considering re selling and buying something else at this point.

Cheers

[andrew whicker]

Video:


https://youtu.be/csJ4C683T5w?si=LGY99wUdziYP-j7B

[Kevin Jenness]

Have you tried a different blade? The weld may be misaligned. Put a straightedge along the back of the blade to check.

Bandsaws are the simplest of woodworking machines. If the wheels are aligned and running true and the blade is straight and properly tensioned it should not be pulsing.

[andrew whicker]

I've tried 6 blades at this point

[Kevin Jenness]

Sorry, I got nothing. It should be heavy enough to make a good boat anchor. Seriously though, are there any independent machinery techs in your area who would check it out? The only other thing I can suggest is putting a dial indicator on the wheels to see if they are out of round or twisted, in which case you could possibly have them machined true.

[Andrew Hughes]

Sounds like you have ruled out the blade so it has to be the tires.
I tried to install tires on a laguna saw once I was unable to make them work. The upper wheel hopped and bounced.
I took the wheels to a saw service where a old man said to me softly with a stern tone you just can’t put tires on them and hope for the best.
The saw ran smooth are they completed the work.
Good Luck

[andrew whicker]

Yeah maybe the tires. That's my last thought too.

The od runout on the bottom wheel w tire installed is around. 008".

Not amazing but seems good enough for a bandsaw?

[andrew whicker]

Top is similar. A few thousandths better

[Kevin Jenness]

How are you measuring runout? That actually sounds like quite a bit and may be causing your problem. There are a number of discussions about truing/crowning bandsaw tires on owwm.org, often on the saw using an adjustable jig and abrasives. It does seem to be common to have to bring new tires into round.

[John TenEyck]

0.008" sounds like quite a lot to me, but are you sure the blade is not in a tension harmonic? Have you changed tension to see if it gets better/worse?

And have you checked that the blades have straight welds, as Kevin suggested? Six blades from the same supplier might give you six unacceptable welds. Different suppliers, probably not.

John

[Tom Trees]

Hi all,

New blades, new tires (flat), new bearings.
Still doesn't rule out a variable apex, the original ones were dressed on the wheel.



Do the wheels need to be slightly out of plane to ensure the blade doesn't move like this? .
The faces of the wheels on most machines bar very few, are nowhere near accurate enough to know, if yer talkin co-planar and using a beam.



I'm seriously considering re selling and buying something else at this point.
And get what?
They don't make anything fully adjustable today, that machine along with some Meber's and perhaps one or two other Italian companies
might be the only example of a 600mm/24" wheeled machine you might find,
and none of them have dressed faces, so there's no getting away without doing so,
(on something without a crisp apex what's dressed on the wheel)
so that means the clueless trial and error ala in the Laguna manual, won't work the same.

I reckon some here might be getting fimiliar with the jobs for the boys philosophy, in which along with throwing off the competition,
also doesn't give the folks who ain't got the time to be modifying a machine what's paid for itself a straight forward recipe.
Things could be much worse ya'know... your bearing journals sound grand :)
but perhaps you need see some misery from the non adjustable designs of which we see today, for my writing to be believed.

All the best
Tom

[andrew whicker]

I'm going to do this exact process including the new tires.

I haven't been impressed with the recommendation that came with my new tires... using gasket adhesive...

https://youtu.be/zz04k-GMF38?si=54u3p4zd2nVAiBK2

Always seemed too thick and never seemed to actually stick.

[andrew whicker]

Also check the runout of the metal wheels after they are cleaned

[Tom Trees]

I don't see why the recommendation of using gasket adhesive being a bad thing, as the best stuff is branded as such, see Van Huskey's posts on the 3M stuff.
That indeed might be for the rubber like tires from Carter, or for the cork/rubber types.

Freehand grinding might actually work, on brand new tires, so long as you don't accidentally touch the apex.
Though on those tires what might be squishy compared to real rubber, the crown might not make all the things you see apparent now disappear,
compared what featured originally, and you might have to align the wheels and ensure the machine is set up for a longer time than what's planned on anything new.

[edit: dressing tires whilst machine being under power, looks extremely dangerous business, I wouldn't suggest someone try,
unless they don't like having arms]
Tom

[Richard Coers]

Might just be me, but looks like it would cut wood good enough. I would do some testing with tension, and go to a smaller blade to see if it was happier. On a really old bandsaw with babbit bearings, I just had to run it with a little preload on the thrust bearing. Maybe not ideal, but it sure got the job done.

[Kevin Jenness]

I'm going to do this exact process including the new tires.

https://youtu.be/zz04k-GMF38?si=54u3p4zd2nVAiBK2

That's a pretty rudimentary method of dressing the tire, but it should improve things. You can make a more rigid setup if need be. As the video maker says, there are many ways of doing the job. I think you will be able to get your bands running smoothly and have a nice running heavy saw.

[Tom Trees]

Looking for trouble without testing alignment, especially considering the age of the machine.
Those bearings might only just be still seated perfectly snugly, and ignoring that could cause a lot of misery.
It doesn't take an age to happen, as you can see some relatively new machines out there which have loose wheel bearings.
It might take the sting out of doing the work facing the wheels, instead of putting all your attention into the OD of them.

Can't expect it to work right, if you've not checked that, and not forgetting the lack of an answer so far, in regards to
how the machine runs without a blade.
There's a good likelihood due to it's age, of being adjusted before, so a factor to consider on such a machine,
and not some new saw what's non-adjustable, in which the workers done the best they could do, without answering back.

Regards
Tom

[Kevin Jenness]

The op has stated that he installed new bearings and the wheels are coplanar. I will assume he didn't install the bearings with a sloppy fit into the journals, and that the lower wheel runs smoothly under power with no blade, but those are possible fundamental issues to look at. Otherwise, what is there left but truing up the tires?

[Erik Loza]

….are you sure the blade is not in a tension harmonic? Have you changed tension to see if it gets better/worse?…And have you checked that the blades have straight welds, as Kevin suggested? Six blades from the same supplier might give you six unacceptable welds. Different suppliers, probably not…. John

I’m with John on this. Andrew, the blade in your video looks under-tensioned to me and I have seen entire batches of blades with funky welds. The litmus test is different blades, from different vendors. I never personally used a tension gauge but maybe it’s warranted in this case?

Another thought: Andrew, you’re working with a machine that was most likely rode hard and put away, wet, for most of it’s life. We (hobbyists) take good care of our equipment but in a shop environment, the bandsaw is the least cared-for machine. For example, I’ve never seen a vintage saw in a production shop that looked like it could be made to “drive like new”, if you get my meaning. I used to think I wanted an vintage Toyota truck but as soon as I could actually drive one, was like, “This thing handles like crap compared to my 4runner!”. Point being that no matter what you do, due to the age and history of this machine, could this be as good as it runs? Have you tried actually cutting any wood with it yet?

Erik

[Tom Trees]

The op has stated that he installed new bearings and the wheels are coplanar. I will assume he didn't install the bearings with a sloppy fit into the journals, and that the lower wheel runs smoothly under power with no blade, but those are possible fundamental issues to look at. Otherwise, what is there left but truing up the tires?

I didn't suggest there might have been a sloppy fit with the bearings, well not yet,
My machine had a bit of intermediate knocking which went away sometimes.
Just for clarity, I'm in no way suggesting to re-investigate wheels/bearings.

And again, since co-planar is a funny old word, as it's a tad involved to achieve a true reading
and not be a few mm off,
and once that's done with the lower wheel, then alignment thereafter using the scribing beam.

That can't be discounted, for the sake of the wheel journals.
To me, that's a lot more important than seeing if you could get away getting tires which would mask the real issue,
which might indeed have came from the factory like that.
Just cuz it's a better design than the newer machines, doesn't mean the wheels were aligned, that could'a been up to the dealers to fettle?

Edit, though saying that, I've not came across any alignment jig for the job, from when fully adjustable Italian saws were being made,
should there be some kind of laser housed in a block, drilled out to the same shaft size to mount onto the wheel shafts, might just be the quickest way to do things,
which would do the job instead of needing to dress the front face of the wheels
to lay a beam against, or perhaps something fancier what General used to do.
513651513675
Fairly obvious they do nothing these days, when you can pick a lemon from any manufacturer, and a very fresh one at that.

ps With alignment sorted doing what could likely be the quickest method, then tramming the tire edges when installing a replaceable tire
thereafter to eliminate chance of a variable apex, should one not have a modern Centauro or other machine featuring an alignment groove for the tires.


All the best
Tom

[andrew whicker]

Took the tires off.. cleaned the wheels until they were completely clean of any residue.

Installed the wheels and measured 0.001" tir top wheel and .0015 to .002 tir bottom wheel.

Much better runouts. The wheel metal surfaces are rough machined so you get a lot of vibration in the indicator even when the wheel is barely moving so that's probably the best I can measure anyway.