How would you true up a bench grinder arbor, not the wheel but the arbor itself?

[Joshua Dinerstein]

Hi Fellow Creekers,

Over in the wood turning forum I have been working thru some problems I am having with sharpening my turning tools. It seems to have boiled down to my Woodcraft slow speed grinder and some unexpected issues with that machine.

To sum it up I started with a nicely running grinder that one day from one moment to the next just stopped working well at all. The tools would bounce on the surface when grinding and no amount of dressing would get rid of the problems I was experiencing.

I went to the extreme of new wheels and a new OneWay balancing system. On the right hand side of the grinder it is perfect. Amazingly smooth running. But after a number of wheels being put on the left nothing on that side runs smoothly.

Last night I got out my dial indicator and found that the small flat area on the arbor that the washers seat up against is extremely true on the very inside of that ledge closest tot he 5/8th inch arbor and SERIOUSLY messed up on the outer rim. With a mil swing of at least 8 and probably closer to 10 according to my dial indicator. No wonder nothing seats well against it, or runs true.

I was getting ready to buy a new grinder and beginning a search for a Baldor or something high-end, but probably old so it would fit into my budge, and then thought: "Why not wait? This is already messed up so let's see if we can't fix it first..." Kind of the "it is already broken so what do I have to lose by trying" mentality.

I went online looking for any information I could find about truing up a grinder and discovered that while there are a million pages about dressing/truing up the wheels themselves there appears to be nothing about fixing the arbor itself.

I sent a PM similar to this to a fellow turner here on the creek and then thought I would widen the audience to see if I couldn't get some help.

Since you guys are at large the only resident upgrading/repairing geniuses that I know I am hoping someone has some ideas.


For my partI thought about just getting out my small diamond file and with the grinder running see if I couldn't true it up. With a good number of small passes.

Attached is a photo, that I swiped from here on the creek rather than one of my grinder at home. I added some small red arrows to show how small that little ledge that the washers mount onto is in this grinder. The inner each true to a scary degree. The outer edge messed up to multiple mils of thickness.

Any advice, thoughts, or suggestions for me?

Thanks!
Joshua

P.S. if all else fails anyone have a great recommendation on a truly awesome bench grinder to purchase next? :)

[Dennis Ford]

I think you can do this. A fine file should work pretty well for this job. I would darken the area with a felt tip and gently touch the diamond file against the spinning arbor. Then stop the grinder and look to see where the file cut through the ink. If it is really bad, you may want to take some of the high spots down with the grinder stopped. That should reduce bouncing of the file.

[Joshua Dinerstein]

I think you can do this. A fine file should work pretty well for this job. I would darken the area with a felt tip and gently touch the diamond file against the spinning arbor. Then stop the grinder and look to see where the file cut through the ink. If it is really bad, you may want to take some of the high spots down with the grinder stopped. That should reduce bouncing of the file.

Ah.... Now that is a great idea. Thanks for the suggestion. I do it with my turning tools but I didn't think about doing it for this. Thanks for the suggestion!

Joshua

[Rich Tesoroni]

Never had any luck filing to adjust. Think I'd pull the shaft and check it on the lathe and see all the places it's out. Might be able to bend it back too.

If you file too much you'll have a non-round shaft.

Rich

[Matt Kestenbaum]

Ugh,...I have that grinder and have put new norton 3X wheels on it and they clearly are not running true...I was thinking about the One Way balancing kits. Between the wheel and kits and seeing your arbor issues I think I am going to stop now, before any more good money follows bad.

Sorry I am too busy trying to master flat, square and parallel to be much help on this machinery challenge, BUT thank you very much for widening the discussion before I exercised the Lee Valley free shipping event to "fix" my grinder!

[John McClanahan]

Look at it this way, if you can't get it trued up, you can always put a buffing wheel on that side and use it for buffing. At least it won't be junk.

John

[Steven DeMars]

Buy a BALDOR and admire your now new buffer . . . .

Steve:)

[Ken Fitzgerald]

I'd hate to see a new Baldor used as a buffer.

[Joshua Dinerstein]

Ugh,...I have that grinder and have put new norton 3X wheels on it and they clearly are not running true...I was thinking about the One Way balancing kits. Between the wheel and kits and seeing your arbor issues I think I am going to stop now, before any more good money follows bad.
Before you take too much of this all to heart, you need to know that on the left hand-side it runs so true that it is amazing. Others have had similar success. It is just the 1 side. I would honestly recommend the balancing system regardless. It is amazing when it can and does work.


BUT thank you very much for widening the discussion before I exercised the Lee Valley free shipping event to "fix" my grinder!
Thanks for letting me know about this. I have been watching a few things I have wanted for awhile and this is a great chance to get them.

Joshua

[Van Huskey]

I'd hate to see a new Baldor used as a buffer.


Baldor does make pure buffers though they are not inexpensive.

[Rob Cunningham]

Joshua,
If you try to true up the arbor with a file, be very careful. Make sure you have a handle on the file or the tang could be thrust into your hand if you get a catch. I've seen it happen to someone, it's not pretty.

[Greg R Bradley]

I bought the 8" Woodcraft grinder you reference. It is a complete POS. I also bought a Grizzly 6" grinder at about the same price point - also a complete POS. I bought a Jet 8" unit for $169. It is quite good. If the Woodcraft & Grizzly units are worth $100, then it should have been $269.
I have 7" Dayton and 8" Baldor that are older units and they are excellent.

As the surface speed of the wheel increases you quickly leave the point at which a unit is good for sharpening and becomes useful only for material removal. Normal speed for 7-8" units is 3450rpm. 1725rpm for 10-12". These are used for material removal. To sharpen something, you are going to want slower surface speed to reduce heat. That is why the 8" Woodcraft is 1725rpm, giving you the larger wheel for less hollow grind than 6" with the lower surface speed to cut down heat.

Too bad Jet doesn't have a 8" 1725 unit.

[Joshua Dinerstein]

Yeah, I really need to give fixing this one a go. I have just been planning my attack. I will probably give it a whirl tonight. If I can fix this one I am just going to stay with it. If I can't then I have to buy something new.

I have wondered about Jet and some of the others. Price has become an issue. A few too many Murphies have raised there head recently including an unexpected trip back east for the wife in an hour or so. As a result buying something like a Baldor feels like a pipe dream at the moment. I need to get this working, which is cheap as I already own it, or get a replacement that is cheaper than that but not cheap again.

I have done a bunch of searching and there seem like a few posibilities. Grainger has a Dayton unit for < $400, there are the Jet units like were just mentioned, and I keep seeing Palmgren show up. Anyone know anything about those?

I found an old Dayton in the classifieds here in Utah for $100. Looked OK on paper at first but it was a 7" and was high speed and has been thoroughly beaten up. So not quite what I was looking for.

So wish me luck on getting this thing cleaned up and working right. :)

Joshua

[Joshua Dinerstein]

Well... It was an interesting attempt. I got it trued pretty nicely. The shaft measures true with my dial indicator. The surface of the shoulder is now true within any great reason. I mounted the wheel and got it mounted and tightened the nut.

It still spins untrue and there were lots of odd rattling noises that later went away. I would say within about 2 minutes of running. I was trying to locate it when it stopped, which is kind of sad. Makes it just a tad harder.

I figure I am about to cut my losses and just get something new. Anyway, I don't really have any other ideas at the moment for trying to fix it.

Joshua

[Myk Rian]

Did you ever contact Woodcraft about it?
They might have done something about it for you.

[Joshua Dinerstein]

Did you ever contact Woodcraft about it?
They might have done something about it for you.

I did. I have owned it longer than the warranty period. They were sympathetic but that was all.

Joshua

[Steven DeMars]

I'd hate to see a new Baldor used as a buffer.

No No No . . . .

Use the old grinder as a buffer . . . .

Steve:)

[Greg Portland]

I was getting ready to buy a new grinder and beginning a search for a Baldor or something high-endGet the Grizzly Industrial instead of the Baldor, it's the same level of quality at a significantly lower price. I went through the research when my old Delta hobby-quality grinder died. The Grizzly was built specifically as a "Baldor-killer". I have mine paired with Norton 3x stones. By the way, the motor runs much cooler than the motor on my Baldor buffer...

http://www.grizzly.com/products/8-1-HP-Heavy-Duty-Bench-Grinder/G0596

[Joshua Dinerstein]

I was thinking about some of what was going on when I tried to true this all up. I wasn't sure I had things really square and true. So I had a thought this morning that worked out very well. I laminated 4 pieces of 3/4" MDF together. I got them as flat and true as I could.

Then this evening I drilled a 5/8th" hole through the stacked blocks. I was able to put various pieces of sand paper of different grits on the bottom face of the block. It worked well to make sure things were really square.

The wobble is now down to the lowest levels yet but still present enough to annoy and make me want to try something else. So at some point I am going to have to get another grinder. For now I think I will just live with using the right hand wheel only.

But all-in-all the trick with the mdf and the sand paper was worth mentioning.

Joshua

[Derek Stockley]

I have a ryobi 8" grinder and was having considerable trouble getting it to run nicely too. Did the same thing as you - got all the upgrades and they helped. Then I took a closer look at the nut on the left side and it actually turned out that the nut is my problem. It's tapped off-centre and off-perpendicular to the face.

If the shaft is messed up, fixing the damage is only part of the equation - what caused it to get messed up?

[Joshua Dinerstein]

If the shaft is messed up, fixing the damage is only part of the equation - what caused it to get messed up?

Yeah that is pretty much the question I keep going thru. The thing ran true for the most part, i.e. well enough that I never noticed any problems, until 1 day. So there was some kind of an event. I do not know what it might have been. I did take the wheels off so it might have been an issue of it was tightened down wrong but tightly before and I was unable to duplicate it when I took things apart and put them back together.

I will check the nut though nothing I have seen would indicate to me that it was damaged or wrong.

I have received a few suggestions in a PM that I am going to try next. Wish me luck. :)

Joshua

[Ken Fitzgerald]

Joshua,

I have that same Woodcraft grinder. I had a vibration problem. I had the exact same problem that Derek describes. The nut on one end....this was the left-handed threaded one...the hole wasn't drilled square to the face of the nut and thus when tightened, the nut only mated with washer about 20-25% of the face of the washer. I found a left-handed replacement nut at my local Ace Hardware. That resolved the issue.

I was able to wiggle the wheel when the defective nut was tightened properly. I looked at the nut and you could see it wasn't mating entirely with the retaining washer for the grinder wheel.

That bad nut was allowing the wheel to wobble horizontally. It was most noticeable when you shut the grinder off as it passed through it's normal mechanical resonant frequency range.

Good luck.

[David Hostetler]

How old is that grinder? Perhaps it may be covered under warranty? This does sound like a serious manufacturing defect to me...