The Bench Grinder walking issue

[picclock]

Hi Experts

I've just moved my bench grinder (and lathe etc) to another place and now the thing is walking like crazy. I removed both wheels, spun it up, and although there was vibration it was at a low level. I then put the 'good' wheel back and spun it a few times by hand to see if it was well balanced and it stopped in random places, with no obvious sign of eccentricity. However now the grinder is back to walking  .

I trued both of the wheels with a diamond dresser, and then roughened the surface with a steel star wheel type before I decided to rip it apart. I am reluctant to fix it to the bench because I lose the space and if I did everything else would vibrate. Likewise I don't really have room for a pedestal.

Any good ideas appreciated - I don't really have the cash to spare for a replacement at the moment so it will have to be something cheap and cheerful. Tried rubber mats without a lot of success.

Best Regards

picclock

[dickda1]

I assume the grinder does not walk without the wheels or with one wheel attached?

Assuming the grinder is mostly in balance, changing mass or spindle speed may move it out of a resonant condition.  Running the shaft of the grinder at a higher or lower speed (if it has an external pulley) may do the trick.  Adding (or subtracting) mass might help - adding a small sand bag on top or attaching it to a plywood plate.

Have you ever removed the shaft from the grinder and trued the shaft/mounting plate combination on the lathe?  This did the trick for me.

Take a look here (particularly videos 3 and 4 of the series):

&feature=related

-Dick

[HS93]

I have mine bolted to a 12" square or for those in the EU 300mm square of 3/4 ply I then just have a quick cramp to hold it down , mine did a bit of walking  till I bolted it down and dressed the stones, its good as when not inuse I can slide it out of the way and in case there are any Health and saftey types out there I have the apropeate qualifications to change and dress wheels, (maybee out of date now though)

Peter

[Chuck in E. TN]

Dick,
Thanks for taking the time to put your video together. I'm saving hard to get that grinder and do the same tune-up.
Did you have to replace the wheels, or did they dress up o.k.?

Chuck in E. TN

[DaveH]

Chuck in E.TN.

See if you can find a grinder without wheels. Normally a better quality machine.

 

DaveH

[doubleboost]

Before i moved house and only had a 8/6 shed in the garden i had my clark grinder fastned to a piece of 20 mill mdf.
It used to walk all over the bench , i put 4 rubber exhaust mountings on the base board (rubber bobbin type with the threaded end removed from one end) job sorted it ran much quiter as well
John

[dickda1]

Chuck,

I didn't produce that video, but pulled it off the net when I bought a Harbor Freight tool grinder.  When run, it rattled like an old washing machine.  I put rubber pads underneath it and used "c" clamps to hold it to the bench.  Still rattled so much that I was pretty sure I would never be able to true the wheels.  The flanges had something  like .03" of runout.

I followed the video instructions, mounted the spindle with mounting flanges attached on my lathe and trued them.

I can balance a nickel on the the top of the running grinder.  (However, like most rotary machines, it does run through a resonant point of vibration until it reaches final speed).

You absolutely must true the wheels.  I don't use carbide tools so I replaced the green wheels with type 50 white wheels and trued them with an industrial diamond.

It was fun, simple project on my lathe that led to a useful result.

Dick

[picclock]

@ dickda - Thanks for the video pointer.
The part I need is really in sections 4 and 5. I got to the stage of trying to remove the backing plates before I looked at it, so I can see now that it needs a lot more force to do that. Even without the wheels attached mine is not that smooth so there may be other issues at play here. Anyhow I will strip it down and see what I can do with it. I hope it strips down as easily as the one in the video .. .

Best Regards

picclock

[picclock]

OK, I've found the major source of vibration. The inside of one of the wheels uses a plastic sleeve for centring, this was loose on the shaft and loose inside the wheel. I made up a solid aluminium sleeve to a good fit and now its more like it used to be.

I'm now going to skim the face washers which have a fair bit of runout so that I can get it a lot better - although it wasn't until it moved location the problem occurred - so it may just be the loose wheel shifted.

Thanks once again for the video link Dickda1 - never would have attempted such major mods until I saw the video.

Best Regards

picclock

[Chuck in E. TN]

Dickda1,

Where did you get your white wheels? Will the green ones not handle HSS?

This grinder is on sale now for $175. Looking for a useable 20% or better coupon.

Chuck in E. TN

[dickda1]

Hi Chuck,

The Harbor Freight frame is a Baldour knockoff.  With some work, it is pretty sweet.

Don't use green wheels on hss.  The wheels are way too soft and will glaze over immediately.  They are for rough grind on carbide only.

The mounting flanges take a wheel with 1 1/4 bore.  The deal is that they are type 50 plate mounted:
http://www.bettymills.com/shop/product/view/CGW%20Abrasives/CGW421-34948.html?source=froogle2&utm_source=froogle2&utm_medium=cpc&utm_campaign=parts&utm_keyword=CGW421-34948&utm_content=Facility

You can buy simple cup wheels on Amazon for cheap, but they lack the 4 mounting holes.  The grinder can be run in reverse so this would probably not be a good idea.
http://www.amazon.com/Straight-White-Aluminum-Oxide-Grinding/dp/B0007PZJ8G/ref=sr_1_10?ie=UTF8&qid=1310011565&sr=8-10
-Dick