making bushings for grinding wheels

[Steve Tiedman]

This weekend I'll be installing a fresh set of Norton 6" aluminum oxide grinding wheels on my 25-year-old Milwaukee 3600rpm bench grinder.

Expecting the best but planning for the worst with the factory plastic bushings, has anyone ever made wood wheel bushings? Any words of wisdom for doing so? Thanks.

 

[Richard Coers]

Precision is not easy. You will need a precision mandrel of some sort since the id of the bushing is the start of making concentric diameters and perpendicular faces.

 

[Steve Tiedman]

Okay, a challenge. Thanks.

 

[Tim Hunter]

The bushing ends aren’t critical. The bushing should be slightly narrower than the wheel. The ID and OD need to be concentric (within ~0.01”); The wheel OD will be dressed true. Wood is fine; I’ve used such for many years.

Tim

 

[Doug Rasmussen]

Why wood? If the common plastic bushings aren't exact enough make better plastic or metal ones.

A few ways a bushing could be made come immediately to mind . One way would be to start with a piece of bushing material to make both the ID and OD in the same chucking. Another way would be to make the bore first, slide that onto a precision tapered mandrel held between centers to make the OD. Wood being such a non-homogenous material it would not be my choice.

I suppose a wood bushing would give some coolness bragging rights, otherwise it seems a bit silly.

To get best use of a dressed wheel it has to be dressed correctly. That usually means using a single point diamond angled precisely to the wheel face and guided in a holder across the face (not hand guided). Wheel mounting accuracy gained by a precision bushing could likely be overwritten by improper dressing. Proper dressing requires a precision dressing setup for the bench grinder (years ago Delta offered such a setup for their higher end bench grinders). The common hand held cluster diamond dresser won't do it.

 

[robo hippy]

I am pretty sure that there are bushings made for grinding wheels. Not sure if your supplier would know of where you can get some or not. Maybe the fastener stores would know? Grainger or similar stores? The plastic ones are junk!

robo hippy

 

[Doug Rasmussen]

I am pretty sure that there are bushings made for grinding wheels. Not sure if your supplier would know of where you can get some or not. Maybe the fastener stores would know? Grainger or similar stores? The plastic ones are junk!

robo hippy

Of course there are bushings made for grinding wheels. The ones I have came with quality grinding wheels, they're plastic, some may be phenolic. They aren't junk... They're available through industrial tooling houses.

What exactly are the issues you have with plastic bushings?

There are so many issues with bench grinders like low grade bearings in inexpensive imports, stamped washers, run out of spindles, not balanced armatures, not dressing wheels properly and so on. Attacking an industry standard like plastic bushings which are the least of problems seems pointless.

 

[Steve Tiedman]

On a whim this afternoon...

I put a one-revolution wrap of electical tape around the shaft before slipping on the wheel with the plastic bushings. No go, too tight. Replaced the tape with one revolution of 20# copy paper, and the bushing is now a snug slip fit on the shaft. Why stop there... I put a wrap of paper at the outer bushing-to-wheel contact patch and it took care of slop out there. Nifty. I snugged the nut, spun the wheels, and found a good amount of side-to-side wobble. Jam the other wheel with a wood shim to hold everything still, loosen the nut of the new wheel and hold the wheel stationary, rotate the outer steel washer 90 degrees, snug the nut and check for wobble. Better but not great. Played with the washer again a few degrees a couple more times until the wobble became acceptable. Now I just need to dress the face of the wheel and I'll be good for general utility grinding.

 

[Webb Willmott]

Amazon sells aluminum arbor bushings for around $10.

 

[Brian Gustin]

On a whim this afternoon...

I put a one-revolution wrap of electical tape around the shaft before slipping on the wheel with the plastic bushings. No go, too tight. Replaced the tape with one revolution of 20# copy paper, and the bushing is now a snug slip fit on the shaft. Why stop there... I put a wrap of paper at the outer bushing-to-wheel contact patch and it took care of slop out there. Nifty. I snugged the nut, spun the wheels, and found a good amount of side-to-side wobble. Jam the other wheel with a wood shim to hold everything still, loosen the nut of the new wheel and hold the wheel stationary, rotate the outer steel washer 90 degrees, snug the nut and check for wobble. Better but not great. Played with the washer again a few degrees a couple more times until the wobble became acceptable. Now I just need to dress the face of the wheel and I'll be good for general utility grinding.

Which is why I don't mind a slightly loose fit on the bushings - that "slop" in the bushings can allow the wheel to "wobble" straight as the nut is snugged down on the flange washers (otherwise washers may actually flex) so that wheel alignment/wobble can be fine tuned at the shoulder of the wheel shaft where it meets with the inner flange (and/or where inner flange meets the wheel) any out of roundness is then taken care of by the dressing.

 

[Doug Rasmussen]

Amazon sells aluminum arbor bushings for around $10.

Aluminum bushing are more trouble because the bushings come in 1" length meaning they have to be shortened. Much easier to shorten a plastic bushing carefully holding it on the bandsaw.

I've never used aluminum bushings, in fact I'm surprised so many sellers offer them. Plastic is all I've ever used, mostly since the tooling houses I deal with don't sell aluminum bushings.

Plastic is the industry standard.

 

[Jon Rista]

Just curious, why make them?

When I bought my CBN wheels, I picked up two sets of the spherical washers for them. IIRC, each set was $11...

Regarding wood...what happens if a washer snaps during operation?

 

[John K Jordan]

Aluminum bushing are more trouble because the bushings come in 1" length meaning they have to be shortened. Much easier to shorten a plastic bushing carefully holding it on the bandsaw.

In case anyone is interested, you can easily cut aluminum on a wood-cutting bandsaw, table saw, etc. I've cut squares and even aluminum door thresholds.
If the bushing is a short tube, the only problem might be holding it safely/securely.

I'd turn the end of a square wood blank round to accept the bushing snugly, leaving the rest of the blank square and long enough to hold and be held square by the saw's miter gauge. Make the fit snug enough to keep the bushing from spinning. The wood needs to be sized so the bot of the bushing is well-supported on the table. Simply push slowly through the blade. A blade with more teeth per inch will make a smoother cut but a rough cut can be cleaned up with a file.

You can also jam the bushing on a piece of wood held in a chuck and turned round to fit and shorten the bushing on the wood lathe with a parting tool. I've turned a lot of aluminum on the wood lathe but not bushings. The lathe would be quicker, cleaner, and perhaps less stressful than the bandsaw for some.

More important than the bushing may be the right side plates. I had to make some to allow a wire brush to fit on the Metabo grinder in my welding shop.
BTW, with a metal lathe, shortening metal bushings and making arbor adapters and side plates are easy.

JKJ

 

[Steve Tiedman]

The main reason I chose not to make wood bushings was the shaft size. It is a hair or two under 1/2".

My intention was to chuck a piece of good, stable wood (some beech, maybe hickory) on the lathe, and tailstock drill a 1/2" hole, then turn the outer diameter to be a precise slip fit for each wheel. Then use a parting tool to cut off my new bushing. Bandsaw not necessary. But not having a 63/64" bit, or more likely a 127/128" bit (does that exist, and would it drill true to size?), I'd then have the same fitment issue of the plastic bushing- a slightly oversized hole on a slightly undersized shaft. I think my paper shims on the plastic bushings have served the purpose.

 

[John K Jordan]

But not having a 63/64" bit, or more likely a 127/128" bit (does that exist, and would it drill true to size?),

63/64" is very close to 25mm, bits are available.
Good forstner bits can drill very close to true diameter. Twist drill bits, not so much, "depending".

[OK, I'm off on a drilling tangent:]

I start all twist drilled holes with a center drill, made metal lathes. A set is very inexpensive, and worth using. The short, stout shafts makes a precise starting hole which minimizex flexing and wobbling in a longer twist bit..



Another thing about drilling that can improve precision: I've gone to taper shank drill bits for many sizes. The taper shank eliminates the Jacobs drill chuck and fits directly into the tailstock. This is especially helpful for deep holes.


(The smaller drills have a #1MT and need an inexpensive #1 to #2MT adapter.)
So quick to use - pop one in the tailstock and drill.

A few taper shank bits and a #1-to-#2 adapter:


I started acquiring taper shank bits after watching a demo where Rudy Lopez used a shortened 1" bit to drill out a goblet to speed up hollowing. I found a closeout and bought a bunch at $1 each then later bought more. Much more convenient than a Jacobs chuck, especially if carrying stuff to a demo.

[end of tangent]

JKJ

 

[John K Jordan]

The main reason I chose not to make wood bushings was the shaft size. It is a hair or two under 1/2".

My intention was to chuck a piece of good, stable wood (some beech, maybe hickory) on the lathe, and tailstock drill a 1/2" hole, then turn the outer diameter to be a precise slip fit for each wheel.

But after the extended drilling tangent... If I wanted a wooden sleeve/bushing I probably make it a different way: Mount a short blank in a chuck, drill a slightly smaller diameter hole, then use a small NRS or small spindle gouge in shear scraping mode to enlarge the hole to fit, just like refining the inside of a lidded box. Then turn the outside to fit, part off cleanly with a skew chisel.

I've made a number of small boxes like this for needle cases or pill bottles. Dense, fine-grained wood is nice. It's pretty easy to get a precise fit.

These little boxes have thin-walled tenons, long enough to keep them from accidentally opening in a pocket or bag.



JKJ

 

[Kevin Jenness]

Mcmaster Carr

 

[robo hippy]

Plastic bushings wear out quickly, and they seem to be very inconsistent in diameter and wall thickness. Similar to the blades that come on your bandsaw when you buy new.....

robo hippy

 

[Doug Rasmussen]

I start all twist drilled holes with a center drill, made metal lathes. A set is very inexpensive, and worth using. The short, stout shafts makes a precise starting hole which minimizex flexing and wobbling in a longer twist bit..

This primarily applies to drilling in metal.

Center drills have a special problem, the fragile tip. Every book of machine shop hints wil have a way to remove a broken tip and it ain't easy to do. Not worth the risk. Center drills have their primary purpose of making 60 degree centers for lathe centers and not much else.

Here's a spotting drill, the better way to spot starting hole locations. A good many shops have given up on the center drill for spotting in favor of the spotting drill. Less fragile tip with a thin web for easy starting on rough castings or slightly angled surfaces. They come in different tip angles although the 90 degree is the most common.

 

[Doug Rasmussen]

Plastic bushings wear out quickly, and they seem to be very inconsistent in diameter and wall thickness.

Hmmm... Are we talking about the same thing here? Plastic bushing as mentioned here are to adapt a grinding wheel with a large hole to a bench grinder with a smaller arbor. Like a grinding wheel with a 5/8" hole to a grinder with a 1/2" arbors.

I have never seen any indication of wear on the plastic bushing I've had and used for many years. What would cause objectionable wear? There might be slight inconsistent dimensions between manufacturers as there are in grinding wheel holes and grinder arbors, not significant enough to be a relevant issue.

I'm pointing this out because there are a lot of noobs reading this. Plastic grinding wheel adapter bushings are the industry standard and there is absolutely nothing wrong with them.

 

[John K Jordan]

Center drills have a special problem, the fragile tip.

This is true for metal working, but I don't think it's an issue at the wood lathe.

I also have and use the CNC spotting drills. After some years of use and experimenting, I like the center drill better for some drill sizes for wood. I use the largest one the most.

 

[Richard Coers]

Plastic bushings wear out quickly, and they seem to be very inconsistent in diameter and wall thickness. Similar to the blades that come on your bandsaw when you buy new.....

robo hippy

If you are wearing out a grinding wheel bushing, there is definitely some other issue! There should be zero wear since there is no friction or even spinning for that matter.

 

[Webb Willmott]

I don’t really understand why the OP didn’t buy grinding wheels for the correct size arbor………

 

[Steve Tiedman]

I don’t really understand why the OP didn’t buy grinding wheels for the correct size arbor………

That's me!

Because I was shopping for general purpose, multi-material grinding wheels. These aren't high-tech, limited use wheels like the CBN wheels on my other grinder. I'll use them for everything from low and high carbon steels, and non-ferrous metals as the need arises. This is the wheel- aluminum oxide, 6" x 3/4" x 1" hole with spacers. I bought a coarse 36 grit and a medium 60 grit.

https://a.co/d/iM7s8V6

These kinds of wheels are typically coming with spacers. It's cheaper for the manufacturer to make one shaft hole size with spacers than manufacture for every shaft size.

I've used Pacific, CGW, and Norton stone wheels over the years. And the OEM Baldor and Milwaukee labeled wheels that came with my 2 grinders had spacers. I've never bought one that was offered for specific shaft sizes. I know they were, and maybe still are, out there, but it was not a buying priority for me.

 

[Bill Alston]

This primarily applies to drilling in metal.

Center drills have a special problem, the fragile tip. Every book of machine shop hints wil have a way to remove a broken tip and it ain't easy to do. Not worth the risk. Center drills have their primary purpose of making 60 degree centers for lathe centers and not much else.

Here's a spotting drill, the better way to spot starting hole locations. A good many shops have given up on the center drill for spotting in favor of the spotting drill. Less fragile tip with a thin web for easy starting on rough castings or slightly angled surfaces. They come in different tip angles although the 90 degree is the most common.

View attachment 76077

Agreed. I got into the habit of using spotting drills years ago so I use them whenever I want to start a hole, be it Metal Lathe, Wood Lathe or Milling Machine.

 

[robo hippy]

Standard friable grinding wheels do not come spin and bubble balanced like the CBN wheels do. Unless the user trues and balances the wheel first, the wheel will not run true, and the plastics are not as durable as metal. They could make high quality plastic bushings, but generally they do not go that way.

robo hippy

 

[Tim Hunter]

Robo is right. You guys are making way too big of a deal about bushings for friable wheels. In fact, they need a bit of radial clearance so the flanges can dictate squareness to the arbor. All this snobbish chatter about precision just isn’t necessary. The wheels are to be trued each time they are mounted.

Tim

 

[Doug Rasmussen]

Robo is right. You guys are making way too big of a deal about bushings for friable wheels. In fact, they need a bit of radial clearance so the flanges can dictate squareness to the arbor. All this snobbish chatter about precision just isn’t necessary. The wheels are to be trued each time they are mounted.

Tim

Huh? What is he right about? From post #16 Robo said: "Plastic bushings wear out quickly, and they seem to be very inconsistent in diameter and wall thickness." Elsewhere he said: "The plastic ones are junk"

And what snobbish chatter about precision?

This forum is full of noobs who can easily be influenced. Undoubtedly, a number of them are now thinking metal bushings are needed so they won't wear out and that plastic bushings lack consistently accurate sizing.

FWIW, here's my 30 year collection of "junk" plastic grinding wheel bushing. No wear and consistent sizing. Not a metal bushing in the bunch. Not shown are the plastic reducer bushings from 1-1/4" hole grinding wheels for precision grinders. Notice some are narrowed down for thinner grinding wheels.

 

[Tim Hunter]

Plastic bushings tend not to be high quality…and don’t need to be. And there is no need for precision mandrels to make suitable bushings.

Tim

 

[Steve Tiedman]

An update- wheel #1, the 60 grit, is installed and running as well as human hands can make it. The provided plastic bushing are in use as outlined in post #24 above. Correction- my wheels are 3/4" wide, not 1".

Speaking of wheel width, guess which dummy ordered the course 36 grit as a 1" wide instead of 3/4"? Yep, this dummy. No, it will not fit, tried. 1" only allows for about 1.5 twists of thread on the mounting nut. Shipping it back in swap for the 3/4" 36 grit.