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Grinder Wheels

Discussion in 'QUESTIONS & ANSWERS (Get Help Fast Here!)' started by Hukshawn, Dec 30, 2016.

  1. Hukshawn

    Hukshawn Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    I got an 8" bench grinder for Christmas. Not of terribly great quality, but I asked for this one, so whatever. I have a 6" with a stone and a wire wheel. I wanted something bigger for grinding tool bits. This one works nice. The wheels are heavy so takes a while to get up to speed, but maaaan are they out of round. Thing walks across the bench and makes a hell of a noise that vibrates the house.
    I have a flat diamond dresser that I use on the 6" and got that wheel pretty true, but I worked on these 8" for quite a while. Garage is cloudy from stone dust. I have the face pretty true but the sides travel back and forth almost a 1/16". I can't seems to true them up. I have the dresser pushed against the rest to try to keep it steady as I grind. Just not happening.
    Ideas?

    I've almost considered rigging them up in the lathe, but that might warrant a tear down and clean once I'm done to get rid of all the damaging dust...
     
  2. intjonmiller

    intjonmiller United States Active Member Active Member

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    I assume you're using the usual plastic grinding wheel bushings/adapters? Those things are TERRIBLE. If you have a lathe you should make some simple aluminum ones that act as bushings and washers in one. The OD of the bushing section should be a bit smaller than the ID of the grinding wheel so that the aluminum can't expand when hot and crack the wheel. That was my first ever lathe project and it has served me very well.



    cc491e31ec5388a3994e857c5807c4a1.jpg
     
  3. Hukshawn

    Hukshawn Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    Ya I think I may have to take it all apart this weekend and see what's up. They're way too wobbly to be just the wheels... even cheap Chinese wheels, I assume they are still trued SOME how...? Or are they just molded and shipped?
     
  4. Bob Korves

    Bob Korves H-M Supporter - Premium Content H-M Supporter-Premium

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    Don't mess with the wheels until you find out the bearing condition and fit, and the runout of the spindle itself. Sometimes the plates on the sides of the wheels are also poorly machined and cause issues. Make sure you have good blotters on the wheels, and I agree with Jon about the plastic bushings, even worse when there is more than one stacked one inside the other. Start with no wheels or anything, just bare spindle, and see how it runs. If that is not good, sell it and start over. If that is smooth, put a wheel on one side, making sure everything fits correctly without slop or runout, then run it with just the one wheel.
     
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  5. Hukshawn

    Hukshawn Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    Hmmm, okay. I did notice the washers had a wobble to them, but hard to see around the shrouds. Sounds like washer lathing may be in my future. (If the shafts are out then it's just going back to the store, it was bought new)
     
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  6. intjonmiller

    intjonmiller United States Active Member Active Member

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    A grinder just has to spin the wheels, and do so smoothly. While there is a difference between the budget ones and the better ones, for most people the budget ones are sufficient if you get a good sample.

    Some have better tool rests than others, but I'm pretty sure even the good ones still suck (only the reversible, double-sided tool grinders have particularly useful tool rests). If it spins smoothly without the wheel, and it seems like the bearings aren't crap, then you can probably make it work. But keep in mind that it's possible for the shaft to be bent and still spin relatively smoothly without a wheel mounted, but never with one mounted. I returned three wire wheels before realizing that mine had been damaged on one side. No vibration problems at all with a wheel only on the other side. That's the troubleshooting process Bob mentioned.
     
  7. Bob Korves

    Bob Korves H-M Supporter - Premium Content H-M Supporter-Premium

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    You should be able to visually see runout at the shaft ends with the wheels removed if any is present. If you find runout, check for a loose bearing to shaft fit as well as for a bent shaft. Import machine, no doubt, and you are the QC inspector...
     
    Last edited: Dec 30, 2016
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  8. intjonmiller

    intjonmiller United States Active Member Active Member

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    In my case the run out was too slight to see directly, and I wasn't able to get a good indicator reading on the shaft with more than a decade of scratches. That also makes it hard to identify the bend to try to straighten it, but as a now almost 15 year old Harbor Freight grinder that only cost me $30 or so at the time, I'm not going to bother fixing it.

    The irony is that the week before I discovered that it was damaged I gave my brother a nice Buffalo grinder that my wife's grandfather passed on to us. I didn't see the need for two 6" bench grinders, so I gave him the better one. It has to be at least 20 years old and still takes a good 3 or 4 minutes to spin down.
     
  9. Hukshawn

    Hukshawn Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    I'll take the wheels off and have a look. Il set up the dial test indicator if need be.

    Thanks guys. I never thought of the shaft and bushings.
     
  10. f350ca

    f350ca Canada Active User Active Member

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    Just went through this with the Chinese one I bought for my planer blade grinder. The stamped washers were no where near flat, made a heavy one to register on the shoulder of the shaft and used the original on the outside. Took the side wobble out of the wheel.
    You might want to consider buying better wheels, any of the ones I've seen come with these grinders are little more than round rocks.

    Greg
     
  11. Hukshawn

    Hukshawn Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    Lol. Round rocks...
    I'll admit, aside from the wobble, the wheels grind surprisingly nicely. I like the shoulder bushing idea. I think that is what I will do.
     
  12. Hukshawn

    Hukshawn Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    Well, here we go...
     

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  13. Hukshawn

    Hukshawn Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    No run out on the shaft and negligible run out on that plastic bushing. But I think the issue is with the retaining washers and the fact that they just sit on this lock ring... there isn't actually anything locking it square to the shaft. So I think a bushing with a back plate is necessary.
     

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  14. Hukshawn

    Hukshawn Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    I made a bushing and backplate. Just out of aluminum. The shaft is 5/8" but a big 5/8... I drilled and reamed a 5/8" hole but it's like .003" too small and I don't want to pound it on the shaft. So that was hurdle #1. #2 is I made the piece between centers with a dog. I have a live center in the TS but for the spindle I have a convoluted mt2 dead center in an mt3 sleeve. Both are old and very worn and ****ty... the piece turned with a wobble... so that doesn't help either. Gonna need a new better mt3 dead center and just throw away the sleeve as its old and worn and no good now. I suppose I could also just turn the 2" stock in the TS as its only about 8" long now, but I'd rather avoid having to part the piece off in the end.... Soooo, I'll make another attempt later.
    That's my update...
     
  15. f350ca

    f350ca Canada Active User Active Member

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    I have a Princess Auto 8 inch, looks similar. It was always really slow coming up to speed, then one day wouldn't start without me giving it a spin. Decided it was time to replace it, so bought a cheap Canadian Tire one on sale. Was going to the motor rewind shop so thought I'd get him to check the capacitor in the dead grinder, of course it was dead, put the new one in and it starts in a quarter of the time it did before. Now a useful tool.

    Greg
     
  16. Hukshawn

    Hukshawn Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    Ya it's a princess auto grinder. A pro point.
     
  17. intjonmiller

    intjonmiller United States Active Member Active Member

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    I made mine from a soup can I filled with molten aluminum, before I knew to not use so much extruded (pure) aluminum. That's part of the reason for the poor surface finish. That and not knowing nearly enough about bit geometry, feeds & speeds, etc.

    Anyway, I chucked the whole chunk (after cutting off the can), faced the end, bored it for my grinder shaft size, turned down the large OD until it looked nice and seemed like a good size, then after marking out the area between what would become the flanges, I hogged away the material in the middle with a general turning bit. I got them down to the correct smaller OD, then used a parting bit to clean up the shoulders, then parted off the outer one, faced the second one to length, then parted it off as well. No centers or complicated workholding needed.
     
  18. Hukshawn

    Hukshawn Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    I did it between centers because I'm whittling away at this 2" chunk of aluminum I bought a while back. I'm trying not to waste any by cutting off more than I need to chuck.
     
  19. Tozguy

    Tozguy Active User H-M Supporter-Premium

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    In my experience the bore in those grind wheels is not very accurate. It is probably not a good idea to rely on it and the bushing to align the wheel. A snug fitting bushing is not necessarily desirable. The side stabilizer plates (or back plates) are all important to hold the wheel perpendicular to the shaft and reduce wobble. On one of my grinders it was the poor quality of the nut that was forcing the plate askew.

    With a new wheel mounted and held with low tension on the side plates, I would turn it by hand to see how round the wheel is. Sometimes, the wheel can be tapped lightly on the circumference with a wood dowel to reduce run out. Some play in the bushing can be of help here. After that, and tightening the nut, the wheel needs to be dressed to get zero run out on the grinding surface.
     
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  20. Hukshawn

    Hukshawn Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    Ya I agree. This situation is a lot more tricky than any other grinder I've had cause the shaft has no shoulder to rest on. It's just a spring clip... all of the squareness to the shaft is relied upon by the bushing and backplate. How stupid is that?...
    I did make one last night but I messed it up. Bored it out .003" too much. And it wobbles. Made a small bushing to fit into the big one, screwed that up too.... was fun
     
  21. Tozguy

    Tozguy Active User H-M Supporter-Premium

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    Don't forget to check the nut. You might have to turn an external thread to a close fit with the nut and then use it to face the nut. I can't emphasize enough the importance of a square faced nut.
     
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  22. intjonmiller

    intjonmiller United States Active Member Active Member

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    If the ID of the bushings is a close fit on the shaft then it will be very difficult for anything to push it out of square. With the smaller OD slightly undersized as I said up top, the ID of the grinding wheels becomes irrelevant. The wider the flanges section the less impact an inaccurate nut can have. Square there is certainly ideal, but this design largely eliminates the need to worry about that. The ID size is key, and making both sides at once as I described makes it easier to make sure they match.

    One more thing that occurred to me is that you probably don't want your soft aluminum to bear againt that hard snap ring. Yes, it is an odd design without a hard shoulder to bear against. Put a steel washer in first (again, a close fit to the shaft would be ideal) to prevent the snap ring from damaging the flange-bushing thing.

    Oh, and I didn't say it and it's probably obvious, but the combined depth of the two bushing sections must be less than the width of the wheel so that they don't meet in the middle.
     
  23. Tozguy

    Tozguy Active User H-M Supporter-Premium

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  24. intjonmiller

    intjonmiller United States Active Member Active Member

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    I didn't say it shouldn't be. I said that the fit of the bushings minimizes the impact of the nut not being square. I specifically said that square is ideal. But it might not actually be necessary to go to the work to face it off if the flange and bushing are made right. If the nut is particularly far off of square then that's another matter. In the configuration I described and showed (which is a different design than the diagram you showed) it will have the least impact of any of the components. Not none, just least, again assuming it's close to square.
     
  25. Tozguy

    Tozguy Active User H-M Supporter-Premium

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    Depends on your standards I guess. For a one time job, that will bear up forever after, to me it is well worth the trouble to make it good in every way. The nut is the source of pressure to the whole system.
     
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  26. Hukshawn

    Hukshawn Canada H-M Supporter - Premium Content H-M Supporter-Premium

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    I finished up one side. I used the stock nut and washer on the outside but used my bushing and flange on the inside. Those parts run true enough that I was able to determine that the crazy run out is actually in the wheels. I just put it all back together and honed the wheels as true as I could get them to a useable (non walking across the bench) state... I took a lot of meat off but they run okay. this will do for now.

    On a side note, I have been considering a silicone carbide wheel for the few carbide tools I have been using. The aluminum oxide wheels obviously don't touch them, but the dressing wet stone I have does do a bit, but not very much. I have one tool I can't use cause it has a chip. Would be nice to grind back to a point.
    Anyone with any experience want to chime in and tell me if it's worth buying?
     
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  27. intjonmiller

    intjonmiller United States Active Member Active Member

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    Discussions involving differing opinions are decidedly not the same as arguing. I'm sorry if it came across any other way, but at least for me it's just straightforward discussion.
     
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  28. royesses

    royesses United States H-M Supporter - Premium Content H-M Supporter-Premium

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    I have a green silicon carbide wheel on one side of my 8" bench grinder. The other side has a blue AO wheel. Both are Camel brand. The silicon carbide is superior to an AO wheel for grinding carbide. They do wear down fast but that is normal. I got mine on Ebay for somewhere in the US $20.00 range. I made 3" 6061 integrated washers/bushings for them very similar to Tozguy's link above. I then use a T shape diamond wheel dresser to get them true. On my grinder (Porter Cable) I use the washer with integrated bushing on the outside and the single washer on the inside against the shaft step. The shaft threads start inside the adapter and have a taper so that just a washer would be loose and sloppy on the nut side of the shaft. This throws the whole assembly out of balance because of the off center washer. My way uses the length of the bushing to keep the wheel 90° to the shaft and centered. Please excuse the poor drawing.
    grinding wheel adapter sketch 2.jpg
     
    Last edited: Jan 2, 2017
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  29. 12bolts

    12bolts Global Moderator Staff Member Active Member

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    This is a good educational thread. Lets just keep it civil please
     
  30. 12bolts

    12bolts Global Moderator Staff Member Active Member

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    You can make a dead centre easily enough. Just set up to cut a MT3 to suit your spindle out of really any old stock at hand. Then just insert it and turn a point. You will have a dead nuts square centre for the job. If you damage it or find it is out slightly after reinstalling it you can bring it back to true again simply by touching it up.
    Dont throw it away! You WILL find a use for it one day.

    Cheers Phil
     
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