how do you square up a disk sander?

J.McDonald Knives

J.McDonald Knives

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Jan 28, 2007
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i just pickuped an aluminum 8" disk sander adapter for my grinder and when i put it on it was off center. i got the face trued up but i have one spot on the disk that does not want to come down so easily. its right on the edge of it. what are a few suggestions to true it up so i dont get any vibrations from it?
 
I am not sure what sander your talking about. If it is one of those multi tools that attach to the end of a bench grinder with a disc and a belt there is an adjustment so that the track lever works across the whole wheel sureface. I nwould need to see a picture to remind myself which bolt but I did work it out at a mates house a year or 2 ago. If it is just a flat metal disk that spins round I am not sure.

A bit more description of the out of alignment may also help others better advise you. Is the disc wobbling on the flat or outside edge.
 
the outside edge is not perfectly round. what it is a disk sanding adapter to be fitted onto the shaft of the motor. i had to drill 2 holes and tap them for set screws. i used 10/32 x 1/4" set screws for it. if i cant get this to work i have another option i can try later but will requite me to go back to grandpas house. he has a 12" one that i could reshape to 8". i hope that helps some.
 
Ok I am asuming the set screws were bored in behind a flat round plate.
Way the dis hole the same size as the shaft going in. If it is loose and off to one side may be some thin metal shim material could pack it back to center.

The other way is to turn the motor into a lathe. Lock in a cutter or file and spin the disc to trim it down. There is a high potential for danger be care full.

If your still at the buying gear stage I use my vertical drill press as a rough lathe for turning small objects. I use a file. The 8" disc spinning around may not be so easy on the machine. I have never done it just an Idea if the shims don't work.
 
its a tight and snug fit on the shaft. i had to file down the shaft so it would fit this sander. set screws are behind the plate. i tried to just turn it on and file it down but it still vibrates like mad. the motor spins at 3450RPMs. 1/3HP motor. waht i really need is a totally solid place to mount it that isnt affected by vibrations and clamp the grinder down so that it wont vibrate either and just sit there with a file. but i dont have a place to do that. i might try and make an adapter so i can stick it in my drill press and turn it on at a slow speed. or if i knew someone with a lathe that would help. i have tried to find the high spots and sand them down on my 1x30. its working some. im just trying to find other ways to accomplis my goal. all else fails i can hold off and buy a motor and the adapter.
 
"its a tight and snug fit on the shaft. i had to file down the shaft so it would fit this sander."

You probably shouldn't have filed the shaft on the motor. It could be spinning out of round now. You should of bored out the collar of the disc to the shaft size. Or check the collar to see if it's perpendicular to the disc, that would also make it spin out of true.
It's hard to tell without pics but some discs also have to be ballanced. Usually by removing material from the backside with drill holes or a grinder.
I would try again with a new motor.
 
That motor is probably useless now. Disc may be damaged from putting it on the damaged shaft,too.
 
the shaft was reshaped by turning it on and just filing it while its spinning. i did it on another one too and even took a micrometer to it to make sure it was all the same.
 
I am at a complete loss.

You won't use an angle grinder to clean up your RR track anvil face, because you just wouldn't feel right about it, but...

You will turn down a motor shaft by hand-filing it, and then set to destroying your disk by trying to remove enough metal to get it to balance on a wrecked shaft, which is hopeless.

The guys are right: Find another motor. Leave the shaft alone. Don't turn it down. Don't build it up with weld filler and turn it to fit. Leave it alone. Bore or bush the disk to fit the shaft. Rebalance the disk. If you or somone you know doesn't have the technology to bore or bush the disk and rebalance it, find a motor with the correct size shaft. You can't caveman something that spins at high RPM.
 
i know what im doing on the shaft. the anvil is different. by the time i get it flat it will have ripples or will be curved. i know my limits. to me using an angle grinder to reface my anvil is too much for me. plus i only have a 4" angle grnder. im not taht skilled with it. yes i will be cutting out my blade shapes with it but not too close tho. im not too bad with the cutting disks but with the grinding disks im not that great. does it make sense now?
 
Try to find a slower motor. 3450 is too fast imho. 1750 or slower is what I would recommend. Also, you have a mic do you have a dial indicator?? if so use it on the sfaft and see how bad it is. It is probably out by more than .025. Next time see if you can trade a machinist into doing the work for a knife instead of trying it with hand tools. I have been using discs for 15 yrs now and do not own a belt grinder. My first disc was out .015 and vibrated like mad. That was at 1750rpm. 3600 will just amplify the problem. I finally made a disc that is only out .002 or less on a 1 inch motor shaft and I had to drive it on. I do not ever want to have to take the thing off. My current disc is run off a VFD 220 single phase in 220 three phase out. The variable speed is great.

Chuck
 
Check some garage sales for a craftsman 4x36 belt/6or 8" disk grinder. You could also just get a disk gimmick to stick on a power drill. I **almost** coulda had a similar problem when I built my 2x72 grinder- the tracking on it was bad, despite the the tracking wheel adjustment gimmick- powered with a direct drive wheel...I trued up the driver wheel on the shaft instead of monkeying with the shaft the wheel slid onto. NEVER monkey with the motor shaft.

You could always use a file to draw file the steel flat. After filing the anvil face, this'll be a piece of cake. I'm a big fan of the power drill... its a good buffer (with the buffer gimmick shaft), its a flat grinder( with the disk gimmick attached) and it also drills holes. Sometimes things turn out better the less technical you have to be...

A word about them angle grinders, they're not just good on steel...they work great on thumbs. Really, they do. But if you're using a rail section as an anvil, you can grind a series of parallel bevels across the face, color the whole face with a sharpee and draw file the bevels into one flast surface. Using your tools is a sure fire way to become more skilled at their use.

Also, if you've got access to a 12" disk, why turn it down to 8"? Ebay has some great chinese machines that have a disk and belt...
 
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