# Disc Sander/Grinder?



## pelallito (Aug 22, 2009)

Hello,
I am thinking about making a 9" disc grinder/sander for my shop. I am thinking of using 1/2" steel plate and attaching a boss(if I am spelling it right),with a key way cut into it, to it, so that I can attach it to the motor. After attaching it mechanically with bolts and perhaps welding it into place. I plan to turn everything as one unit on my lathe to balance it, get rid of any run out and make it vibration proof.
Can you tell me any reason why this won't work? Any suggestions on making it better would be happily accepted.
The reason for 9" is that I can use normal sandpaper on it. All I have to do is glue it on and trim it in the shape of the disc.
The motor will be reversible, and the disc will have a 1 degree taper on the face. 
Thanks for the help.
Fred


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## vlmarshall (Aug 22, 2009)

Choose a disc size that matches a redily available self-adhesive sanding disc, and you'll be a lot happier, I think. You'll also change paper when it needs it, rather than struggling through the last half of a job with old paper. 

Also, I'd avoid tapering the disc, and make an adjustable rest, or at least a rest as close to 90 degrees from the wheel as I could get it.


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## Tin Falcon (Aug 22, 2009)

Fred:
 I have one of these and it gets qite a bit of use. mostly the belt.
http://www.grizzlyindustrial.com/products/Combination-Sander-6-x-48-Belt-9-Disc-Z-Series/G1014Z

if you realy just want a disk look at theses.

http://www.grizzlyindustrial.com/products/12-Disc-Sander/G7297 for $ 160 it may not be worth messing with a build.
that said if you do build one make sure it is safe. The rim of that grizzly disk i posted is going about 60 miles an hour what if it gets loose in the shop and goes for a walk. HMM. 
The disk needs to be properly balanced an a pully system to the motor could save wear and tear on the motor. 
Vernon gives good advice here. the Paper" used for machine disks and belt is not paper at all but cloth it is a lot heavier than hand sand paper. 
Tin


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## ghart3 (Aug 22, 2009)

Fred,  Made disk sander and added thread to motor shaft. Then threaded boss that was welded to disk.  Disk is 12" but could make smaller diameter disk if wanted later.

Solved problem of pivot point changing as angle is changed by having a single clamping know that holds table to base.  This works out real good for changing paper, changing angle and then adjusting for table to disk alignment and clearance.

Make templates for setting adjustment of angles.  Easy way is to print on paper and then glue to something, I used 1/8" tempered hard board.  Cut and sand to lines on your paper and you'll have fairly accurate setting gauges.

Gary


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## bentprop (Aug 22, 2009)

My disk sander is just a round piece of MFD screwed to an aluminium pully.Pully set-screwed to motor shaft.Takes standard 6" sanding disks.Cheap and cheerful.Just need to scrape off the glue when changing disk.I can live with that.


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## firebird (Aug 23, 2009)

Hi Fred

A disc sander is one bit of must have kit in my opinion. Click this link to see how I made mine.

http://www.homemodelenginemachinist.com/index.php?topic=691.0

Cheers

Rich


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## pelallito (Aug 23, 2009)

Vernon- 9" paper disc is available, but not always in all of the grits I might want to use. The reason for the taper is so that when you grin something long, you don't hit on the other side.
Tin- I will look into using a pulley system.

ghart3- I am taking a close look at your pictures for ideas.

bentprop- It's recommended that I put gasket material on the steel disc, which would do a similar job that your MDF does. 

firebird-I will go to your link immediately. I liked what you did. I was given a 3 phase motor all I have to do is wire a plug on it and connect it to my VFD. Then i will control speed and direction.

Thanks for the replies and ideas!


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## Kermit (Aug 24, 2009)

I would seriously consider not driving it directly with the motor shaft. A disc that large will cause considerable bending torque at the motor shaft bushing if you are using the outer face of it. It will work but it will be loose and wobbling in no time short. Driving it mounted on a very short mandrel with a pulley is better in my opinion. a smaller disc like a 6 inch would have proportionaly less bending stress direct mounted to the motor shaft. 

Let us know how it goes which ever methods you use 
Kermit


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## hudmut (Aug 24, 2009)

Well i have made one at work (ill post some pics to night) all out of mdf and a 1hp motor just about the same Way you are talking about but one thig i did do to stop it jumping in to life when you push go is fit a soft start switch. the drive its self is a 4 inch steel disc with a 25mm bar welded to the back all turned up in the lathe then it was keyed there is all so a bolt up the center in to the the motor shaft.. i got the idea after seeing the record power one we sell in the shop at work witch works the same way and is 12" not 9 so you should be fine. but like i said mine does have soft start


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## pelallito (Aug 24, 2009)

Kermit, 
I am going to think about what I just read. What I am trying to copy with steel is made out of aluminum normally. But I don't know how to weld aluminum.
Hudmut,
I went back to my original post and realized that I forgot to mention that it was going to go on a 3 phase motor. My VFD has a ramp up or soft start feature that I can play with the programming. It will also allow me to reverse the motor to grind from the other side of the disc.
This is what I want to copy-http://www.beaumontmetalworks.com/index.html
Regards,
Fred


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