Good morning guys, I have a really good 1/2 hp motor and 8" face plate salvaged from another machine. I want to build this up into a 12" disc sander and am looking for info and advice on how to proceed, before screwing it up. 

I have watched a couple youtube videos and found one thing about using either a bearing and/or skateboard wheel to back the disc to help with deflection. Revolution rpm is a standard 1725 rpm. Right now its being used as a weight for a top glue up. Started my build Lew thanks again for your help.

Edited January 19, 20206 yr by Pat Meeuwissen

Your face plate looks beefy enough to use alone.  Put some sandpaper on it and give it a try.  Not much pressure should be applied to the plate.  Let the sandpaper do its job.  If you need lots of pressure the paper needs changed.

I would mount plywood with some adjustments for balance. Make bigger holes for adjustment.. too far out of balance could hurt the bearings. 

48 minutes ago, HandyDan said:

Your face plate looks beefy enough to use alone.  Put some sandpaper on it and give it a try.  Not much pressure should be applied to the plate.  Let the sandpaper do its job.  If you need lots of pressure the paper needs changed.

I know since that's the way I have been using it. I want a large faceplate, because I have larger items to sand.

33 minutes ago, BillyJack said:

I would mount plywood with some adjustments for balance. Make bigger holes for adjustment.. too far out of balance could hurt the bearings. 

That is one way of doing it, and it will work.  If you do not want to add the plywood you can balance the wheel as is using stick on wheel weights.   They come segmented in .25 ounce sections but are easy enough to cut down to a smaller weight.  I would not buy a box of them but any auto repair place that has a tire machine will have them.  Just ask, I have several customers that come in and want oddball stuff we toss away or have millions of.  

 

 

40 minutes ago, BillyJack said:

I would mount plywood with some adjustments for balance. Make bigger holes for adjustment.. too far out of balance could hurt the bearings. 

I'm not familiar with how to do this. Can you give me some more info on how to do this?

9 minutes ago, Pat Meeuwissen said:

I'm not familiar with how to do this. Can you give me some more info on how to do this?

Try this video.  The balance part starts at 4.00 minutes.

 

 

Oblong or slot for adjustment....

 

Pat it might be easier and safer if you just bought a 12" disk. I just now checked Grizzly's price on a 12" disk for their G7297 model sander and is 38.00.

    I use 3 different 8" disk in my shop with different grits and for what I do the 8" disk is much cheaper on sand paper for I cut up the regular 9 x 11" sheets and use the 3M spray stickum. 

I did check the 9" disk price only and it is about one dollar cheaper than the 12" disk only.. 

  I bought 3 Delta 1" x 42" belt-disk sanders some years ago at auctions and use 36 grit belt and disk paper on  one machine, 60 grit belt and disk on another machine and 120 grit belt and disk on the third sander and this works prefect for my so called carving challenges...

I use to think I would buy the 9" disk only and replace all three machines but actually these already do great the way they are...I did notice if a person goes larger than 9 inches wide on the disk then the sand paper goes sky high compared to the regular 9 x 11" regular 3M or Norton paper.  I don't consider the other sand papers to be equal in quality so I never check their prices! But there again that is only my opinion and if guys are happy with what they use that's what its all about....

I have four Shopsmith 12" discs. One is velcro. I'll never make that mistake again! Velco might be ok for RO use, though I'd rather use PSA. I buy Shopsmith's excellent disk sandpaper. Not cheap, though. It's about $4.50 apiece.