12" disc sander RPMs

[S obsessed]

I am contemplating building a 12" disc sander. I have a 1hp leeson dc motor that operates at 3000 rpms at 120v. I run it at 90v and it is still around 2800 rpms and can turn it down to a crawl. I plan to mount this below the sander with a belt drive gear reduction. The disc sanders I see are around 1700-2000 rpms. I am wondering if 2000 rpms is what I should shoot for or if a little more would be better. I am not sure I will have the horsepower for more or not anyway. This will be for general finishing like what most guys use 9" sanders for. Anyone have any insight on this?

 

[Crag the Brewer]

Why do you want a 12" wide disk?
are you going to find cost effective paper or disks for it?

Disk grinders use a Lot of paper, and quickly.
9" is pretty cheap to source. I cut mine from sheets, and use the scraps later.


disks don't need a Lot of power.
And you will not need to go very fast

 

[Richard338]

The most important feature is VFD.

 

[S obsessed]

Why do you want a 12" wide disk?
are you going to find cost effective paper or disks for it?

Disk grinders use a Lot of paper, and quickly.
9" is pretty cheap to source. I cut mine from sheets, and use the scraps later.

I could see the benefits of having a larger disc for things such as machined items in the shop that aren't knives. As an autobody guy I value a good quality psa disc and the 12" are only a few dollars more than 9" and with the extra circumference I would figure they would last longer to justify the price increase. I can see that you can get some ceramic sheets that would be around $1 per 9" cutout and that is quite the good deal. I have a tube of 3m feathering adhesive that I could use. I heard they aren't making it anymore and I don't like the idea of having to use contact cement or something that requires any cleanup as I swap sheets. So I guess I was planning for the future and using psa discs. Also I can swing 12" on my lathe without removing the block and could actually make a 16" sander if I pulled the gap block but those discs are harder to come by and 12" is fairly popular. Perhaps I should build the sander as I planned with belt drive for a 12" disc but instead make it 9" with 1:1 drive and see if it is something I even get some use out of. I can then use up my feathering adhesive also. However I would still like to know the idea about speed for future reference and if the 2k rpms is good for 12" discs.

The most important feature is VFD.

Thanks for your feedback. No VFD on this one. It is dc so it uses a different type of controller. It is variable speed from full on to barely turning which is what I assume you were getting at.

 

[Richard338]

Yes, I get the best use from mine flattening handle parts. I often hold the piece against the disc and then start it turning. This avoids little mistakes from not landing flush on the moving disc.