Harbor freight 10" disc sander

Matt Rochester

Matt Rochester

Joined
Nov 28, 2014
Messages
1,864
I've needed/wanted a disc sander for a while. I will be using it mostly for flattening and to bevel scales. Anyone have one of these? I was in there the other day and they were marked down to $69 and I may can use the 20% off coupon too. Can I upgrade the motor and put a vfd on it later or am I better off just getting a better one to start? Thanks.

Edit: I just looked for it on the net and can't find it. It seems they have a 12" for $169 but I know for sure I saw a 10" for $69. I will ride up there and check it out tomorrow.
 
Matt R, Sandpaper comes in 9 x 11 inch sheets which is why 9 inch disc sanders are the norm. The prices you got on a 10" or a 12' sound good now but the sanding discs will eat your wallet alive. Try to find a deal on a 9 inch or even an 8 inch disc sander so you can use sheet paper with 3M feathering compound adhesive or 3M spray adhesive on your discs. You will save a lot of money and have a huge selection of good sandpapers. Larry

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Matt, I think you will be happier in the long run if you build a good one.
Do you have a vfd? You can run both a belt and disc off of one vfd. Motors can be found pretty cheap and a good disc that's balanced will probably perform way better than one from harbor freight.
I haven't used a harbor freight disc, but I can't imagine it being as good as a Beaumont disc or one of the Rod Neilson discs.
Or the coveted Nathan the machinist holy grail discs (if you can find one).
 
Josh Rider said:
Matt, I think you will be happier in the long run if you build a good one.
Do you have a vfd? You can run both a belt and disc off of one vfd. Motors can be found pretty cheap and a good disc that's balanced will probably perform way better than one from harbor freight.
I haven't used a harbor freight disc, but I can't imagine it being as good as a Beaumont disc or one of the Rod Neilson discs.
Or the coveted Nathan the machinist holy grail discs (if you can find one).
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I don't have a vfd but I'm about to build another grinder and it will have one. I found a 1.5 hp and vfd on eBay for $250 or so. I think I can get a Beaumont disc for $85??? Anyway, then I will need to build or purchase an adjustable work rest.
 
Matt R said:
I don't have a vfd but I'm about to build another grinder and it will have one. I found a 1.5 hp and vfd on eBay for $250 or so. I think I can get a Beaumont disc for $85??? Anyway, then I will need to build or purchase an adjustable work rest.
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The work rest Kevin Powers designed is excellent if you know a welder or if you weld. I went that route. A local fab company water jetted the design and my buddy welded it up (it could have been bolted together too). Kevin uploaded the plans and offered it for free on this forum. That's probably the most economical way to get a very sturdy, adjustable work rest.
 
Josh Rider said:
The work rest Kevin Powers designed is excellent if you know a welder or if you weld. I went that route. A local fab company water jetted the design and my buddy welded it up (it could have been bolted together too). Kevin uploaded the plans and offered it for free on this forum. That's probably the most economical way to get a very sturdy, adjustable work rest.
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Seems like I remember seeing that a while back. I do weld and have a place that can water jet. I guess while I'm building my grinder I will build a disc as well. Thanks fellas.
 
Total newbie here. But why does it need to be rotating sandpaper?

Couldn't one take one of these dual wheel grinder wheels and make that spin? It's completely made out of abrasive and if used until it's gone it'll be much cheaper than sand paper.
The only potential disadvantages I see is that the surface would have to be straightened occasionally and that maybe it's too heavy to bring up to speed safely in a self made rig.
Thanks.
 
Jens Schuetz said:
Total newbie here. But why does it need to be rotating sandpaper?

Couldn't one take one of these dual wheel grinder wheels and make that spin? It's completely made out of abrasive and if used until it's gone it'll be much cheaper than sand paper.
The only potential disadvantages I see is that the surface would have to be straightened occasionally and that maybe it's too heavy to bring up to speed safely in a self made rig.
Thanks.
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A good disc grinder will make things flat, and flat is important when making a knife, especially for assembling the scales. Bench grinders on the other hand are only able to do a concave grind which will change in radius as the wheel wears down.
 
TonyRV2 said:
A good disc grinder will make things flat, and flat is important when making a knife, especially for assembling the scales. Bench grinders on the other hand are only able to do a concave grind which will change in radius as the wheel wears down.
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Yes. My idea and probably not good was to not use it the normal way but the flat outside of that wheel.
 
You're correct in that not being a good idea Jens. Bench grinders are not meant to be side loaded, although I suppose we've all done it at some point or another. You certainly don't want to press up against one with the amount of force necessary to grind steel. There's a right tool for every job, and usually the right tool is the safer tool in my experience. A disc sander is the proper tool to grind things flat, so is a belt grinder with a flat platen, it just doesn't have as much surface area. Beyond that, to really get things flat to within thousandths of an inch, a surface grinder would be the way to go. Of course there are also milling machines that are used to get things flat to even higher precisions, but I thought we'd just stick to sanders and grinders. ;-)
 
Grinding on the side of a regular bench grinder grinding wheel can cause wear that weakens the wheel and causes the wheel to "blow up", i.e. come apart at high speed. Chunks of stone flying through the air...this is why the guards on bench grinders tend to look overbuilt...they aren't.

However, you can buy grinding wheels designed for grinding on the side of the wheel. Why don't we use those instead of disk sanders?

Well first off, they are not really intended to be used over the full surface the way a disk sander can be, but it has more to do with the difference between a grindstone and sandpaper.

Grinding wheels are manufactured with a balance between rate of abrasive wear and rate of abrasive loss. Once the abrasive on the surface of my wheel is dull, I'd like it to be released and fresh sharp abrasive be exposed. Trying to grind on dull abrasive wastes time and causes frictional heating. So we dress the wheel to remove the dull abrasive. A friable wheel breaks down more quickly so you have more fresh abrasive on the surface. But a friable wheel wears out of shape quickly, so again you have to dress the wheel into shape, and then flatten what you just ground on the not flat wheel.

I can replace the abrasive surface on a disk sander very quickly, and at pretty low cost if my disk is 9" in diameter. And my disk is always just about as flat as it ever was.
 
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