Grit progression on 12" disc sander?

L

Leon Husock

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Jul 17, 2019
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I'm thinking of buying a Grizzly disc sander (best one I can afford and it should at least be flat, as opposed to what I've heard about Harbor Freight). What grits do you use most on a disc sander? Do you get up to the 400+ grits often, or is it mostly for roughly flattening things and then you do the polishing work on a different machine/by hand?
 
I usually do 120 - 200 - 400 depending on how badly I messed up the grinds and how much I have to fix. Have you looked at the long term price difference of using 12" discs vs. being able to put a sheet of sandpaper on a 9" disc and trim it down? I don't know much about the Grizzly model but if they offer a 9" option you might want to consider it from a long term abrasive cost perspective.
 
I would highly recommend a 9" disk sander vs a 12" disk. For the 12" you NEED to buy the disks sized for it, with a 9" you can use any sandpaper sheets you have on hand. I would also recommend to just build your own. I built my 9" VFD disk sander for sub $250. I got a 1/2 HP motor for under $100, the disk was $90, and mounting bracket was $75ish. I had a extra VFD so that was money saved but if you have a grinder with VFD you can tap off that and use it on this machine too
 
Unfortunately I don't have much in the way of engineering skills to build my own equipment, or a spare VFD motor. But the 12" grizzly is only $229 and I have a gift certificate to them to use anyway. I'm not seeing anyone selling a disc sander smaller than 12" that isn't part of a combo with a belt sander and those look kind of cheap and crappy; while it'd definitely save me some money to get one smaller than 12", the discs on Supergrit aren't cripplingly expensive (ranging from $1.70/disc to $1.20/disc). I'm not planning to do much stock removal with it so hopefully I won't burn through discs too fast. I just really want to be able to make stuff *flat*.
 
Here is a link to the TruGrit models (I have one of these with a VFD and 1 degree bevel disc).

https://trugrit.com/product-category/machines-parts/disc-grinders-machines-parts/

They are in a different price class than the Grizzly, and I am not sure you are open to spending anywhere near this kind of money for a disc grinder, but I can attest to the quality of these units. They are heavy duty, use an easily replaceable motor and disc(s), and everything is straight and true. Being able to use a VFD is a huge help especially if you are doing anything post heat treat on these. 220 and 400 grit discs spinning at 1750 RPM will heat up your material quickly.

I'm not trying to talk you out of the Grizzly but I did want to pass along a recommendation on a very good machine for the our use case as knife makers.
 
Thanks, Jason! Unfortunately I just don't have the cash to get the really higher-end machines right now (I'm running a Grizzly as my 2x72 grinder with a mod to pop the platen forward). I do have an old pottery wheel with an adjustable speed, but I'd have to figure out how to mount a work table to it and have it be super level. Honestly, a lot of what I want this for is flattening tangs, handle blocks, and bolsters as much as for actual blades. I also just found that Home Depot sells a WEN brand disc sander for $185, but of course I didn't find that out till after I got the Grizzly gift certificate for my birthday. Ah, well. But yeah, at some point further down the line when I have more space and more disposable income there'll be a lot of upgrades coming to my shop.
 
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