Harbor Freight 12” Disk Sander

Howard1

Howard1

Joined
Jan 16, 2017
Messages
207
i just bought the above and I love it. However, the disk is not flat. It is slightly concave, about 1/4” in at the center. Additionally, the rim projects slightly out. If you hold a flat piece of wood from the center past the rim the projection shows itself in the unevenness. How can I flatten out the disk. I know that a machine shop can cut it like a brake rotor but that is pricy. I’m wondering if a thin flat piece of aluminum can be glued on like the glass we use on a platten? At $139 with a 1750 rpm motor speed I’m not taking it back. I can probably work around the distortion but would prefer not to. Thanks folks.
 
IMHO, they are junk. The shaft is soft steel and too small. The disc is very soft and not flat. It easily bends and the whole disc wobbles. Everyone I know that got one trashed it in less than a year.

A 9" disk of steel or thick aluminum on a 3/4" motor shaft .... and a VFD will make a much better disc sander.
 
Stacy E. Apelt - Bladesmith said:
IMHO, they are junk. The shaft is soft steel and too small. The disc is very soft and not flat. It easily bends and the whole disc wobbles. Everyone I know that got one trashed it in less than a year.

A 9" disk of steel or thick aluminum on a 3/4" motor shaft .... and a VFD will make a much better disc sander.
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Ouch! I love how gentle you always are. It reminds me of shop class in 8th grade. Just kidding. I always appreciate your advice. FYI you gave me advice about making a 12" fillet knife that I am just finishing. I think that it will be just fine. Thanks for that. Now back to the matter at hand...I guess I could get another job. Where should I look for all the above?
 
Check out tru grit. They have a good selection.
 
What has been said^^^. ———/////// Only Cry once! Not every time you use it ...............,,,Trugrit....
 
For what its worth, I've got one and like it. They are good for some things and not others. For radiusing the front of scales, roughly flattening handle material, squaring up handle material, cleaning up the profile of templates, ect they work great. I keep a 100 grit zirconia disc on mine and only have to change it a few times a year.

Now for making things super flat, or doing anything to blades, or other tiny/fussy work, they are basically worthless. A 9" variable speed disc is MUCH better for all of that.

Myself I'd consider them different tools for different applications, and I wouldn't want to be without either.
 
This disc grinder talk made me take a trip down memory lane:
Several years back I was buying equipment from a closed up machine and woodworking shop. The old guy who owned it had died. HIs son and another fellow were getting the place emptied out. I had filled my SUV twice, spending less than $300, and was back again. I had bought 4 large granite surface plates for $10 each, a 12" X 240" wood belt sander with a 1HP 3 phase motor for $50, boxes of calipers and other small measuring stuff at $20 for the whole box, a Japanese 10" flat lap for sharpening tools for $30, a hundred pounds of SC sandpaper for $10, etc..
They had a HUGE 3 phase disc grinder sitting in the back. I never measured it but it was either 24" or 30". It had a cover that covered the bottom half, and an adjustable work table that stuck out about 24". It was set up for a dust collector. I am sure it weighed a thousand pounds or more. The fellow said he would take $100 for it. I had no place for it, but for $100 I was willing to go get a trailer, and he said they would load it with a forklift. I asked if the 4 foot high stack of several hundred new PSA sanding discs (24 grit to 400 grit) and two extra backing discs (one rubber and one phenolic) went with it. He said he didn't know. I waited a while while he tried to call the son of the fellow who had died. He then left to go see if he was at "the house". I was left there all alone, and after 45 minutes I left with the load I had already paid for.
I came back the next day, and all the remaining equipment ( big lathes, mills, etc.) had been loaded into a scrap metal recycling truck ... including the disc sander. He probably got $0.05 a pound for it. The discs were still there, and he said he would take $30 for all of them, but they were useless without the machine. Worst thing was he had my phone number. He could have called me. He did give me several rolls of 12" wide cloth backed abrasive paper in a very heavy grit for free. I may try to cut it to fit a 9" disc sander someday, but it looks to be 24 grit, soI don't know if it has much knifemaking use.
 
I have a 1/2 HP 3 phase motor from automation direct. and a kbac VFD. The VFD is simple, like the one I have on my belt grinder, but it's not sealed (so it's cheaper). I put a plastic bag over it, and it's been fine. It isn't really close to my belt grinder, so there isn't the usual rain of metal dust everywhere. I got my disc from a place online, (sorry, can't remember the place) that sells oem parts. It is the replacement 9" disc for a craftsman unit. It's not the best, but it works great for what I do (flattening scales, squaring up bolsters).
 
Stacy E. Apelt - Bladesmith said:
This disc grinder talk made me take a trip down memory lane:
Several years back I was buying equipment from a closed up machine and woodworking shop. The old guy who owned it had died. HIs son and another fellow were getting the place emptied out. I had filled my SUV twice, spending less than $300, and was back again. I had bought 4 large granite surface plates for $10 each, a 12" X 240" wood belt sander with a 1HP 3 phase motor for $50, boxes of calipers and other small measuring stuff at $20 for the whole box, a Japanese 10" flat lap for sharpening tools for $30, a hundred pounds of SC sandpaper for $10, etc..
They had a HUGE 3 phase disc grinder sitting in the back. I never measured it but it was either 24" or 30". It had a cover that covered the bottom half, and an adjustable work table that stuck out about 24". It was set up for a dust collector. I am sure it weighed a thousand pounds or more. The fellow said he would take $100 for it. I had no place for it, but for $100 I was willing to go get a trailer, and he said they would load it with a forklift. I asked if the 4 foot high stack of several hundred new PSA sanding discs (24 grit to 400 grit) and two extra backing discs (one rubber and one phenolic) went with it. He said he didn't know. I waited a while while he tried to call the son of the fellow who had died. He then left to go see if he was at "the house". I was left there all alone, and after 45 minutes I left with the load I had already paid for.
I came back the next day, and all the remaining equipment ( big lathes, mills, etc.) had been loaded into a scrap metal recycling truck ... including the disc sander. He probably got $0.05 a pound for it. The discs were still there, and he said he would take $30 for all of them, but they were useless without the machine. Worst thing was he had my phone number. He could have called me. He did give me several rolls of 12" wide cloth backed abrasive paper in a very heavy grit for free. I may try to cut it to fit a 9" disc sander someday, but it looks to be 24 grit, soI don't know if it has much knifemaking use.
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That's a sad story... I've been looking for one of those big disc sanders. One of my family back in Germany has (or at least had) a either a pattern making or cabinetmaking shop (it was never really clear) and he had a 1 meter disc sander. They would start it in the morning and just let it run all day as it took a decent bit to get up to speed, and over an hour to stop spinning. I'd be very happy with a 16-20" disc such as on old Rockwell or Powermatic.
 
Kevin's post points out a valid point. There is no real need for a disc sander to be 1HP. A 3/4HP motor is enough, and with a lighter touch, 1/2HP will work. The VFDs for that size are really cheap. I have bought batches of three .75KW VFDs for less than $50.
 
Howard1 said:
i just bought the above and I love it. However, the disk is not flat. It is slightly concave, about 1/4” in at the center. Additionally, the rim projects slightly out. If you hold a flat piece of wood from the center past the rim the projection shows itself in the unevenness. How can I flatten out the disk. I know that a machine shop can cut it like a brake rotor but that is pricy. I’m wondering if a thin flat piece of aluminum can be glued on like the glass we use on a platten? At $139 with a 1750 rpm motor speed I’m not taking it back. I can probably work around the distortion but would prefer not to. Thanks folks.
Click to expand...
Can you wrap sandpaper around a piece of steel and flatten the disc using the motor? In other words, true up the disc with a sanding block. Just a thought...
 
Yes ... and No. It will work, but if anything goes wrong, it may make the disc worse. A better method is to put a 3" piece of round stock in the disc and take the disc to a machine shop. They can mount it on the lathe and take a few cuts off.
 
Dang, almost bought a Harbor Freight 12 disc sander then I found this thread. Saved me some cash, Thanks guys
 
I have a 10" HF dis sander and, while it definitely has limitations, I use it very often and have found it more than adequate for what I need. I would love to have a better model with a reverse switch and better table. Bought it 5 years ago for $80.

I use it for profiling blanks, scales, grinding in swedges and a myriad of other uses. When it dies I will probably upgrade, but for now...good to go.
 
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