Bench Grinder/Polisher Shopping

YL82

YL82

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I've read several threads on bench polishers/bench grinders and preferences for Harbor Freights 3/4 HP units, etc.

I don't have a bench grinder or any type of polishing system aside from a Dremel tool. I like the idea of having a grinder for sharpening lawn mower blades and one that I can polish with.

Lowe's carries PORTER CABLE 6" (2.5 AMP) and 8" (5 AMP) (dually) Bench Grinders with a Max. of 3450 RPM.

Can't seem to find HP ratings for these and Lowes can't tell me either, so I set out to calculate HP for the Porter Cable 8" 5 AMP unit to compare it to HF's 8" 9.6 AMP Bench Grinder which has a Max of 3583 RPM.

Assuming an Efficiency of 48.6% (I back calculated to get this), and 120V and using the following formula:

HP= (Volts X Amps X Eff.) / 746 = (120 X 5.0 X 0.486)/746 = a wimpy 0.4 HP or 2/5 HP.

LOWES PORTER CABLE 8" Bench Grinder: $119 + TN Sales Tax (9.5%)=$130.31.

HARBOR FREIGHT 8" Bench Grinder: $54.99+$6.99 S&H+ $5.73 Tax = $67.71.

On paper (or Ipad) looks like I can get a higher spec grinder from HF for about half the price in a color that's TN Volunteer Orange. :D

Is the HF 8" Bench Grinder easily convertible to use polishing wheels by taking off all of the annoying Safety guards?
 
I have an 8" combo unit from Harbor Freight. It has a grinding wheel on one side, buffing wheel on the other. It works very well. I recently got the 6" buffing bench unit from HF. It doesn't work as well. No power or torque. You press the item you're buffing too hard against the wheel and it slows right down. If I knew this was going to happen, I would have paid more and got another 8" unit.

If you look at the body style of a buffer vs a grinder, you'll notice the buffer wheel mount sticks out much more from the base or body. This gives you more room to work the part around the wheel. If you're looking to do much buffing, I'd get a buffing unit and just stick a grinding wheel on it occasionally if you want to grind something.
 
Good suggestions in your 2nd paragraph, 5twins.

I had started to comment on HF's dual grinder/ polisher, but the comment didn't make the final cut before I hit the Reply button. I noticed the lower Amp rating, but didn't pick up on the difference in the mount design.
 
If I was to go with HF's 8" dual Buffer for $89.99, how would I want to use the 2 wheels?

Different polishing compounds on each wheel?

I've never polished anything aside from using cordless hand drills, etc.
 
YamaLovin76 said:
If I was to go with HF's 8" dual Buffer for $89.99, how would I want to use the 2 wheels?

Different polishing compounds on each wheel?

I've never polished anything aside from using cordless hand drills, etc.
Click to expand...

Some folks use each end for a different compound as you say, using one end for aluminum and the other for stainless steel, or one for aluminum and the other for buffing compounds for painted stuff. Depends on what you are doing the most of.

On bench grinders, in my experience, most rated with less than 3/4 HP are pretty weak and not worth your money for turning a grinding stone.
 
Technically, you are supposed to use a different wheel for every compound. That's why I picked up the 6" bench buffer in addition to the 8" I already had. I now have 3 different wheels, one for coarse, medium, and fine. In actual practice, I find I don't need much more than the coarse. Using coarse black emory compound on my 8" wheel will remove the scratches left by 400 paper. I sand first with 320, then 400 (wet), then buff with the black emory. I've tried the medium brown tripoli and high polish white but they really don't seem to change the shine much from what the black emory gives me. Hand polishing with a cream polish like Mothers (OK) or Blue Magic (better) is the final step after buffing.

I recommend McMaster Carr for the compounds. You can get giant like 2 1/2 pound bars for about the same price as most other places sell the 1 pound bars.

If you have the buffer but no compounds yet and want to try it out, plain old rubbing compound in the red plastic tubs works quite well for a compound. That's what I used to use before I got the real compounds.
 
Excellent information, 5twins! I appreciate the advice/recommendations.

Backing up a bit, I've seen youtube videos and read threads/posts about removing clear coat from crankcase covers using MC-containing paint remover.

I can't say that I see any obvious signs of the presence of clear-coat on my Bicentennial year covers. The Yamaha looks nice & shiny on my right cover. Should I just assume the factory clear coating is there and slap on the flesh-dissolving paint remover?
 
As far as I know, it was used all along. You could try just a dab in one small area. If the finish wrinkles all up, that's the clear coat. Tape off or keep the stripper away from the black lettered areas or it will remove them too. I stay about 1/2" away all the way around the lettering. You end up just having to sand the clear off in that area but it's not a lot so it's not too big a deal.
 
Good tip, 5twins. Knowing me, I probably would have lathered up the stripper all over my damn lettering w/o such a warning.

Seems like I read on here somewhere that clearcoat was more heavily applied on the latter year 650's, but don't hold me to that. Matters not, I suppose. As you suggested, I'll just test it out on a small area. Thank You.
 
They all had it when they left the factory. I think the later bikes had a different formula. On the old ones a lot of times a couple of shots of carb cleaner will remove the clear coat.
I like a sisal wheel and black on one side cotton and white on the other of my 8" HF.
I have all the parts except a round tuit for the 5HP monster buffer project. That thing should be able to shoot an engine cover through the wall of the pole barn.
 
You might want to pick up one of these from HF, not so much for the compound but for the wheels .....

http://www.harborfreight.com/4-piece-buffing-kit-43657.html

They don't do much when used in a drill, it spins too slow, but stick them in a die grinder and you've really got something. They're great for getting into the smaller areas the bench mount wheel won't. Great for the "rain gutter" on the flanged alloy wheels and around the spoke nipple holes too.
 
5twins said:
You might want to pick up one of these from HF, not so much for the compound but for the wheels .....

http://www.harborfreight.com/4-piece-buffing-kit-43657.html

They don't do much when used in a drill, it spins too slow, but stick them in a die grinder and you've really got something. They're great for getting into the smaller areas the bench mount wheel won't. Great for the "rain gutter" on the flanged alloy wheels and around the spoke nipple holes too.
Click to expand...

I use those for spot work when I have to replace rivets on polished surfaces. A word of caution, they don't do too well with 20,000 RPM free speed for long! Keep them into the work. :laugh:
 
I just tried a quick method I saw on an Eastwood video to check for the presence of clear coat on my crankcase covers. I applied some Autosol on a clean, white rag and rubbed briskly on the cover in a small area. If rag turns black, you're on bare metal, if rag is relatively clean or white, you've got a clear coat to remove. My Rag stayed clean, so I get to use paint remover.

I had watched a 47 minute YouTube video from Eastwood that was quite a crash-course for me since I had no idea of how to any of this compounding, buffing stuff before.
 
I guess I should warn you, buffing is a dirty job. I didn't realize how much until I happened to go inside and look in a mirror after an hour or so doing a rim. I looked like I just came out of a coal mine, lol. I wear a face shield now if I'm going to be doing it for any extended period of time.
 
I'm an Industrial Hygienist by trade, so I'd also have to suggest safety glasses under the face shield and an N95 disposable dust mask that is NIOSH approved.:)
 
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