Topic: Can you put 8" wheels on a 6" Bench Buffer?

[Really?]

I picked up a HF 6" bench buffer from HF, really cheap.  I was just wondering what issues I would see if a 8" wheel were put on.  I imagine if you did one side the other side would also need to be 8".

[fuzzybutt]

i would think you'd need to raise it up some if it  was bench mounted.

[Really?]

No bench.  I picked up that heavy pedestal from HF for like $23, so it would not have clearance issues.  Can't have workbench till this house sell's and I can buy another one.

[fuzzybutt]

i would think then that as long as the spindle diameter was the same then it shouldnt be a problem. the only problem i can forsee is if that the speed might not be as high due to weight differences of the bonnets.

[Really?]

Kewl, thanks Fuzzy!

[mystic_1]

A unit of measurement that I have seen bandied about in discussions on polishing is Surface Feet Per Minute.  So, let's say you're turning at 700rpm with a 6 inch diameter disc.  C = pi * D so the circumference is 3.14159 * 6 inches or about 18 inches or 1.5 feet per turn, times 700 rpm = 1050 SFPM.

Now go to an 8 inch disc turning at the same speed.  C = pi * D, 3.14159 * 8 = 25 inches or so, around 2.1 feet, times 700rpm = about 1470 SFPM.

So, assuming your buffer is strong enough to turn at the same speed with the larger buff, the effect is higher surface speed where the part meets the buff.  However, since there's more leverage on a larger wheel you'll get more slowdown once you offer the part to the buff.

If you go too high on the speed, the compound will tend to liquify and fling off the wheel, plus the part can overheat easily.  Also more chance of the part getting snatched from your hand.  However the higher SFPM can give more aggressive polishing action.

Personally I stick with the disc size that the buffer/grinder is rated for.  Your mileage may vary.

mystic_1

[mgautreau]

I just bought one of those 6" buffers today.  The problem is that the motor barely has enough HP to turn the 6" wheels so putting 8" wheels on it will only compound the problem.  It takes very little pressure on the wheels to stop the motor.  I'm going to see if I can take mine back to get the 8" model.  I've used a friends HF 8" and it had plenty of HP.

[Clyde]

After I had a look at a friends buffer which did not have enough HP for 6 inch, I shopped around for highest HP I could find with the smaller grinders.
Mine is good enough for 6 inch, but no good for 8 inch.

[Really?]

While I was polishing the lower fork tubes, I noticed I could stop it perty easy but then I may have been pushing to hard.  The upper triple I did is the best I have ever done.  Love this thing.

Guess the 8"ers are out.  I'll stick with the 6".  It is working for me so far.

This is in the kitchen at night with not to bright a light.  You can still see most of my kitchen in the center.  In the daylight it is crazy shiny.

[mystic_1]

Looks great!  Are you using multiple compounds?

A possible winter project I'm considering is making up a polishing shaft with a jackshaft bolted to the end of my workbench, driven via gears or pulleys to an AC motor under the bench.  That way I could gear it for better torque, and regulate speed either via drive ratios or a motor controller.  I'll go for it if I can make it on the cheap, otherwise my Craftsman 6" bench grinder is OK for most things.

mystic_1

[Really?]

That triple was a lot of work, almost gave up a couple times and just painted it.  I used the red stuff that came with the dremel and the soft cone polishing bit (that helped remove the casting marks) and a white stick with the bench buffer.

[dusterdude]

i bought an el cheapo grinder earlier this year,what a piece of crap.my next one is going to be a dewalt.