Bench Grinder as a Buffer

[pruss]

Thanks Torque! That makes good sense... helps my brain get through the math/physics to have a simple analogy.
-- Pat

 

[ghost]

Good post Torque! That simplified it for me too.
In case anyone reading this still isn't sure about getting a bench grinder, I still use a variable speed electric drill clamped on a small worktable with the Beall kit with good results. It just requires changing the pad for each compound you use. I plan to get a grinder soon since I'm really into restorations, but the drill set up would work if you don't plan on getting too obsessed with pipes....yeah... :roll:

 

[chagovatoloco]

Understood!
smaller wheel = faster rpm = less sfm
larger wheel = slower rpm = more sfm
right?

 

[torque]

Glad that helped It really is a little counter-intuitive at first blush so the bicycle analogy helps (I actually have to think about it each time just to get it straight in my own mind, lol)
@chagovatoloco
smaller wheel + faster rpm = same sfm
as
larger wheel + slower rpm = same sfm

 

[mkelaw]

smaller wheel + faster rpm = same sfm
as
larger wheel + slower rpm = same sfm

This is sort of like the Abbott & Costello "Who's on First?" routine. Torque nailed it and is correct. The outer surface of a larger wheel travels a longer distance than any place on the wheel closer to the shaft. If it travels a longer distance in the same number of revolutions, it's going faster.
It's possible to buff at 3500 RPM's but it's a crap shoot and not nearly as effective as using a slower speed. You can be as careful as possible but if you catch an edge, the piece will be launched at high speed and, unless you're working in a rubber room, probably broken.
The other issue which I don't think has been discussed yet is the type of buffs you use. The ones you're likely to find at the local hardware will probably be 4 to 5 inches in diameter and stitched to hold the plies of fabric together. When that kind of a buff is spinning even at 1750, it's hard as a rock and produce a lot of heat which makes it difficult to properly apply carnauba to the stummel. It also improves the chances of launching the piece you're buffing. Also, the fabrics for buffs is not all the same. I'd recommend going to Pipe Makers Emporium. They sell larger unstitched buffs which are intended for applying wax, tripoli buffing and white diamond buffing. They're also marked as such so that it's hard to mix them up (the last thing you want to do). Or better yet, call them and talk to Carolyn who is very helpful.
Someplace on ASP there's a lengthy technical paper on buffing. It provides about ten times as much information as you need but all the basics there and are very helpful to anyone who is just starting using a buffer on pipes.

 

[bryanf]

As a machinist and owner of a CNC programming business, I deal with SFPM all the time.
pruss is 100% correct and on the money.
Let's see if this makes sense....if your motor is going 3500 RPM, it doesn't matter if the wheel is a 1" diameter, or a 1000" diameter. It is going to revolve 3500 times per minute.
An 8" wheel carrying 3500 RPM is going 7330 SFPM.

A 4" wheel carrying the same 3500 RPM is only going 3665 SFPM.
In order for the 4" wheel to carry the same SFPM as the 8", it would need to spin 7000 RPM.
However, it was stated that 1750 is the perfect RPM for buffing. Assuming that is in reference to a standard 8" wheel, then converting that to SFPM, you get a recommendation of 3665 SFPM. So,by using a 4" wheel on a 3500 RPM grinder, you are achieving the exact SFPM that is recommended.
SFPM is the important factor, NOT RPM, as SFPM maintains a constant removal rate, no matter the diameter. This is why CNC lathes will adjust automatically and spin faster and faster as you cut across a face towards centerline- to maintain SFPM and the material removal rate. Imagine if you were to buff on a 1000" diameter wheel spinning 3500 RPM. It would remove a LOT more material than a 1" wheel spinning at the same speed.

 

[zack24]

The argument on SFPM is correct...but I think there's a big safety difference between a slow 8" wheel and a fast4" wheel. The big wheel gives a larger contact patch due to the extra circumference- seems to be a lot less "grabby". I use 8" and 10" wheels at 1725. That's still too fast for wax work...

 

[pruss]

The big wheel gives a larger contact patch due to the extra circumference- seems to be a lot less "grabby".

Amen! I've built the wish list out for expanding my pipe-cave. I can't wait for the day when I have a proper buffer and can use my bench grinder for it's intended purpose... sharpening tools for a lathe. Right now I'm in deep research... which is fun, but I can't wait to start bringing some equipment into the cave.
-- Pat

 

[zack24]

The most outrageous machine I ever worked on was a floor mounted polishing lathe- 5hp motor. 2" shaft and 24" wheels...used mainly for metal polishing....Took 30 seconds to spin down when you cut the power...not exactly OSHA approved...

 

[dochudson]

with one of these your grinder can be whatever speed you would like it to be..

link

 

[ssjones]

Harbor Freight has one as well, $20.

http://www.harborfreight.com/router-speed-control-43060.html

 

[drwatson]

I use a converted bench grinder, just have to be really careful..

 

[kashmir]

The thing about buffing wheels is that it real easy to erase nomenclature, or reduce vulcanite stem diameters so they don't exactly match the strummel. I used to have one, but after ruining a few cherished estates, I sold the thing, and do everything by hand now.

 

[ssjones]

I was at a Harbor Freight today and saw they had the Variable Speed router for $20. I've seen these referenced when discussing alternatives to proper speed buffing motors, but never actually heard from someone who used one.
I had a 20% coupon on my phone so I picked one up. I just tried it on my 3,650 RPM Sears buffing motor (two arbor). I don't think it worked very well at all and I'll return it on a future trip. The speed does vary, but when I put pressure against the wheel, I can easily stop the motor by the pad. The motor then has to slowly wind back up to the dialed in speed. It sure doesn't sound good and the motor sounds strained. That probably isn't good for the life of the motor. Even running at full speed, I can slow the motor with moderate pressure on the pad. So, by my experience, cross this one off your list.
And as Eric posted, these things are wood/stem removal machines, so proceed with caution!
http://www.harborfreight.com/router-speed-control-43060.html

 

[tbradsim1]

T

he safest thing for someone who is just a smoker and only needs to buff is a 2 head old timey shoe polisher, got one red and black buffers, works damn good , bought mine on the bay for 40$,

 

[ssjones]

I'll by sticking with my old furnace motor and swapping pads until something else comes along.

 

[johnnyiii]

HOW MUCH buffing does it need?? I'm not a pipe restorer but am a professional carpenter and finisher. I would buff it by hand at first. Would you put a buffer to your dining room table? If it is made out of metal don't answer that.