Adjustable Air Mini-Die Grinder Advise Please :)

[fcastro]

Hi guys, I am in the process of polishing a set of aluminum rims and have been reading about what the ideal speed to use us (3600-7000rpm) and what size wheel to use etc and now I need to make a decision as to what tool to get the job done. A polishing or bench grinder is out of my budget range. Aside from that I think it would be hard to use an 8inch wheel in a lot of the parts on the rim.

So with that said, I have found 2 mini-die grinder that say they have adjustable speeds on them. But the problem is they never say what the slowest speed would be once adjusted. The max speed is 25,000 which is way too fast for polishing. I was thinking 4"inch wheels and adjusting the die-grinder to 7000 rpm (not sure if that is possible)

Campbell Hausfeld PL1520 Pro 1/4" Mini Die Grinder:
http://www.amazon.com/Campbell-Hausf.../dp/B000Q5VHWO

Chicago Pneumatic CP876 Air Mini Air Die Grinder:
http://www.amazon.com/Chicago-Pneuma...4217277&sr=1-2

Anyone have any experience here as to speed and or which one is best? Or if this is even possible?

thanks in advance!

[tbreaden]

I have several die grinders that I use. But I use the CP-876 more than the others. It has a good amount of torque, I installed a inline brass regulator on it so you can adjust speed. I use 4" wheels most of the time but also use 3", flap wheels and felt bobs. It will work on most wheels fine.

[Rasper]

I have spent the past two days polishing stainless with two die grinders, one straight and one angle. I have been using a variety of buffs: 3 inch sewn buffs, one inch diameter felt bobs, 1/2 inch felt bobs, and 3/8 inch felt bobs. I use them at full speed and at all other speeds too. I just control it with my hand on the trigger. Be sure to tape the chucks so you won't gouge your work. And wear goggles. Anything spinning at 20,000 rpm will hurt your eyes if it turns loose.

(Sears sells an adapter for the Roto-Zip tool that fits a 1/4 inch chuck and holds Dremel sized bits, for about 7 dollars. It uses an allen wrench to hold in the Dremel bit. That way I can use the 1/2 inch and smaller felt bobs, with 1/8 inch shanks, in the die grinder.)

Richard

[Rasper]

Also, I have some Chicago Pneumatic air tools and they are of exceptional quality for the price. I am a Chicago Pneumatics fan.

[fcastro]

Hey guys thanks for the feedback. After reading and posting in a few sites almost everyone has told me that my compressor isn't going to have enough juice to run a grinder. It might but it would be on non-stop and craftman says to not have it on for more then 15 min.

So I may opt now for a high speed drill. Figure I can reuse a drill down the road.

I'm looking in this: Dewalt217 (0-4000 RPM)
http://www.toolbarn.com/product/dewalt/DW217/

I have had some serious issues trying to find a high speed drill. I figure at 4000RPM I can slap a 4" buff on this and be fine. All the other drills I have found run at 3000 or 3500 kind of odd I thought.

Anyone have any feedback about the drill situation? I have read up in the forums but not much data turned up.

[justme102]

Dont waste your money at an new expensive drill!
I have fu**ed up about 6 drills or more in the last years. Believe me, they wont run much time. And about 2500upm is enough. Buy a cheap (used) drill at ebay or so.
I have also killed a new die grinder from a big company in less than a half year.
So i would recommend a cheap drill or you spend big money on a professionell flexible shaft machine. I did it, and i dont regret my decission till now...

[fcastro]

justme102, no kidding?? Do you attribute the drills dying because of extended use etc?

[mpierich]

Originally Posted by justme102

Dont waste your money at an new expensive drill!
I have fu**ed up about 6 drills or more in the last years. Believe me, they wont run much time. And about 2500upm is enough. Buy a cheap (used) drill at ebay or so.
I have also killed a new die grinder from a big company in less than a half year.
So i would recommend a cheap drill or you spend big money on a professionell flexible shaft machine. I did it, and i dont regret my decission till now...

Actually, I agree. Electric drills burn up quickly. I was lucky enough to trade some polishing for a 1-1/4" diameter flex shaft, but it's not economical to buy one unless you do it professionally. The $20 air die grinders work fine for high speeds but you need a good compressor. I got a decent electric die grinder at Harbor Freight and it is holding up very well - in fact it's my main machine for initial steps. With a motor speed control (such as sold for routers), I could use my die grinder for polishing as well, but I have the flex shaft for that.

[Rasper]

Electric drills are designed for drilling. Most of the force is straight in line with the motor shaft so the bearings don't have to withstand much side thrust. The opposite is true with polishing. It's all side thrust. Electric drill bearings just aren't up to it. Hence the wisdom in using cheap used throw-away drills from yard sales.

Richard

[justme102]

Yes. The problem is the side thrust and the metallic dust from grinding/polishing. Also the running time is able to kill the gears/bearings. Most of these machines designed to run a short time. To drill a hole into something... If you use them for polishing they run hours - and thats to long for some machines.
But whats about a cheap drill and a flexible shaft for the drill?