[hualon]

I'm a newbie that's using a CNC machine equipped with a rotozip as the spindle. I have had pretty good success cutting .02" brass sheet but I've run into problems where even at a very slow cutting rate the bit will get too hot and/or lose its cutting ability.

What bit material would be best for cutting .02" brass (2D straight-through cuts) and what speed should I be running? Do I need to use some sort of coolant for the cuts?

Thanks!

[thething84]

brass is one of the few freecutting material. No cutting fluid is needed as brass is a self lubricating material.
Make sure the cutter u are using is sharp, and trail and error with feed rate etc. Shouldn't really have any problem with cutting it

[Lew Hartswick]

Your "Rotozip" is probably running way to fast for brass. They were intended
for things like dry wall and wood . If you slow it down it may not have enough
torque to do the job.
...lew...

[hualon]

Can you tell me how fast it's supposed to go?

[blackbeard52]

Speed and feed are pretty much a matter of opinion. Tool manufacturers will give a standard that mostly work. Having said that it has been my experience that what Lew said is correct. I think the rotozip turns about 30,000 rpm and is way above what you should be cutting. and lowering to say 10,000 would help but the tool would bog down almost immediately because torque is reduced to 1/4 at that speed. Now there are a few tricks that work...I am assuming you are not using a wild alloy in brass(brass being an alloy anyway). Cutting with as few flutes as you can is best. turning at that speed the more relief in flute depth is premimum. So a single or 2 flute 1/2" bit will cut better than a 1/4 of the same bit material. and straight flutes will break up the chips better as spiral flute seem to curl the chips and is very undesirable in removal of debris. Due to the lead content in brass TIN coating doesnt seem to help with tool wear and in most cases hampers it. Since it is a free machining material no cutting fluid needs to be used. In most situations the use of high speed tool material and not carbide is used but at the speeds you are turning carbide might be a good option.

Just my experience and opinion hope it helps.
Bob