Cutting Brass

Talk about all things CNC
WillAdams
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Re: Cutting Brass

Post by WillAdams » Tue Jul 22, 2014 5:28 pm

The lead is pretty tightly bound up in the balance of the brass alloy, so one's exposure is pretty minimal.

It wasn't that long ago that people would re-cast lead deadblow mallets at garages, &c. (but c.f., the story behind why Boeing got rid of all lead deadblow mallets on the shop floor) --- while it's something to take seriously and be careful of since it does accumulate, CA65 is more of a hindrance than a reasonable guideline IMO.
Shapeoko 3XL #0006 w/Makita RT0701 Router w/0.125″ and ¼″ Elaire precision collets
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secretspy711
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Re: Cutting Brass

Post by secretspy711 » Tue Jul 22, 2014 7:42 pm

whenever I see a metal part being made in a machine shop, I'm always baffled at how slowly the spindle is turning. Maybe you could try using a speed control? The DeWalt is up around 30k rpm with no speed control. I think maybe something less than 10k might be needed.

I have this one, it works really well, speeds are consistent.
http://www.amazon.com/gp/product/B001JH ... UTF8&psc=1

I see that brass has been added to the wiki... but mentions nothing about spindle speed.
Shapeoko 2 #5510: 1200 x 500 mm, Makita RT0701

hanselcj
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Re: Cutting Brass

Post by hanselcj » Tue Jul 22, 2014 7:59 pm

The wiki addition was my parameters. I wouldn't put much stock in those. After researching a bit on the brass material types, I see that the shim stock I have is not supposed to be very machinable. Took me a bit to find out what I have.

I bit the bullet and went with a mcmaster order of a few different types of engrave-able and easy machine brass. This gives me some things to play with. One of my other desires is to make a set of dovetail gauges for my woodworking. 1/8" brass ought to be awesome assuming I can get through it. I should have updates by the end of the weekend with my results.

-Chase
Shapeoko 2 #4951: Xbox 360 Pendant, Z-axis lead screw and NEMA23 upgrade, DW660 with Loc-Line dust collection, Googly Eyes, Swivel cutter attachment.

cvoinescu
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Re: Cutting Brass

Post by cvoinescu » Tue Jul 22, 2014 9:24 pm

secretspy711 wrote:whenever I see a metal part being made in a machine shop, I'm always baffled at how slowly the spindle is turning. Maybe you could try using a speed control? The DeWalt is up around 30k rpm with no speed control. I think maybe something less than 10k might be needed.
The first problem with that is that with open-loop control, torque decreases a lot when you reduce speed. The "real" spindles you see may turn slowly, but they have a lot of torque. This can be done with closed-loop control (e.g. SuperPID or a similar unit), but you run into another problem: the DW660 and similar spindles are cooled by a small impeller on the same shaft as the motor. When they turn slowly at high torque, they generate as much heat, if not more, than when running at their normal, high speed -- but the little fan is turning much slower, so they'll overheat. If you solve the cooling problem (external fan?), it is possible to use closed-loop control on a DW660 to get high torque at low speed.

The second problem is that this approach requires a very stiff machine, which the Shapeoko isn't.
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hanselcj
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Re: Cutting Brass

Post by hanselcj » Fri Jul 25, 2014 6:43 pm

I got the brass in from mcmaster, but blew a motor driver. One of the wires worked a little loose and now the Y axis doesnt work any more. Results are going to have to wait another week or two.

-Chase
Shapeoko 2 #4951: Xbox 360 Pendant, Z-axis lead screw and NEMA23 upgrade, DW660 with Loc-Line dust collection, Googly Eyes, Swivel cutter attachment.

hanselcj
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Location: Central Florida (east coast)

Re: Cutting Brass

Post by hanselcj » Fri Aug 08, 2014 8:16 pm

I got the blown driver replaced, and ended up building an electronics enclosure in the process. I ran out of time to do much experimenting with brass, but what little I was able to do turn out well. It is a dovetail marking gauge.

Image

I used 353 engravers brass from mcmaster (360 brass seems to be a good option too). If anyone has a good source, please pass it along. I couldn't find it any thinner than 1/16", and it was 25 bucks for a 6"x6" piece.

3 flute straight bit
0.063" diameter
0.01" stepdown
5"/min feed rates

The machining looks really great in my opinion. I could probably step up the speeds or start taking bigger bites. I will work through a handfull of my brass projects and report back with the best parameters I had.

-Chase
Shapeoko 2 #4951: Xbox 360 Pendant, Z-axis lead screw and NEMA23 upgrade, DW660 with Loc-Line dust collection, Googly Eyes, Swivel cutter attachment.

Scire
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Re: Cutting Brass

Post by Scire » Mon Oct 13, 2014 2:49 pm

If there is a metals Supermarket nearby, i paid about the same for a footl length of 3/8" deep and 4" wide bit of bar. its c360.

http://metalsupermarkets.com/

Good luck.

Scire

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