Plasma Cutter

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Re: Plasma Cutter

Postby Cre8ivdsgn » Mon Oct 01, 2012 3:15 pm

Seems to make excellent sense to me. I quick look at McMaster says that the pitch diameter of 0.625 yelds a 1.963" per revolution of the pinion. I don't recall your drive versus driven pullies, but a 2:1 ratio would keep torque reasonable for NEMA 17 motors, I think (given probable axis weights).

More importantly the 24 pitch 15 tooth is still a 1/4" bore, making axles easy.

And its pretty easy to simply order from McMaster (I am preuming that is who you went with). Still, Moore does do nice stuff. One company I know has them make a pinion with axle as one solid piece. In quantity, and at least for industrial grade, the pricing can be reasonable for that sort of thing. It isn't reasonable for the one and two piece world of the home manufacturer though!

Still thinking out loud...
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Re: Plasma Cutter

Postby bobt » Mon Oct 01, 2012 5:49 pm

Bart - Is it possible to move this thread into its own forum group like the Ordbot group as I want to build one of these units as soon as you release any documentation and such. It seems that YOU are the center of the universe with using MakerSlide and implementing it's usage for small shops.

Many Thanks for you efforts with this.

Bob Teeter
"What Box"
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Re: Plasma Cutter

Postby lasersafe1 » Tue Oct 02, 2012 8:58 pm

Cre8ivdsgn wrote:Seems to make excellent sense to me. I quick look at McMaster says that the pitch diameter of 0.625 yelds a 1.963" per revolution of the pinion. I don't recall your drive versus driven pullies, but a 2:1 ratio would keep torque reasonable for NEMA 17 motors, I think (given probable axis weights).


I'm not seeing the logic behind NEMA17. Price difference is minimal for NEMA23, and why give up the great performance of NEMA23? A few lost steps and you're screwed if you undersize the motor. That being said, have you seen the cute little NEMA 8 motors on Pololu.com for $16? They would be good for building that new "post card laser cutter".
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Re: Plasma Cutter

Postby bdring » Tue Oct 02, 2012 11:20 pm

I might try it with both size motors. The only one I really don't know about is the Z. Will the detent torque hold up the torch? I kind of think it will with the drive ratio helping add some torque.
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Re: Plasma Cutter

Postby macona » Thu Oct 04, 2012 2:59 am

lasersafe1 wrote:
macona wrote:Plasma cutting of aluminum is usually not very pretty.


According to many posts over at CNCzone, this was true until about 5 years ago. Apparently the new inverter controls of the best systems can produce results on aluminum that are very clean with no slag using only air. Accuracies down to .003", which approaches that of laser and water cutting.

The model that Bart has purchased is among these newer types. Perhaps we will soon start to see videos of his cuts. It took me a few months to get my laser "dialed in" to be satisfactory on every type of material. I'm sure Bart is going through the same thing now as he jumps between his many projects.



It is more torch design than anything. Thats is where the innovation is, especially with the hi-def stuff.

Inverter plasma cutters have been around since the 80's with the early Linde/LTec plasma cutters and all of Hypertherm's portlable plasma cutters since the old Max42 have been inverters. Inverter is just a fancy name for a switched mode power supply.
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Floating Z Demo

Postby bdring » Wed Oct 10, 2012 4:12 pm

Here is a demo of the floating Z.

The torch is on a carriage that floats on the Z axis. When the Z goes down the torch tip will hit the material, but still allow the Z to move by "floating up" on the axis. As the Z is over traveling a limit switch is triggered. The over travel distance is consistent and known so instead of setting the Z to zero with the limit switch is triggered it sets it to -0.268 in my case. If you listen you can here the limit switch click in the video.

This allows you to rezero before each pierce if you like. The code would look like this.

G28.1 Z0 (Home Z)
G0 Z0.15 (move to piece height)
...turn on torch...wait a bit to pierce...run profile...turn off torch...retract..

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Hot Snowflakes Are Falling at buildlog.net

Postby bdring » Wed Oct 10, 2012 7:26 pm

Here is a test run of the CNC Plasma Cutter. I am cutting out a PS:One Snowflake Logo.



pl_snowflake.JPG
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Re: Plasma Cutter

Postby lasersafe1 » Wed Oct 10, 2012 7:47 pm

Super Awesomeness! What is the wall power draw on your cutter? That sure would have taken a whole lot longer in my mill! How 'bout some Ninja throwing stars?
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Re: Plasma Cutter

Postby bdring » Wed Oct 10, 2012 8:09 pm

That cut was run at like 80ipm at 30Amps. I have run it up to about 180ips while cutting without a problem at that same power. I can go up to 45Amps. I have million variables to play with for a while, but the results are pretty cool.

The neighbors are already lining up with projects.
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Control Box Schematic

Postby bdring » Sat Oct 13, 2012 1:24 am

Here is my schematic for the control box. See the PDF for better resolution

ctrl_schm.jpg
Attachments
plasma_box_schematic.pdf
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