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Old 03-12-2013, 10:42 PM
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edwardn edwardn is offline
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Default cnc plasma cut part

A fellow brought in a part from a vacuum truck that he wanted me to copy and make for him, the old plate was made out of 1/16" and he wanted the new one made from 1/4", he supplied the new metal plate. I drew the pattern in Corel draw, ran it threw sheet cam and while in there set the cut sequence so the torch wouldn't pass over pieces already cut to avoid tip ups.. This is my first attempt at cnc cutting 1/4" plate, I used a 80 amp nozzle set at 80 amps on my 1250 hypertherm and ran it at 105" per minute as the their recommended settings.

http://youtu.be/uKdBsENWdek

http://youtu.be/b6dGMw9V8CI


Since this was my first attempt at ¼” plate I decided to give myself 3 test cuts before cutting the actually part, the cuts were ok so I went ahead and cut the rest out, sorry for the shaky video, I was multi-tasking and nervous as I haven’t used my machine since last summer. I always like to add some water while cutting as it helps keep down the smoke, especially using 80 amp

http://youtu.be/nDG23gKmxkQ

http://youtu.be/P0XkPFXRi1o

The finished part:

http://youtu.be/r9s-Lmx41UA


EDD
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Old 03-12-2013, 11:13 PM
ephotrod ephotrod is offline
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Edd,
I've never used a cnc plasma, but I still have a question. Why wouldn't you start the cut of each small hole in the hole to be cut out as opposed to the edge of the holes.
Josh
Very nice job, I enjoyed watching.
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Old 03-13-2013, 12:05 AM
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edwardn edwardn is offline
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Quote:
Originally Posted by ephotrod View Post
Edd,
I've never used a cnc plasma, but I still have a question. Why wouldn't you start the cut of each small hole in the hole to be cut out as opposed to the edge of the holes.
Josh
Very nice job, I enjoyed watching.
Thanks Josh
With cnc you have inside and outside cuts, or line cuts.... the 3 test cuts were outside the part i wanted to cut so they were cut as outside, so the pierce, lead in lead out cuts started on the outside of the piece, the cut outs inside the large ring were inside cuts so the pierce, lead ins lead outs were on the scrap piece being removed, you can also see that the test cuts being outside cuts are going in a clockwise direction while the inside cuts go counter clockwise, outside clock wise cuts have less kerf angle due to the rotation or swirl movement of the plasma arc in relation to the direction the torch is traveling... it is important in most cases that the pierce points are off the cut line because when piercing it will blow a larger hole than the cut line and you will see a burr or indent in the cut, so the lead ins/outs play the role in eliminating this... I use Sheetcam to convert my Corel Draw .dxf files to G-code and when set up properly it will automatically determine all the inside/outside cuts and add the lead ins/outs on its own, I just need to decide what kind of lead ins I want to use, and how long I want them, pierce time etc plus as I did with this part, number the cut sequence so the torch isnt passing over pieces I already cut to avoid crashing into tip ups. I hope that helped answer your question.
Regards
EDD
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Old 03-13-2013, 06:50 AM
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allessence allessence is offline
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Nice job..

I'd love to get one of those in the shop.. Only problem is I'd have to work outside.
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Old 03-13-2013, 07:58 AM
jimcolt jimcolt is offline
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Josh,

The software that comes with most plasma cnc machines post processes the part drawing (usually an autocad format .dxf file) and adds lead ins and lead outs that will start the cut in scrap material and end the cut in scrap...if desired. When you pierce through material with a plasma torch the pierce hole is wider than the cut (once the torch is moving)....so if the pierce was done on the cut path you would have a divot in the cut part. The same post processing software also compensates for the width of the cut (kerf) and automatically sets the cut direction (plasma cutting has a good side and a bad side) for best accuracy and cut quality.

The part (1/4" steel) cut in the videos was cut at 80 amps using a Hypertherm air plasma. 80 amps will provide the fastest speed for this systm, however if you desired better edge angularity and edge smoothness he could have cut the part using a 40 amp nozzle at a slower speed...the edge would be much nicer if that was necessary for the finished part.

Jim Colt Hypertherm


Quote:
Originally Posted by ephotrod View Post
Edd,
I've never used a cnc plasma, but I still have a question. Why wouldn't you start the cut of each small hole in the hole to be cut out as opposed to the edge of the holes.
Josh
Very nice job, I enjoyed watching.
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Old 03-13-2013, 08:09 AM
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platypus20 platypus20 is offline
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I was at the LWS, last week, they have 2 pieces of equipment on the display floor that I want, they have a Scotsman 40 ton ironworker (with many numerous attachments) at $9800, thats single phase and they have a 4' x 4' Torchmate CNC plasma table (with computer software and the plasma cutter power source) a demo, at $9950. I wouldn't need or want the plasma cutter as I already have a adequate supply, but its a package, they won't break up.
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Old 03-13-2013, 08:24 AM
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So, what ya gonna make out of all them little circle drops?!?
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Old 03-13-2013, 08:50 AM
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Edd, if you are nervous with 1/4" you should get yourself some 5/8" plate to practice with You will lose your nervousness of 1/4" quickly when you see what that machine will do.
I cut 1/4 with Finecut tips with 50 amps at 48 ipm. If it is all straight lines I will tweak to the speed to 50+ inches.
Like Jim says it is hard to get a smooth cut on such thin material at 80 amps.
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Old 03-13-2013, 08:51 AM
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Quote:
Originally Posted by platypus20 View Post
I was at the LWS, last week, they have 2 pieces of equipment on the display floor that I want, they have a Scotsman 40 ton ironworker (with many numerous attachments) at $9800, thats single phase and they have a 4' x 4' Torchmate CNC plasma table (with computer software and the plasma cutter power source) a demo, at $9950. I wouldn't need or want the plasma cutter as I already have a adequate supply, but its a package, they won't break up.
I would recommend the Torchmate, as you can have a contest and give away the extra plasma source for a prize
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Old 03-13-2013, 09:17 AM
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Quote:
Originally Posted by Ironman View Post
Edd, if you are nervous with 1/4" you should get yourself some 5/8" plate to practice with You will lose your nervousness of 1/4" quickly when you see what that machine will do.
I cut 1/4 with Finecut tips with 50 amps at 48 ipm. If it is all straight lines I will tweak to the speed to 50+ inches.
Like Jim says it is hard to get a smooth cut on such thin material at 80 amps.
Hi Gerry

The 80 amp did a good job, there was a little dross here and there but that was it and it didn't really matter any ways, if anything I could have increased the ipm. I wasn't nervous because of cutting 1/4" it was because I haven't used my table for quite some time and the last time I was cutting 16 ounce copper sheet which in my opinion is more complex than thicker material. I use the 40 amp fine cut for most of what I do but its good to also experiment with other options as well, I have 40 amp shielded but opted for the 80 amp to see what it could do as I dont the opportunity very often to crank up my plasma cutter to the max. Hypertherms manual is pretty much bang on for settings so it makes it a lot easier trying out something different for a change.
EDD
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