"Origami" CNC Plasma Build - folding 1200 x 600mm cut area

Started doing some investigation into piercing strategies after some conversations on the topic.   To start with how to leverage the wiggle leadin that sheetcam supports.   Here are a couple of little videos that showed a dry run of (a) the wiggle under normal plasmac control and (b) using my custom plasmac with a new pin set to True.

(a) In the first part of the video you will see the normal probe sequence then a short wait, the torch drops to cut height then the wiggle and cuting morion continues.
(b)in the second half the video shows the probe then goes immediately into wiggle and then after ~3 wiggles the torch drops to cut height and continues on with cutting.


This second video is doing the actual cut with an active torch as shown by (b) above.   This is 27A on 6mm mild steel in an attempt to mimic a thick steel pierce".  First tome ever done on this setting so obviously tuning to be done on the number of wiggles.  But it does prove that the process will execute on a live torch.


The next line of investigation will be in to the ramp leadin pierce that sheetcam supports.

Cheers - J.

After reading the Hypertherm paper on moving pierce (ramp pierce) I have a little progress.  I tried using
 sheetcam generated code but it relies on having z gcode kept by qtplasmac.  This also got messy as you need to touch Z0 off as material top. I decided I wanted to keep the “throw material on, align/zero xy home and go. So that meant doing all the Z ramp heigh change inside plasmac.

After quite a bit of code reading and scribbles I have an initial ramping pierce using the height stage transitions per hypertherm. Next will be the  speeds and associated transition time points for them.  That being Gouge, Intermediate/Crawl and Cut. 

here is a sim pic of the ramp from pierce height to pierce end height then to cut height.

 

cheers - J

A liitle update.   We have a water table with slats!
 

Also recently being doing some testing of piercing steel that is thick (for my plama).  I have a Cutskill 60 by Cigweld (sub brand of ESAB) and while it claims to be able to clean cut up to 20mm the ability to pierce is a very different kettle of fish.  Max pierce of 15mm at 60Amps is the limit I am looking to break. Versus having to do edge starts.  Breaking that limit without stuffing the consumables on each pierce.  To that end this testing in 16mm steel at 60Amps.


Top of pierce and cut
 
Bottom of pierce.  Left side is previous test and has been cleaned. The right side is not cleaned.
 
Consumables post two pierces.  These were not new before that having done a number of cuts.
 
 

No picture of it folded?

Hmmm ,,, pretty sure I have some before putting all the slats in.

After some initial cutting and some stress testing I conluded that the gantry needed dual linear rails.  On HGR15 rail the bearings are pretty good but they are weakest on twist around the length of the rail.  i.e. if you look down the length of the rail and twist the bearing left or tight on the axis the is way way way more movement then when you are looking at the rail face on (such that the moiunting holes are all facing you) and you then try and twist the bearing block left/right (good luck moving it).

This meant that when doing "high" accelerations and movement speeds it was easy to create wobble in the torch.   SO two rails will lock that right down.  And it does.  So design advice to anyone else doing this, either consider 25mm rail (it's propbably going to better in that direction) or dual 15mms.

A few pics attached.   Once things are all back together I will retest and post results.

Cheers - J.