Is there a way to improve the cut quality of small circles with the Plasma EX controller? This plate is 3/8” thick with 1/2” diameter circles. I’m using the 3/8” Steel Material Profile in the EX Controller. Torch is a Hypertherm 45xp.
I don’t have a video of the small circles but here’s a link to it cutting the large circle and I’m not sure if the trail of sparks leading slightly ahead of the cut indicate a problem. By the way, this is on a high static pressure downdraft table. Plasma Cut Video
Are the large outer circles out of round, or just the small ones?
A couple of other questions: What are you using to create your G code, and can you post that G code here so I can take a look at it?
Also, is the out of roundness proportional to the hole size, or the same absolute difference independent of hole size[*]? Is there any correlation between the unround section and the piercing location?
[*] i.e. is it always off by 10%, or always off by 3mm
Thanks guys. I just double checked and the larger circle is out of round as well. The large circle has the following diameter dimensions: X 8.351”, Y 8.366”, Diagonal of XY 8.372”
The smaller circle is harder to measure because I already welded them but they appear to be out of round by the following diameter dimensions: X 0.500”, Y 0.524”, Diagonal of XY 0.540”
(All of these measurements were taken from the top side of the cut so that the bevel didn’t affect these dimensions)
I also noticed that the natural beveled angle of the plasma cut switches from going to the outside of the cut to the inside during the middle of the toolpath? I thought that it would only reverse directions if the toolpath rotation was changed from climb to conventional.
Attached is the toolpath that was created with Aspire and the EX Plasma Post Processor.
Airbag Plate Mount.cnc (3.9 KB)
You might have a couple of things going on here…
First rule out any mechanical issues: X and Y Axes - Troubleshooting
Then we can dig into your toolpath. The air swirl on a plasma torch is clockwise, and as such the “good” side of the cut is to the right.
In your G code file you’re spinning clockwise on your small circles on the inside, and counterclockwise on the big outer circle. This means that the “good” side of your cut is in your scrap.
You can switch your cut direction in Vectric by using “conventional” instead of “climb” (or vica versa)
On the small circles it’s hard to get those accurate given how plasma works, when you do that pierce you blow a big hole in the metal, and when you come back around on the cut the torch is trying to find more metal to cut, and it looks like it found some on the outside of your circle.
I think reversing your cut direction will help here. Also you have pierced somewhat in the middle of the cirlce which is good, try and go more in the middle. Looks like you have a little overcut distance too which is also good.
For small holes you won’t ever get them perfect, but you can certainly get better than you have.
Try that out.
Thanks Eric. I’ll do some troubleshooting with the Mechanical issues. Also, I had selected Conventional in Aspire…so are you saying I should use Climb? I’ve attached the Aspire file below.
Airbag Plate Mount.crv3d (120 KB)
The “good” side of the cut is to the right in plasma, so your climb/convention selection depends on what you consider the “good” side.
Since you have a large circle with parts inside you would want the big outside cut going clockwise, looks like you have it counter clockwise.
Your inside circles you’d want counter clockwise because you want the “good” side of the cut to the right (because your scrap is in the middle)
Even though you have “conventional” selected there your cut appears to be going counterclockwise (on the large outside cut)
Thanks Eric and I did some more testing. Since I have a dual machine, I cut some 1” circles with the router and they came out good (within +/- 0.002”). I haven’t been able to find any noticeable mechanical slop. Is there a way that I can compare settings/parameters between my Router Profile on the EX Control and the Plasma Profile just to make sure something isn’t off in the control?
If your router is cutting well than this isn’t a mechanical issue, this is a plasma strategy issue. Try my advice above for cutting direction
I adjusted the small hole toolpath to counterclockwise and also adjusted the lead in to start further away which has helped. It’s still varies in roundness from 0.500” to 0.530”. The last picture with the scrap still in the middle was another test on 1/8” plate to see if material thickness made a difference but it was about the same.
You could keep messing with leads and over cuts to dial it more… and the end of the day however small holes are hard in plasma.
You might consider a fine cut tip on thinner metals.
I’m not a plasma user, but looking at your photos I have to wonder… could your torch be emitting a non-circular plasma? So that it has a wider kerf in the Y direction than in the X direction?