STV Torch Height and other issues

[Pyro1983]

Hey guys, my first post ever here. Also a newbie to cnc plasma! I've done a ton of reading and can't be more pleased with the vast amount of info on here! So, I pulled a dxf file from this site, cut it and inspected it as I'm still dialing in my table. It is a 5x5 STV CNC pro 5 fully welded table, magnetic breakaway, gear reduction , floating head hooked to a hypertherm 45xp. I haven't made a ton of cuts yet but the ones I HAVE made, have improved each time. So on this latest design, I noticed I have very rough curved sections. So doing my research on here I found that having a ton of nodes in a design can cause this. Did my reading after making sure everything on the machine was still rigid which it was. So I pulled it up in inkscape and sure enough, it's got a bazillion nodes on all the curves. So I THINK that's what's causing that issue. My next issue/question is my torch height. I did some testing via physical measurements with the THC turned off and cutting straight lines. With the cut height set to .06, the physical height of the torch was well over that...probably over .150 (didn't get exact measurement) As a quick fix I had to set my torch height to .03 for it to be physically at .06 - so my actual question (finally lol) would be, How can I get my set cut height to match my physical measured height? Physical Pierce height is higher than the entered value as well thats why its set to .1... I will try posting a few pictures with this post. Thanks in advance and sorry for the long post!

[acourtjester]

First off I would look at the steps per for you Z axis, the table follows the G-code. So if the calibration for the Z is off so will be the torch height.
Did you buy the table used or new? Another thing is slippage of the drive assembly for the Z axis, motor turning torch not moving this can be slight but will affect the height.

[weldguy]

The rough cut edges could be the high node count, easy to get a cleaner design with no more nodes than required and see if that helps.

As for your cut height with THC off I am not familiar with STV setup but its possible if it has a floating head material sensing that the floating head switch is adjustable so you can move it allowing the switch to activate sooner and take up that extra .090" or there could be an offset adjustment in the software that will accomplish the same thing.

Let us know what you find.

[Pyro1983]

Well, turned out to be a fairly simple fix. Had to adjust the floating head switch correction parameter. That got it very close to the programmed heights so I'm satisfied with that and will let the THC take care of the rest. As far as the rough corners, I cleaned up a lot of unnecessary nodes and ran another one and it looks pretty smooth. Had a slight bevel (bottom of the material was bigger) so I raided the voltage a bit and that seemed to be the ticket. Still trying small tweaks here and there to get the finest kerf possible. Got some fine cut tips on the way. With the 45xp, are guys turning down the amperage to get really fine cuts? Running low amps, low cut speeds and little to no pierce delay? When cutting 16 gauge or thinner, would it be advisable to make the pierce height the same as the cut height since it's super fast? I was doing a few test lines again and noticed the pierce was good, then a short section where it didn't cut through and then the remainder of the line was good. I'm assuming the area left uncut was where the torch was on its way down from the pierce height.

[adbuch]

To address the node count in Inkscape, you can use the "Path, Simplify" tool.

David

[adbuch]

If your table can handle it, I would recommend cutting at Hypertherm "Book Specs" using the FineCut consumables for 10 ga. and thinner material. See the first cut chart below.

There is also a cut chart for Low Speed FineCut. Second chart.

Make sure your pierce delay time is sufficient so that the pierce completes before the torch begins moving along the cut path. With the exception of 14 ga. steel, the best cuts will result from using the Hypertherm mechanized cut chart settings.

If you have the capability - set your corner acceleration to around 0.02 to 0.05 G. For brand new FineCut consumables, set your cut height to around 0.075" to 0.080" for the first several hundred pierces - and then drop back to 0.060" cut height for the remainder of the consumable (electrode/nozzle) life.

David

FineCut Mild Steel.jpg (71.02 KiB) Viewed 934 times

Low Speed FineCut Mild Steel.jpg (63.66 KiB) Viewed 934 times

[acourtjester]

With some fine cuts you can drop your pierce height too, with you fine tune you can play with the numbers to get things as you want it. David pointing out the node count, something many don't think about is each node is a line of code, which can affect the cutting. This comes in as part of the planning of a cut, a cleaner G-code, and part of learning plasma CNC. Use the search function here to go back and read other posts about different topics to see what others have said about things.
Have fun