Height issues

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sawdust1
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Height issues

Post by sawdust1 »

I know I am missing something in my settings, my torch always cut too high. Occasionally not able to pierce.
I have a Miller 375 Cutmate that I run at about 27 amps.

I am using Sheetcam 6.0.15

Under options / job options i have thickness of material 1.5mm
rapid clearance 5mm
Height of material above table 0mm
plunge safety 5mm
under post processor top of work or top of table I have tried both
Pierce height 2mm
cut height 1.55mm


I always seem to end up with a travel height of 6.5mm pierce at 4 cut height of 3mm. These height may not be precise, I have no way of measuring under my torch except a thin wood shim.

If someone could see what I am doing wrong I would appreciate it.

David
sawdust1
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Re: Height issues

Post by sawdust1 »

Got this solved... with an accident.

I use linux cnc, there is a setting you select top of work piece, top of table or top of spoilboard. Even though I kept selecting top of table therefore bottom of metal it kept reverting and then would cut too high. I accidentley turned the computer off and it saved the setting!
david
pupdogg
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Re: Height issues

Post by pupdogg »

Hi @sawdust1, I think I'm having the same problem as well. Can you please explain where I can find this setting?
sphurley
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Re: Height issues

Post by sphurley »

Sawdust, If you are using Mach and SheetCam and you don't have an floating head or ohmic touchoff, then you need to make sure you set the Z axis offset it both Mach and Sheetcam to 0.0, Or some say you must use 0.001 or it defaults to .04. You should see this in the G-code.
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sawdust1
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Re: Height issues

Post by sawdust1 »

I use Sheetcam and LinuxCNC No floating head or touchoff. I had managed to set my zero at the top of the material and that was causing me grief. I got it changed to the bottom of material/top of spoilboard but it would not stay there until I accidentley unplugged the computer. The computer remembered after the restart.

I cannot find however where the devil that setting was located! I remember it was hard to find the first time too.
I would like to put a floating head in there, I have the parts just have not gotten around to it. I do not normally cut large pieces so there is no issue.
David
Rtodahl01
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Re: Height issues

Post by Rtodahl01 »

I am having this problem too
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djreiswig
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Re: Height issues

Post by djreiswig »

Is there a switch offset programmed into your post processor? I'm not sure how that could affect a table without a floating head.
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acourtjester
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Re: Height issues

Post by acourtjester »

I may not understand your system setup but you are using the word "Spoilboard" this is usually for a wood routing function. you are looking at the bottom of the material not the top of the metal (plasma), this is looking at the material thickness. This is so you don't rout through the material and hit the spoilbaord. With plasma you need to know where the top of the metal is for the setting the pierce height. I don't know about LinuxCNC but do you use a post processor, if you do it will be different for routing verses plasma as routing you move down for cutting and plasma you move up from the top of the metal.
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Rtodahl01
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Re: Height issues

Post by Rtodahl01 »

I will try reseting to top of material
Thanks
tcaudle
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Re: Height issues

Post by tcaudle »

The problem with metal is it warps when its cut. sometimes just a little sometimes a lot. So the "Top Of Material" changes. The Linux system in its Work offsets only knows where the last touch off said the material was . Setting it one time with no touch off will result in bad pierces and /or bad cuts. In plasma cutting its all about Arc Gap (distance between the top of material and the nozzle of the torch) a change of even .01 inch can make a difference when you are cutting at .06. While the THC should be able to track the material as it changes it still has that (first) zero in the Work offset so when you tell it to pierce at say .150 it assumes the top of material is still where it started and if the material warps your actual pierce hight will be more or less than that. Also the plunge from pierce to cut hieght is to a specific distance (all before the THC even cuts in) . Automated cutting without IHS (touch off) is only usable on really flat material that does not warp if you have material that is flat and does not warp then you don't need a THC..
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