Nil wiggle, max melt

[BensPlasmaAu]

I have sorted out the wiggle. It was the jammed drives. I need to redesign the drive to take a much bigger drive shaft and some new timing gears. But for the meantime it seem to be working and thats where i'll leave it for a bit.

So i did this cut of a sign, i thought i had everything worked out in terms of CAD, sheetcam and how it cut. But the issues i have had is beyond me. I use BobCAD to design the thing, and Sheetcam for the toolpath. I thought i would get clever and add a cutting rule to slow down on corners. This was a mass failure due to the sign being pretty intricate. It was "On all corners, slow to 60% 5mm before. DTHC to off. 100% feed 5mm after corner and DTHC to on" This basically caused everything to melt away into lovely balls of molten metal and slag. So i redid it and removed all cut rule. The below pictures is what i ended up with.

It seems that regardless of removing the cut rules, it slows down on all the curves so much that again molten metal and slag is caused. So to see how it all works in the background, i have attached the CAD file and the SheetCam .tap The dxf to sheetcam bit has been interesting as even though i have an inside layer and an outside layer to sort the offset of the cuts the lead ins and outs are being put on the wrong side of the line. It's definitely something i've done, just not sure what.

EE Sign files.zip

(215.55 KiB) Downloaded 62 times

I hope someone can take a few moments and load up these files and see how they go on their machine. If you have the same issues as me then it is all in the files and the process i created them. If it work great, then it's got something to do with the machine setup.

Thanks in advance again

Ben

[sphurley]

EEfixed.dxf

(382.46 KiB) Downloaded 74 times

Ben try this DXF

[motoguy]

She. Sheetcam puts the lead in/lead out on the "wrong" side, I've found it's usually a drawing issue. Non-closed curve, line looping over itself at a node, duplicate lines, etc.

[BensPlasmaAu]

EEfixed.dxf

Ben try this DXF

Thanks Steve, ill give ita go. What do you usefor your designing and fixing for that matter?

[sphurley]

I use Aspire from Vectric. I came from the wood world and 3d it is over kill for plasma but it has a feature that shows the open nodes (you had >1500) and
allows you to fix them with one click. I like clicks but can't draw like you!

[BensPlasmaAu]

EEfixed.dxf

Ben try this DXF

Hi Steve

I don't have the internets running at the workshop right so i havent had a chance to get your dxf a try. I did try a new way of doing things with designing. I do the basic design in Inkscape, then if i need to do anything more in depth, i send it to the cad and ammend it from there. Im not good enough with inkscape to work out how to do everything in that. Anyway, i cut the node count down drastically.

I sent it off to the plasma and it didnt cut nearly as smooth. Slowing down on node points again. I went back into mach3 and found the CV settings and changed the toggle LED's (i guess you could call them that). I tried again and it cut smooth as. The corners of letters are unfortunately rounded, but there is no slow down for each node.

I think i need to turn the CV settings down a bit. Its currently set to 1 and im pretty sure i read someone in the forum say that they found they needed to run at .79.

I was going to add some pictures, but for some reason it wont allow me to add photos from the gallery anymore. Ill post some when i get home.

[RAD]

Did you get this fixed? I had rounding on corners when doing pen traces of small lettering of 1/2" high, it was also not smooth lines especially at high ipm, I found that lowering accel. and velocity helped alot, I think one is relative to the other and you need the right ratio for smooth sharp corners, for my machine 0.2 sec to full velocity seems to work best. I am not sure if I'm correct tho. Can anyone confirm. I had no luck with adjusting cv settings. But adjusting velocity and acceleration helped.

[BensPlasmaAu]

Hi RAD,

I havent fixed it entirely yet. For the time being it will have to do though. I have things to cut and money to make lol. I will have to fiddle with the velocity and acceleration when i get the machine back up and running. But first, i need a replacement PWM sensor. DAMMIT!!! See new thread.......

I have to try and convert everyones velocity though from imperial to metric, it kind of confuses me when people are saying 300 ipm and i have to convert it to 7000mm/min. I sometime start overthinking things and realising that i am waayyy too high in my settings, then realise that i'm somewhere near OK. I then have to go back to the workshop again and again to retry settings. I'll get it back up and running and post more on this thread.

Ben