Plasma table build, first question....

**Davek0974** · 12-01-2014

Hi all,
looking to build a small table for my plasma, before getting in too deep with plans I have one question...

My torch is a contact start, the head can be dragged or used at a small distance, is this unit suitable?

its an R-Tech 30A unit but as I only want to cut stuff up to about 5mm it's worked ok so far.

It's a bit of a deal breaker so is it any good or not?

**Lee Roberts** · 12-01-2014

I dont know much about Plasma heads but i do remember seeing one being used where the head would come down and touch off the metal and then start. So i think you could use it this way as well ?

.Me

**Davek0974** · 13-01-2014

Hmm, just checked the website again, it states it has "HF arc start", this is the unit... P30C Plasma Cutter, 240v, R-Tech Plasma Cutting Equipment So hopefully it will do the job, I was looking at manual torch height for simplicity/cost. Dave

**Davek0974** · 13-01-2014

Hmm, to save time and money I thought I'd ring R-Tech as they have been very helpful in the past. It seems my torch would not be good for CNC as it is a contact-start head and CNC really needs an HF Pilot arc. He said it "might" work but the arc may not always strike when told and that would waste the work-piece. Sounds like my project is not going far unless i sell my plasma and upgrade the unit which would blow most of my budget.

**Davek0974** · 13-01-2014

Thinking on some more, I could likely build the table first then upgrade my plasma later on to one with a pilot arc, that should work better.

next question is, can this be done without torch height control?

adding this seems to be very expensive and would blow all of my budget on that part alone, is there a manual height option that works?

**Davek0974** · 14-01-2014

Upon doing some more web searching, I found a couple of excellent pages... Home Page And Scratch Build scratch build cnc table (plasma and router) - bit-tech.net Forums Both show budget builds and the last one is so amazing that it practically says "Just bung it together and it will work". The first thread uses a drag-torch as well although he does mention it's limitations. So in light of these discoveries I think I will proceed to the fag-packet stage and start drawing up some ideas of frame and motion methods. I'm using 44mm structural aluminium for the chassis as i have tons of it, might run the carriage bearings direct onto the frame rails or possibly fit some plate to each side and use V-rollers top and bottom. My criteria so far are... Cheap, Small, Light, Table-top. I'm looking at T5 belt drive to both sides of the gantry via a main drive shaft with one stepper driving it via a reduction system. Again the X axis will be T5 belt drive as i have a box full of useful T5 pulleys Probably 3Nm Nema23 motors, drive gear from ebay, mach3, sheetcam etc Anyone wants to throw ideas in please feel free.

**Peter Fouché** · 19-01-2014

I'm looking into a bigger project but I also want to use my chinese plasma in it. I always keep my torch in contact during cutting. I plan to spring load the torch to follow undulations in the surface.

**Davek0974** · 27-01-2014

Originally Posted by Peter Fouché

I'm looking into a bigger project but I also want to use my chinese plasma in it. I always keep my torch in contact during cutting. I plan to spring load the torch to follow undulations in the surface.

How does it handle piercing?

my torch will pierce at 90deg but prefers being angled over a bit until pierced.

it may be over engineering it but maybe the torch could be mounted on a cradle that when driven into the work makes the torch tip over and then self-corrects when the z axis is lifted, so maybe it would pierce at -10mm and cut at +1.5mm??

just wondering.

i got the carriage mounted today and fitted the z-axis to it, pictures to follow, looking at connecting my drive belts to the gantry now.