[5vzfehilux]

I was given an allmax CUT416 for free (that might be the issue right there). Pretty stoked to get it set up and try it out, so I hooked it up to the neighbour's old compressor and of course had to chase leaks out of that (happily nothing more than a runaround with a spanner nipping up fittings). Anyway, after having to do the same thing with the plasma the whole show was now air tight and ready to go.
I set the plasma to about 0.5MPA and 35 amps (max is 40) off we went with some 4mm plate that I had stripped the gal off beforehand. It cut pretty easily but with only an autodarkening welding helmet that jumped straight to the tig shade setting and no experience, I couldn't really see what I was doing so I missed both ends so the plate ended up still in one piece just with a fairly neat for a noob gouge down the middle. The torch was not dragged or touching the plate the whole time. I thought nothing shade 5 glasses and lots lots more practice couldn't fix.
The cutting tip looked a little worse for wear after just one run with some dark grey oxidising but I thought it would be good enough to finish the job and do another run. The other bits like the little white plastic ring diffuser and electrode looked a bit worn as well. If this is how it normally operates, no wonder you can buy consumables in bulk.
Second time around pressed the button and the usual hiss of air but no arc whatsoever and none ever since. After another few button presses (which started the air every time), I grabbed a complete new set of consumables except for the white cup bit that looked fine and same drama - no arc. The closest I was able to get to an arc was a tiny flash of light about the same as you'd get from a little bulb torch with flat batteries.
The machine is budget spec chinese stuff and the torch is the little PT31/LG40 style 2 prong plug. Interestingly, pulling the new consumables out, there are little 'arc spots' on every piece like a noob learning stick welding and getting little arc strikes - the double ended electrode and the cutting tip have these, so it's like power got thru but the whole thing short circuited or something. Pretty sure there's only one way to put it all together, electrode goes in first, then plastic gas ring, then cutting tip on top and then white plastic hood that screws down to hold it all in tight.
So I'm trying to work out why there's no arc. If I can get air thru fine then I'm assuming that the torch button switch is ok. As for why there's no arc or the tiniest flash of one, I can't work that out but are there any tests that can be done to work out where the problem would be ? I guess it can only be the torch or the machine itself. It has a tiny 0.5amp fuse and I checked that and it looks fine.
Also gives me an idea of compressor size I need as the compressor says it's a 7.3cfm with a 21 litre tank. It pumps up to 115psi and then auto cuts out and then cuts back in but not sure at what point it does that. Anyway I found that 21 litres does not go very far at all.

[Oscar]

Unless that compressor pump is a monster-sized pump, there's no way you're getting 7.3 CFM with a 21 Liter tank. That compressor is blowing air up your......



Could be you just simply do not have enough air and there might be a pressure switch that doesn't let you ignite the arc unless there is sufficient pressure. Hook it up to a real compressor. Minimum 20 GALLONS (75 LITERS) with a 2HP+ pump. Once you rule out the air issue, then you can look at carefully placing the compressor in one of these:





























Since there likely isn't an easy fix for bargain-basement chinese plasma cutters unless the part that is malfunctioning is showing physical signs of distress (burnt/melting/etc).

[5vzfehilux]

Thanks Oscar, I think what you mentioned about the compressor could be a topic in itself, ie what you really need to run a plasma plus how the lower-end compressors report their output. The sticker on the pump says "Air Displacement" 7.3CFM, maybe they got the digits switched around.

Given the tank runs to zero very quickly, it could be a low-pressure sensing issue as you said.

[JayWal]

My TD Cutmaster has a low pressure sensor. Every now and then I'll go to cut something and when I hit the trigger I get air but no arc. After chasing my ground clamp for 5 mins I do eventually realise the breaker for my compressor is still flipped off and the line pressure is too low.

Sent from my SM-G970W using Tapatalk

[BillE.Dee]

Oscar,,,,just asking about the air supply for a plasma machine. How do the self contained units (never had one) make enough air ? Or is that just for a tiny machine? I am making lots of air at the shop, but do notice that IF the air isn't turned on, I can't get any reaction (zip, nadda, nuttin) when I press the trigger.


5v - how far away are you holding the torch from the material ? I know it can't be draggin on the surface, but they should be pretty close to get the arc going and keep it. Also, I don't know anything about the machine you have,,,is there a separate wire for power to the torch other than the trigger (I think it's called "pilot arc") ? Do you have a flow meter to test to see how much air is coming out the torch when you press the trigger ? Just make sure you don't have the ground hooked to the tester or the torch doesn't have the power wire connected to the machine.

[noddybrian]

Not heard of that exact model but every generic 40amp chinesium cutter I seen does not have air pressure limit switches - they will attempt to work with or without air - they will happily run on import 2> 2-1/2 hp 25 liter economy compressors with a PT31 torch & .9mm tip - the majority will require an earth path so the part must be earthed & the tip must touch the part at least to initiate the arc - they are generally used as a drag tip but as they are un-shielded have a short service life - they have a crude HF arc start & there are points onboard for that which require cleaning & gapping - also even without the fairly bad machining tolerance of parts there are several lengths of consumables - is it possible you have a miss match causing the tip & shroud to touch ? a picture of the torch parts would help clarify this.

[5vzfehilux]

5v - how far away are you holding the torch from the material ? I know it can't be draggin on the surface, but they should be pretty close to get the arc going and keep it.

I can't remember for sure, but the first time when it worked as it should, it was held just off the work piece like with tig welding and ran fairly consistently.

Also, I don't know anything about the machine you have,,,is there a separate wire for power to the torch other than the trigger (I think it's called "pilot arc") ? Do you have a flow meter to test to see how much air is coming out the torch when you press the trigger ?

Really no idea sorry. It's a 2-pin female plug on the torch and the gas line for air is separate. I don't have a flow meter for testing and wouldn't know what type to get to test it. It's definitely a decent hiss though and runs the compressor tank down with no trouble.

Not heard of that exact model but every generic 40amp chinesium cutter I seen does not have air pressure limit switches - they will attempt to work with or without air

I agree ... I think the specs of this machine would mean no air pressure sensor so it would run regardless even if that potentially caused damage.

- is it possible you have a miss match causing the tip & shroud to touch ? a picture of the torch parts would help clarify this.

This got me, along the lines of "check the simple stuff first". The consumables could possibly be wrong as I ordered them based off a website photo, although the sales guy I spoke to said these should be the ones that fit after I told him it was a PT31 torch (don't know this for sure other than it looks exactly like every other PT31 I see on the web). But specifically, what do you mean by the shroud and tip touching, ie if they do, does that mean the torch won't work? I'll get some pics up sometime today but I can't see how all the consumable pieces could stay held in the torch if the shroud didn't screw down via the thread on the torch head and bind onto the tip flange?

Thanks heaps for all the replies from everyone.

[5vzfehilux]

Here are some photos showing the 2 pin plug.

Next is the torch with consumables in order of how I put it together, from left to right. This is the set used that first time it worked and just from that short run things got pretty dirty.

[noddybrian]

Yes that is a generic PT31 torch - the consumables look fine - I meant there are 2common lengths of them & an oddity extra long 1 - you have what is generally referred to as the extended sort & appear to be a matching pair- with regard to touching I meant if you had a long electrode & short contact tip or missed the swirl ring out ! it can happen - unsure of your model but it appears to be a multi process which I never seen - are the switches all in the right place ? also you can plug the earth clamp into the positive or negative - any chance you got this wrong way round ?

[5vzfehilux]

Thanks again noddybrian,

Well after mucking round with it more including rechecking the torch plug wiring at the machine end (when I got the machine the wires had frayed and were touching so I resoldered when i got it), jamming the plug back into the machine as far as it would go and holding the button down the whole time when operating... we are in business. 60psi and 30 amps it had no trouble blasting thru 4mm plate that I had de-gal'd with acid. Pretty stoked it is now up and running.

I had ordered a new pack of consumables from china a month ago that actually finally arrived the day I was mucking round with the machine again and tried them and they fitted even better than the ones I'd bought from a local supplier. The band in the middle of the electrode sat properly in the cup of the torch head whereas the local stuff was a tiny bit narrower in diameter and so had a bit of play. Either set seems to work as well as the other though so I'm pretty happy I didn't waste money.

The cutting arc or whatever you call it is very fine and it picks up the slightest wobbles in your hand better than any tig setup could so I need a lot more practice and working out how to use some angle as a straight edge brace for it.

unsure of your model but it appears to be a multi process which I never seen

Yes it's a DC TIG MMA cutter in one. I haven't tried the welding side yet but I don't need either as I have an ACDC tig, but i might give it a go one day.

Anyway, thanks a lot again for your interest.

[noddybrian]

Really glad you got it working - some folks are really bitchy about the Chinese stuff but for the money they are not that bad - kerf is usually narrow as the 40 amp tips only have a 0.9mm hole so using a straight edge guide helps - it's normal to have to have the tip just touching the work for it to light up & you do have to hold the button in the entire time cutting - consumable life is poor so it makes sense to keep plenty as they are very cheap - if the tolerances make the swirl ring loose there is a tendancy for the electrode not to stay centered & this makes worse the inherent problem of the plasma coming out slightly off center / angled - gives even worse life of outer tip & crooked cuts - it's all a trade off for price - for light use they do fine - usually they will cut 10mm steel - maybe 12mm but that's kinda severance not clean - hope it continues to work & you get used to it - very useful tool to have around.