MPCNC plasma cutter

[TigTigger]

Just been looking at the Ender 3 3D Printers. Seems to be a wide range of prices. Assume some are clones. Is it worth getting a genuine Creality one?

 

[chrisg3103]

Not sure whats out there at the moment, but things get copied all the time, even clones of clones.
youtube is always a handy source for comparisons i find, personally i found the ender 3 to be a bit problematic when i got it, the bed was awful, got much better first layers from my trusty anet. But think this is a known issue and they have maybe sorted it? Its a mine field of printers now, all offering aluminium construction, v groove rollers ect

Bit of progress,

Got the thrust bearing assembly sorted

Old v new part, new bit has the steeper attached and has a pocket for a thrust bearing. Assembled there is no movement, time will tell if its worthwhile? looking at the parts it might be possible to make a conversion piece to sit in or bolt to the original part to save printing a whole new one?

Got some clip on ferrites for the stepper cables, kind of peeing into the wind without shielding the board at the moment but put them on anyway

My vents for the table finally arrived so got back to the plasma side of things,

Working area clad in aluminium, because thats what i had, domed vents fitted to try and stop hot particals being drawn in directly and the edges sealed with fire retardant silicone, that stuff reeks. printed some brackets to hold the burning bars too, see how they hold up...

Two vents are linked by ducting and directed to the bottom of the trolley

Need to get a flat to round coupler to get the fan hooked up then see how much draw there is in the table/sump thing. Not hoping for miracles here, just enough to draw the noxious fumes outside and keep the dust contained in the table

 

[Bladevane]

I use strips of fireproof blanket to lay on top of the table and surround the workpiece to ensure as much filth as possible gets extracted downwards and out rather than into the room. Works well.
(eBay item number: 233191696851)

 

[chrisg3103]

Thats a very good idea! all hooked up and did a worst case test with a smoke match

Not much draw there
In reality the badness will be blasted downward anyway, flung a match into the pan and the smoke got drawn away, but restricting the top surface bit certainly wont hurt.

Found a post saying to add the command G4 S0.7 to the cut start command, this is supposed to start the plasma and pause the program for 0.7 seconds to let it pierce, sounds good, didnt work! But think in hindsight its because i wrote g4 s0.7 think capitals matter

Is quite a bit of dross, dont know itf it because of the speeds and whatnot or just because its aluminium but a big improvement from doing it onto the floor!
Also not one glitch from the controller, maybe the ferrites are working, will upload a video one i have it on the youtube

 

[chrisg3103]

 

[Dev]

Just been looking at the Ender 3 3D Printers. Seems to be a wide range of prices. Assume some are clones. Is it worth getting a genuine Creality one?

They’re all clones and you can assume the price difference is QC. Which is unsettling;
They don’t look like much but the heated bed electronics are using some serious current.
Under rated wires, poorly crimped or slack connectors are common and cause a real fire risk.
This is compounded if you’re going to be printing bigger things - the longest print I’ve done was just over 3 days but 12-18hrs is common.

 

[daedalusminos]

I bought my 3D printer as a kit a few years ago.... it's actually served me very well, and no reason for others not go this route. The only thing I'd improve is the acrylic frame, but other than that it's got the Mk 8 extruder, heated Al bed, control is via Ramps V1.4....which needs modifying to improve the bed heater drive FET but it's a known problem.

 

[daedalusminos]

@chrisg3103 what's the finish on the Screwfix conduit like? I'm weighing up whether to go for that or stainless.

 

[chrisg3103]

If you can find stainless at a reasonable price I'd go for that. Think the conduit is galvanized so not the smoothest, plus I'm sure the zinc will wear pretty quick, but it's cheap and the tubes can be rotated a few times if you end up with grooves I suppose?
If your on a budget I'd go with the conduit till you know your going to get the use of the machine then upgrade

 

[daedalusminos]

Think I'll see what stainless is available... meanwhile quite good progress with the printing, only really corner bits and toolmount left...

 

[chrisg3103]

looking very snazzy, amazing how much printing time can go into so few parts
An update on any non extortionate supplies of stainless would be handy if you find one, in my tube search i did find another source of 25mm tube, not stainless but - https://www.ikea.com/gb/en/p/antilop-highchair-leg-80279946/ limits the size but is cheap

Slight update, run some feed tests yesterday and forgot to turn on the regulator at the compressor. Turns out these cut50's dont have a pressure interlock! so it happily fired up with no air and melted the tip and nozzle before i could kill it, think the torch may have suffered a bit and im hoping non of the fragile electronics haven't gone pop. Dosn't seem like enough air is coming out, will try a few things but i have a pressure switch on order to try and retrofit and make it a teeny bit safer...

 

[daedalusminos]

Not found any bargains on St/St tube...looks to be about £10/m. I might have a look at heavy duty wardrobe rail...probably only 1mm wall thickness which may be an issue but it is chrome plated.

 

[daedalusminos]

This looks hopeful 1.6mm wall thickness:

https://www.tradesystems.co.uk/T253...ated-round-tube-Heavy-Duty-T253M.html#SID=153

£12.60 for 3m - postage a bit steep at £12!

 

[Hood]

I haven't bought 25mm stainless tube for a long time, usually 1" but for 1.5mm wall (yes I know, mix of metric Imperial ) it was £4.50 plus VAT per metre and 3mm wall was £10, both were dull polish. That was from Richard Austin Alloys.


Edit

Forgot that that was 316 so 304 should be a fair bit cheaper.

 

[chrisg3103]

little update,

Here is what happens if you run a cut 50 for a few seconds with no air

electrode no too bad but the nozzle totally melted!
i have bought a T and a normaly open pressure switch to fit into the regulator on the back of the plasma, will wire it into the trigger circuit so it needs pressure before it will allow it to fire again. not any room inside so it a bit of a bodge.. while i was waiting for the parts i had a go with the extended electrodes i bought for the pt-31 torch.
At first i thought i had damaged the actual torch with the melting and all, when triggered there was barely any pressure at the nozzle. bit of head scratching i found the extra length of the electrode was plugging the air passage!

The air comes up the central hole and through drillings to the outer ring of holes, but the electrode was sitting past that step there ^ so drilled it a little deeper, seemed to work!
But i was getting horrible cuts with the extended electrode, thought i would swap back to the AG60 torch that was giving me the horrible interferance issues, maybe the new setup will help? nope, still crashing the board, but lovely cuts when it worked.

Top hole it the extended electrode pt-31, bottom AG-60.

Then there is this abomination left is standard electrode, right extended. It also messed up the board with interference and gave it a weird cut, but the arc looks like its all over the place.
Bought some standard length electrodes and the cut quality instantly improved, but i was getting pesky interference issues again!

A plate of fails, all different fails but interference related, so tried the old conspiracy theorists favorite trick and gave the electronics a tinfoil hat...

Worked brilliantly what can i say?
I am designing an enclosure i can cut on the machine and enclose the electronics in, i have GX16 connectors to route the cables though already, bought some copper tape to cover the seams and have bought extended IDC cables so i can locate the display and control somewhere more convenient.
Also while looking at plasma torches i found the P-80 style plasma torch, looks interesting, i have one on the slow boat from china to test it out.
At the moment im using the PT-31 with a jumper wire to the nozzle and a controller wrapped in tinfoil Next test of the tinfoil insulation i to refit the noisy AG-60 and see if i can get it to crash, when i have some more spare time.

 

[chrisg3103]

Well the P-80 torch arrived, looked good, but was worse than the AG-60 for noise be good to use it though as its possible to buy different sized nozzles for it, but not for me!
So back to the trusty PT-31, but i was having issues with the jamming a wire between the ceramic ad the nozzle technique, it would either angle the nozzle giving a horrible cut or get too close to the plasma and melt off! so tried a few different things, one that actually worked was using copper tape as a conductor.

Was a bit skeptical as to its current carrying limit but that picture was taken after i accidentaly left the ground clamp off the metal being cut and it did quite a long cut on only the pilot arc! and its still going strong.

So the machine has been doing a bit of real work, making an enclosure for the flaky electronics.

still throws a wobbly now and again but going well.

And my first attempts at TIG welding not done much with the plasma as i have been playing with the TIG, still ongoing though. any update on the other MPCNC's?

 

[garethp]

I've got as far as printing the feet for mine, partly to get it started and partly to keep testing and modifying the cheap anet a8 I bought.

 

[Vlad]

Hello! Can you help? My MPCNC has a backlash of 2 mm axis z. If not laziness, share STL under the thrust bearing and the size of the bearing for ordering, as well as the blue T8 coupling, please.

 

[daedalusminos]

any update on the other MPCNC's

Been on holiday for a couple of weeks so not too much progress. All the printing is complete with only one fail - the tool holder, it's tall with small contact area so I had to adjust the bed adhesion on the second run.

I'm trying to source S/St tube, some relatively S/St conduit on eBay but no response from seller. I also need to sort out a work table and decide upon final size.

Unfortunately all this is in parallel with another couple of projects so progress is slow.

 

[decca]

Still printing in between everything else. Just got the 2 x 12hr prints to go and I’m done.