Plasma Cutter CNC - beginner requires help!

[puffernutter]

This is an ongoing project that hasn't quite yet got to fruition, has cost me about 3 x what I expected, but has been largely bodged together by myself using some off the shelf bits and others I have made. I've had great fun doing it and learned a lot! Does that sound familiar?

I have got to the point I am looking for the sort of bed that people use for these. Currently this is on a 50x50 sq steel frame with a big area of nothing in the middle.

I was wondering about using steel honeycomb, but what do other people use to support their workpiece?

Cheers

Peter

 

[chrisg3103]

I used bits of flat bar, propped up with 3d printed brackets, because you know how well plastic and heat get on? Not gone horribly wrong yet but not had a lot of use. I wouldn't get anything too fancy though, the bars do get mangled by the plasma, i see them as a consumable

 

[Parm]

View attachment 256912
I used bits of flat bar, propped up with 3d printed brackets, because you know how well plastic and heat get on? Not gone horribly wrong yet but not had a lot of use. I wouldn't get anything too fancy though, the bars do get mangled by the plasma, i see them as a consumable

All the ones I’ve ever seen have been just like that, and yes the bars are a consumable, eventually

Not too sure about the 3D printed brackets though

 

[hotponyshoes]

I wouldn't use honeycomb as once a small area is worn away you will either have to put parts in a different place each time or replace the whole lot at once.
I would stick with the tried/tested steel flat bar.
Make sure the outer supports are deep enough that the length of the slats is not too critical.
Buy a few 6m lengths of flat, cable tie them all togeather and cut through a load at once with a slim disc.
You will get a decent life out of them as you can flip them over and move them around the table as they get eaten away.
Heavy gauge weld mesh would be another option but I would go for the flats myself.

 

[awemawson]

Have three supports for the vertical flat bars so that you can give then a slight curve. Most cuts are orthogonal ie 0 or 90 degrees and if they happen to line up with a bar it makes a big mess. Curving reduces the amount of cutting of the bars. Make bars easily removable as small areas will get more intense use and you can move bars about to even out the wear. Bars can be inverted to make best use before scrapping

 

[Agroshield]

A lot of those I have seen have points on the top. See also: https://www.everlastgenerators.com/forums/showthread.php/3580-Plasma-table-support

 

[hotponyshoes]

It's easy to cut slats with points yourself.
You just need a cnc plasma cutter....

 

[awemawson]

I use standard 50 mm x 3 mm black steel bars so cheap and easy to replace. The fancy box shapes are a pain in the neck to move bars around, and if you want pointy bits it takes quite a time and a bit of waste to cut them.

No - curved bars for me - far simpler in the long run

 

[puffernutter]

All, thank you. Lots more to think about! The pictures of cutter set ups help as well!

Cheers

Peter

 

[Ali]

I’ll second the wavy pattern, the strip only needs to be 1mm and when it’s wrecked just turn it upside down.

 

[awemawson]

Peter,

My slat holders are simply lengths of 50 x 50 mm angle iron with slots cut to take the bars. As I cut some heavy plate at times I wanted the support to be substantial so having the extra central support not only allowed me to curve the slats but also support more weight.

 

[hotponyshoes]

You can add thicker ones for support for heavy bits if you want, just make every 10th slot bigger or something. But make them scaled up as thicker is disproportionately more expensive
Ie, drop 8mm flats in there if you are cutting heavy section but the rest of the time use 4x2mm slats in the same gap the rest of the time as 4m of 2mm is often cheaper than 1m of 8mm.
Or just make up some small spacers to stop the thinner flats wobbling around or cut slots for heavy bars between the regular slots for the thin bars.

 

[awemawson]

It's not so much the total weight of the plate that you are cutting, it's the action of loading and unloading. Inevitably maneuvering a heavy plate it's not going to be exactly in the same plane as the top of the slats. If your slats are flimsy they will bend when the plate catches them in the loading process.

For my usage 3 mm has worked out very well - my jobs range between 1 mm Zintec to 15 mm ms plate but mostly are 1.2 - 3 mm ms.

 

[gerrymoore]

Peter, I used 30mm x 3mm strip. Lasted a long time and I used to turn it over. Have you got a water bath underneath? Even with water everything in my workshop got a covering of very fine black dust even though I had an extractor right over the plasma torch. This was one of the reasons I stopped as I already had a very bad sinus problem. Now I get a local place to laser cut (to perfection) my drawings, in cold rolled, cheaper than I could myself ....

 

[awemawson]

I have an inverted hood under the table and a massive axial fan sucking all the detritus directly outside. On the (rare) occasion that the fan doesn’t start (M8 via relay from Mach3) you VERY soon know from the fumes in the workshop.

 

[James1979]

I have an inverted hood under the table and a massive axial fan sucking all the detritus directly outside. On the (rare) occasion that the fan doesn’t start (M8 via relay from Mach3) you VERY soon know from the fumes in the workshop.

Thanks for the M8 tip, m8 That'll come in really handy for me as it'll save the fan chugging away all the time. Do you need to insert the command or can you get sheet cam to do it for you?

 

[awemawson]

I modified the post processor so that it inserts an M8 at the beginning of the code and an M9 at the end.

 

[James1979]

Thanks I’ll give it a go

 

[puffernutter]

Talking of M8! I have modified my plasma cutter to parallel the torch switch (mine is a very noddy bit of kit!) I was going to turn it on and off through the CNC, do you leave it on for the whole cut or turn off when changing directions?

I also see on the web there are clever (read expensive) bits of kit that continuously adjust the height of the torch during a cut (current feedback to the Z axis) are those needed for home workshop use?

Cheers

Peter

 

[gerrymoore]

Hi Peter..leave the torch on during the cuts. THC or torch height control is a pita to set up and as long as your using new steel not necessary...I never needed it in 7 years of cutting....but others may disagree!