Rebuilding Oxyfuel to Plasma

[chrugel]

Hello there!
I have been hanging arround cnczone for quite som time now beacause i find the world of cnc systems very interesting.
At the workshop that is located where I work they have been talking for quite some time now that they really need a plasma cnc cutting machine.
Not knowing when to shut up i said "Why dont you just rebuild your old Oxy fuel machine innto a plasma cnc?" Guess who got the assignment?

The machine in question is an esab ULTRAREX UXB oxyfuel cutter that we whish to retrofit with a plasma CNC system.


I have thought of several approches:
A torchmate retrofit kit, probably servo based.
A candcnc retrofit kit, probably with servos.
Not buying a kit but buying the components we see fit.

What would the best way of doing this be?
(Or have i placed my self in deep ****!?)


The problems i see comming our way is that we need a certain speed to get nice cuts with plasma an thin alu plates. the moving parts on this machine is very heavy! probably about ~80 kg. This means a rather big servo is needed to drive this axis.
Would i 1hp brushless servo be sufficient?


Know anyone who has done a similar conversion before?

best regards
Chris

[Med-Pac]

Sounds like you have your hands full. If your going to go through that much work to retrofit your current machine, maybe a redesign of the gantry would work. Some 80/20 extrusion is an excellent option, especially for a plasma.

Here's a pic of our torchmate. The gantry is 3" x 4", we also used some 3"x6" when we built our router.

Mike

[Med-Pac]

forgot the pic

[jpgdesigns]

do you still want to use the optical trace head?
if so then check with esab about an upgrade to add a cnc controller and drive package. the specs on your machine give a max speed of 1000mm per min. fine for oxy, but not for plasma. esab's uxc machine has optical and cnc which can support plasma cutting speeds up to 3000mm per min. as well as oxy.
It may be alot less hassle to upgrade through esab. yes it will cost more up front but you will have an intergrated system that you know works and can get support on.

[chrugel]

Originally Posted by Med-Pac Sounds like you have your hands full. If your going to go through that much work to retrofit your current machine, maybe a redesign of the gantry would work. Some 80/20 extrusion is an excellent option, especially for a plasma. Here's a pic of our torchmate. The gantry is 3" x 4", we also used some 3"x6" when we built our router. Mike

Thank you for your reply Mike,
That sounds pretty clever, might be easier to make the gantry lighter than to speed up the current one.

Originally Posted by jpgdesigns do you still want to use the optical trace head? if so then check with esab about an upgrade to add a cnc controller and drive package. the specs on your machine give a max speed of 1000mm per min. fine for oxy, but not for plasma. esab's uxc machine has optical and cnc which can support plasma cutting speeds up to 3000mm per min. as well as oxy. It may be alot less hassle to upgrade through esab. yes it will cost more up front but you will have an intergrated system that you know works and can get support on.

No we don't intend to use the optical trace head.
That was our first thought to, to get it upgradet from esab but they seem very reluctant to upgrade our current one. The wanted to sell us a new one at the cost of moore than 100.000$.
We were hoping to get more than 3000mm out of it beacause we believe this is to slow for aluplates thinner than 1/4"
We are going to contact ESAB again and ask spesific for the possibility of upgrading it to the 3000 mm version.

thank you very much for your reply!

regards
chris

[Med-Pac]

Plus, there would be less stress on the machine, and replacement parts should be easier to come across if you need them.

Mike

[millman52]

Although it's more work, I'd get rid of the existing operating system including the tracing eye..... Get rid of the eye your table will take up 1/2 the space.

As to drive motors, Use what you wish. If it were me, I'd use steppers. I'm quite sure you can get in excess of 3000 mm per min. The cost is lower on the entire system & not nearly as prone to RF noise.

What is the cutting size capacity of your table?

I'd think you can keep your budget well under $5000.00 US. Unless you really go out there on software.

[jpgdesigns]

Here is another option for upgrading your machine:
https://www.hypertherm.com/library/f...EDGE892260.pdf

[chrugel]

Originally Posted by millman52 Although it's more work, I'd get rid of the existing operating system including the tracing eye..... Get rid of the eye your table will take up 1/2 the space. As to drive motors, Use what you wish. If it were me, I'd use steppers. I'm quite sure you can get in excess of 3000 mm per min. The cost is lower on the entire system & not nearly as prone to RF noise. What is the cutting size capacity of your table? I'd think you can keep your budget well under $5000.00 US. Unless you really go out there on software.

Hi,
That is pretty much what i intend to do, remove everything, just use the mechanical table as a basis. Probably also convert to a ballscrew drive system on the heavy axis sinte the drive system there today is friction based. A metal wheel running on a steel beam.
I also wanted a stepper based system mainly beacause of simplicity but the decisionmakers want a servobased system. I think they are scared by the nature of open loop systems.

I think the cuttingsize is about 1 x3m if I'm not misstaken.

jpgdesign, that looked really like a good alternative, I'll present it to my superiors and see what they think of it.

I really hope i can convince them to choose a complete conversion kit.

best regards
Chris

[millman52]

Originally Posted by chrugel Hi, Probably also convert to a ballscrew drive system on the heavy axis sinte the drive system there today is friction based. A metal wheel running on a steel beam. I also wanted a stepper based system mainly beacause of simplicity but the decisionmakers want a servobased system. I think they are scared by the nature of open loop systems. I think the cuttingsize is about 1 x3m if I'm not misstaken. I really hope i can convince them to choose a complete conversion kit. best regards Chris

Ballscrew will not be nearly as forgiving to the harsh environment as Rack & Pinion. In addition on the 3M run you probably will not be able to keep the whip or wobble out of a screw. That is unless you fix the screw solid & drive the ball nut along the screw. Still the really fine metallic dust will be almost impossible to keep from contaminating the sustem causing premature failure of the screws.



To each his own on stepper vs servo. ("I think they are scared by the nature of open loop systems.") To me holds little value. Wonder if they realise the desktop printers & even larger such devices like map plotters. They depend on to make picture perfect letters, invoices, etc. are almost all stepper based systems.

Where the amount of weight (gantry) being moved isn't huge, and there are no cutting forces (router, endmill, etc.) to counteract. The expense & complexity of wiring + additional parts (encoders) to go bad,or get dirty & give false information, in a servo system doesn't make sense.

I am using one of CandCNC's stepper systems W THC. It works great & is simple to get hooked up & running. I have no experience with other systems so I can't advise you how WWW.CandCNC.com stacks up against others out there. I only know they are selling a good product & stand behind it if you have trouble.

Good luck in your adventure.

Neil

[chrugel]

Hi.
Neal, I had no idea that there would be so much trouble with using a ballscrew. We probably need to think of something else . . .
Our cutting table has an underlying ventilation system that could help to reduce the dust problem a little?

I Agree with you when it comes to steppers, it would be a much simpler system with steppers instead of servos, but what speed can we expect with steppers? I'll try and convince them, but they have the money and they are calling the shots.

This is how we are planning on doing it now:
Machine-control: Mach3

CAM: SheetCAM

CAD: SolidEDGE

BLDC servos with controllers from stappenmotor.nl one 750w for the heavy axis 350W for the other. Stepper for height control. ( Maybe we are talking steppers on all axis in a while if they can be convinced)

THC from either Campbell design or CandCNC

Paralell breakoutboard from campbell design.

2" ballscrew to replace the drive system on the heavy axis ( This probably need to be revised).

Am I missing any vital components?

regards
Chris

[millman52]

I am running 740 oz in steppers on a table designed as 5' X 10' cutting capacity the gantry is all steel & overall length is around 6'. An educated guess on the weight including all motors, drive reduction assemblys, wire, hoses, solenoid valves, Ox/Fuel torch head, etc. to weigh in excess of 100#

I have (2) steppers on the long axis in a master/slave configuration. It is easily achieving 200 IPM or if I am converting correctly apx. 5000 MM per min.
The only time I have lost position was accidentally hitting an "E" stop button while under rapid move. Even then It didn't cause a problem as I simply came home & re-referenced the X & Y to 0.00

For the THC If you regurlarly cut thin material, especially thin stainless Go with the THC1000 from CandCNC.com Campbell's THC is a good unit but will struggle keeping up with rapidly warping materials & continually search for & overshoot the targeted height.

A 2" ballscrew is huge, heavy, & way overkill for the project at hand. Again I'd use rack & pinion

Something else I should ask or get clarified. I have been assuming your machine is a gantry design & not cantilever. If it is cantilever it will be nearly impossible to cut at high speeds with plasma. You just will not be able to control the flexing under rapid movement changes.

I want to make it clear I have no affiliation with www.CandCNC.com . I would seriously take a look at using their Power supply & controls. Price alone doesn't tell all the story. Tom has went to great lengths to build a product with a tremendous amount of self preservation built into it. Not to mention everything is pretty much Plug-N-Play.

It's one thing to save some $ & spend loads more time wiring, testing, then troubleshooting. if your table is home shop or hobby. I'm of the opinion if you need the conversion of the table in a timely manner & need to depend on it daily. Your companys money would be well spent to get that part of the conversion in a package deal. Whether it be stepper or servo everything is designed to work together & self protect each respective component right back to the PC.

I am not nearly as experienced with CNC control as many of the others on this board. My comments are from my own personal experience & merely my opinion. Here is a link to my build log for my table. Started building new 5 X 10 table today Somewhere toward the end are a few short video clips of the table cutting & moving under rapid moves. That should give you some idea of the speed you can achieve with a stepper system. Keep in mind my steppers are 740 oz. in. & much more powerful steppers are avalible.

Neil