CNC Plasma Table without a Powered Z Axis

[dmrracingllc]

Hi All,

I am working on building my own small 2x2 CNC plasma table for making brackets for my hot rods in my garage and maybe some simple lawn art. I have a very limited budget on this project and I know that by not using a powered Z axis I can save a lot of money on hardware, electronics, and motors. I have both a cheap HF start plasama cutter (I know about the grounding issues) and a Hypertherm Powermax 30 that I would want to run on the table.

My question is, will this setup work without having a powered Z to handle pierce height and cut height? Basically I would set the Z to the appropriate cut height and just have it pierce at this height. Now I know that this will probably decrease the lifetime of my consumables but I'm wondering how bad will it really be If I'm not using this thing every day and I'm not in production. I'm not looking for posts about people convincing me to switch to a powered Z axis I'm just wondering how bad the drawbacks are of not having one. I know that some plasma tables like the old Torchmate 2x2's and even the Baeleigh PT-22 plasma table don't come with a powered Z axis so I know it must be somewhat doable.

Any input would be greatly appreciated!!

[jimcolt]

-The reason machines have pierce height settings is for consumable parts life. If you make one pierce at the cut height on material thicker than 1/8" expect the molten metal blowback to damage the nozzle orifice on the torch. When the nozzle orifice is damaged, expect the cut angularity on all subsequent parts to vary rather dramatically on each axis. If you don't care about consumable life, cut quality or edge angularity then you can pierce at the cut height. A Hypertherm plasma running on a machine with accurate pierce height and cut height will achieve thousands of starts and over 10,000 inches of cut with similar cut quality. Without height control expect 1/4 to 1/3 of that life.

- The other option is to pierce and cut at the pierce height. This will produce a wider kerf, more heat distortion (warpage) as well as dross and uniform but severe edge angularity.

- Cut height on plasma height controls is the real time control after the pierce is achieved. Is it done by electronically monitory the arc voltage, which is proportional to arc length. Good performing height controls will maintain the suggested cut height (often .060" from the material to the torch) within about + - .005". This is necessary for best cut quality. There is not a cutting table or a sheet or plate of steel on the planet that is flat within .005", especially after some heat added from the cutting process.

Can you cut without height control? Yes, and many do. You will save purchase price upfront (by not adding height control to your machine) but it will cost you more every time you use the system (more secondary cleanup and grinding of parts, more torch consumable usage).

Jim Colt Hypertherm

[Old Iron]

Jim's post is dead on point and needs no more comment added to it.
Just one respectfully asked question, why even join this forum if you don't want to better yourself equipment wise?

[AdrianH]

Jim's post is dead on point and needs no more comment added to it.
Just one respectfully asked question, why even join this forum if you don't want to better yourself equipment wise?

Just perhaps not everyone is commercial and can afford to have full systems, building as you go can be for many the only way to start and need to have some progress before improvement!

To the original OP have a look on ebay there are some stepper Z lifter systems from China that may be able to be used for a small cost, they only lift around 60mm but I think could be used for a lightweight torch.

Try this link to ebay.uk it would give you an idea what to search for.
https://www.ebay.co.uk/sch/i.html?_odkw ... 0&_sacat=0
Anyway have fun, ask away and if we can help we will.

Cheers
Adrian

[61 Sunliner]

I have a 2x4 Growth series Torchmate (no longer available) I have been cutting for over 6 years with manual height control. So long it is second nature to me, you just have to babysit the machine while cutting and constantly adjust. I'm sure Avhc is a desirable asset but I bought my machine on a whim and couldn't afford to spend more on the height control than I did on the table. I have a PM45 and I can easily cut a full 4x10 sheet of 16 gauge full artsy stuff on a set of consumables.
I would say with a 2x2 go for it with manual height control and get your feet wet, learn about cutting and grow with it. If you find you cut enough to justify Avhc add it later.
Mike

[jimcolt]

I fully understand budgets...I was young once and trying to equip my shop....I bought a lot of used equipment as well as "low cost" (I don't like the word "cheap"). stuff.

The main point I like to make about height control....is that if you don't have it, try not to get discouraged by less than acceptable cut quality, having to babysit the machine, and higher cost for consumables. There are thousands running CNC plasma without height control. In my position I work with these users everyday helping them learn that the plasma only melts metal, the motion control, the software, the height control and the consumables (design and technology level) are what make good cuts.

As I said....yes, you can cut without height control!

On my shop cnc plasma's (home hobby shop) I can nest 100 parts, push the start button and go mow the lawn. When I return to my shop either the cuts are done....or the machine is idling, stopped due to a collision or error code (low air pressure) with no damage incurred. I guarantee that even in my hobby operation that the height controls cost (about a $3k upgrade on my machine when I bought it 12 years ago) has paid for itself many times over in consumables cost, less grinding, no need to babysit, less scrap parts cut.

Jim Colt Hypertherm

[asuratman]

Sorry, I want to ask on this old post. Can you give me a hint on how to wire from plasma cutter (no pilot arc) without THC to BOB to get start and stop machine ?

[asuratman]

Hello,
After long searching, I found how to wire the trigger. I have all axis on my table working well, what I need is trigger wiring. This is what I want. So sorry for the second time.

[DXF]

I fully understand budgets...I was young once and trying to equip my shop....I bought a lot of used equipment as well as "low cost" (I don't like the word "cheap"). stuff.

The main point I like to make about height control....is that if you don't have it, try not to get discouraged by less than acceptable cut quality, having to babysit the machine, and higher cost for consumables. There are thousands running CNC plasma without height control. In my position I work with these users everyday helping them learn that the plasma only melts metal, the motion control, the software, the height control and the consumables (design and technology level) are what make good cuts.

As I said....yes, you can cut without height control!

On my shop cnc plasma's (home hobby shop) I can nest 100 parts, push the start button and go mow the lawn. When I return to my shop either the cuts are done....or the machine is idling, stopped due to a collision or error code (low air pressure) with no damage incurred. I guarantee that even in my hobby operation that the height controls cost (about a $3k upgrade on my machine when I bought it 12 years ago) has paid for itself many times over in consumables cost, less grinding, no need to babysit, less scrap parts cut.

Jim Colt Hypertherm

[acourtjester]

On some of the less expensive plasma units they have a separate jack on the front panel that is the trigger for firing the torch. That is a 2 pin connector and these can be hooked to you BOB board output relay to fire the torch under G-code control on the BOB boards I have used the pin for the relay is pin 9 and it also needs to be setup in Mach so that pin will signal an output for the relay. Some other BOBs us a different pin to do this, look in the manual for the BOB and use their info.

plasma unit.JPG

[asuratman]

Thanks acourtjester, I bought the one with switch on/off like you show to me. No more miss wiring. It worked very easy.