CNC with touch cut plasma system

[freedom2000]

Hi all,

I am quite new in the CNC world and even newer in the plasma cutter community.

Rather than a long introduction please visit my web page devoted to my hobbies : http://freedom2000.free.fr/index.html

I would like to buy a small chineese plasma cutter 50A. It is a "touch to cut" system. Do you think that such a system is convenient for a cnc;
could I use it in the following manner ?

- z axis down to touch
- arc ignition
- z axis up
- cnc cutting
- arc off

is there a risk to burn the torch if starting the arc in plain material ?

another question : what do you think about this cheap unit :
http://www.pellet-mill.de/shop/article_CUT-50A/INVERTER-CUT-50.html?sessid=HTSKjXzd2q4MlVABgRDjPHrs0lhNDaAOYA1MwYlOsCIcrfSlc9gmPgbKPAlks3xR&shop_param=cid%3D16%26aid%3DCUT-50A%26

or the same in english http://www.rsweld.com/Air-Plasma-Cut...t40-Cut50-376/




thanks in advance

JP

[DanOSB]

from my experience and i suggest ya get a good quality brand name plasma cutter to reduce headache and problems

such as hypertherm (i suggest ya get hypertherm machine)

[freedom2000]

Originally Posted by DanOSB from my experience and i suggest ya get a good quality brand name plasma cutter to reduce headache and problems such as hypertherm (i suggest ya get hypertherm machine)

Yes thanks for the advice --> I will probably choose a better brand

However, this answers only partially to my questions...

The most important for me is to know if it is possible or not to use a simple plasma cutter "touch to start cutting" with a CNC or if it is mandatory to use an "auto start device" (that is the torch doesn't need to touch the metal to start cutting --> see this nice smiley !!! ).

JP

[DanOSB]

for my cnc using hypertherm i have a microswitch so before i start peircing the part it touch the metal and then go back up to .125" then cut the material

the perfect height of peirce will make the consumable last longer

if you are cutting too low or too high it can shorten the life of consumable..

[Edwardo]

Jp

Im not sure what touch to start cutting means, i looked at the web site and tried to find more information on that, but there isnt much to go on, if it means the torch is touching the plate to fire and cut i would assume it is a sheild on the nozzle allowing you to drag the torch along the metal while cutting, this would apply to hand torch cutting only, most cnc machines lower the torch and touch the metal, lift off to peirce height, peirce, then lower to the cutting height and begin cutting, with cnc your torch is vertical and the further away from the plate you are while peircing the less of the chance of spatter blowing back up into your nossle and ruining the nozzle/electrode...( consumables )
I also tried to find a list of consumables for the cutter you mentioned, maybe its me but i couldnt locate that either on their web site, what i did find was a list of safety procedures for there plasma cutters, do's and dont's... which was interesting to read. I dont know what the price tag is on this cutter, but sometimes less expensive tools cost more in the long run by poor performance and lost time due to break downs, lack of support from the manufacturer, cost of consumables, and wasted material from bad cuts... If you are just going to use it as a hand held cutter is may be ok, if you have plans in the future for using it for cnc i would seriously consider upgrading to one of the more common brand name cutters like Hypertherm as DanOSB mentioned, i own a 1250 Hypertherm and it works flawlessly, and there are different types and sizes of nozzles for different range of application, they have a newer style 45 amp cutter availible now, from what i have heard and read it cuts beautifully and is priced around $ 1600 US, Hypertherm specialize in plasma cutters, its all they make and they take safety seriously....and after reading the safety part on rstar web site it may be something to consider also...and Hypertherm being a more popular cutter, there are more users on sites like this one that can help you if and when you decide to go cnc.....

Regards

EDD

[freedom2000]

Originally Posted by Edwardo Jp most cnc machines lower the torch and touch the metal, lift off to peirce height, peirce, then lower to the cutting height and begin cutting, with cnc your torch is vertical and the further away from the plate you are while peircing the less of the chance of spatter blowing back up into your nossle and ruining the nozzle/electrode...( consumables ) Regards EDD

Thanks so much for these clear explainations and advices. It is exactly what I wanted to know.
To be fully clear, can you confirm that the torch ignition starts as soon as the torch is in contact with the metal ?

JP

[Edwardo]

Negative on that.... the torch lowers and touches the metal before firering, it does this to find the top of the metal, height will vary with different thicknesses of metal, then rises to a pre-set peirce height, then fires and blows a hole through the metal, then the torch lowers to the pre-set cutting hieght and continues cutting... this all happens within a very short period of time... with thicker metal you can also set a peirce delay to ensure that the hole is completely blown through the metal before the torch begins to lower to the cutting height to avoid the splash back of molten metal into the torch nozzle. Ideally with my torch and cnc, you never want the torch to touch the metal when it is peircing or cutting, it will ruin the nozzle and possible the the electrode inside... which is the least damage that can occur.... check youtube and seach Dynatorch... there are videos that show the cnc plasma torches working, you will see what i mean...

EDD

[freedom2000]

Originally Posted by Edwardo Negative on that.... the torch lowers and touches the metal before firering, it does this to find the top of the metal, height will vary with different thicknesses of metal, then rises to a pre-set peirce height, then fires and blows a hole through the metal, then the torch lowers to the pre-set cutting hieght and continues cutting... this all happens within a very short period of time... with thicker metal you can also set a peirce delay to ensure that the hole is completely blown through the metal before the torch begins to lower to the cutting height to avoid the splash back of molten metal into the torch nozzle. Ideally with my torch and cnc, you never want the torch to touch the metal when it is peircing or cutting, it will ruin the nozzle and possible the the electrode inside... which is the least damage that can occur.... check youtube and seach Dynatorch... there are videos that show the cnc plasma torches working, you will see what i mean... EDD

OK thanks again. This was the final precision that I wanted to get !

The cheap model that I suggested is ONLY starting the arc when touching the metal. You have then to climb up a bit. But while this happens the torch is on... which can probably ruin the torch during this (short) delay ???

JP

[Torchhead]

Contact start plasma torches that use the workpiece for arc start are not going to work for mechanized (CNC) cutting. At the very least get a plasma cutter that has HF start so it will start an arc in the air. It's difficult enough to get a good plasma cut without throwing in a toy plasma cutter.

TOM Caudle
www.CandCNC.com

[freedom2000]

Originally Posted by Torchhead Contact start plasma torches that use the workpiece for arc start are not going to work for mechanized (CNC) cutting. At the very least get a plasma cutter that has HF start so it will start an arc in the air. It's difficult enough to get a good plasma cut without throwing in a toy plasma cutter. TOM Caudle www.CandCNC.com

OK gentlemen,

It's clear enough now, I will NOT buy this plasma cutter and look for a good one.

Thanks again for your help.

JP

[encswsm]

I say thanks too I was wondering how they worked

[slammedxonair]

go for a hypertherm you can't go wrong with them.