Cut 40 Plasma

[Pat4d]

I am thinking of getting one of the Cut 40 plasma cutters off E-bay. I intend to use it for 1 - 2 mm plate and the odd bit of 6mm but that would be the max. I have a Nutool 50ltr compressor for which I don't know the output. I have read various posts ranging from requirements of 90 psi to 30 psi and flow rates of 150 to 200 L/min. This equates to about 7 cfm which I think my compressor should be OK with.

Could anyone clarify the exact requirements.

Thanks,

Pat.

 

[drjim]

I have a CUT40 or equivalent (green box Rehmann) and it runs fine off my 25L Wolf compressor or the 25L powercraft one I also have. It might need to stop every so often if doing massive cuts, but on the stuff I've done so far - cutting brackets etc out of 3mm plate mainly - it's been fine.

Jim

 

[eil]

My Cut40 came with a little air filter/regulator, but I would advise you to fit one on your little Nutool compressor also to give you as dry as possible air supply.

 

[Pikey365]

CUT-40 Plasma cutter.

I bought one of these back in Febuary 2009, I blew the first one up and the second one I pulled out of the box yesterday to cut some 1 mm angle off my trailer and after 3 cuts it decided to switch the OC light on and stop. I waited for 2 minutes and turned it back on, no OC light but when I went to strike an arc no arc and a red OC light on? The thing will not strike an arc. Has anyone got any ideas? Everything looks fine and nothing melted inside.

 

[Rob R-Tech Welding]

Hi There

The Generic cut-40's from China are mostly built using Mosfet power modules which are very un-reliable. IGBT devices only use 2/4 devices in total and are ultra-reliable compared to mosfets which use lots of devices put together, maybe 12 for 1 IGBT. IGBT's are obviosuly much more expensive.

First things first, always change torch consumables and ensure no water is in air supply, this can cause havoc on ALL plasma cutters.

If the O/C light is on it can be for two reasons depending on model (so many cut-40's are made by many manufacturers and are all different inside, an engineers nightmare)

1. Duty cycle has been exceeded, let machine cool down with fan running, when light goes off start using again. This does not sound like your fault

2. Turn machine on, all looks fine, fans spin up etc, when trigger pressed the input amperage/voltage or output amperage/voltage is too high/low and machine senses this and shuts down machine to protect itself and brings on the warning O/C light. This can happen as soon as trigger is pressed even if not near work, or press trigger all ok, when touching work O.C light comes on.

As said if it is a mosfet machine it may be some of these components failing but not blown, hence causes a short and high amp draw. If the Mosfets are OK, it could be the firing PCB which turns these on telling them to do something they shouldn't. For testing this you need an oscilloscope.

You can try removing all PCB connections and plugging back in again to just incase one hasn't seated properly. Also check for dry joints on back of PCB's and around the mosfets (black devices 12mmx12mmx2-3mm with 3 legs on it).

It may be a case you can't see the problem (most likely), if so send it back to supplier you purchased from, if this it not possible, take to your local welding equipment supplier for repair.

Remember when working on an inverter, allways remove from mains supply and leave for 15 minutes before working on to let the high voltage capacitors discharge, these can store about 600VDC!

Hope this helps you Pikey365.

 

[Pikey365]

Ok, thanks for that info. Straight over my bald head dude but interesting and nice to have someone spend some time trying to help. Thankyou.