help with hobart 250ci

[bryan2]

I've never used a plasma cutter before and just bought a new hobart 250ci - I'm having trouble maintaining a cutting arc. I'm working in a cement floor barn - no heat and sometimes freezing temps, if that makes a difference in operation.

The problem is that what I start to cut the arc stops after 3-4 seconds without making a cut.....here are some comments:

I have a dedicated electrical outlet with adequate guage wire.
none of the fault lights come on to indicate a problem
i've replaced the tip without any change in results
on one occassion I found moisture inside the tip - never happened again
when i first used it it cut OK for half an hour, but was not impressed with speed
with the current problem I've tried cutting 1/8" new aluminum to be sure I had a good ground, but no change

What should I do to find and solve the problem? any help or suggestions would be appreciated. thanks.

[Northweldor]

Bryan:

If this is new, and still under warranty, I would first contact the vendor and ask, and also call Hobart tech support to make them aware of your problem. (do this before aggressive trouble-shooting since this may void your warranty). They are usually very helpful at guiding you through some tests which will diagnose your problem.

[great white TJ]

I have a 250ci and it does not like Alum. The Alum. needs a lot of heat to cut it, I htink that the 1/8" Alum. is just a bit to much for the 250ci.

[Northweldor]

I have a 250ci and it does not like Alum. The Alum. needs a lot of heat to cut it, I htink that the 1/8" Alum. is just a bit to much for the 250ci.

While the 250CI is only rated at 1/16" for aluminum, it still should be able to handle 1/8", although very slowly, and duty cycle may be a problem. The melting point of aluminum is 1220 F. degrees and the 30000 F. instantly generated by the plasma arc should allow a severance quality cut. However, this OP is having the arc "stop after three or 4 secs without making a cut" and "no fault lights are on". While this may be due to any number of operator faults, technical support from Hobart is still his best bet.

[bryan2]

Can anyone refer me to a picture online that shows the torch assembled, but without the retaining cup? I ordered a replacement swirl ring but didn't pay close attention to which side of the ring is down and it's proper location in the assembly. I have the diagram that shows the components exploded but it doesn't show the ring seated. thanks.

[Northweldor]

Section 6-3 of your manual doesn't caution you about which side is up, but shows assembly location. I suggest, a) it doesn't matter, or, b)It will only fit the proper way. Try it and if your cup light doesn't indicate properly, reverse it.

[bryan2]

thanks for the reply and suggestion....I would prefer to see a picture rather than experiment but if no luck will give it a try. thanks again...
bryan

[Hobart Expert Keith]

Suggestions from our plasma techs

5 Keys to a good cut
1) Work Clamp, needs a good electrical connection. If you are cutting on rusty, galvanized, painted or dirty material you will need to grind off a place for the work clamp, the torch will cut through just fine though.

2) Consumables, If they are worn then it will cause arc outages. Check your manual for information on when to change the consumables

3) Standoff distance, Remember electricity is lazy it wants to take the path or least resistance. If you get too far away from the work piece resistance between the work piece and electrode (cutting circuit) is much higher than the resistance between the tip and electrode (pilot circuit). This will cause the machine to stay in pilot and shut off after the five seconds.

4) Retaining cup, If the cup is on too tight it prevents the electrode from moving freely. This will in turn prevent the arc from transferring.

5) Air supply, if there is any moisture in the air supply then it can prevent arc transfer and arc outages.

The swirl ring can be installed either direction according to our plasma techs.

[bryan2]

I assembled the cutter with new consumables and it has been working fine so far. One note....the swirl ring appears to fit in only one direction with the set I received so didn't need to make any decisions in that regard.

Thanks very much to all for the help.....much appreciated.
bryan