Is it dangerous (to the machine) to pull the trigger away from metal?

[skotl]

Someone (apologies - I forget who) had suggested that I shouldn't have pulled the trigger on my (now broken) cut-50 with the torch in the air as that could damage it.

Now I noticed SBK's plasma cutter in the for sale section and spotted the switch for "Test Gas / Cutting". Is that because of this? Once I get a replacement cut50, how would one check for gas flow without firing it in the air?

SBK's unit;

 

[chevy2]

Cant see how momentarily firing the trigger can damage it?
after all with a mask/goggles on you may miss the workpiece occaisionally when you first hit the trigger,
if true then pretty much every plasma would break?

when i turn mine on at first i have a habit of hitting the trigger and firing the pilot arc, being doing that since i've owned it.

 

[Norm]

Mines hf start and I have triggered it accidentally in the air and also when cutting over a void i.e on the sheet then in thin air then back on the sheet again without any issues so far, this is an extract from a cut 40 user manual and they seem to advocate triggering in the air to check pressure, don't know if that's correct but can't see any other way you could check if the unit doesn't have a test switch.

To Begin
Turn the Power Switch to the ON position.
Position yourself to where you can read the air
pressure. Press the torch switch (air will exhaust
from torch, adjust the air regulator to read
approximately 60 to 70 pounds (PSI) and release
torch switch.
Note: The Air pressure has a generally acceptable
range of 50 to 80 PSI. You may experiment as
desired… but be careful not to lower the pressure
too much as consumable damage will occur.
Secure ground clamp to work piece. Connect
clamp to main part of work piece, not the part
being removed.
CUTTING
Drag Cutting
Position torch tip slightly above work piece,
press torch switch and lower torch tip toward
work piece until contact is made and cutting arc
is established. After cutting arc is established,
move the torch in the desired direction keeping
the torch tip slightly angled, maintaining contact
with the work piece. Avoid moving too fast as
would be indicated by sparks radiating from the
topside of work piece. Move the torch just fast
enough to maintain sparks concentration at the
underside of the work-piece and making sure
the material is completely cut through before
moving on. Adjust drag speed as
desired/required.
Stand- off Cutting
In some cases, it may be beneficial to cut with the
torch tip raised above the work-piece
approximately 1/16" to 1/8” to reduce material
blowback into the tip and to maximize penetration
of thick material cuts. An example of "stand-off
cutting" would be used when penetration cutting or
gouging operation is being performed. You can
use this technique when cutting sheet metal to
reduce the chance of splatter-back tip damage.
Piercing
For piercing, position the tip
approximately 1/8" (3.2 mm) above the
work piece. Angle the torch slightly to
direct sparks away from the torch tip and
operator. Initiate the pilot arc and lower
the tip of the torch until the main cutting
arc transfers, sparks start. Start the pierce
off the cutting line on the scrap piece or
template and then continue the cut onto
the cutting line. Hold the torch
perpendicular to the work piece after the
pierce is complete and continue cutting as
desired. Clean spatter and scale from the
shield cup and the tip as soon as
possible.
Quality Cuts
Dross (slag) is the excess material that

 

[skotl]

Great - thanks, guys.

 

[J.B. Welding]

Its not great as it draws a lot of current, its trying to find earth somewhere. Off work-piece arcing will burn up tips and electrodes prematurely but shouldn't really kill the machine. Its not an internal fuse issue is it? If you turn the amp setting right down on some machines it just vents the air through with no current, maybe not yours though......

 

[gordon stephenson]

I have always believed it is bad practice to air fire the torch and never do so. Will have to ask the question of the Hypertherm guru Jim Colt on the USA welding web forum, He has worked for Hypertherm a very long time,

 

[skotl]

I have always believed it is bad practice to air fire the torch and never do so. Will have to ask the question of the Hypertherm guru Jim Colt on the USA welding web forum, He has worked for Hypertherm a very long time,

That would be great - thanks, Gordon!

 

[skotl]

Its not great as it draws a lot of current, its trying to find earth somewhere. Off work-piece arcing will burn up tips and electrodes prematurely but shouldn't really kill the machine. Its not an internal fuse issue is it? If you turn the amp setting right down on some machines it just vents the air through with no current, maybe not yours though......

When I turn it right down, the amp meter still reads 2 or 3.

I couldn't see any internal fuses, and all the electronics still work with the rather obvious exception of the arc. Not to start another "it's bust" thread here, tho.

I guess when I finally get it fixed / replaced, I'll set the gas by pointing the tip at a scrap piece of metal. The regulator on the back has a stoplock on it so I guess I only need to set it once.

 

[scotty41]

Firing in the air will not harm it all, its not really firing in air, inside the torch is positive and negative, HF kick starts the spark or jumps the gap and the compressed air blows the plasma flame out the torch, non HF uses some sort of spring system to start the arc, sometimes called contact start, if you killed it firing in air look for a large resistor that will be on the clamp side, forgot like the friend above said firing in air wastes consumables.

 

[J.B. Welding]

Firing in the air will not harm it all

forgot like the friend above said firing in air wastes consumables

I'm not making this stuff up mate I remember that from a Hypertherm do's and don'ts DVD. Makes sense to me not to arc up away from an elecrtical path back to the machine?

 

[gordon stephenson]

Hi, chaps. The wonder of the internet, just got this reply from Jim Colt the absolute Hypertherm and any plasma cutter in general GURU. So now we know!!


Hypertherms Powermax systems use a starting system called "Blowback start", which uses a spring loaded electrode to break a short circuit, creating a high intensity spark that ionizes the gas and starts the plasma arc. All of Hypertherms high end industrial plasma cutters (HSD130, MaxPro200, all HPRXD systems) use a high voltage, high frequency discharge between the electrode and the nozzle (inside the torch) to ionize the gas, starting the plasma arc.

The high frequency starting method which was used in all plasma systems for many years (1957 thru the present) was the original way to start a plasma. The Blowback method was invented by Hypertherm in the early 1980's in order to reduce costs, weight, complexity, and electrical noise in portable plasma cutters....primarily hand torch systems.

High Frequency start is very reliable, but can create electrical noise in the form of RF (radio frequency) that can effect the performance of computers and sensitive electronics. High frequency start is used in all of Hypertherms high end mechanized plasma systems because it allows us to manufacture torches and consumables to the utmost levels of precision, (electrode, nozzle, and gas flow concentricity) which provide the tightest cut tolerances (angularity, dross).

Blowback start allows the plasma power supply to be less costly, is a reliable starting method, and makes low cost plasma cutters smaller and lighter. An added benefit is that the system does not produce the high frequency RF noise that the industrial systems do.

There are many low cost import plasma cutters that still use high frequency start technology.....as most are copies of older technology.

Now......do not confuse high frequency with a pilot arc start! Most high frequency start plasma torches can support a pilot arc. All blowback plasma torches can support a pilot arc. A pilot arc is essentially a non-transferred plasma arc that can be fired in air. When a Hypertherm Powermax torch is triggered away from metal....you see a strong, bluish flame exit through the nozzle orifice....that is the pilot arc. The pilot arc was introduced in plasma torches in the early 1960's.....it allows the torch to rapidly burn through rust, dirt, primer, etc to allow the main cutting arc to complete the circuit to the material being cut.

Firing a pilot arc in the air serves no useful purpose. It will very rapidly erode the nozzle orifice.....which will effect cut quality. Different design plasma cutters will have varying effects to consumables when there are a lot of non transferred pilot arcs. The better designs have minimal effect as they have very carefully controlled and monitored pilot arc gas and amperage levels......others (read older technology) will destroy the nozzle and electrode rapidly.

Hope this answers the questions!

Jim Colt Hypertherm

 

[scotty41]

Agreed




.

 

[J.B. Welding]

Firing a pilot arc in the air serves no useful purpose. It will very rapidly erode the nozzle orifice.....

Agreed

?

 

[scotty41]

Where does it say it will break your machine. go back to the original question, can firing in air damage a plasma cutter NO! is the answer, ask Jim Colt, after all I have talked to Jim for the last 10 years

 

[Wozzaaah]

I can confirm that Mr Jim Colt Hypertherm is correct, firing pilot arc ones in the air destroys the nozzles pretty quickly.

 

[scotty41]

Can it break the machine?

 

[Wozzaaah]

It didn't break mine, I just got through the first set of consumables a bit quicker than I expected.

 

[Wozzaaah]

@J.B. Welding and @scotty41 , reading back through this thread I'm a little confused:

Off work-piece arcing will burn up tips and electrodes prematurely but shouldn't really kill the machine.

Firing in the air will not harm it all,

forgot like the friend above said firing in air wastes consumables.

I'm not making this stuff up mate I remember that from a Hypertherm do's and don'ts DVD

You're actually agreeing with other but bickering about it?

 

[skotl]

@J.B. Welding and @scotty41 , reading back through this thread I'm a little confused:

You're actually agreeing with other but bickering about it?

Nice

Sooooooooooooo..... firing the torch in the air will shorten the life of the consumables but will likely not blow up the unit. Correct..?
Meaning that's not what did for mine (again, not wanting to replicate the "busticated" thread in this one).

Back to setting the correct air pressure - just do this on a piece of scrap metal, and effectively set it "for life" and lock the regulator?

Cheers all

 

[Wallace]

Back to setting the correct air pressure - just do this on a piece of scrap metal, and effectively set it "for life" and lock the regulator?

Cheers all

That's what I did with mine, how long does the air stay on when you release the trigger on yours? I have a Trafimet CB50 torch, the trigger is very light and exposed so easy to trigger accidentally especially when you have gloves on. I'll bear all this info in mind to see if the nozzles last longer by trying not to activate the pilot arc in the air, I don't remember anything about it in the manual.