Plasma cutting along a drawn line?

[HandLogger]

I realize that this isn't technically a welding question, but I couldn't find the perfect forum board, so here goes...

Has anyone ever hand cut along a drawn line using a plasma cutter? ...and, if you have, what did you use to draw the lines with?

I've never used a plasma cutter before, but I understand that the light emitted during the cutting process is super bright; hence, my question.

[52 Ford]

I realize that this isn't technically a welding question, but I couldn't find the perfect forum board, so here goes...

Has anyone ever hand cut along a drawn line using a plasma cutter? ...and, if you have, what did you use to draw the lines with?

I've never used a plasma cutter before, but I understand that the light emitted during the cutting process is super bright; hence, my question.

Paint markers and Sharpies.

For most cuts, you're going to be a lot better off using a guide. Figure out how far to offset your guide.

Make sure you wear some shade 5 or darker goggles. https://www.lincolnelectric.com/en/products/k4708-1 mine are similar to these. You might want a darker shade, though.

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[Oldiron2]

I agree about using a guide when making long straight cuts, but sometimes, such as when cutting curves, a guide would be hard to make or to use. If one knows the system/torch and doesn't have to vary speed or stand-off distance to keep from loosing the cut, once started, the jet doesn't need to be watched. Keep the head behind the torch so the side of the tip follows the line, allowing for how much off-center the side is if not going straight left or right. Reflected/refracted light will generally be enough to see a well-scribed or a white (or aluminum) marker line on the workpiece. If the metal is too shinny, first coat it with Dykem. I can't remember when I haven't used my old shade 5 gas welding goggles when plasma cutting, although I must have used a hood a time or two when I wanted to use reading glasses for better vision.

Another important point: don't ever get old and shaky; the plasma torch accentuates such movement.


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[Sberry]

I do most cuts by hand, its almost instinct after torch for so long. Sometimes I hide the arc, usually use safety glasses, dark is fine. The light is bright but the current is low and l do watch it if I am trying to be really accurate. Also do use some guides, mostly paint stick of yardsticks and cut holes with saw in some luan for rounds.

[Rondo]

I like to use Silver Streaks or Silver Pencils. They light up very well from the plasma arc or torch flame.

[Oscar]

I like to use Silver Streaks or Silver Pencils. They light up very well from the plasma arc or torch flame.

I love the line, but man are they way too soft and break easily. I was hoping the silver pencils were going to have a tougher silver center compared to the mechanical feeder pencil with the individual leads, but nope. The were pretty bad IMO. I'll just stick to the mechanical pencil and soapstone as well.

[Brand X]

Depending of cut amps, shade 3 can be used also.. It can help with seeing the line on sheet metal. Drag tips also play a roll in keeping the arc below the plate..I normally wear #5 for standoff cutting, or CNC cutting.

[Oldiron2]

Paint markers and Sharpies.

For most cuts, you're going to be a lot better off using a guide. Figure out how far to offset your guide.

Make sure you wear some shade 5 or darker goggles. https://www.lincolnelectric.com/en/products/k4708-1 mine are similar to these. You might want a darker shade, though.

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[Lis2323]

as others have said using a straight edge as a guide (if possible) would be my first choice …





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[SweetMK]

I agree with those who have said use a guide,,,, B U T,,
When you absolutely have to free-hand cut,, there is a simple rule to follow that improves cut quality 400%

Only cut left to right, (or right to left) as that is the most accurate way that you can move your hands.
Do NOT cut towards you, or away from you.

If you cut side to side (left to right,, etc) it is easy to practice the cut with the torch off, simply moving the torch to see if you have the range of motion needed.

Practicing towards, or away from you is almost impossible.

I had been taught this at US Navy Shipfitter "A" School (now called Hull Maintenance Technician "A" School) .

Some years later, I attended a trade show, and a welding supply had a guy demonstrating the "magic" that could be done with a cutting torch.
Well, I noticed that he would reposition his body for EVERY cut, to make sure that the cut would proceed, side to side.

[Lis2323]

I agree with those who have said use a guide,,,, B U T,,
When you absolutely have to free-hand cut,, there is a simple rule to follow that improves cut quality 400%

Only cut left to right, (or right to left) as that is the most accurate way that you can move your hands.
Do NOT cut towards you, or away from you.

If you cut side to side (left to right,, etc) it is easy to practice the cut with the torch off, simply moving the torch to see if you have the range of motion needed.

Practicing towards, or away from you is almost impossible.

I had been taught this at US Navy Shipfitter "A" School (now called Hull Maintenance Technician "A" School) .

Some years later, I attended a trade show, and a welding supply had a guy demonstrating the "magic" that could be done with a cutting torch.
Well, I noticed that he would reposition his body for EVERY cut, to make sure that the cut would proceed, side to side.

Excellent advice.

If I may add, IF cutting with a guide the opposite may work better. PULL towards you (when using a guide) if possible for better control.

OH. And when cutting circles I go clockwise if I’m in a hurry and counterclockwise if I’m getting paid by the hour.


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[Lis2323]

And a “little” off topic but important none the less ….




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[Oscar]

Only cut left to right, (or right to left)[/B] as that is the most accurate way that you can move your hands.
Do NOT cut towards you, or away from you.

Good call for free-hand cutting. If you drag the torch to or from yourself, you're not using your hands but rather you're using your shoulder/elbow muscles which typically do not have the same motor-control/dexterity that your hand/wrist/fingers do.

[psacustomcreations]

Here are a couple pics to help show how the plasma height, torch angle, and speed affect cut quality.

The last pic shows how cut direction affects quality on curves, circles, or whatever.









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[HandLogger]

A very kind friend of mine loaned me a nearly-new Hypertherm 45xp to try out, so I took all of the advice I received in this thread and put it to the test: several times.

The 45xp struggled to cut 1/4" mild (with way too much dross), much less the 1/2" stuff I've seen cut in YT videos. Anyway, a Hypertherm and a good air dryer system is quite the investment to make just to "hope" that it works. If I ever get a chance to use this machine again, I think that I'll figure out how to dry the air first.

In the end, my thought is that keeping one's air dry must be as important as everyone says it is. Other than enclosing the machine in a room that had a big dehumidifier in it, I had nothing else to dry the air with. I used our Makita portable electrical compressor to supply the air (85 psi), which it did quite well, but, once again, no air dryer in the system.

Perhaps a tank of air instead of a compressor (just to test with)? Any thoughts?

[Oscar]

The 45xp struggled to cut 1/4" mild (with way too much dross), much less the 1/2" stuff I've seen cut in YT videos.

Unless the machine is compromised, I'd say the user, not the machine, struggled to make the cut by 1. Being a first time user of plasma cutters and 2. Not filtering/drying the air. The 45xp is pretty well documented to be a bada!& plasma. Just like welding, it does take some practice. A tank of compressed air would only help if it is clean and dry, thus eliminating one variable.

[Meltedmetal]

Dry air is certainly desirable but I don't think lack of it is your problem unless your seeing water blow out of the torch. 1/4" should be a snooze for a 45XP. How big is your compressor? I'd suspect your cutting speed is too slow.See the post above yours. Does your friend use this 45XP? Ask for some instruction.

[HandLogger]

Dry air is certainly desirable but I don't think lack of it is your problem unless your seeing water blow out of the torch. 1/4" should be a snooze for a 45XP. How big is your compressor? I'd suspect your cutting speed is too slow.See the post above yours. Does your friend use this 45XP? Ask for some instruction.

Thanks for the productive comment, Melted Metal. The 3 hp twin-nailer compressor is rated for over 6 cfm at 90 psi, but the tank is small at 5.2 gallons. I set it according to a YT video I watched in which the guy testing a 45 Amp plasma cutter was cutting 1/4" mild with pretty good results (the same thickness I was trying to cut). As for getting instruction, the fellow I borrowed it from hasn't used it much, either, so he was hoping that I'd bring back some tips for him.

I was thinking about returning the 45xp today...but I think that I'll give it one more try with new consumables installed. Now that I've read what you had to say about "dry air," I'm thinking that I may have been using worn consumables.

[Oscar]

If the electrode is pitted more than 1mm and if the cutting tip orifice is already elongated to th point of looking like an oval, it's time to change them.

[HandLogger]

Follow up: As I mentioned in my last post, I gave the Hypertherm 45xp another try with [part of the] new consumables. Specifically, I changed the nozzle and the shield/cap, but still had no joy. I didn't have a new electrode or a swirl ring, so I have to assume that they were in need of replacement. In the end, I tried to cut 1/4" mild steel numerous times with the 45xp with no satisfactory results....so I gave the machine the best scrubbing it's ever had and returned it to the owner.

[tapwelder]

Good call for free-hand cutting. If you drag the torch to or from yourself, you're not using your hands but rather you're using your shoulder/elbow muscles which typically do not have the same motor-control/dexterity that your hand/wrist/fingers do.

I agree, If I am drag cutting, I pull toward me 100 percent, if possible. I cannot push successfully very often. Pushing seem to feel sticky or jerky. The extra mass from using the upper arms does assist straight cuts for me.

Plasma torches are light not an much mass as o/a torches. O/a torches never touch the work. Plasma to torches being dragged is kinda like a light car on a bumpy road with zero suspension.

[52 Ford]

Follow up: As I mentioned in my last post, I gave the Hypertherm 45xp another try with [part of the] new consumables. Specifically, I changed the nozzle and the shield/cap, but still had no joy. I didn't have a new electrode or a swirl ring, so I have to assume that they were in need of replacement. In the end, I tried to cut 1/4" mild steel numerous times with the 45xp with no satisfactory results....so I gave the machine the best scrubbing it's ever had and returned it to the owner.

To me, it sounds like you didn't have the ground clamp attached to the work. With my 50A plasma cutter, I can saw through 1/4" material with just the pilot arc.. I usually run my plasma cutter off of a Bostitch 6 gallon pancake air compressor. It just BARELY keeps up, but it's more convenient than having to start up one of the bigger compressors. Your compressor should be more than sufficient.

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[whtbaron]

To me, it sounds like you didn't have the ground clamp attached to the work. With my 50A plasma cutter, I can saw through 1/4" material with just the pilot arc.. I usually run my plasma cutter off of a Bostitch 6 gallon pancake air compressor. It just BARELY keeps up, but it's more convenient than having to start up one of the bigger compressors. Your compressor should be more than sufficient.

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Or possibly a burnt connection within the ground clamp itself...

[vwguy3]

When I drag cut I don’t use shaded glasses.
The arc is in the kerf. Gouging?, by all means I use a shade 5 shield same as flame cutting and when using a heating head.

[Oldiron2]

Follow up: As I mentioned in my last post, I gave the Hypertherm 45xp another try with [part of the] new consumables. Specifically, I changed the nozzle and the shield/cap, but still had no joy. I didn't have a new electrode or a swirl ring, so I have to assume that they were in need of replacement. In the end, I tried to cut 1/4" mild steel numerous times with the 45xp with no satisfactory results....so I gave the machine the best scrubbing it's ever had and returned it to the owner.

If I had been in that situation, I would have called Hypotherm and asked for assistance. The company is (or used to be) known for having good customer service, for understanding its products, and for knowing most of the things that can go wrong. It isn't too late to do so; even though you don't have the machine in front of you, you probably remember enough about it to explain the situation's details well enough to have a meaningful conversation. Your friend might also benefit from doing that, assuming he has the same problem if he tries using the cutter.

I don't have a Hypotherm, but when my electrodes wear too short, the torch just won't 'fire'.