Cutting too slow ?

[slimshady20043]

Can cutting at not enough IPM cause you to lose your arc ?? Yesterday I had a half a sheet filled with stuff I wanted to cut and the torch lost its arch probably 7 - 10 times. My partner decided to slow the ipm percentage down and it seemed to make it worse. I was using fine cut consumables per hypertherm book. Recommended ipm was 150 i think and I had it at 140 as 150 seemed crazy fast. .16 guage. Not sure why it randomly ( or maybe not randomly) loses its arc. I lost 7 pieces out of 11. So I won't be cutting more than a piece or two at a time anymore !! Hard lesson learned but its overwith. Any help would be greatly appreciated. I tried looking for an answer in this forumn first but I couldnt really find anything definitive!

Thanks Again,
Slim

[natewelding]

if its cutting a ton of smaller pieces, perhaps when the pieces are falling out and its going so fast its not sensing the plate?

[jimcolt]

Cutting too slow on thin materials can cause "arc blowout"....this will occur in tight corners, areas where the arc almost traces back over itself, etc. By going slower the cut path gets wider.....this increases the torch arc voltage....and once the internal arc voltage in the power supply gets too high the arc will shut off....as the power supply thinks there is no metal under the torch. You don't say what your machine is....or wheter or not you have height control, etc., so I am speculating a bit here.

If you have height control, and you have a machine with good speed capability and excellent acceleration....you will not have arc blowout. The cut speeds listed in the Hyperthem manual are correct....ye in some cases the recommended speeds are faster than some machines are capable of.

Jim Colt Hypertherm

[slimshady20043]

Thanks Jim,
I have a hyper 1650. Yes we have THC. I guess I am just going to have to see if I can replicate the problem and figure it out. I understand that if its cutting close to another line it may fault out. It was doing it while cutting the final outside cut of a big piece. Which is where I got confused. I am very new to this and have learned a lot in a month. I really think it has to do with speed. I dont know why, just makes sense in my head. lol. If it is cutting a straight line that is 10" long, it shouldn't lose the arc unless I am travelling to slow ?? I was getting the .14 gauge dialed in but we switched to .16 and I am struggling with it. Also, the caps are silver for the fine cut setup and all the rest are copper colored. When I checked everything after it was done, the cap wasn't silver anymore, it was copper looking like the rest of the consumables. This might be irrelevant but figured I would throw it in anyways.
Thanks again Jim,

Slim

[slimshady20043]

B&B systems table

[muzza]

I'm not familiar with B&B, what software do you use?
If your running Mach3 there are many users here and we may be able to help.
You say you lose arc, assuming you are using Mach3, does the machine stop altogether?, does the machine keep moving but the torch stop?
If the machine stops altogether, what does the screen tell you?, is the torch on/off light still on or off? is the torch volts running close to the preset, is the tip saver light coming on etc.
The more info you can provide the better.
Also you say that you lost 7 pieces out of 11, you shouldn't lose them, you should be able to pick the cut back up and keep going.
Murray

[slimshady20043]

I'm not familiar with B&B, what software do you use?
If your running Mach3 there are many users here and we may be able to help.
You say you lose arc, assuming you are using Mach3, does the machine stop altogether?, does the machine keep moving but the torch stop?
If the machine stops altogether, what does the screen tell you?, is the torch on/off light still on or off? is the torch volts running close to the preset, is the tip saver light coming on etc.
The more info you can provide the better.
Also you say that you lost 7 pieces out of 11, you shouldn't lose them, you should be able to pick the cut back up and keep going.
Murray

Had to quote so I could answer everything. LOL. I do use Mach 3. It will lose arc and then travel approximately 2 inches. Then the machine stops. The fire torch light, run, and THC light all turn red. I have to hit stop and then if i hit run again it will resume the machine without re- touching off (z zero to material). By torch volts I am not sure exactly what you mean. I have no idea where the tip saver light is. And, I would LOVE to know how to start from a certain line in the program so I don't lose my pieces anymore. I will take a screenshot next time it happens (hopefully never) haha. I have only been in it a month and everything I know about it so far I have learned through experimentation or by reading the quality threads on here. WHICH IS A HUGE HELP !! Sorry I cant provide more info as I am not at the shop but when I get back to the shop, I will definitely take some screen shots and try to be more noticeable about the options in Mach3.

I really appreciate everybody's help !! It's pretty hard starting this up by myself with zero previous experience or anybody to guide me !

Thanks again,
Slim

[muzza]

G'day Slim,
In your PM to me you mentioned an earlier link I put up http://arclightcnc.com/training.html (thanks to Arclight for making this available). I'd suggest that you find a bit of time to work through the videos. The first one will give you a better understanding of all the parts of the screen and where the bits are I questioned. On following videos he explains thing in a bit more detail.

How to re-start from a point in the g code/drawing is explained in video 8. Most times I use the method he explains of scrolling the G code back to the end of the previous cut and using the run from here function (don't forget what he tells you about zeroing the Z)

I know what it's like starting out with something new although when I started with Sheetcam and Mach3 I already had a fair bit of experience with Plasmacam so I sort of knew what I was trying to achieve. Watching the videos up front didn't make as much sense as it did once I started experiencing a few dramas and then it made a lot more sense, almost like having to fall off a bike a few times to really work out how to ride it.

After watching the videos you'll have a better idea of what your looking for and what may be causing it. If you still need help don't hesitate to ask, I am sure myself and others will do our best to help you out.
Murray

[abmagrum]

Yep, Go to the Archlight web page . click on training, I think you want the 2 test cut videos .
Scott shows you how to zero the machine. And then zero youre work piece . So if you run into problems you can go back to zero .And go back to the problem erea and start cutting again. each video is only like 10 minutes . but it shows exactly what to do.you can check out the other videos if you want help designing.

hope this helps
Al

[slimshady20043]

I must have an older version of mach 3 because it looks nothing like the one in the video. We do not have a tip saver feature and a feed hold feature. The platform in the videos looks much more user friendly than the one that I have. I am going to go look and see if there is an update for ours ( hopefully) Thanks all for the help. I'll keep re watching the recovery video until I fully understand it. Thanks again everybody !

[slimshady20043]

Anybody ever feel like they want to puke right before they hit run on their machine ?? Well, I do. AND I HATE IT !!!! I am to the point that I don't even want to run anymore stuff. It petered out on me again on the 3rd pierce !!!!!!!!!! WTF ?????? No idea what is going on and it is crazy frustrating. Maybe the screen shot can provide some clues ?? Also, does anybody live near northwest Ohio ? I need to get my shit together asap as I just rented space in a store and business will be booming. Thanks again everybody. Your help is appreciated in more than I can put in words !!

Im gonna go home and cry now. lol

[slimshady20043]

Well, I got it figured out and it was so simple it made me feel like an idiot. But hey, I guess you don't know what you don't know until you know what you don't know. Thanks to everybody who helped out. Apparently my THC likes a little higher voltage than what the hypertherm book calls for. I run anywhere from 8 - 11 volts higher than the book recommends and she runs smooth as a top !

[trucutcnc]

Could be the voltage divider ratio the THC is set up for is not the same as what the plasma is set for. If that's the case, the THC set voltage will not read correctly. If you're using the Hypertherm voltage divider for the 1650, it is preset at 50:1. If the THC is not set up to use the same divider ratio, you're numbers will not match.

If you're a stickler for having the numbers match you can look into that....or just make note of your best cut settings and use it as is.

[jimcolt]

The voltage suggestions in the Hypertherm manuals are accurate under laboratory conditions....which is where these voltages were developed. They are monitored using high accuracy voltage monitoring equipment, and assume that: 1. new consumables are in the torch, 2. Air pressure and flow are set exactly as the operators manual suggests, 3. cut speed is set exactly as the manual suggests, 4. Work ground is connected securely, 5. The electrical interface between the Hypertherm output voltag and your THC voltage input is done correctly,. 6. That your THC is calibrated at a known arc voltage.

Change cut speed.....the voltage to height ratio will change, as consumables wear.....the voltage to height ration will change, if air pressure changes.....the voltage to height ratio will change, etc. The height control curcuitry relies on a lot of parameters......so the voltages listed in the operators manual are good starting points. If the torch is too close....increase the voltage on your THC, if it is too high, decrease the voltage on your THC.

Some torch height controls will automatically calibrate the arc voltage at a fixed height before every cut....most height controls however rely on the operator for occasional tweaking to ensure that the physical height suggested in the manual remains correct and constant.


Jim Colt Hypertherm

Well, I got it figured out and it was so simple it made me feel like an idiot. But hey, I guess you don't know what you don't know until you know what you don't know. Thanks to everybody who helped out. Apparently my THC likes a little higher voltage than what the hypertherm book calls for. I run anywhere from 8 - 11 volts higher than the book recommends and she runs smooth as a top !

[slimshady20043]

Jim, your a genius in your profession ! I am relatively new at this ( month and half) and I had a good idea all along what was happening. With my lack of knowledge, I didn't know the proper way to adjust for it. Talked to table manufacturer and he helped me out. Thanks for your input. Many fellow metallurgists (including myself) would struggle without your help !

Thanks again for your input,
Slim