Is it really needed? Arc Voltage Torch Height Control

[schoobie]

Just trying to justify and understand the $2,399 bucks to be spent on this accessory.

I want to start a shop and this accessory represents a third of the cost of the machine.

Is this accessory needed only to cut high precision parts? Or is needed even for simple and non-industrial cuts?

Is this nice-to-have only or a must?

Need some reference to do the purchase.

Thanks!

[Torchhead]

Do some research. You can get a Digital Torch Height (aka ATHC) for less than 1/3 of that price including the control software.

You need to provide some form of height control unless you have a spring loaded head and a drag tip. You have to cut at .063 above the material moving at 100 to 300 IPM. Thin material buckles enough to cause tip crashes. If the material is not perfectly level you have added problems.

For 2400 bucks you can get a complete electronics bundle including motors, drives and power control with a digital THC.

Tom Caudle
www.CandCNC.com
http://www.CandCNC.com/SolutionsMenu.htm

[schoobie]

The one I am looking at is the one Torchmate has on its catalog.

[Mike@Torchmate]

Depending on what you are cutting I would almost justify it as a must unless you intend to build some type of manual plate following height control for the torch.

If you are cutting light gauge material up to slightly thicker plate (.1875" or .25") the material will most likely warp causing the tip to crash and drag on the plate, which ruins consumables and will likely ruin your cut as well. The AVHC will retract a certain distance in between cuts, so that when the torch is rapid traveling across the plate at 300 i/pm tip-ups in the plate won't hit the torch causing even further damage. At the beginning of every cut it also re-senses the material to ensure it is starting at the right height.

When you add up the cost of burnt up consumables, ruined plates of material, and potential broken torch head, it does not take long to make up for it's price.

[LenMcC]

i'm planning to order a torchmate with athc in early january, and i expect the athc to be worth every penny.

[schoobie]

what sizes are you choosing for the table?

[LenMcC]

4x8 or 4x10. i'm 90% sure we're getting the 4x8. we receive material in 4x8 sheets, and soon we'll be moving to 4x10s, but we don't cut more than 4ft wide strips off the long dimension at a time, so we have no need for the extra 2ft, i don't think.

also, we cut expanded and perforated aluminum, which i'm pretty sure would wreak havvoc on the torch head without the height control.

[Mike@Torchmate]

Originally Posted by LenMcC also, we cut expanded and perforated aluminum, which i'm pretty sure would wreak havvoc on the torch head without the height control.

If you are cutting expanded or perforated material the height control will have to be set in manual mode and special precautions must be taken to ensure the torch tip does not move below the material. The pierce sensing must be set so that at the bottom of the AVHC travel the torch tip is sitting above the material. This would ensure that even if it senses over air the torch still backs up to the correct cutting height and does not drag the material.

[LenMcC]

yeah, i figured we would have to set a minimum plunge so the machine doesn't think the material dropped away. you don't see perforated sheet as a problem, though, right mike? i know i talked to someone (probably not at torchmate) that said perforated is no problem. i may have seen a video of a plasma table cutting perforated, too, but maybe not...

[Mike@Torchmate]

Originally Posted by LenMcC yeah, i figured we would have to set a minimum plunge so the machine doesn't think the material dropped away. you don't see perforated sheet as a problem, though, right mike? i know i talked to someone (probably not at torchmate) that said perforated is no problem. i may have seen a video of a plasma table cutting perforated, too, but maybe not...

We have cut perforated material a lot here in the shop. There are a few conditions though. It has to be done in manual mode, otherwise when the cutting arc moves from pilot to transfer arc the voltage reading will change dramatically causing the height control to respond. The second is that the plasma cutter has to be in the Perforated material cutting mode in order to maintain the pilot arc across the gap and as soon as it senses the material it activates the cutting arc again. The last is the cutting speed, if it's too fast the arc may not transfer in time to sever the material.

[LenMcC]

Originally Posted by Mike@Torchmate Perforated material cutting mode

i like the sound of that mode. fortunately, we will cut primarily one perforated pattern in one thickness, so that should make dialing in settings easier.

these could be ignorant questions, but:
1) does transfering between pilot and cutting arc so many times each cut shorten the life of consumables or the machine or anything else?
2) what's the difference between pilot and cutting arcs? why can't it maintain the cutting arc across small gaps?
3) do slower speeds mean more dross? or do slower speeds mean we'd just need to reduce the current (and/or other settings) to match the speed?
4) does manual mode mean the height control is disabled?

thanks!!

[Mike@Torchmate]

1) does transfering between pilot and cutting arc so many times each cut shorten the life of consumables or the machine or anything else?

Yes, it can wear out the consumables faster, depending on a few factors like speed and the size of the gap the torch will have to cut across.

2) what's the difference between pilot and cutting arcs? why can't it maintain the cutting arc across small gaps?

The pilot arc is a small arc where it is basically searching for the ground through the material, once it has found that ground the machine transfers to a cutting arc which is where the amperage comes into play. It can maintain a cutting arc across small enough gaps where the torch can be severing one cut and then make contact with the next.

3) do slower speeds mean more dross? or do slower speeds mean we'd just need to reduce the current (and/or other settings) to match the speed?

In general you would use the appropriate speed and amperage settings as you would for the same thickness in flat plate, and then adjust from there. If you slow it down alot you may need to decrease the amperage on the plasma cutter to compensate, otherwise it could result in more dross build up.

4) does manual mode mean the height control is disabled?

The AVHC would not be completely disabled no, it will still sense pierce height and retract between cuts. It will just maintain the pierce height across the entire cut.



Hope that has answered your questions so far.