THC is it really needed?

[williamd]

Hi Guys, I tried searching but apparently the words "Torch Height Control" is common, that the search feature on this site won't pull up results.

My question is, is the THC really necessary..? If I was to cut, say.... 16ga, 1/4" even 3/8" steel...?

[beefy]

If you want good edge quality then definitely. With no THC your table would have to be perfectly flat relative to the axis. Hypertherm for instance has a cut height of about 1.5mm, easy to get away from even with just a bit of slag on the slats.

Thin steel can warp a lot when cutting and can easilly end up touching the torch if you haven't got THC.

A good THC will have a means of touching off before piercing, then retract to a pierce height, blow a hole through, then come down to cut height. Piercing at cut height could stuff up consumeables much quicker.

Keith.

[jimcolt]

You can certainly cut without torch height control, but expect the following:

1. Proper cut height is critical to dross free cutting, warp free cutting, and good edge angularity. As an example...the Hypertherm Powermax torchs cut most material at .060" off the plate. If you are .010" higher, the kerf gets wider, the edge angularity gets worse, the higher heat input to the plate will start to cause dross and warpage. There is no plate that will remain flat within .010" over a distance of about 2 feet.

2. Once materials get to about 3/16" thick....plasma torches need to pierce at a higher height than they need to cut at. Typically you pierce at 1.5 to 2 times the cut height...this avoids molten metal blowback from doubl arcing the nozzle, which will damage the shape of the nozzle orifice affecting cut quality on every subsequent cut. Those without height control have the choice of setting the height higher to make the nozzle last longer (with the cutting effects listed above as a result of improper cut height) or setting the height at the cut height and purchasing nozzles at a much higher rate, thereby increasing cut costs.

3.With a good functioning height control, pierce height , pierce dlay time, cut height and arc voltage feedback cut height is automated. You can program 100 parts to cut on a plate and go do something else in your shop. Without height control you will have to stand by the machine and cut each part to ensure no plate collisions or torch damage.

If you have a small machine...such as a 2 x 2 and it will just be used for occasional one - off parts...you can get away without THC. Anything larger than 2 x2 and I firmly recommend height control. Worth every penny.

Jim Colt Hypertherm

[kbenz]

I've been running without for many years. but for the exact reasons above, if I could swing($) avhc i would sure have it

[williamd]

Thanks guys, that's very good to know! For the moment, I'll have to do without... Start making a few dollars and then I'll jump on the upgrade. Hopefully, I won't be banging my head on the wall in the meantime,

[Stout]

Before I had ever used one, I did not think I needed it. My old Esab unit never had a THC and I made a bit of money on that machine for almost 7 years. Maybe the torch height was not that big of an issue with that machine. It was more of a brute force type of cutting operation. You just had to watch it cut the entire job and adjust the height manually. It was a real PITA. I did look into a few THC's and they were expensive upgrades. This one, an ohmic sensor, looked reasonably inexpensive. But I never followed up on a purchase.

http://www.cnc4pc.com/Store/osc/product ... cts_id=330

Now I run a THC and it is a dream. Seriously, I would not run a machine without one. With collision detection and the THC, I just setup the job and press go. I check on proper operation every so often, but it does such a good job, I don't worry too much.

[Marty]

I totally agree with Stout

No way would I not have a THC system....I ordered my table with both a THC system and a magnetic breakaway torch holder................the benefits of each?..............THC allows you to stay within reach of your table (to shut down in case of train wreck crash or torch dive) while it is cutting instead af sitting on a chair 2 feet away babtysitting a 20 minute cut sequence....I can multi task and complete other tasks in the shop while warching the torch from the corner of my eye........instead of staring from The Babysitting Chair..........the Magnetic breakaway torch holder is excellant just in case my attention is not 100% while I am multi tasking in my shop.......without a break away torch holder and there is an ugly train wreck/collision, your touch can be damaged and mine costs me hundreds to replace a damaged torch headand worse yet......I could lose the ability to be cutting product for a promised delivery date......life offers us headache avoidance options.........I try to take them!

[jimcolt]

PlasmaCam with full featured height control....auto calibrates the arc voltage before every cut cycle (no voltage setting, compensates for consumable wear and speed changes) and also equipped with a Hypertherm Powermax85 mini machine torch, SnapnCut collision breakaway, and plug and play electrical interface (one plug in cable from PlasmaCam to the Powermax is the entire electrical interface between the plasma and cnc).
My son....who just learned to run the machine yesterday is in my shop doing a 300 piece (6 - 4 x 8 sheets) order of 18 ga. parts. Is able to walk away from the machine and do some secondary (wire brushing) cleanup of the parts as they come off the table.

The THC definitely takes the babysitting need away from cnc plasma cutting. On the PlasmaCam it is only a $1000 option, and worth evvery penny. Two jobs like the one being done right now and the THC is paid for. One saved broken torch (occasional collisions are inevitable) by the SnapnCut, and it is paid for (under $300).

Jim Colt