THC and Cut Quality Issues

**michiganiron** · 04-06-2009, 02:29 PM

We are running a Hypertherm powermax 1650 with a machine torch head on a 4'x8' ez-router plasma table. Having a couple of issues right now, any help would be much appreciated.

First, Having problems with the torch height controller. When the THC is turned on the torch head wants to dive straight into the workpiece as soon as the program is run. A couple of things i have noticed, the down LED in Mach 3 is always on, whether the THC is turned on or not. The down LED on the THC panel underneath the keyboard never comes on. Any ideas?

Second, we have been getting terrible cut quality with the machine lately. Im sure some of this can be attributed to the THC not working, but I think there is more to it. We have been getting oval holes and holes that are so beveled that if they are 9/16" on the top side, a half inch bolt wont even fit through the backside of the hole. The cut quality seems to be better on regular edges, but we seem to still be getting more bevel than we should. This even happens right after consumables have been changed out.

Any input is much appreciated

**jimcolt** · 04-06-2009, 04:04 PM

Bad bevels and changing bevels are caused by incorrect height and consumables that have been damaged by incorrect height. You can destroy a nozzle on the very first pierce if the height is not maintained correctly. I would suggest you get help from who supplied the machine and THC.

Jim

**michiganiron** · 04-06-2009, 04:10 PM

Thanks Jim, I have left a message and emailed ez-router about this issue, they are just a little slow on responding sometimes, was hoping to get some input on the THC issue so i can get it resolved as quickly as possible as Im sure this is most of the bad cut quality cause.

**jimcolt** · 04-06-2009, 04:21 PM

I'd help but I am not familiar with their THC system. Generally if the torch is diving into the plate then it means that the arc voltage setting is too low (the z axis is trying to correct the voltage by getting closer to the plate).....I don't know how you set the arc voltage on your machine (some call it "tip" voltage.....since the voltage is developed between the electrode and the plate...then it should be called arc voltage)...but if you dial in a much higher number....the torch should not dive. Too high and the torch will rise too high off the plate....too low and it will crash into the plate. When the voltage setting is just right then your torch will ride at the manufacturers specified height (from your Hypertherm manual) off the plate.

Does your system have initial height sensing....in other words does it find the surface of the plate then retract to the proper pierce height...then pierce?

Jim

**michiganiron** · 04-06-2009, 04:43 PM

Our system does touch down onto the plate and then go to the pierce height set in the machining g-code. It does this for every new pierce throughtout a program.

I have played around with the arc voltage setting on the THC a little bit, still cant seem to have any affect on the torch head diving. If i dont use the THC the arc voltage readout is right around the reccommended arc voltage setting when first starting a cut, although obviously varies quite a bit as the torch moves along the material.

**jimcolt** · 04-06-2009, 05:10 PM

Could be a poor ground....you may want to attach the work clamp directly to the plate you are cutting. It is also possible that the polarity is reversed on your voltage divider? I've seen than more than once over the years!

Jim

**jimcolt** · 04-07-2009, 07:32 AM

Here are the first parts I cut with my new PlasmaCam table with a Hypertherm Powermax45 yesterday....some 1/8" aluminum treadplate, some rusty 20 ga. steel, some 1/4" and 1/2" steel. the holes in the 1/4" go from 3/16" to 1"...there is some taper in the holes but they are perfectly round top and bottom.

Jim

**michiganiron** · 04-07-2009, 08:51 AM

I will check out the polarity on the voltage divider, that is something i didnt think of and havent had anyone suggest yet, thanks jim.

**michiganiron** · 04-07-2009, 10:14 AM

One last update, found that the problem was on my end, had the tip height set to low for how thick of material i was trying to cut, and was forcing the tip into the workpiece. Thanks for all the help.

**coalstove** · 04-07-2009, 01:33 PM

Which type of "arcOk" and voltage sensing are you using, ez router distributed 2 types, one that uses a current transformer and one that take the signals from the Hypertherm main board. Been down this path already, between John at ez router and Tom at CandC(torchead here) we were able to solve my problems, both great guy's maybe Tom can chime in, or send him a PM. If not PM me for a number to call and maybe I can get you through it, but am surprised that John has not been able to help, call them back an ask for him.

**coalstove** · 04-07-2009, 01:35 PM

By the way if you are using fine cut consumbles, which you should be for thin stuff, buy the ohmic deflector for your torch, Jim Colt turned me onto this and has saved the lives of many consumbles