THC Setting Issue?

[Davek0974]

I have got it working on slow cuts now, I lowered the HYS setting to 1 and increased Mach3 RATE to 10% now it cuts good at slow speed

On a faster cut i see it follows upwards very nicely but does not follow downwards fast enough, leaving me with a very big cut height.

If the metal is shaped 0mm - 10mm - 0mm across the X axis, it will follow 0mm - 10mm but then it will finish on about 5mm not 0mm.

Any ideas??

[Davek0974]

Well it looks like the THC is just no good, if i tune it for slow cuts it works well, but could never manage a cut at 3300mm/min, pretty certain if up the tuning to go faster it will bunny-hop on slow cuts due to overcompensating. :(

Anyone recommend a THC ?

I have tried contacting CandCNC but had no response yet.

I had this reply from Proma....

"THC 150 has about 150ms (0,1 - 0,15s ) processing time, o don't sure what many time need mach for reaction.
total time isn't very well for it. I think that better is use model SD (step dir) or full system MD+DV. both systems works alone (without software) and total delay time is about 70-80ms - for high speed still it's not very fast but better that compact THC."

Sounds like speed is not their thing?

[Robin Hewitt]

I think your problem is those Americans. They all make huge plasma cutters driven by enormous stepper motors and when it comes to THC the Z axis already has a huge stepper motor on it.
Maybe a second lightweight DC motor driven Z axis mounted on the MEGA stepper driven Z axis could be the solution. You do not actually need 2 tons of lifting force to move a plasma head.

[Davek0974]

I see where you are coming from but I designed and built this table myself ;)

Its driven by tw medium size Nema23 motors for X & Y plus a small Nema23 motor on the Z axis, it has a floating head etc.

I think the main issue is poor loop response time of the Proma THC unit, its fine on slower cuts but get up to 2300mm/min and higher and it cant cope.

Cant find a different unit that will work with my little Hypertherm 30xp though, they all want built in outputs for the THC and I don't have that.

[quickcut]

try cncdirect.co.za. his thc works very well for me

[Davek0974]

Thanks, just emailed
them

[tommylight]

I have 4 of Proma THC and been using them for over 2 months so here is where i am at:
3mm mild steel light bent at 2-3 cm per feet i can cut at 5500mm/min at 60A all day long, mostly use it at 3000-3600mm/min at 30A so i do not bother to be near the machine at all
2mm mild steel cut mostly @4200mm/min @30A
Back to your problem: you did not mention the delay--> lower it on the THC so you get faster response from it, and if this does not help, you might need to change the computer or do a fresh install.
B.T.W i use linux exlusively but i had a winXP/Mach3 setup for a client that does production work with it on a 3.5mX2m work envelope with a Hypertherm MAX100.
Regards,
Tom