blow holes in plasma cutting

Davek0974 · Post by **Davek0974** » Wed Feb 18, 2015 1:49 pm

Sounds good, thanks Les

however, as i already use the "normal" end delay it could get a bit messy

How far into the realms of dreamland would it be to get the check-box added to the cut screen as an option "Pierce both ends"????

Post by **Les Newell** » Wed Feb 18, 2015 1:57 pm

I don't really see that it will work very well and this is a pretty unusual request so I'm afraid I probably won't add it.

Try manually adding a delay to the g-code before it turns the torch off. If that gives you the effect you want I'll explain how to tweak the post to add an extra parameter to the tool definition for a pre torch off delay.

Davek0974 · Post by **Davek0974** » Wed Feb 18, 2015 2:07 pm

That sounds just as good, thanks for that Les.

I will test it as soon as possible and report back.

Dave

Davek0974 · Post by **Davek0974** » Wed Feb 18, 2015 7:25 pm

Well, I did have a mess-about tonight, I tried pausing for a second at the end of the cut, had surprisingly little effect really, very slight hole but nothing like a pierce.

Then I tried a reverse pierce - make the cut, then keep the torch on at the end and lift back to pierce height before stopping the torch. This gave a reasonable effect but was still smaller than the start pierce.

Piercing at cut height made very little difference and would likely be bad for the consumables.

The final test was a full pierce - move to the end of the cut, make a pierce, drop to cut height and stop the torch, lift back up. Then move back to the start and cut towards the pierce hole. This gave perfect results as expected - a line with a matching pierce at each end.

So, the question is, can the POST be modded to make a pierce at the end location first ???

The only other way is to mark one end of all open cuts in the CAD stage then "drill" these with the plasma as a first op.

Post by **Les Newell** » Wed Feb 18, 2015 9:16 pm

Unfortunately the post doesn't know where the end of the cut is until it gets there. It would not be able to pierce the ends first.

Davek0974 · Post by **Davek0974** » Wed Feb 18, 2015 10:22 pm

Guessed as much

Just have to go for the CAD option I guess.

tumbleweed · Post by **tumbleweed** » Sat Feb 28, 2015 4:42 am

I have really enjoyed all the replies to this issue. Here I thought I was the only one with this problem.

Vmax549 · Post by **Vmax549** » Sun Mar 01, 2015 2:30 am

The problem is the M3 has a slight delay to it as it uses DospinCW() to start the spindle. There IS an alternative. You change teh M3 code to do a direct ouputstart

ActivateSignal(output1) IF your M3 is tied to output1 , look in the spindle section for the output# that is used with M3.

I would also change teh M5 to DeactivateSignal(output1) as well.

You also can try starting on the fly with all delays turned off including the THC delay so as soon as it see the arc it starts to move. Pierce as LOW as possible the Z move to cut height adds delay to table motion.

Also try reseting the Mach delay to MS instead of Sec.

I have done some nice pierces on the fly I will just have to look and see exactly how I did it back then. The pierce and line looked the same. Now this is on THIN guage stock 18ga.

(;-) TP

Vmax549 · Post by **Vmax549** » Tue Mar 03, 2015 4:13 am

OK I had to stop back by the shop to check on that. The way I do it is put a switch across the ARC OK input signal going into Mach3. That way it sees that it is ready to go as soon as the M3 signal is given. It will strike the arc at the same time start moving. Kinda like a gouge start. But it makes a very clean start of the line. NOW this only works on thin Guage material where you have a lot more POWER than you have material(;-).

I just added a Relay and switch it with a Mcode for ease of use.

(;-) TP

Davek0974 · Post by **Davek0974** » Tue Mar 03, 2015 1:01 pm

Interesting, is that relay fitted as well as having the M3 set to ActivateSignal etc????

Vmax549 · Post by **Vmax549** » Fri Mar 06, 2015 10:06 pm

Yes that is correct. Relay fitted AND acitvateSignal.

(;-) TP

Davek0974 · Post by **Davek0974** » Mon Apr 06, 2015 5:24 pm

Well I've changed the macro codes and find the best result is by piercing at cut height so no delay for z moves, also turning off the torch 1.5mm before the end of cut when doing shapes gets rid of any divots.

Works pretty well.