You could also do the pierces with a older set of consumables. Then put in new ones and run the program. Piercing is extremely hard on consumables.
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That is a very good idea Phillip!
I think that might really make a difference. You might try something like 50% for the holes. It will create more bottom side dross but that is easier to clean-up than those conical holes.
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Wow I thought it was a joke but I tried it and it generated remarkably good cuts!
In practice I hacked the simple nc file by hand adding a section like this:
(2D Profile2)
G0 X1.258 Y-14.2
G92 Z0.
G38.2 Z-127. F2540.
G38.4 Z12.7 F508.
G92 Z0.
G0 Z0.508 (IHS Springback + Backlash)
G92 Z0.
G0 Z3.81 (Pierce Height)
M3
G4 P1.8
G0 Z1.016 (Cut Height)
H1
G1 X6.258 F420.
H0
M5
G0 Z30.0
G0 X50.0
G4 P10.0
(Change consumables)
In practice, I copy/pasted all but the last three or four lines of the start of a cut, beginning with the IHS routine. That pierces the stock and does the very first part of the lead-in, stops the torch and moves away from the pierced spot. I wasn’t able to make M0 work on this control so I just added a 10s pause, and the operator must press the pause button on FireControl, swap consumables, and resume. The program continues with a regular (note the reduced pierce delay G4 P0.6):
G0 X1.258 Y-14.2
G92 Z0.
G38.2 Z-127. F2540.
G38.4 Z12.7 F508.
G92 Z0.
G0 Z0.508 (IHS Springback + Backlash)
G92 Z0.
G0 Z3.81 (Pierce Height)
M3
G4 P0.6
G0 Z1.016 (Cut Height)
H1
G1 X6.258 F420.
(onCircular: cx=6.258130073547363 cy=-12.699999809265137)
G3 X7.758 Y-12.7 I0. J1.5 F420.
G1 Y12.7 F450.
(onCircular: cx=0 cy=12.699999809265137)
G3 X-7.758 I-7.758 J0.
G1 Y-12.7
(onCircular: cx=0 cy=-12.699999809265137)
G3 X7.758 I7.758 J0.
H0
M5
G0 Z25.4
This made a slot that is cut very straight, I was amazed. A brand new tip used without ever having to pierce stock produces a remarkable quality. And when it wears out some, it can be used to pierce instead and a new one to do the cuts.
Now, modifying everything by hand is going to get old real fast on a real part with multiple pierces, so I might consider writing either a post-post-processor or adding it to the existing Fusion 360 post-processor (tedious)
4 Likes
I got that idea from a YouTube hack he was piercing 1 inch plate. My thinking the easiest way with mechanical parts would be. Pause the program after pierce then do a run from here at the next pierce point. Continue that for all pierces. Then change to new consumables and run the program as normal.
Doing a pierce only add on would be a amazing tool too.
Another thing to consider if your torch moves before a pierce is complete it came cause issues with consumables quick too . What amps are you cutting this 1/2 material?
2 Likes
I have a 60A machine (Primeweld CUT60) and that is what I use for 1/2" plate, with a 1.1mm nozzle. I made a post-post processor, that takes a program and for all the pierces in the program it generates a sequence of pre-piercing, then it waits so the operator can swap consumables. I have not tested the sequence yet on the Crossfire, if the test is successful later today I will attach it here
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Piercing is the hardest thing on consumables. If you need holes smaller then 3/4" then just mark and drill them. Also plasma cut holes are pron to cracking.
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Yeah I confirm that by using a tip to perform all the piercings then pausing, swapping to a new consumable tip, the resulting cut is remarkable. In practice, the issues I was having initially were due to the tip becoming fouled and I was getting very uneven walls.
I will attach (I’m on the wrong computer right now) a post-post-processor that takes a F360 generated program and performs all the pierces first; then it waits 30s (at that point you need to “Pause” in FireControl and swap to a new tip).
It requires Python3 and was tested on a “Mac” computer. I cut a pretty complex part out of 1/2in and it came out very good. Right now it’s a little more than a proof of concept and requires an operator that is willing to check the resulting G-code (or a dry run)
Let me know if there is any sort of interest in making this more generic and maybe part of the enhanced post-processor that should be floating around
2 Likes
What would be nice, and it may be a fusion thing only…
Do a helical pierce. Keep the blast back going out at an angle may save the tip.
Even a reduced feed rate for plunge would be nice…again, Fusion issue I think.
Only really applies to those of us who play with the .5"+ materials. I would love to be able to pierce 3/4 and 1 instead of edge start or pre drilling all my cut starts.
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My first plasma was a rw45. I actually did do some piercings on 3/4 plate nasty though and not the best situation.
Sheetcam does have a wiggle pierce which I really haven’t tried to use. I believe they also have a ramp pierce as well.
It is a different ballgame with oxy fuel just thought it is interesting. We have parts cut out of 8.5 plate they pierce with no predrill.
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Come on people we are talking about a Langmuir hobby table. That should be used with plasma cutters from 30 to 60 amps. Cutting maybe up to 3/8".
If you want to be cutting 1/2" and thicker metal fork out the 50/100 grand and get a real plasma table or water jet or a laser setup.
5 Likes
Well me personally I don’t have between 50 and 100k. When I need a part made and need to push my equipments limits. I am going to do it. I think a lot of us will.
Here is a screenshot of what I think langmuir considered as capabilities for the pro table. 
I believe 1/2 which is what the op is talking about is well within the capabilities of the table itself. Now ones plasma cutter is a different story. The rw45 is rated to cut 1/2.
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But don’t you know George, that is part of the fun of trying to get the most horsepower out of a VW bug.
I do get your point, though.
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Yeah well, the company is not going to Pony up that kind of money so I can build stuff for them. So I have to go out by a CNC plasma table and a dated used hundred amp plasma cutter so I can make the big stuff.
A CNC table is a CNC table, it moves a Plasma torch around. Now, if one uses a tiny plasma cutter machine, one might argue that it’s not powerful enough or that the actual plasma stream is not “high definition”, I have a buddy that has a fancy Lincoln Plasma CNC at work and “it’s always broken” he says.
Now, back to the subject at hand, modifying the Fusion360 post-processor so that the pierce operation does a ramp or some helical path is borderline trivial; but what is that the “big boys” machines do?
This said, when one is doing a part out of thick plate, even tossing one or more tips for the pierces alone is no big deal when the stock costs likely 10-20x the price of a new tip. This post-post I made allows to do all the pierces first, then pauses for you to change out to a new tip, and then it cuts very well, honestly I was really surprised. No need to get a 100,000 dollars machine when one can buy new consumables in bulk.
Here is the python script, I will try to make it an option in Fusion 360 at some point if people are interested (had to change it to a .txt otherwise the dumb Forum won’t allow me to upload)
postpost-piercefirst.txt (2.3 KB)
1 Like
I alway appreciate what you “bring to the table!”
Get it?! 
Thanks for your effort.
Well, the difficult part is not really fixing up a one-time program to do something special, but to make the feature available to the public in an easy way. The last release of a post-processor made by Langmuir was many years ago. I wish they just open-sourced it and made it available for improvements. Me dumping a script on a forum post is not a sustainable way for the community to benefit from it 
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Just my 2 cents, but I bought this table to cut 1/2 steel. I got it with the RW45. It has not let me down. There is a learning/tweeking curve, but I expected that. I didnt go into this thinking I was buyng a highend table that was plug and play. I buy consumables as needed and bill them per project. ( every project buys at least 2 sets, included in the billing) I have cut A36, 4130, AR500, and 416 all in .5 inch. Other then tweeking the feeds and speeds I do not have any issues. Stock setup.
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