Dross Free Fine Cut

[rons]

That's 14ga. CR with a PM65 at 38 amps 90 volts DTHC ON, 100% dross free

[gamble]

Cool. What speed

[rons]

I didn't remember i will check my shop pc tomorrow

[little blue choo]

That is AWESOME. I wish I could get cuts like that.

[steel 35]

While your at it what height!

[rons]

N0010 (Filename: Crossfit5 2nd and 3rd.tap)
N0020 (Post processor: DTHC-HYT-TAP_SoftPierce+Marker-rev11D.scpost)
N0030 (Date: 22/06/2016)
N0040 G20 (Units: Inches)
N0050 F1
N0060 G53 G90 G40
N0070 (Part: Crossfit5 2nd and 3rd)
N0080 (Operation: Outside Offset, Color 373435, T103: fine cut details)
N0090 (tool number: 103 Distance between Touch-offs: 5 Feedrate: 100)
N0100(Preset Volts: 90) (Preset AMPS: 38)
N0110 ( Air Pressure Preset: 75)
N0120 ( Soft Pierce : 60 percent )
N0130 (This code for use with Ether-Cut upgrade 10-15-14 or later)
N0140( Suggested Tip Size: 45 ) ( DTHC Delay: 1 sec )
N0150 ( Min Cut Length for DTHC ON : 1 units )
N0160 S900 (Global DTHC ON/OFF is ON )
N0170 S10 (Turn off DTHC at the beginning)
N0180 S390 (Preset Volts set to 90 Volts)
N0190 S438
N0200 S875
N0210 S510 (DTHC Delay set to 1 Seconds)
N0220 S712 (DTHCIV tuning set to level 2)
N0230 S701 (Clear S Register)
N0240 M00
N0250(Paused: Check the DTHC Settings Hit RUN to continue)
N0260 G00 Z0.394
N0270 X2.880 Y2.601
N0280 M900 (Check for Z active)
N0290 G28.1 Z0.02 (Start Touch-Off )
N0300 G92 Z0.0
N0310 G00 Z0.063 (Switch Offset Lift)
N0320 G92 Z0.0
N0330 G00 Z0.150
N0340 M03
N0350 G01 Z0.090 F125.0
N0360 F75.0
N0370 S20 (DTHC is on)
N0380 X2.863 Y2.616 F100.0
N0390 X2.861 Y2.617
N0400 G02 X1.387 Y5.999 I3.109 J3.368
N0410 X1.400 Y6.339 I4.662 J-0.013
N0420 S10 (THC OFF)
N0430 X1.474 Y6.881 I4.649 J-0.353
N0440 G01 X1.477 Y6.899

[acourtjester]

Ok a question for the experts in the attached image there are 2 speed setting on 1 command line.
I would think the last on of F75 would be what Mach uses is that correct?

speed.jpg (17.88 KiB) Viewed 3138 times

speed.jpg (17.88 KiB) Viewed 3138 times

[tcaudle]

Not on the same line. If it has a different line number it'
s treated as a separate command, G-code parses the line and actually reads the feedrate PRIOR to the move so line M0350 line moves Z at 125 to .090 ....(??) that is your plunge rate on Z but the .090 is confusing because that is CUT HEIGHT.
THEN after that move the Feedrate is set to 75 IPM for the upcoming XY moves. Feedraes are modal meaning they stay the same until you change them. You can execute a feedrate (or other parameter like an S command) on a separate line

[acourtjester]

Ok then what is the need for line 360 if Mach reads the feed rate PRIOR to a move then the F100.0 on line 380 would set the speed at 100.

[rons]

I didn't make any changes that is straight out of Sheetcam

[rons]

I know the cuts are good but should I be making any other changes to the G Code?
I really twisted the standard Hypertherm Fine cut numbers but the results were getting better and better and more important the DTHC works as good as the 45 or 65 amp, just a guess but does the high volts that make the DTHC work better with fine cut.
Also I put a red tape flag on the top of Z motor shaft so I can see that it is turning is really helpful

[little blue choo]

You keep making cuts like this and I'm coming to Charlotte!

Rick

[rons]

Bring your train that's Rig is Cool

[sphurley]

He has "soft pierce" turned on, not sure if he has HY-T RS485 (doesn't mention it) but it slows down the pierce speed from the normal setting (he has 125ipm so 125x.60= 75ipm) and lowers the pierce current (if he had RS485 control) , then the speed of S100 comes back into play at line 380.

[rons]

I am not using soft pierce on purpose I didn't realize it was on, I have the USB 485 Hub but not the HY-T connect.
If I turn off the soft pierce will that improve the divots?
Thanks
Ron

[sphurley]

It's a toss up. Make up a notebook and run test cuts on what works for You and your machine. Soft pierce with RS485 "can" double consumable life (as it was intended). Playing with speed/velocity, delay, amps, air pressure, consumable, height all effect divots. The new Linux CNC (no windows or Mach) will help a lot (soon to have it) as you eliminate 99% of the lag/delay of the commands being read vs. actually happening. If you search divot on here there is a world of knowledge from Jim Colt and others that can "almost" eliminate divots on open cuts.

[Brand X]

Now if you can get bevel free, and dross free, you will be on to something.. Those always will be at a different parameter for most cuts..

[Metriccar]

I have yet to ever get 100% dross free consistently. At the very least there will be dross in the corners where it slows down.

I've just learned to live with it.

[rons]

Not much bevel either, remember its Plasma very happy

[Brand X]

can't really see in that pic. but stand it on it's edge, and sent another picture.. :)Really is not a issue with 14 ga anyway..

[jimcolt]

Lets not forget....we are talking about air plasma cutting on entry level cnc machines. You can buy a whole 5 x 10 cnc with an air plasma for less than $20k. Expect good cutting speed, a wide range of materials, and decent cut quality....but certainly not perfect. You will have some dross, some edge angularity as well as some anomalies in the cut edge that are caused by inaccuracies in the motion, the height control, the plasma, the air purity, etc.

Want a better cut?

Starting at about $80k you can get an industrial precision cnc machine with an oxygen based 130 amp high definition plasma. Longer consumable life, lower cutting costs, almost no edge hardening, relatively square cut edges, faster cut speeds.....and a cnc machine built to last with little maintenance. You will still get occasional dross, though very easy to remove with oxygen based high definition plasma on steel.

Somewhere between $120k and $150k you can buy a 4 x 8 abrasive waterjet machine. Almost perfect cut quality on any material you choose to cut....tolerances in the +-.003" range, no dross, no metallurgical changes to steel, no warpage. Agonizingly slow cut speeds, high cutting costs. Cut quality is comparable to machining on steel.

Laser on a 4 x 8 table that can cut steel in the same thickness range as a 65 amp plasma (production to 5/8" thick) and really excels speed-wise and cut quality wise on materials thinner than 1/4" can be purchased at between $400k and $500k. The laser will be slower than plasma at thicknesses of 1/4" and above, but will have a narrower kerf and better tolerances. Generally dross free on everything as long as the settings are all correct.

So....we can continue to strive for the best cut quality with our "affordable" air plasma based entry level (or you can call them "light industrial"), but once you get as good as it gets....it is almost pointless to keep trying to get 100% dross free and perfect edge angularity and no edge anomalies (divots, roughness, etc.). You can put an air plasma on an industrial precision cnc machine (and I have on multiple occasions) and things will get better, the price will be higher as well......but it still won't match the performance of a high definition class oxygen plasma on steel.

I will say that process engineers at Hypertherm are working at developing air plasma consumables and process specs that will allow us to cut thinner materials at slower speeds......which will allow machines to stay within their speed range that allows the mechanics and electronics to stay within their best range for stability. In the past we have always asked for "thicker, faster" cutting from our lab guys.....now we are asking for "thinner, slower" and they are a bit confused! We will eventually see air plasma cutters do better on the thinner materials.....and being able to cut at lower power with the correct consumables at lower speeds will likely be the key.

Jim Colt Hypertherm

[cpreston]

Jim, that is almost the exact same specs that I run with a PM 65, FC, 70 ipm 39A on 12 G

[Brand X]

Lower amp nozzles for the 65-85/etc machines are long overdue.. I have had great luck from the Themal dynamics, and Esab cutters with that option. Just somewhere around 30 amps will be sweet..Esab PT-37 was really something special there.. 20/30 amp nozzles. also the 15 amp low end had perfect divots for plasma marking. Did not have to mess around with programing, other then put a pause in to turn the current up after marking was done..