Sitting in here in a snowmobile suit. 
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I have a ground rod for my powder coating I could use right by my table.
Maybe I will look into doing something after all
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If you don’t have a problem or don’t have anyone else in the shop Tig welding you probably won’t need it.
I will say this, it will be cheaper than a sheet of steel…
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So do I have this right, is that just showing a ground to the table itself?
My understanding is that it is not added in the post processor for Fusion, since there is a setting in Fusion for that. I don’t use Fusion, so I can’t say for sure.
Sheetcam doesn’t have a setting for springback/backlash, so the post processor adds the line for .020" backlash.
This is the IHS sequence of commands:
G92 Z0.
G38.2 Z-5.0 F100.0
G38.4 Z0.5 F20.0
G92 Z0.0
G0 Z0.02 (IHS Backlash)
G92 Z0.0
G0 Z0.15 (Pierce Height)
M3
G4 P0.4
G1 Z0.06 F100.0 (Cut Height)
You can easily check your Fusion code by creating a file with zero springback and checking to see if that line (labeled as IHS backlash in my sample above) is in the code. You can open the file by using Notepad or a similar text viewer
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The DC work clamp wire is actually attached to the earth ground rod. You must use a very large copper cable to it. Like #1 copper wire. The path of least resistance. Get it?
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That is right if you remember we had this discussion before. Being cloud based is one of by biggest turn offs. My other faults with Autodesk just sounds like I am criticizing them. I have always liked Autodesk I used AutoCAD 2000 for several years and loved it.
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Ideally you install one copper grounding rod or a grounding plate near the table that the bus bar from the table can attached to.
Your electrical panel should have a plate or rod natively installed to it.
The path between those two points underground become your low impedance pass which in theory should mop up any noise.
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Fusion does differ from SheetCAM in that it takes the springback value and adds .020" for backlash. This is built in to the Post. (See below.)
(v1.6-af)
G90 G94
G17
G20
H0
(2D Profile1)
G0 X1.4744 Y1.996
G92 Z0.
G38.2 Z-5. F100.
G38.4 Z0.5 F20.
G92 Z0.
G0 Z0.04 (IHS Springback + Backlash)
G92 Z0.
G0 Z0.15 (Pierce Height)
M3
G4 P0.8
G0 Z0.063 (Cut Height)
H1
If the resulting cut height is off, I’ve been reducing spring back & cut height in Fusion to achieve my target. (Usually .060".)
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Yeah Simon, I was just looking at my G-code in Notepad as David @ds690 suggested, and saw that Fusion added another 0.020" to my 0.020" IHS spring-back setting.
So, testing on my machine has revealed that it has very little Z-axis backlash. I’m not sure if this is because it’s brand new, or because Langmuir’s Z-axis assembly has very little backlash by design? David’s test was set to a 0.063" cut height and I was measuring 0.065" and @Phillipw’s test was set to a 0.080" cut height and I was measuring between 0.083" and 0.084"; net result of BOTH tests was a cut height 2-4 thou HIGH (opposite direction of backlash). Perhaps I need to monitor the IHS process to see if those measurements change with use over time?
Regardless, it sounds like I need to set my cut height 0.020" lower than what is desired in Fusion 360, or go into my G-code and parenthesis out the backlash settings manually. The end result is that my cuts on 3/8" plate were happening at ~0.103" instead of 0.060" and I had no reason to even suspect it.
I find this all VERY interesting since Langmuir’s default software is Fusion (because it’s free), and their post-processing tutorial series suggests using the 0.020" IHS setting with no mention of backlash, and because TOO HIGH cuts seem to be a very common problem for new Langmuir users (the Facebook group is full of them).
I’m extremely grateful for these forums right now, but can’t help but be a little bit frustrated that there isn’t better information in the Langmuir instructions and setup tutorials. Between unintentionally setting my cut-height 0.040" too high, and the ambiguous wording in the instruction manual about where the “ground clamp” was supposed to go, I was never going to have a successful first cut.
Throw in that backwards swirl ring on my brand new machine torch (Tecmo’s fault, even though I guess they claim swirl ring orientation is irrelevant), and I truly made a mess out of my first 3/8" plate.
I still had some THC “bobbing” that I might ultimately have to contend with, but I think I’m on the right track now. Hopefully these 150 posts will be helpful to another “newb”, assuming they have the patience to wade through them…
Alas, I continue to wait for steel and consumables (we’re snowed in now).
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If your measured cut height on 3/8" (which should have 0 spring back) is ~.100", I’d change the spring back in Fusion to 0.00" and reduce your target height to 0.043". This should produce a target cut height of 0.063" after all is said and done.
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When your z is bobbing look on the fire control screen to make sure your his switch isn’t tripping.
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I hear what you’re saying, but I also want to know why. Why is 0.020” backlash built in when my Z seems to have none?
And, my cut height seems to be landing a few thou higher than where it’s set (including the automatic backlash setting), so on my particular machine I’d want to dial in 0.040” to land around 0.063”, which also doesn’t make a lot of sense if the Z is supposed to have some backlash…
Also, why is 0.063” desired over 0.060”. Is that on all materials and thicknesses?
I don’t know…I’m probably splitting hairs at this point, but these are the things I’m curious about…
I agree on the ‘why’ regarding the backlash. It’s hard coded into the post. But only for the Fusion post. SheetCAM does not add the additional .020. I’d love to see an option box to change the backlash amount added to a future Fusion post processor.
As far as target cut height, we run a RazorCUT 45. For the most part we use Hypertherm’s cut charts as a starting point. For 3/8" material my chart says .06 cut height. Prior to installing THC (we ran for ~18 months) we used the provided shims to establish height and speeds. The default shim is .063". I don’t think I’d worry about the difference of .003, but feel free to test each way.
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FireControl-v1.7.cps.txt (18.5 KB)
Sometimes you just have to say “Why wait…”
I did some tweeking to the Fusion post. You now have an option to set the backlash in the post menu. I hope Langmuir doesn’t mind…
To use, remove the .txt from the end of the file name, then import into Fusion.
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@Simsworx, I’m trying to wrap my brain around this.
-
Zeroing the Z coordinate, wherever it is currently.
-
Plunging -5 all the way down into the material until lifter contact switch triggers and stops Z travel.
-
Retracting Z 1/2”…to reset the preload spring position!? (this is the move I don’t understand…wouldn’t this large of a move also negate any backlash)?
-
Zeroing the Z coordinate again.
-
Retracting additional 0.020” to account for any backlash between the -5 plunge and 0.5 retract steps.
-
Zeroing the Z coordinate a third time (presumably at true zero, but in my case ~0.023” above the work.
-
Moving up to set pierce height coordinate.
-
Piercing.
-
Moving down to set cut height coordinate.
Do I understand this correctly?
So, here’s where I’m lost.
It seems like most of you are running Sheetcam for post, and probably NOT dialing in any backlash? Or maybe you are…?
My question is, is everybody running the Fire Control v1.6 protocol in Fusion 360 (with its 0.020” automatic backlash move) experiencing a cut height ~0.020” above their setting? Does this move become necessary as the Z-axis breaks in?
I appreciate the new protocol, Terrance, and I will use it, but I’m confused why Langmuir programmed that backlash setting in, in the first place.
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From the G-code posted -
G92 Z0. - Sets Z at 0, regardless of current location
G38.2 Z-5.0 F100.0 - Probe Z down 5", stop when IHS switch opens.
G38.4 Z0.5 F20.0 - Probe Z up 0.5", stop when IHS switch closes.
G92 Z0.0 - Set current Z height as 0
G0 Z0.02 (IHS Backlash) - Travel up 0.02 to take up backlash. If you had Springback entered, it would be here as well.
G92 Z0.0 - Set current Z height as 0
The pierce height, piercing, and move to cut height are correct.
I started with SheetCAM when learning Crossfire. I do, however, have background with Inventor HSM, which is almost identical to Fusion’s manufacturing. Once we installed the IHS / Z-Axis, I started looking at Fusion to speed our production. Mind you, if I draw in AutoCAD, SheetCAM is faster for me. For raw design / G-code - Fusion seems nice.
As far as Fire Control 1.6 post, the post adds a fixed 0.020 to the Spingback value. I can’t answer to necessity as our Z-axis is 2 months old. If it was necessary, why did they only add it to the Fusion post?
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Ahhhh…This makes the backlash setting seem completely unnecessary. If the IHS switch has closed, then any backlash has already been taken up (backlash being the difference between when the lead screw starts turning and the z travel begins).
I wonder if this setting is just an oversight on @langmuirsystems part…
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Someone with more clout than I should pass @Simsworx FireControl v1.7 up the ladder to see about getting it officially released? @toolboy?
This very thing is causing a lot of frustration over on the FB group.
Thank you everyone for all the help working through my problem. We had a huge snow storm overnight, so I couldn’t get to the steel yard today, and my consumables didn’t show up either.
That means this rusty scrap of 16ga I found was cut on those same wasted 60amp (1.1) consumables shown in my previous post. Far from ideal, but I was eager-beaver.
This time I used Primeweld’s box stock book settings for 16ga (30a, 55psi, 110ipm). The things I changed from my failed cuts on 3/8” material are as follows:
#1) Attached Work Clamp to the material
#2) Installed swirl ring correctly
#3) Used Feedrate Optimization value of 60%
#4) Eliminated the 0.020” backlash setting
#5) Used less IHS Springback (dialed in 0.015” since this was only 16ga material).
The cut went flawlessly. The minimal backside dross knocked off easily. A couple of the cut lines are a tiny bit jagged. But I think this could totally be due to the wasted (or too large) consumables. I’m confident the next time I try 3/8” I’ll be able to nail it.
Thanks Again!
Design by Jason Brock
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