Looking for some help dialing in a Proma SD on a new machine

[xnaron]

THC >> the miniTHC has proved to be a nice THC for me + simple and is available shipping from the US and is a little less than the price THC I believe

https://minithc.com/

Thanks I was also looking at this one as I would like to add an ohmic touch off probe when I upgrade to the hypertherm.

[xnaron]

So the plan is to pickup the Powermax 45xp and get a machine torch for it. I'll add the ohmic probe add on. I'll be ditching the proximity sensors when I do this. I'll keep this thread to contrast the difference in dross between my herocut and the 45xp.

[acourtjester]

Great to have a plan as your always looking forward.

[xnaron]

Found a deal on a powermax 65 now facing a dilemma. Details here viewtopic.php?f=3&t=30695

[xnaron]

I went for the used Powermax 65. I got it for a good deal at $1325 usd ($1800 cdn). It was dirty but not abused and cleaned up well. It has 181 hours on it and was built mid 2015. I did a couple of cuts with it yesterday to test but haven't gone further to see how much improvement I will get on the dross. I ran out of 16 gauge. I did some test cuts in some 3mm and they turned out ok. I want to replace the Proma SD with a better THC. Hoping that will also help with the dross. I find the Proma is clunky and hard to get dialed in. That is probably mostly my fault due to my lack of experience with plasma cutting in general.

As it sat on the counter of the Hypertherm dealer I bought it from.

After cleanup

[_jay_]

Hi, i use the same cheapo Z axis, and i cant make it accelerate too fast or it'll loose steps, what is you driver setting ?

And have a 4 inch piece of 10mm linear rail attached to it and the cutting head slides up and down with no effort except the weight of the torch assembly with a proximity sensor detecting the linear rail bloc, very accurate even on thin material.

[xnaron]

I'm using 1/8 inch stepping and 1.5 amps with a TB6600 driver (cheapo from amazon) Steps per inch around in the 10,000's How fast are you trying to run your axis? I have mine set really low right now. I think around 20ipm.

[xnaron]

I have the Proma SD disabled for this cut and it turned out really well. It is a small piece on pretty flat stock. This is my second cut attempt on the new machine torch for the Powermax 65. Also first test with the magnetic breakaway torch. I'm pretty sure I am going to go with MiniTHC for torch height control. Unfortunately I'll need to modify my controller and ditch the stock langmuir and go with my ethernet smooth stepper. Ugh a lot of rewiring ahead. I think I am going to just build a new controller. I already have most of the parts on hand. Just need an enclosure.





Small shop tour

[Rodw]

If you have to buy a Smoothstepper and a THC, you might like to look at LInuxCNC's PLasmac config with a Mesa 7i96 and a THCAD-5 (assuming you have a 50:1 divider) otherwise a THCAD-10. This is the best featured setup by far right now and you'll have change out of $200.

See: http://linuxcnc.org/docs/2.8/html/plasm ... guide.html

[xnaron]

If you have to buy a Smoothstepper and a THC, you might like to look at LInuxCNC's PLasmac config with a Mesa 7i96 and a THCAD-5 (assuming you have a 50:1 divider) otherwise a THCAD-10. This is the best featured setup by far right now and you'll have change out of $200.

See: http://linuxcnc.org/docs/2.8/html/plasm ... guide.html

I do have the smooth stepper already from a previous project that has been decommissioned. I wouldn't mind trying Plasmac and the price is right for sure. Are you using it now? What are you using to generate your gcode? I've been using fusion 360 with the mach 3 post processor. I've recently installed sheetcam and have been learning that.

Thanks,
Brendin

[Rodw]

Yes I still use Plasmac. That will never change. I use the Mesa 7i76e, a THCAD-10 for arc voltage and a THCAD-5 for ohmic sensing. THe 7i76e has more I/O pins 16 outputs, 32 inputs plus it can manage two MPG dials. The 7i96 can do that too but at the expense of input pins so its not really viable in my view. The THCAD-5 for Ohmic frees up two I/O pins on the 7i96 which will be handy.

Plasmac has post processors for Sheetcam and Fusion 360. I use Sheetcam. The one thing that may catch you out is that PLasmac manages its materials internally and the GUI provides a dropdown. It has a script that will copy a Sheetcam Toolset into Plasmac. So I Set everything up in Sheetcam and exported it to plasmac and it works perfect. The post processor tells Plasmac which material to load. I'm not sure if it imports from F360 and I'm not sure if F360 does nesting like Sheetcam does.

[xnaron]

Looks like the 7i96 is out of stock. I did stumble upon the 7i76e though and thanks for confirming it works for this application. One thing I am not clear on is if I would need two thcad-5's. One for ohmic and one fore thc? Also was looking at the docs for plasmac and it needs linux cnc 2.8 or higher. I haven't been able to find a version higher than 2.7.

[robertspark]

. The 7i96 can do that too but at the expense of input pins so its not really viable in my view.

7i96 can drive 5 axis, has 11 inputs and 6 isolated outputs

http://store.mesanet.com/index.php?rout ... uct_id=311

how many inputs do you need with a plasma cutter?

most can get by with a standard lpt port.... 5 inputs and 12 inputs.... all shared by the step and dir signals and any other outputs required

it's very viable!.... but it depends how much you want to spread stuff out... such as if you have limit + home switches and if you share 1 input (better to split to 2 if you have a gantry to square which with the crossfire you don't)

[Rodw]

It depends how far you want to go. I have used all 32 inputs on my plasma machine. You must use two home switches on the Y axis with Linuxcnc if a gantry machine. The 11 inputs on a 7i96 does everything you need with shared home/limit switches but if you want to add a MPG, you loose 2 inputs. I could not make it work then and be full featured.
See below:
This is using a THCAD for Ohmic sensing. The standard Linuxcnc relay setup requires 2 more pins...

[xnaron]

Ok back to trying to dial in the Proma SD. I found a video on youtube that showed the voltage calibration setting for a 45xp. You set the cal to 170. I did a test cut and this put me with +/- 1V on a test cut on my Powermax 65. I am cutting 11 gauge mild steel (measures ~ 0.115"). The cut chart puts me at about 107 IPM and 78V. I set the proma to 79V as I think it is reading a volt or so low. Pierce height 0.150 and cut height 0.60". These parts are cut with the shielded finecut nozzle setup at 45 amps.

Some of the cuts were almost dross free. A lot of the dross was fairly easy to remove and some took some persuasion.

Is a shape like this tricky to cut dross free? Any suggestions to make improvements?

Mach 3
x and Y set to max 300 IPM and acceleration is 40 inch per second.

[djreiswig]

You've got a lot of direction changes on that part, so I doubt your cutting at full speed very much of the time. That probably accounts for a lot of the dross. I'd say it looks pretty good, and if it comes off easy I think you're doing good.

[robertspark]

fwiw = nothing

looks ok to me, but not a good test pattern imo ... what are you trying to test and measure against?

is the part accurate against the drawing? is it under or overcut

with higher acceleration less dross will be apparent ... but it will never be laser.....

if using sheetcam, tighter inside corners can be provided by a little slowdown before the corner via code snippet.

tighter outside corners can be done by an outside loop or triangle as part of the operation in sheetcam

YMMV.... we all do something different from our perspective or experience

[xnaron]

Here are some end caps that will hold hold some rail carriages on my z axis. The small holes are 3mm (a little less than 1/8") the larger holes are 5mm. These came out to within 0.03mm of the design in the major dimensions. I think the holes are sloppy because of the lead in and lead out I used. Being new to this I'm just learning what works and what doesn't. Right now I am using fusion 360 to generate the gcode for Mach 3. I am spending time learning sheetcam and will try that soon. The proma SD was active for these cuts.

[acourtjester]

Here is a site with SheetCam tutorials that may help, SheetCam has a function to see the kerf on the screen so you can see if there is a problem.
Images show both versions of SheetCam this also shows lead in/outs when used
here is the play list for SheetCam
https://www.youtube.com/c/Arclightcncpl ... /playlists

[robertspark]

the recommended guidance for holes is no less than a diameter of less than 2x to 3x the material thickness.

thc should be off for holes and arcs of less than about 20 to 25mm diameter (3/4 - 1").

given the arc / holes will have a lower feedrate to allow the tail to keep up with the head of the cut and minimise bevel (60-70% of optimum linear feedrate) the voltage will be higher given the kerf will be wider as the torch is slower moving and has a tendency to cut / blow away more material so the thc will try to dive to reduce the voltage being sensed.

sorry I have not used fusion 360 for plasma / profile cutting. so I do not know how you add code snippets and path rules to fusion 360. I am not aware of another program that allows for this for plasma or has such an easy to edit post processor as sheetcam for plasma. but my knowledge is limited to only what I have found and used. the post processor editing in Autodesk hsm for fusion360 and inventor look complex.... but maybe they are not after a few days and weeks at editing them.

[xnaron]

@robertspark - ok so my 3mm holes were rather ambitious I actually have a way to turn off the THC using a relay. It switched the 50:1 voltage into the PromaSD off or on. I suppose I could figure out how to add that to the gcode. (I am using sheet cam right now to setup a test cut)

@acourtjester - Thank you I am working through a sheetcam test cut now.

Sheetcam Questions while I have your guys attention
- Is there somewhere I can download all the hypertherm tools for sheetcam rather than create them by hand?
- I am a little hazy on the post processor I need to use. I need G31 for my probe but right now my THC is not integrated in Mach 3 so not sure which post processor I should select?

Thanks,
Brendin

Annotation 2020-07-12 183138.png (35.12 KiB) Viewed 1553 times

[acourtjester]

I would start out with a simple one like Mach 3 Plasma I have attached 2 post processors with the G31 for probe,not sure but you should be able to use one of them.
here is the set I have, there are other tool in there but all the hypertherm tools I use. You will need to get into SheetCam and under file go down to save "toolset as" and find where on your hard drive they will be saved then unzip this file and there is a toolset to copy to the other location, Back in SheetCam you will go back to the open toolset and select the one you just copied and it should open so you can look at it and use what you want. You can edit any of them and then save the toolset with your own name (what ever you want) so you can load it when you need to after that.

toms tools Price added tools 2-14-2020.zip

(1.92 KiB) Downloaded 51 times

Plasma PriceCNC AVHC10 THC zFloat With Pierce Delay- G31 Tom's edit.zip

(1.49 KiB) Downloaded 50 times

Plasma PriceCNC AVHC10 THC zFloat 2 Les With Pierce Delay- G31 ROB edit.zip

(1.51 KiB) Downloaded 50 times

[xnaron]

Ok here is my first test cut with sheet cam. I used the same cut settings as I had in Fusion 360. I will have to double check my switch offset value for the sheetcam post processor. This cut was pretty messy and the holes sloppy. I also attached my sheetcam job.


Next 2 are the sheet cam

Fusion 360 post processor 2 on bottom. Sheetcam post processor 1 on top. The bottom sides are after cleanup.

[xnaron]

From the video I took of the cut it definitely doesnt't look like it did the right thing with pierce and cut height.

Watching it again it looks like the only pierce it did at the pierce height was the first one.

Update. Looks like mach 3 has a bug with pierce delay below 1 sec. Fix is to check G04 dwell in me in the general tab. Then you need to specify the delay in ms in the post processor. I will try that tomorrow,

[Rodw]

With small holes, the best way to manage them is to spot the hole position with a plasma drill tool as a seperate sheetcam operation and drill them manually later. At a simple level, enable pierce normally and stop when ArcOK turns on. This may need changes to your post processor. I've been able to drill out such spotted holes to M3 clearance holes with no issues (on 2mm thick material). On my plasma cutter, I now the turn the torch on for 220 milliseconds which gives a finer spot. But any shorter, the torch will not even fire. I find in 2mm I can cut clearance holes for M5 and 9mm holes to insert M6 nutserts without cleanup.

You may find some Hypertherm toolsets on the CandCNC web site.