Few cut quality issues

[Flatline16]

Im using a hypertherm 65 with 45 amp tip. Candcnc ethercut and sheetcam are the programs Im using. I am having trouble dthc so it has been turned off for the time being. A few issues Im having:

1. When I cut a part there is divot where the torch starts. I have put a lead in of .20" and I have been using with and with out lead oit to try to figure it out. What are some solutions to get rid of the divot and a smooth part.

2. When I cut open lines, the plasma profile leave a circle...straight line....circle. What is a solution to remove those to create a true straight line? If appears to me that from the time the torch fires to actually moving needa to be decreased.

3. Im also having issues with the material at a bevel but I believe this is cut height fine tuning. I havent found the sweet spot yet.

Any help would be appreciated. Thank you.

[acourtjester]

There have been a few post about divots use the search function in the upper right to find those posts.
Also look for posts by Jim Colt he has posted the thing you are asking about too.

[davek0974]

Item 2 - the circle - line - circle

The first hole is the pierce, to reduce this, make sure your Z axis drops from pierce height to cut height as fast as possible, also keep pierce delay to absolute minimum. On thin material you can try piercing at cut height, but it can damage nozzles. I have spent many hours messing with this issue as I do a fair bit of 'arty' stuff with straight lines - you will never get rid of it, its part of the process.

The last hole is caused by the steel burning after the power is stopped, you can try a sheet cam path rule to shut the torch off just before the end of the cut, again, its very hit and miss, make sure you have no post-cut delay set as well.

I see you have the ether cut, I think you will find the torch-off rule does not work so well on that system.

[beefy]

I see you have the ether cut, I think you will find the torch-off rule does not work so well on that system.

I started a thread on the Candcnc forum about that, or to be more specific the ability to turn the torch off before motion stopped. Many use that technique to prevent divots when cutting circles. Last time I checked there was no solution available. Has to do with timing issues /latency when using the external motion controller (Smoothstepper) instead of the parallel port, quite a pity really. I even contacted the guy at Smoothstepper about it and he ignored my email so I took that as he doesn't have a fix. Maybe it will get fixed down the track ??

For that reason alone I'm sticking to using the parallel port with Mach, and making my own THC.

Keith.

[davek0974]

Sounds a good idea, i have read and am following that thread too.

The new version is going to LinuxCNC which is promised to be far better, knowing Linux a little it most likely will be very good.

I am holding off changing, will stick to my Parallel unit for now.

[beefy]

The last few months I've been learning lots of stuff to do my own Mach3 plasma system and external THC. I like Mach3 for its ease (relative) of customisation, etc BUT I'm also predicting its gradual demise in the future. XP is supposed to be the best operating system for Mach yet you can't even buy it from Microsoft, you have to find it "floating about" on Ebay, etc. Then I've heard Mach doesn't run so good on modern PCs, so if that's true you need an older PC with parallel port, and they will get harder to come by as time goes by (and less reliable being old). And as we've seen, even an external motion control card has its issues.

Tormach abandoned Mach3 and went over to Linux. Now Candcnc is starting to go the Linux route it seems. I think that is quite an indication.

Linuxcnc is free (Mach isn't), Linux is free (XP isn't), plus Linuxcnc is being continually developed (Mach3 isn't). A company called Mesa make a lot of cards that work together with Linuxcnc, they're supposed to be pretty good.

I can see myself getting into Linux at some point just for future proofing, quite a pity after everything I've learned.

Keith.

[davek0974]

Yes, I run the pc's at work, they are mostly XP still as it was the only system that worked. I have slowly started moving over to a VM system now with Win2008 on it, thats how i got my stash of XP pc's

Trouble is, they are all 10 years or so old and are failing rapidly now just through age, I am on my third cnc pc in 9m, they just blow when you boot them up - usually psu goes and takes the main board out.

I think strongly that Linux is the way forwards, its reliable, runs in real-time, you can load it on an SD card so no more hard disk to fail, uses minimum hardware spec pc's, just better all round i think.

I am not buying a MP3500 now, I will build my existing THC system into the new table but await to see what develops with Linux for the final solution.

[beefy]

Yes, I run the pc's at work, they are mostly XP still as it was the only system that worked. I have slowly started moving over to a VM system now with Win2008 on it, thats how i got my stash of XP pc's

Trouble is, they are all 10 years or so old and are failing rapidly now just through age, I am on my third cnc pc in 9m, they just blow when you boot them up - usually psu goes and takes the main board out.

I think strongly that Linux is the way forwards, its reliable, runs in real-time, you can load it on an SD card so no more hard disk to fail, uses minimum hardware spec pc's, just better all round i think.

I am not buying a MP3500 now, I will build my existing THC system into the new table but await to see what develops with Linux for the final solution.

I've also had a few PCs fail on me, but I don't know if it was due to plasma dust, condensation, etc. Since I built a PC enclosure with filtered positive air ventilation I'm still on the first PC. I'm finding the older PCs hard to come by, and when they are available they actually seem to be a higher price and the little bits like ram are the worst, unreliable and getting more scarce.

I'll keep that in mind about the PSU. Might buy a new PSU for the old PCs, just as a safeguard.

Last night, prying my eyelids open, and with non-stop yawning, I read the getting started manual for Linuxcnc. That was torture

Keith.

[vmax549]

Not to worry too much fellars I have Mach3 running tthe plasma on a LPT and 32 bit Win7 and a very modern PC with a lava LPT card(;-) It is bad to the bone fast. and ACTUALLY too fast sometimes for macros in CB. Just had to tweak the macros a bit for timing issues to prevent the race conditions.

MACH3 long may she live(;-).

YEP with Lcnc you have the full range of MESA cards and daugther cards to play with . That includes thc cards( frequency driven not voltage) and Hand pendant cards and massive I/O if ya need it. . Plus lots of isolation cards to boot..

I am looking at the Mesa PCI or PCIe cards . DOES away with ANY usb or eithernet problems. It can talk direct (;-).

(;-) TP

[tcaudle]

We are not going to LCNC because of MACH3. Its still a viable answer and it will work with *most * WIN732 bit parallel port drivers and it works fine with WIN7 32 or 64 with the EtherCut. The problems, as you eluded to, is that its no longer supported. We found that out when we hit some serious snags in syncing up turning the DTHC on/off (or doing anything that was time sensitive) during a cut and part of the issue was in MACH3. It took changes in MACH, changes in the ESS firmware and the DTHC firmware. That was a painful experience. The next version MACH4 is still being developed and is still missing a lot of features. It also means a total rewrite of thousands of lines of code in plugins that binds the hardware close to the toolpath and adds advanced automation. None of the VB scripts are going to work. I am sure there will be some viable THC solutions for MACH4.

The reasons you got no response from the Smooth Stepper guy is that we worked with him for 2 weeks to try and nail down the instant off using M11. it ALMOST worked. The problem is that there is still some latency that depends on a precess being completed in the MACH macro loop and that can vary +- 50 msec. Does not sound like much but when you are running at 225 IPM where we were testing (14ga with 45A current) that can be + or - .1875 inches (.375)
You have to get within 1/8 or less every time BEFORE the end of a closed cut because it's not based on a spot, but on timing, it would vary depending on the cut speed and even the shape you were cutting. Its okay to have a variance in turning the DTHC on/off of that amount but not if you are trying to nail the end of a critical cut.

Because LCNC is realtime (that brings another issue but I will leave that for another thread) you just don't have the sync problems. Motion is not buffered up than processed. So things all happen in real time. MACH4 is said to be a lot faster but that is still unproven. Its hard to do anything real time in Windows and as it gets later in versions it gets more bloated. There are specific reasons we don't support WIN8 or 8.1 with MACH3.

[davek0974]

Thanks Tom, it makes me wonder why the Mach guys still trudge along with Windows when it obviously has many faults when it comes to controlling real-world events like machinery that are timing dependant.

Surely they would be better off expending their skills in moving to better platforms?

Windows is bad enough for basic computing these days let alone control software, even MS knew XP had something or they would not have kept it rolling for so many years.

Mach3 is a brilliant program, thousands of machine operators know this but that does not mean it cannot be done better.

[tcaudle]

okay....here is a brief update after some further testing with MACH3 and EtherCut:

We can make the M10/M11 work in a pretty tight window. Its not instant but Testing shows it is closer to 20msec (.020 sec) of delay and its pretty predictable (not as + or - ). So you can set a torch off Before End Cut rule but that you will need to vary the distance based on the feedrate. It takes a firmware update and a modified post but my guys tell me it works. For now we are not going to release it as a standard update. If you want to try it on an EtherCut then contact me.

.

[Sampson Jones]

Would love to see windows system cnc dumped and a system developed for Mac computers .

[Flatline16]

Have we figured out the issue on the ethercut? I have had to turn the digital torch height control off because it producing garbage. I am highly unsatisfied with the CNC ethercut product. I have called and tried to resolve the issue and I get responses that seem I am bothering them. I sure would like to get this fixed....or I may be sending it back.

[tcaudle]

What do you define as garbage? All the problems you listed before were with the DTHC OFF...not even in the mix. The ONLY "issue" was the "off before end of cut " did not work predictably. That is all. We now have that working on our test setup and it will be released to the users next week. You still have to play with the distance you set because the faster you are cutting, the longer the distance it travels after it gets the torch off signal . the timing is consistent now. So will having that feature fix your garbage cuts?

[Flatline16]

I cant use the table without leaving the dthc off because the torch dives, crashes, will z up and keep going until I stop it and when cutting circles the torch will ramp up as if it it would on a initial pierce. I have to turn it off if I want to cut ANYTHING.

Either the product doesnt work or I have some sort of lemon...I has been problems since I have recieved the ethercut. I had to send the box back on my dime because the green led wasnt on and the drive went out. I have tried to call, post on the support forum and had other user stop by to take a look. All of which seem to be baffled by whats going on with my table.

I havent even messed with the table in over a month. Looking at and the amount of money I have spent pisses me off because it doesnt work as it should.

If you have ANY ideas of whats going on Im willing to try anything.

[davek0974]

I cant use the table without leaving the dthc off because the torch dives, crashes, will z up and keep going until I stop it and when cutting circles the torch will ramp up as if it it would on a initial pierce. I have to turn it off if I want to cut ANYTHING.

Are you using SheetCam?

What distance do you have in "Min Distance for THC" and / or THC Delay in the tool setup?

This sounds like the THC is coming on instantly before the voltage stabilises, just a guess??

[Flatline16]

Sheet cam. The min distance before the thc comes on is 1inch, tried 2inch, 3inch etc... When on it does it has the listed problems. Something is the matter with the product they sent me... Tom has made little to no effort in reaching out to resolve the issue.
Like I said eariler, others with cnc products came to look at the table and were baffled.

[Diesel]

I am having the same type of Z-axis issues with the DTHC-IV/Ethercut.
It's to the point where I'm cutting 1/4" and 1/2" (all I've cut so far...just got the table running a few weeks ago) with DTHC disabled.
I've even tried turning the tuning down to the point where I may as well just shut it off.

What do you define as garbage? All the problems you listed before were with the DTHC OFF...not even in the mix. The ONLY "issue" was the "off before end of cut " did not work predictably. That is all. We now have that working on our test setup and it will be released to the users next week. You still have to play with the distance you set because the faster you are cutting, the longer the distance it travels after it gets the torch off signal . the timing is consistent now. So will having that feature fix your garbage cuts?

Has anyone heard whether or not this "off before end of cut" feature was released to the masses?

Cheers,

Matt

[BTA Plasma]

I can tell you that the learning curve can be very dramatic with a cnc plasma if you werent supported from a table mfg from the get go. Typical gantry kit builders do not stop to consider the interface. They see small dollars up front. Things you cannot do right off the bat


1. Cut using the wrong air pressure
2. Cut using the wrong amperage
3. Cut using a poor ground
4. Cut using the wrong consumables
5. Cut with the wrong settings on the PWM and plasma for divided tip volts
6. Cut with a PC not properly configured
7. Cut with the wrong sheetcam settings
8. Powermax 65-85-105 need the ground cable twisted in all the way

Everybody tries to do those very things. Everybody that doesn't get a PC loaded and tuned and tested with their CNC that is. You could be ironed out quite well and quite fast as long as you have time to explain your issues and listen to guidance on this forum.

[dhelfter]

Matt,
What exactly is not working with your Dthc?
As for turning thc off before end of cut, yes your system was setup with it. If you look in your cut rules you will see it listed and it will have a check mark to always apply it.
Please give me more information as to what on the torch height is not working

Dan
Ldr

[Diesel]

Matt,
What exactly is not working with your Dthc?
As for turning thc off before end of cut, yes your system was setup with it. If you look in your cut rules you will see it listed and it will have a check mark to always apply it.
Please give me more information as to what on the torch height is not working

Dan
Ldr

Sorry, I was commenting on the torch off before the end of the cut...not the DTHC.

On at least 3 occasions (including one today), in the middle of a cut the Z will drive the torch down into the workpiece and keep on going (after the arc is extinguished) until the torch plate pops out of the v-rollers. Luckily, I've been very close to the computer when this happens and have been able to kill it.

Cheers,

Matt