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Dynapath Delta 20 controls - Retrofit or leave alone?

strantor

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#1
I recently picked up a Lagunmatic 110 CNC mill, 1988 vintage. It has a fully functional Delta 20 control system. I have never ran a CNC machine before, so I will be cutting my teeth on it.

A bit of background info... I'm a Controls Engineer. I design control systems for subsea and industrial equipment. Mostly VFDs and PLCs, not much experience with servos and position control. But I want to get into that, especially robots. I was actually looking for an old CNC machine with bad controls, with intent to save money and retrofit the machine to PC control; I just happened to find one that already worked, for a better price than broken ones.

Now that I have a running machine, I don't know how to run it. I'm in the process of printing out the only manual I could find for it (479 pages), and I'm told that's just one of many manuals that should accompany this mill. It seems like a pretty daunting learning curve, with a dearth of resources.

Would time spent learning this system be an investment or a waste? From what I see on eBay, I might be able to get $1500 for the complete Delta 20 system since its fully functional. I assume that should be enough for the retrofit (Mach3 or LinuxCNC or other), which I assume would be more capable and easier to learn. But would I be giving anything up? (is this Dynapath system actually more capable than Mach 3 et. al.?)
 

Tony Wells

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#2
I have some time on a couple of Dynapath controls, and IMO, as far as ease of use and easy to learn, they are one of the best. I'd keep it on there instead of a homebrew system. They are conversational, as well as capable of reading straight G and M code.
 

JimDawson

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#3
I would run the Delta 20 until it dies, then do the upgrade. As Tony says, they are pretty user friendly. Learning how to run a CNC is the fun part, makes you think through the process before you make chips. Air cutting is your friend.:)
 

strantor

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#4
I would run the Delta 20 until it dies, then do the upgrade.
I had the same thought. Learn how this system works and the experience gained would help me to know what to expect out of the retrofit, when the aging electronics inevitably give out.

But on the other hand, right now the Delta 20 system is worth money. Once it croaks, it won't be worth much.
....I assume. I see the controls for sale on eBay for >1,000$. Doesn't mean anybody is buying them for that price, or at all.
 

JimDawson

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#5
I sold my non-working Anilam-M system on Ebay for $250 in about a half hour. I think that means I priced it way too low ;)
 

strantor

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#6
It's been said that the Dynapath system is user friendly. Is it more user friendly than Mach3?
If I "upgraded" (still not sure if it would be an upgrade) to Mach 3, would I be giving up any features that Dynapath offers that modern PC-based systems just don't offer?
If I "upgraded" to Mach 3 would I have any new features? Offhand my understanding is now I would be able to do 3D machining. Right now (I think) all I can do is 2.5D machining (helical interpolation?).
 

JimDawson

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#7
As I have stated before, Mach3 is not my favorite CNC controller, but as I understand it will run up to 6 axis with full coordination. I assume that the new Mach4 program will also have similar capabilities.

If the Delta 20 will run full interpolated 3 axis, then it's just a matter of feeding it the proper G-code. For most projects 2.5D will do everything you want. I didn't add full coordinated motion until I added my 4th axis.
 

strantor

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#10
Mine of course. :grin: I wrote it when I got p***ed at Mach3.
Well that reply was certainly unexpected!
It's awesome that you wrote your own. What was so bad about Mach3 that you needed to roll your own?
Are you close to releasing it?
 

JimDawson

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What was so bad about Mach3 that you needed to roll your own?
Per customer request I installed Mach3 on a commercial router as part of a general controls upgrade. The machine ran fine at lower speeds, but at the production speeds they wanted to run, it just couldn't keep up. Accuracy was not good, missing steps, etc. I even tried installing a Galil Motion Controller that Mach3 was running, the results were better, but still not adequate. So I just sat down and cranked out a CNC program in about 3 weeks, it wasn't pretty but it worked and solved my immediate problem. Rather than the PC program doing the trajectory planning as Mach3 does, I let the Galil controller do the heavy lifting. That is what it was designed to do and it does it very well.

Are you close to releasing it?
The Win7-10 version is in beta release right now. And the best part; it is absolutely free. Runs steppers, closed loop steppers, and servos. Also runs tool changers, has full spindle control, and PLC functions. The downside is that it will only work with Galil Motion Control products.
 

Boswell

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#12
Mach3 has it's limitations and as Jim's message implies, it was not designed for commercial use. Having said that, there are thousands (probably a lot more) of people using MACH3 with little or no issues. Don't try to push production speeds, Use a high quality motion controller and a decent computer you can get very good results. If you want a high speed (time=money) system or a system that will NEVER do something weird then possibly Mach3 or any hobby level system is not the right choice. Of course if you have the skills and inclination to write a better system than MACH3 then that is Awsome !.
 

TomS

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#13
Mach3 has it's limitations and as Jim's message implies, it was not designed for commercial use. Having said that, there are thousands (probably a lot more) of people using MACH3 with little or no issues. Don't try to push production speeds, Use a high quality motion controller and a decent computer you can get very good results. If you want a high speed (time=money) system or a system that will NEVER do something weird then possibly Mach3 or any hobby level system is not the right choice. Of course if you have the skills and inclination to write a better system than MACH3 then that is Awsome !.
Currently I'm using a cheapo import USB BoB with a UC-100 motion controller. I am getting ready to order a PMDX-126 BoB, a PMDX-107 spindle control and a Warp9 ESS. Can you explain a bit further about your statement above that reads, "Use a high quality motion controller and a decent computer you can get very good results." Are you saying accuracy and surface finishes are better, or am I reading too much into this? What are the expected improvements, if any, I can expect to see?

Tom S.
 

JimDawson

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#14
Tom, I'm going to jump in here with an opinion. Not really going to answer your question. There are a lot of devices out there that the vendor is calling a ''motion controller''. In most cases they are not. A motion controller does it's own trajectory planning/execution, most of the devices available require an external device, such as Mach3 on a PC, to do the trajectory planning/execution. Most of these devices could be considered a signal conditioner at best.

A simple example: You tell the motion controller the X Y coordinates of the table/tool move and the motion controller figures out how to accomplish that task, and applies the proper speed, acceleration, and axis coordination based on the setup parameters.
 
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TomS

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Tom, I'm going to jump in here with an opinion. Not really going to answer your question. There are a lot of devices out there that the vendor is calling a ''motion controller''. In most cases they are not. A motion controller does it's own trajectory planning/execution, most of the devices available require an external device, such as Mach3 on a PC, to do the trajectory planning/execution. Most of these devices could be considered a signal conditioner at best.

A simple example: You tell the motion controller the X Y coordinates of the table/tool move and the motion controller figures out how to accomplish that task, and applies the proper speed, acceleration, and axis coordination based on the setup parameters.
Jim - thanks for your input. I respect your opinion and comments because they are usually spot on. The UC100 literature says the device does it's own trajectory planning and execution but my primary reason for going with the PMDX products and ESS is to reduce/eliminate faults associated with the USB equipment. Jbolt and I had similar electronic equipment with likewise similar USB faults. He has indicated once changing to the PMDX BoB and ESS he hasn't had any faults. I wasn't clear on what Boswell meant in his above post and wanted to hear if there are other features and or improvements that I can expect with the new electronics.

Tom S.
 

JimDawson

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Jim - thanks for your input. I respect your opinion and comments because they are usually spot on. The UC100 literature says the device does it's own trajectory planning and execution but my primary reason for going with the PMDX products and ESS is to reduce/eliminate faults associated with the USB equipment. Jbolt and I had similar electronic equipment with likewise similar USB faults. He has indicated once changing to the PMDX BoB and ESS he hasn't had any faults. I wasn't clear on what Boswell meant in his above post and wanted to hear if there are other features and or improvements that I can expect with the new electronics.

Tom S.

You can't argue with success. :)
 

Boswell

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#17
I don't have a formal definition of what a high quality motion controller is and I replaced the chinese motion controller that was installed on my Mill with the smoothstepper Ethernet and the PDMX-126 with the PDMX 126. I my mind, I put these in the "quality" motion controler bucket. My criteria being that they have a good online reputation by users, they have extensive English instructions, the companies that make them are available and have a public presence (accountability). BTW, I not dispute what Jim says about the definition of a motion controller and the smooth stepper might not be truly a motion controller. but whatever you want to call it, the combination of Mach3 on Windows 10 with the Smoothstepper Ethernet board and the PDMX duo is working very well for me and features that were NOT working with the previous chinese motion controller such as backlash compensation and probe inputs are working. I never had a noticeable problem with accuracy before upgrading or after but I am sure I am not pushing my machine anywhere close to the limits. Time is something I seem to have plenty of. Knowledge of CNC and Machining in general is where my learning curve is the steepest.
 

TomS

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I don't have a formal definition of what a high quality motion controller is and I replaced the chinese motion controller that was installed on my Mill with the smoothstepper Ethernet and the PDMX-126 with the PDMX 126. I my mind, I put these in the "quality" motion controler bucket. My criteria being that they have a good online reputation by users, they have extensive English instructions, the companies that make them are available and have a public presence (accountability). BTW, I not dispute what Jim says about the definition of a motion controller and the smooth stepper might not be truly a motion controller. but whatever you want to call it, the combination of Mach3 on Windows 10 with the Smoothstepper Ethernet board and the PDMX duo is working very well for me and features that were NOT working with the previous chinese motion controller such as backlash compensation and probe inputs are working. I never had a noticeable problem with accuracy before upgrading or after but I am sure I am not pushing my machine anywhere close to the limits. Time is something I seem to have plenty of. Knowledge of CNC and Machining in general is where my learning curve is the steepest.
Thanks for clarifying this for me. I've been chasing backlash issues for quite some time and made some mechanical corrections. No matter what I do I still have some backlash. I was hoping that it may be electronic based. Tried backlash compensation and it didn't work well with my current BoB. Maybe the PMDX board will cure this ailment like it did for you.

Tom S.
 

strantor

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#19
I've had very little time to play with the new mill. I do some research on my bathroom breaks, a few times I got to fire it up for a few minutes in the evening. Haven't gotten around to cutting anything with it. Figured out how to run the programs that are already in it, but not how to write my own... I'll figure it out some day soon.

I say all that to soften the blow of the idiot hammer. Until I crawled under it last night and looked, I thought this thing had glass scales on it. It doesn't. I thought that born & bred CNC machines all used glass scales for position feedback. Apparently not.

When I realized it was calculating position based on servo encoder, I decided to test backlash. Man, it's pretty bad. I go one direction and then reverse, it shows position change of .010" before my dial indicator notices. Is that normal for a ball screw machine? It seems to me if it used glass scales it wouldn't matter, but as is I could never make a part with any precision. Do I need to replace ball screws or what? I read that the Delta 20 has backlash compensation hidden away somewhere; I'll try to find it and see if I can make an improvement.
 

JimDawson

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#20
I say all that to soften the blow of the idiot hammer. Until I crawled under it last night and looked, I thought this thing had glass scales on it. It doesn't. I thought that born & bred CNC machines all used glass scales for position feedback. Apparently not.
Very few have scales on the table. The very high end machines do, but most just have encoders on the leadscrew/motor. Not the best system IMHO.

When I realized it was calculating position based on servo encoder, I decided to test backlash. Man, it's pretty bad. I go one direction and then reverse, it shows position change of .010" before my dial indicator notices. Is that normal for a ball screw machine? It seems to me if it used glass scales it wouldn't matter, but as is I could never make a part with any precision. Do I need to replace ball screws or what? I read that the Delta 20 has backlash compensation hidden away somewhere; I'll try to find it and see if I can make an improvement.
I would expect the backlash to be <0.001 on a good, properly adjusted, ball screw. Ideally set to zero backlash by preloading the ball nuts. Backlash comp is a fallacy IMHO. Software can't fix mechanical problems. It can help, but it's a bandaid. Hopefully that machine has double ball nuts and it can be properly adjusted.
 

Tony Wells

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#21
I worked at a shop where we bought 2 identical Webb knee mills with Dynapath controls and one of them was really off on the linearity of the -X- axis tracking. We had the factory guy out and we made a test bar with holes every inch, and some on half inch. We mapped the bar on the CMM and he got into the firmware and copied the mapping into the machine. It was fine after that. Kind of wish I had one of those. They were almost fun to run.
 

strantor

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#22
Hello Gents,
I have an update. After 5mos of stagnation, I'm taking up the project again.

Against some of your better judgement, I've decided to go ahead and retrofit the controls before using the machine. It comes down to a mental thing; when I go out there and look at that CRT it doesn't excite me. I'm not passionate about it and have no desire to learn the Dynapath system. This lack of excitement about the Dynapath controls is a big part of why I haven't made any progress. Every time I picture myself on that machine, it's got a flat touchscreen and a control system that I built. So that's what I'm going to do.

I've pulled an old 2009 Compaq Presario desktop out the no man's land in the back corner of my garage and installed Debian LinuxCNC on it. I've got Mesa board 5i25 and 7i77 on order, should be here tomorrow. I decided to stick with the analog interface (7i77 card) because my servo drives are already set up for analog input (although changeable to step/dir or other inputs by simple parameter change) and because its one inexpensive option that lets me keep the encoder interface to the motion controller (and to the servo drives) for better performance. Other motion control solutions in my price range did not have encoder feedback to the motion controller.

So in the near future I will be selling a working (except for serial port) Delta 20 control system on eBay; how much do you think I should ask for it?
 
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