Dynapath Delta20 - To Retrofit or Not
Hello all, new member here, first post.
In my spare time at home I'm a machining hobbyist and I have been lusting after a CNC mill for years; I finally bought one recently. By day I'm a Controls Engineer; the systems I typically work with are VFD/PLC systems, not much experience with servos or position control, but it's something I'm interested in and wanted to give it a shot. I considered buying a manual machine and CNC-izing it, but eventually decided to try and find an older born & bred CNC machine with a non-working control system for cheap. My plan was to rip out the vintage controls and replace with a PC-based system for whatever reason, thought it would be cool I guess.
The machine I ended up buying (Lagunmatic 110 with Dynapath Delta 20 system, circa 1988) coincidentally actually has a near-fully functioning control system. The previous owner replaced the DC servos with AC servos (two SureServo 1kW and one Fanuc 1kW) and replaced the DC servo amps with Allen Bradley Ultra AC servo drives. He replaced the AC spindle motor and pulley system with a 2.2kW Allen Bradley servo motor and servo drive. The servos and drives alone are probably worth more than I paid for the mill. The only problems with it (so far that I know of) are:
1. The serial interface chips are bad, so no comms with laptop to transfer programs to the machine. The previous owner gave me some replacement chips and I will try installing them, but worst case that doesn't fix the problem. Machining complex parts from PC-generated CAM is the whole reason why I wanted a CNC mill.
2. There is a mystery error that I cannot find in any of the obtainable documentation ("Spindle zero speed overload") which pops up every time you actuate any axis or the spindle. It does not stop the machine but it is quite annoying.
3. There is quite a bit of backlash (about .008" I measured in one axis). I need to check out the ballscrew. But no slop at all in the ways when I yank violently on the table.
4. The wiring is atrocious. Inside the panel is a spaghetti bowl with loose exposed wire ends and dead-end chopped cables hanging all over. Nothing is labeled and it's an electrocution or electrical fire waiting to happen. Everything needs to be re-wired regardless of how I proceed. Probably the reason why I got such a good deal on it.
So my question is this: Should I leave the Dynapath system alone or should I retrofit it with a PC-based system?
Here are some of my conflicting thoughts which are clouding my decision making:
1. I've been told that these PC-based systems using DB25 breakout board are slow. PC serial port just can't keep up, and on top of that calculating tool paths on a system which is also running an OS can't be done as fast as a dedicated CNC controller. Is that true? I already have a dedicated CNC controller, but it's old. Does that mean it is slow? Could I conceivably be introducing a new speed limit by getting rid of it? I don't want to take a step backward in functionality or speed or any other aspect.
2. If I remove the Delta 20 system now I can probably sell it for a decent price since it still works, whereas if I hold off on the retrofit, keep on running it until the day it inevitably craps out, then it will be harder to sell.
3. I've been told that the Dynapath controls and their conversational language are some of the easiest to learn. That's cool, but I would need to put my mindset in a special place in order to get excited about learning an obsolete system that I have every expectation of replacing one day, no matter how "easy" it is to learn. It seems to me that a Mach 3 or LinuxCNC type PC control with GUI and wizards would be even easier.
4. If I retrofit, how much am I going to need to budget, and what am I going to need in order to maintain or improve upon my current speed and functionality? I'm only trying to retrofit the CNC controller; servo drives will remain.
Similar Threads:
Re: Dynapath Delta20 - To Retrofit or Not
Not true at all, a standard current PC has many times the performance of all but very new dedicated CNC controllersOriginally Posted by strantor
A PC will have 1000s of times the path calculating ability of the Dynapath controller.
If you are using the dynapath controller this likely means you have analog interfaced servo
drives with encoder feedback to the controller
This makes LinuxCNC a good retrofit controller choice
Re: Dynapath Delta20 - To Retrofit or Not
Thank you for your reply.
My encoder feedback is definitely going back to the servo drives but I think it is also going to the Dynapath system (I need to verify). I have this idea because the Dynapath system is able to display lag in maintenance mode and also I remember seeing breakout boards for the encoders.
I assumed that the Dynapath system was sending a step/dir to the servo drives but I'm probably wrong (again I need to verify).
After my post was approved I saw at the bottom of it "similar threads." Reading through those threads was taking me down a series of rabbit holes, a lot of which led back to cnccookbook.com. Seems like a pretty good reference for this stuff. Already I have found answers to some of the questions I haven't asked yet. A few days more reading and this thread might be obsolete.
Re: Dynapath Delta20 - To Retrofit or Not
I posted this in CNC Electronics > General CNC Machine Related Electronics >. It was moved to MetalWorking Machines > Uncategorised MetalWorking Machines >. I'm curious why. My selection wasn't random; I did give some thought to which subforum it should go in and I thought it was more applicable where it was, considering it's about the control system (electronics). Maybe someone is trying to help me out though? Maybe this subforum is a known hangout for people who might have the best answers?
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