I am considering a retrofit of an existing 3 axis CNC mill & looking for some advice about it.

At the moment I know zero about the subject of Mach4. I have very limited knowledge of CNC in general & I have to admit that the majority of my knowledge comes from trying to bring this machine back to life.

Cut a long story short I have repaired about ten things on here back to original 1991 spec, run it succesfuly without guards on for a bit & then today put the covers back as they should be & hey presto - It stopped working & put me back to square one. I am sick of this antique tomfoolery & want to bring it into the 21st century. It is way too nice to throw in the scrap in fact geometrically it is perfect & the spindle is lovely.

A mate mentioned Mach4 a while ago & it looks very good. The issues which I feel might make this too difficult & expensive are...

1/ The machine has a closed loop positioning system which I believe is one of the things which make it so accurate & I would like to keep. It uses Heidenhain LS403 scales which claim to be 1 micron precision. It has Indramat axis motors with TDM & KDS drives.

2/ It has Indramat spindle drive & motor with a 2 speed programmable gearbox. Electric actuator 24VDC which was probably designed to operate the electric windows on a Merc wagon.

3/ Z could be horizontal or vertical but manual head change.

The machine is a MAHO MH800W, new 1991
Heidenhain 234 3 axis, similar to Heidenhain 355 & Philips 432.
Manual tool change - Hydraulic drawbolt & pullstuds.
Horizontal & vertical spindles (manual)

Spindle motor 100 - 8000 rpm. 5.5W@1500rpm 100% Controlled with Indramat KDA100
Low box 20 - 607 RPM, High box 608 - 4000 RPM
X & Z axis motor 4.1A cont, 2.2Nm, 4000rpm max . Controlled with Indramat TDM
Y axis motor 18A cont, 9.2Nm, 4000RPM max. Controlled with Indramat KDS
Y is the table & all the guards which I just lifted back on. The uncounterbalanced Y combination weighs about 1.2 tons with the basic table fitted before a job or cutting load goes anywhere near it. Designed to take a tilting table with a built in NC rotary axis. that is why the Y axis is 4 times the size of the X&Z.
The rapids are 5m/min so it is not trying to crack eggs with sticks with a 5mm pitch ballscrew. I suppose it is all about accuracy.

Do I chuck away everything & buy a load of Chinese motors & drives or can I keep the Indramat setup?
Somebody tells me the Indramat motors & drives are inseperable. This where my knowledge ends.

I have been all over the web looking for clues about these lovely but totally obsolete machines & drawn blanks, now in spite of that somehow I know the damn thing inside out. I have been all over this site prior to asking for some guidance, I think the word MAHO comes up about 5 timesper decade under Mach3, similar for Heidenhain & Indramat.

Please can somebody start this off?

Thanks.
Alec.

Hi,

1/ The machine has a closed loop positioning system which I believe is one of the things which make it so accurate & I would like to keep. It uses Heidenhain LS403 scales which claim to be 1 micron precision. It has Indramat axis motors with TDM & KDS drives.

Mach4 is an open loop CNC software solution. If you require the PC to close a position loop then Mach4 is not the right choice, you could squeeze it out with extra hardware but its
probably not worth the effort. LinuxCNC would be a better choice if the REQUIRE the PC to close the position loop.

Most modern servos loops are closed at the servo drive.

For example my 750W Delta servos have a 160,000 count/rev encoder. If I cause Mach to issue step pulses then the servo drive drives the servo to keep up. If it overshoots it will reverse the servo until
it accurate, ie position feedback. The pulses are from Mach4 are open loop, that is it tells the sevro drive to go 10mm say, and the servo drive /servo does it automatically with highly accurate position feedback.
The only time you'd ever hear from the servo drive is if for some reason, overload for example, the servo can't keep up, with any sort of luck hardly ever, I haven't had a servo overload or Following Error fault in many months.

So despite Mach4 NOT being closed loop it can an does control closed loop servos, and on my machine I have set the resolution at 1um, although it could be much greater if I wanted.

I suspect that the servos fitted to your machine are old school analogue servos, and require that the controller provide the PID control loop. Can you post some more details about the servos and drives?

My Delta 750W servos/drives/cables cost $435USD each.......so replacing your existing servos might be an option,not cheap but would be a very direct and useful retrofit. It would mean that you do not have
to program a controller to provide PID functionality, and then tune the PID loop, no mean feat. My concern is that if you elect to reuse the existing servos you could very well get into the situation that the technical
skills required to do so are beyond you.....and that would constitute a major waste of time and resources. Replacing the servos with modern AC servo/drives is still quite a challenge but much easier that trying
to resurrect the old ones.

Just to give you some context....lets say you went with Mach4Hobby:
Mach4Hobby License  $200
Ethernet SmoothStepper motion controller $180
C25 breakout board   $40
3 x Delta 750W B2 series servo kits (servo/drive/cables) $1305
TOTAL  $1725

I'm not in any way suggesting that you'd have to go with this suite of components, it just a ballpark type guide.

A LinuxCNC alternative:

LinuxCNC free, open source
Mesa control board $200
Brain power to program it???
TOTAL $200

Thus you can see that LinuxCNC is very much cheaper because it allows you to resue your servos, whereas the cost of the Mach4 option is dominated by replacing the servos.

Craig

Craig,
Thanks for the reply.
I am keeping an open mind about it.
Alec

i think 1991 was only analog control ,there several hardware producer for Mach with for analog (sure when its analog it must be close loop because also PID need make on the controller) but as my little experience its much batter replace the servo to newer
its not big money and save you alot alot hed ace

Hi,
Vital Systems produce the Hicon Integra motion controller which can be activated to control analog servos. With activations
it costs $1200.  I would not bother, but rather replace the servos with newer units, the two alternatives are cost neutral but
by replacing the servos you have avoided the possibility of one of the original servo drives from crapping out, you cant replace them.

CSMIO/A is another Mach4 ready motion controller that handles analog servos. If you were using Mach3 I'd say do it, it good quality and performance. With Mach4
not so much, its Mach4 plugin is buggy and CSLabs have gone right off the boil as far as fixing it. They have not released any fixes for over a year.
The CSMIO/A costs 600Euro. I find it hard to recommend to spend that sort of money only to get crap support from the manufacturer not matter
how good the controller is.

Craig

If it goes this way then it because of the dreadful expense of looking after these old parts so I would try to keep it modern as possible however not keen on doing R&D on a new model of controller. Part of me says Fagor & damn the expense.
I was out there again today trying to work out why assembling a few guards has caused total despair. Turns out it is because the machine has been switched off for 2 weeks & it is cold & damp in this miserable economic area we call Britain & there is still one more day to go before they declare another year of nonsense rules & regs . So an enclosure heater is on the way.

Hi,
as I posted earlier, yes it is possible to make Mach4 operate analog servos, but the extra hardware cost (Hicon or CSMIO/A) and that you would retain your otherwise obsolete
servos count against that course of action.

If you are dead set on retaining your existing servos then LinuxCNC/Mesa is the answer for you. You will have to accommodate the programming and tuning as best you may,
its a direct consequence of the choice to retain the old school servos.

Modern CNC control technology has moved very distinctly away from controllers that close the loop, ie PID capable, to distributed motion control. The PC or trajectory planner
issues numeric trajectory data to the various servo drives and each servo drive plans and executes it part of the overall motion. The communication protocols are numerous
but EtherCat, ProfiBus and CANOpen have come to dominate. If you were thinking about a modern controller then you'd be a fool to overlook these new control paradigms.

An open loop Step/Direction software solution like Mach4 is still a later generation than a PID capable controller, but not at the 'bleeding edge' like EtherCat. Having said that
Kingstar DO have a Mach4/EtherCat solution, and certainly worth investigating.

It all comes down to the choice as to whether to replace the servos or not. If you choose to replace then you go down one path, if you choose not to replace you go down another.
Post some pics and as many details about the existing servos and drives as you can.

If replacing the servos is on the cards you need to determine exactly what they are. I would guess that they are genuine NEMA sizes, in which case you want to restrict your search for
replacements to NEMA servos, as they would be bolt-in replacements. Delta servos are metric, and while very close to NEMA not identical so retrofitting them can be tricky
even if 'bang for your buck' favors them.

Craig

Totally understand the playoff with old & new servos & drives. Not familiar with all these new terms but I will look them up. Effort to preserve the antiquity has been the first choice & is a bit shaky so If anything gets done it will be with new servos & new tech. The slides, bearings & ball screws are lovely. So the glass linear scales could go on Ebay & maybe pay for some of the new tackle.
The motors are German so it could be either way. I will measure later.

Now this might look as if I want someone else to read it & do all the work but actually it is the easy way to post everything I know about it. All the books & params, everything
https://drive.google.com/drive/folders/1HKzVxqxqxS7pG9r5QkctBwCr2LQ7pGUa?usp=sharing
No dims in there for the motors but the drawings show their spec.

Hi,

The slides, bearings & ball screws are lovely. So the glass linear scales could go on Ebay & maybe pay for some of the new tackle.
The motors are German so it could be either way. I will measure later.

I think your idea to replace the servos is the best choice, as you say the rest of the machine is superb....and you really want to retain that.

You might want to reconsider throwing out the linear scales.

Amongst the features of modern servos is the concept of dual encoders. Each servo will have a rotary encoder attached to the servo shaft, per normal, and
is absolutely essential for Field-Oriented-Control servos but can accept a second encoder (or linear scale) attached to the machine, called 'load sensing'. It will accommodate
any lash or other non-linearity of the machine and is the LAST WORD in position control. This possiblity should be considered very seriously if you already have good linear scales

For instance my 750W Delta B2 series servos, with 160,000 count/rev encoder and NO load sensing, ie the entry level Delta servo is $435 (servo/drive/cables)
The 750W Delta A2 series, with a 1,280,000 count/rev encoder AND load sensing is $540. Thus you get that load sensing feature and a better encoder for about an
extra $100.

This would turn your old but mechanically superb machine into a very much more modern machine with state of the art position sensing and control. Sound appealing?

Craig

You have exposed my lack of understanding of closed loop.
This machine has feedback from rotary encoders on the motor shaft which is backed up by linear scales =Closed loop in my understanding.

Need to learn new jargon I think.