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ISEL cutter retrofit


I wanted to report my experience regarding the retrofitting of an ISEL cutter model GFV 68/52 with servomotors and encoders.

What I write could be of help to those who are about to do a similar thing, it may probably not be the same type of machine you would like to do the intervention on, but some problems encountered will certainly be common to those who are about to do a similar operation.

The story is a long way to read, but I tried to make it enjoyable and above all to make you understand what the times and sensations are when facing similar experiences.





Let's start from the beginning.

Years ago I went to visit a person who showed me there  his company, among the various departments, in a corner, had placed an ISEL cutter model GFV 68/52, it was all dusty and was now used as a support table for junk, boxes and tools.

I asked the owner about it, it was a machine taken in Germany for the purpose of milling aluminum profiles, it had been used very little and then left to dust, now no one used it or knew how to use it.

The cutter saw me and begged me for mercy, he no longer wanted to remain there as if it were an uncomfortable table, I made an offer to the owner who willingly agreed to free up the space and earn something.

I took it home with a van, positioning it in my laboratory, given its size, was not an easy thing, but in the end it was beautifully placed, connected and ready to go again.

The owner, before giving me the cutter, had assured me that it was working, but he could not show me how to use it, it was accompanied by all the manuals, "floppy disk" (yes, the machine is from 1998 and then the CDs were not yet widely used), and technical documentation of all the internal components, all in English.

The first ignition

La prima acc

Now imagine the emotion / attention when I turned it on, and it really turned on, on the 12-inch CTR color monitor the Windows 95 logo appears, FANTASTIC !!, a whole series of incomprehensible icons appear on the desktop.

I visualize the properties of the computer of the machine and I notice that it is a Pentium P54C with 4 Mega (I wrote Mega not Giga), of RAM and a hard disk of about 4 Mega, the cutter control program  ISEL REMOTE 2.2, works under DOS, there is also a CAM program  "ISY-CAM  2.0 ", Acrobat Reader as well as an outdated version of Autocad, but all perfectly operational.

ISEL Servo Motor Control Card UPMV 4/12

Besides switching on the console, I don't trust myself to do anything else, no axis movement, too dangerous to do something blindly, I turn everything off, and spend more than a week reading the manuals and searching the web.

Ten days later, on a Saturday when I am calm and concentrated, I turn the car back on and try to put into practice what I "think" I understand.

The machine management / control program is in DOS, no graphic window but only warnings, tests, axis position and much more, the program asks to reset the axes, I give it the consent and the axes move, they are reset with Z at the top, X and Y at the top left, everything is ok, and the same machine that tells me: "good, come on, you can do it, one thing at a time and you will understand that I am good and working".

Yes, the cutter is dated as a construction but super performing, it was at the top for its time (but also still today), axis guides with recirculating ball bearings, axis movement screws always with ball screws, servomotors with encoder, 2.2 KW electro-spindle controlled by inverter (therefore adjustable speed), 4-station tool change, emergency button with bypass key, operator door with electric safety lock, practically it was already prepared for the compliance with the 2006 machinery regulations / 42 / EC, the car is German ... ..

I push myself further, I try to load a tool automatically, the axes move, they go near the rack for the change, but then they stay still, a message in German appears on the DOS window ... panic, I turn everything off and I go back to reading the manuals .

Eureka, I found, the cutter has the pneumatic opening of the tool change door, I turn everything on, connect the air compressor to the machine and try again, nothing to do, new warning on the screen, the air pressure must be greater than 6 Bar, there is also a pressure switch on the machine that signals if the air pressure is insufficient, great thing, now the tool change works well, a simple tool change for the machine but a big step forward for me.

ISEL Servocontroller  CV 4P
IMG_20190902_122041 - Copia.jpg
ISEL Frequenzumrichter FC 2200 is

Software and hardware

The days go by and I begin to take our hand with the machine, I perform movements, change the tool, turn the electrospindle on and off, vary its speed, everything is fine, while I see it working I make a reflection: this is a machine with operation and controls very complex, it has servomotors with encoders, inverters, limit switches, pressure switches, safety devices and much more, but all managed via DOS by a very modest and obsolete Pentium P54C, no USB or parallel port, only a card on the ISA connector of the PC, if we go to the forums are all looking for the most performing and avant-garde system, nobody wants to deal with 32-bit operating systems, parallel port or computers that are not quad core or more, impossible to have operation ... ..on a pantograph for hobbyists… .if you don't have the top of technology !!.

In my work, I have the opportunity to see numerically controlled operating machines in maintenance, I assure you that the PLCs and PCs that manage them are not the top of the moment, on the contrary, often dated but stable and consolidated systems are used, the simpler things are , the less they break and the more they are appreciated, we are talking about machines worth hundreds of thousands of euros upwards.

In my hobby, I often have people who have pantographs, even well made, purchased or self-built, but who do not know how to set the tool processing speed, how to do a simple axis shift in steps, reset the axes on the piece, set zero on processing, then maybe they would like to switch to "something more serious" for their machine.

For mobile we want the latest and expensive smartphone, difficult to use and set up just to make a phone call, but do you remember what crap that was in Nokia 3310? Too simple, practical, functional, it never discharged, if you had fallen you would have had to step on it to break it, a real rubbish !!

ISEL Pinguin 19" Terminal
ISEL Servo Leistungsendstufe UVE 8012
Sft hrd
ISEL Sicherheitskreis Modul SVM-1

Finished reflection, let's go back to the cutter.
It is time to do the first test machining, but here is the first problem, the machine management program accepts ISO files in .ncp format, practically it is an almost standard format except for the movements expressed in thousandths of a millimeter and not in millimeters, the machine also has a CAM program suitable for making the ISO path in this format, but I should learn to work with this new program and frankly I didn't really want to.

So I decide to use the usual CAM programs I know by making a postprocessor that gives me the ISO file suitable for the machine.

Here too I spent a lot of time, especially to optimize the part inherent to the tool change, if the postprocessor is not well done you can damage the machine due to collisions, I searched in several sites, including foreign ones, for people who had the same need as me, but I found nothing, fortunately I managed it by myself.

Now I am fully operational, I do the design of the machining operations, with my CAM I create the tool path, I give it to the machine control program and she does all the machining perfectly for me, the purpose of purchasing the machine is achieved, now it is fully functional.


First processing

Prima lavorazione

Reason for the update

Motivo aggiornamento

Now you will ask me why I wanted to update it, since it goes so well.

When you set a goal and you reach it then you want to go further, this is how you have fun and learn things, the opportunity, better to say the excuse, to retrofit the cutter was an inconvenience that happened to me during a process.

For an unusual reason when moving the Z axis, the machine stops and gives me an error code, I switch the machine off and on again but nothing moves… panic!

I decide to call the ISEL branch in Italy for assistance, by telephone they recognize the type of machine from the serial number on the plate, and immediately they tell me that it is an outdated model, now out of production, probably there was in the headquarters in Germany still an "elderly" technician who could have helped me, but an intervention of this cost a lot.

So I decided to look for the problem by myself, and in the end it was a banality, the micro of the limit switch in Z was activated, it was enough to manually lower the Z axis, redo the zeros and the machine was back in operation.

This inconvenience made me understand that if something more serious had happened to me, its solution would have been difficult as well as expensive, so it was better to replace all the electronic control part with something that would allow me to get my hands on it myself in case of problems.



The retrofitting adventure begins, that is the hardware and software updating of the electronic control parts, but what to use?

The machine is equipped with control servomotors with encoders and not the classic stepper motors of which I already had operating experience, it would have been a shame to replace these motors, the machine would have lost quality.

The servomotors were connected to specific and very particular drivers which interfaced with electronic cards made directly by ISEL, it would have been difficult for me to reuse these drivers, even the same inverter that controls the electrospindle had a very particular management incomprehensible to me.

I therefore decided for a drastic but necessary solution, I would have kept all the mechanical part of the cutter, with the servomotors and electrospindle, while the whole console with computer, monitor, servo motor control boards, inverters, input and output sensor control unit, would all be removed. in block.

As I removed all these electronic components, I realized how well they had been designed and made, you could see the solidity of construction, the attention to detail, it was all done with criteria, typical of an industrial machine made to last, probably if it were broken something, the repair would not have been impossible, but it was too late to go back.

Start the search first of the drivers for servomotors, on the web I saw several brands and types but then  I happened upon Marco Sinatti's site with the  his driver " DC Servo Drive ", I immediately had the feeling that it was something done well, done by those who know what he was doing, and I immediately had it confirmed when I received from Marco the three drivers complete with the calibration monitoring card: beautiful, well made, with care, also perfect in their operation and calibration.

The calibration of a servo motor driver was the thing that worried me most, it is not like for stepper motors where everything is trivial, here it is necessary to calibrate, in addition to the working current, also three parameters of the PID according to the structure where they work , following the instructions of Marco and his calibration program, in 20 minutes the calibration was performed for all three axes.


Machine control

Controllo macchina

Having overcome the obstacle of operating the servomotors, I had to decide which cutter control program to use.

I knew Mach3 well, too easy to use this, I also knew USBCNC, as did UCNC, Colibrì instead I had always heard about it and this time it was a good opportunity to try it.

I then take the Colibri card and also the handwheel for moving the axes, I carry out the assembly of this card, together with the three driver cards of the servomotors and power supply unit, on an aluminum plate.


For the electrospindle, I initially take a Bonfiglioli inverter and connect it directly to the electrospindle to test it in manual control, fortunately I had put a current control ammeter that made me understand that something was wrong, an absorption of 60 Amper is absolutely not good , I immediately stop the test before frying the electrospindle windings.
I try better and discover that for that electrospindle you need an EMERSON inverter, calibrated at a certain frequency and with certain parameters, once this new inverter arrives, I try it and this time everything is fine; this has served me as a lesson, I recommend, when you have to connect an inverter to an electrospindle, make sure it is the right one and set the correct operating parameters, otherwise: irreparably damage something !!

I am now at a good point, the card for the inputs / outputs of the various devices to be interfaced with the Colibri card is still missing, this card, enclosed in a metal box, I made it myself, providing the inputs for opening the gear rack cover. tool, opening sensor of said cover, electro-spindle gripper control solenoid valve, automatic tool reset, air pressure sensor and other things, originally the machine had a similar control box, but it was too complex to decipher its operation, I preferred to do it again.

I install a computer (used), it's a Pentium 3 desktop with 32-bit WXP, I connect an LCD monitor, keyboard and mouse to it.

Here we are, I'm ready for the first start, the emotion is not like the first time, because I already know what awaits me: the whole system configuration.

First of all, the resolution of the axes and their maximum speed must be set, according to the pitch of the screws and the resolution of the servomotors with encoder, obviously also the correct direction of movement, this must be done both on the Colibrì program and in the configuration program of the servomotors.
Still on the Colibrì settings, I enter the useful dimension of the axes to give the machine the purpose of managing the work area once it has been reset with the three limit switches.
The more complex the configuration for the tool change, the position for each tool change station, the speed of approach to the change, the pauses and the actuation of the solenoid valve for opening and closing the electrospindle collet must be given. to be done carefully and carefully, if something is wrong, mechanical damage is caused by collision.

Then I move on to the automatic tool reset system, this was a function not foreseen in the original machine, but a small device made by me and an appropriate configuration on Colibri, makes it work well.

In general, the board and the Colibrì program did not give me big problems, even the configuration of all the devices of the machine, including the tool change, went well, I recommend using a USB cable connecting the PC and the Colibrì that is of good quality and that it has the two ferrites near the ends (ferrites are those weird cylindrical bulges).

And now here we are, everything turns on, the axes move and reset, I go to automatically load a tool, everything is fine, I try to start the electrospindle and …… poof, the house lifesaving device is gone.

I get pissed off with his wife, she certainly has the washing machine on and she skips the meter, but it's not like that, if the lifesaver goes out it's not because of an absorption overload.

I try several times and the same thing always happens, if it happens when I turn on the electrospindle, the problem is the inverter ... ..

Eventually I find that I have to disable the filter  EMI on the inverter, this, if connected, sends me small currents on the home network that go to make me jump the circuit breaker, while I am there, I also put a 220 Volt input noise filter in the electrical panel of the machine.


Emerson Commander SK
Box Ingressi/Uscite
Inverter e Box controlli
Azzeratore utensile automatico

Well, this was my adventure with the retrofit of the ISEL cutter  GFV 68/52, I had a lot of fun and learned many things that will be useful to me both for my hobbies and in my real work, "learn the art and put it aside"

Good retrofitting to all.

PS, if you have an original ISEL machine and are looking for spare parts, I have all the removed part available, they are now “rare and unobtainable” pieces, the ones I have are certainly functional and little used.

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