Mikron WF41 C mill
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  1. #1
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    Default Mikron WF41 C mill info needed

    Hello, first time poster here.

    I've been looking for operation and maintenance manual for this machine, but having zero luck finding anything useful at all.

    I very recently acquired such machine in a non-working condition (was bought via an auction house, so basically zero operational history) as a first more or less serious milling machine for my home shop, and now am starting to gather more info about it to begin the troubleshooting process or even upgrading to a more modern motion control.

    Has anyone any experience with this model, typical problems, or things I should check first? And a source for manuals for this machine would be very helpful.

    thanks, J

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    After few weeks of bouncing my request for the documentation from one Mikron support office to the other, paying couple hundred euros, I finally received Operators manual, mechanical part and Electric documentation which should relate to the Heidenhain TNC 355 I have on this machine.

    I took pictures of some of the essentials from the mechanical manual, and table of contents for the electric one, here are links where anyone can download them, I will not upload whole manuals, I don't know if there are any copyright restrictions or anything, but if someone needs a page or two of something that I didn't already upload, I will try to respond in a timely manner with a link to a pdf.

    WF41C/TNC 355 electro documentation TOC
    WF41C Operators manual, mechanical, TOC and essentials

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    Quote Originally Posted by jz79 View Post
    After few weeks of bouncing my request for the documentation from one Mikron support office to the other, paying couple hundred euros, I finally received Operators manual, mechanical part and Electric documentation which should relate to the Heidenhain TNC 355 I have on this machine.

    I took pictures of some of the essentials from the mechanical manual, and table of contents for the electric one, here are links where anyone can download them, I will not upload whole manuals, I don't know if there are any copyright restrictions or anything, but if someone needs a page or two of something that I didn't already upload, I will try to respond in a timely manner with a link to a pdf.

    WF41C/TNC 355 electro documentation TOC
    WF41C Operators manual, mechanical, TOC and essentials
    I there, i am repairing a board from a machine like this, it burned some components, is there some pages of your manual about the boards and the components in it?

    Best regards

    Thank you for your help.

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    Unfortunately no, schematics are only for the cable wiring connections, there are also couple small board component layout diagrams (like one for the gearbox on the spindle), but no circuit diagrams for the boards, nothing at all for the driver boards.

    If the components on your board are burnt and unreadable, post some pictures, and I can compare with mine, and see what the nominals are.

    J.

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    Recently had some time to devote to this WC41 I bought back in 2017, after fixing some electronics issues:
    * bad 74HC14 inverting schmitt trigger that handles inputs E4;5;6;23;24;25, caused some of these to be low and some high regardless if I tried to manually pull inputs down/up - which caused PLC error messages that couldn't be cleared

    * bad +15V voltage regulator (LM340-15) inside the Bosch TR15 servo drive power supply board - symptom - all red leds after power up, interestingly there is an error in the original Bosch circuit diagrams, the K1 relay is actually normally closed, so as to start up the TDA1060 generator via V11, when the T1 is getting energized, the circuit opens the K1 relay (and so does the external 24V supply, if PLC detects an error), if there is no external +24 applied and the TDA1060 circuit doesn't fire up, then it may lead to R5/R7 resistors heating up which I think Milacron saw happen when he posted about 038035 board problems in this old thread here - deckel-fp4nc-troubles, those scanned schematics helped me a lot!
    for diagnosis and testing I powered the board up on the bench via an autotransformer and full bridge rectifier + cap to get the desired 245V DC at P+ and P- inputs, you can see test point measurement notes under normal working conditions, TP3 3.4V is what the tester showed, in reality the signal there is short impulses at around 24kHz as far as I remember, and a sawtooth form on the TP4, the 1V is what a tester will show set on DC
    There is a slight jitter on all 3 axis, +/- 0.003mm, I haven't yet checked the other boards for bad caps, nor have I did any maintenance on the servo motors and tachogenerators, so that is next on the list.
    bosch-038035.jpg

    after these repairs, and supplying +24DC to inputs E85 and E87 (X5/2 and X6/12 on the addition I/O board) to clear tool changer (that I dismantled), I was finally able to reference the machine, as it turned out, the TNC is set up to read distance marks on the scales, so it doesn't need to travel to the axis reference switch, just to the next distance mark on the scale, which is nice

    there was another curious thing, spindle gearbox is operated via small DC motors through reduction gearing, one of those motors had its inputs the wrong way around, meaning that if certain speeds were asked from the TNC, it would be unable to switch to them, since that one motor would want to spin in the wrong direction and the TNC would error after a certain timeout period, reversed the wiring and fixed that problem, one curious thing remains - during the gear change, the spindle motor is not energized, and there seems to be no other actuator to help the gears switch, but the link between the gear change motor and the "handle" in the gearbox is via a twist spring, so it seems that Micron engineers opted that the gear fork will be left under tension (because the gear didn't engage), and the next time the spindle motor is fired up, it will fall into place - not the best solution IMHO... if I wiggle the spindle when the gear changes are happening, it goes much smoother

    there are few other issues yet to solve, like replacing way wipers that broke into pieces after getting the axis moving... the hand wheel pendant is causing some trouble - when it is connected, it is impossible to switch to hand wheel mode on the TNC, but there is some obviously bodged tumbler installed on the hand wheel case, that when switched, causes the TNC to enter the hand wheel mode, and the encoder itself will not work, I connected the hand wheel from the Fehlmann (same type of encoder and connector), and the axis moved with it

    anyhow, weird combination of problems, that would make the machine unusable if only one of them was present... almost seems as if some of that was deliberate to make the machine unusable, or that someone was poking around in it without much clue and caused some additional damage, but it has been a great relief for me now that it to sprung back to life, waiting for DIN 2080 pull studs to arrive in couple days so as to be able to make some test cuts, right now don't have a single tool holder with that pull stud unfortunately

    regarding the way wipers, some of them are moulded type - black rubber on steel are in good condition, the other ones (in the pictures), with the greenish rubber material seal in aluminum are basically falling apart, so far I found only one source for the stock material, but due to the current virus pandemic, will probably not be able to get them for at least a month
    wiper stock source - Way Wipers - EITEC

    p.s. it seems that these machines are no longer supported by Mikron, I asked them for machine parameters (before I found out they have not been lost after it sitting without electricity for 3 year or more), and they said they are not able to help, so I'll soon scan both of the manuals I have (electrical and mechanical, which sadly doesn't contain detail drawings) for this particular machine and post them for anyone who might need them, along with the parameters list and the PLC program

    20200318_112739.jpg20200318_112831.jpg20200318_112920.jpg20200318_113028.jpg

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    Congratulations on getting the machine running. It sounds like quite a marathon!

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    thanks, it was quite a good experience getting it up and running as far as it is now, didn't take all that long too, maybe 3-4 full days from starting to wiring it back up to nearly fully functional, learned quite a few more things about the TNC control as well, still need to do the geometry checks on axis, and one piece of information I don't have yet, but want to definitely check is the draw bar force, the number is not mentioned in the manual, will have to check NC Deckel manuals, since the Deckel used the same grip design (DIN 2080), the force should be the same, I want to check that before taking it apart to measure and order new belleville washers

    here are links to manuals on my google drive:
    mikron wf41c electro documentation TNC355_12MB.pdf
    mikron wf41c operators manual mechanical part_17MB.pdf
    and the input cascade for the TNC355 processor board
    schematic for TNC355 inputs E0-E31

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    and here are machine parameters for my machine
    there was one very peculiar thing, I wrote those parameters off the screen the first time I powered the machine up, and I'm quite sure I didn't make any mistakes, but when I tried to upload them back via serial port, it would error out at MP32;33;34;35, turned out that TNC won't allow such a high value there: "2745", but it can be a singe digit + decimal value, meaning - it would accept "2.745", and the other 2 parameter lists I googled up for 355 control also show a small numerical value there
    mikron wf41c tcd18 tnc355.pdf
    that value is called "Differential factor for axis X/Y/Z/4th", so that jitter I'm seeing right now might be because of this, need to look into that a bit more

    and for reference couple others parameter lists:
    0511172206.jpg 0511172206a.jpg img503.jpg.0fe6ac22a710f81701f52c18be78fb25.jpg img504.jpg.8705e467b91e604252a27970182b2304.jpg

    p.s. limit switch values in MP44~51 will be machine specific, they will have no effect before the machine will reference, but after that it may display "Limit -" or + if the range set in those parameters doesn't mach distance coded marks on the scales that are on that particular machine, to find out limits on your machine, after the machine has referenced, press MOD, then up/down arrows to find "display" and using "ENT" key make the display cycle through ACT/NOM/LAG/REF modes, REF mode is what you want, that will show where the machine actually thinks it is on that particular scale, move each axis to just before limit switches and put those values into MP44~51

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    received few din2080 pull studs from Singer a couple days ago, and bought few new holders as well to do some test cuts, and confirmed the suspicion about worn taper in the vertical head, probably due to weak belleville washer stack, I blued up tapers in both spindles and the result is in the photo, left one is the horizontal spindle, which seems like it has never been used, no signs of any wear at all, and the right one is from the vertical head, ignore the mark in the yellow rectangle, I touched the spindle taper during removal, bottom 1/3 of the taper basically doesn't make any contact

    suggestions as to where to send the spindle cartridge are welcome, Singer perhaps? hopefully the bearings are fine, and I might get away with just the taper regrind

    test piece in the photo is 1045 steel, 50mm 90 degree shoulder mill at 600rpm and 600mm/min 1mm depth of cut, notice the vibration signs near the holes, couldn't get a decent finish on steel while side cutting with an end mill as well, vibrates and chatters in both x and y

    20200326_170132.jpg 20200326_170833.jpg 20200326_203412.jpg 20200326_211639.jpg

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    Don't know about Latvia, but here in the US there are specialists that will come to your shop and re-grind your spindle taper in place.
    Most spindle rebuilding services can do his as well....

    If you have access to a good grinder i would be tempted to grind a "tool" from cast iron to mimic the taper, charge it with diamond and lap the spindle...
    Would need to dress the tool often during the process to keep the taper straight and true.

    Would contact Singer about a re-grind. Would need to have a self contained spindle cartridge for Singer i would think to do this work, a commercial spindle re-builder would be able to grind a loose spindle if
    that is needed.

    Cheers Ross

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    I already tried asking around local machine shops, and it seems that there are only couple offering mostly electronics repairs, no re-grind service unfortunately.
    I googled up few spindle repair shops in both UK and Germany, and a user here in PM pointed me to a company in Switzerland that is an official partner of GF group (which Mikron is part of) that offers rebuilding services, time to take it apart and build a transport box... while waiting on replies from them.

    While I was fiddling with tool holders in that vertical spindle, I indicated for runout one of the better holders I had, and even repeated seating of the holder resulted in nearly zero runout when measured around 80mm from the spindle face, but I could get the indicator needle to move just by applying radial force to the holder, axially it returned to zero, so hopefully the bearings are fine and I'll get away with just the taper regrind...

    One thing still perplexes me though, this is a tool changer machine (TCD18), there is a braking resistor for the spindle motor, there is also a hall sensor on the vertical spindle (presumably for positioning), yet I couldn't get the spindle to stop consistently at the same orientation (for a tool change operation, drive dogs are fixed rigid at the spindle), sometimes it would stop 3-4 times in a row roughly at the same rotational angle, then next few times it would stop "randomly", same behavior in either high or low rpm. Original wiring diagram for the spindle motor (2 speed 3 phase induction motor) includes only contactors to switch the speeds and direction and braking resistor, and it matches what I see in the control cabinet, there is nothing that could turn the motor slowly to position the spindle for a tool change, and which could also help during gear changes...

    pic of the tcd18 tool changer arm:
    mikron-tcd18.jpg

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    On older Dialog4 Deckel and on Maho 700P, spindle indexing & gear meshing is done by powering the motor over 3 resistors for very short time.

    Usually makes a couple of "klonk" noises:
    YouTube

    There should be a relay with 3 rather large resistors in the control box for that.

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    I've seen videos of Mahos and Deckels switching gears and noticed that they seem to "twitch" the motor to help the gears mesh, and that is what surprised me with this machine - there is no spindle motor activity at all during the gear change, control has no problems turning the motor on/off, both speeds work like they should.

    I attached a photo of the motor wiring, apart from the soft start inductors (L271) I don't see any other current limiting possibility to softly nudge the motor back/forth during gear changes

    That soft start circuit seems to work as it should, on every motor start the K271 contactor is open for couple seconds allowing the current to flow through the inductors (audible hum can be heard during this time as proof of that), and then, when motor spins up, the K271 closes up to bypass L271 inductors, but again - there is no contactor clicking or anything of the sort during a gear change...

    spindle_motor_wiring.jpg

    edit: regarding the spindle taper situation, after talking to couple local shops I decided I'll give hard turning with a CBN a try, I'm a bit afraid to ship it anywhere as well, since the pandemic situation turning to worse might mean my spindle might get stuck somewhere for months...

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    So I didn't have a suitable way of holding a CBN cutter, and the ones I have are too large for this, and I ended up borrowing a Kennametal "20mm" boring bar with KCU10 WNMG insert, 300rpm with 20mm/min feed, final cuts were 0,015mm deep radially, in total had to remove about 0,5mm in diameter to clean up 95% at the bottom end of the taper - so the bell mouthing of the taper was quite significant, first passes had quite a lot of "singing" - chatter, but last couple were very silent, there is just a hint of vibration at the bottom end of the taper where the interrupted cut it

    Had to fiddle with servo tuning before attempting this, to eliminate the trailing error, and managed to adjust it to be around +/-0.001mm according to TNCs positional display set to LAG mode

    bluing up the taper to get the impression on the tools resulted in a much better pattern, not ideal, something seems to be off at the top 1/3 on one side (I need to adjust the pull rod, check for any burrs there etc, haven't done it yet), I forgot to take picture sadly, but overall the couple tests cuts I made showed a lot less vibration/chatter than before, so this was a definite improvement, but I'll probably send it out to be reground after the pandemic situation improves

    few pics showing the pattern after couple passes and then finished taper, the vid shows indicating with 0,002mm DTI, my error was to mount it on the vice instead of the vertical head, so there is some drift, it settles near the end of the video

    40taper-turning-1.jpg 40taper-turning-2.jpg 40taper-turning-3.jpg



    edit: might have been little less removed in the diameter, the tool sits about 1mm deeper into the taper now, so it could about 0,3mm total removed in the diameter

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