So I bought a used Mikini...


Page 1 of 2 12 LastLast
Results 1 to 12 of 13

Thread: So I bought a used Mikini...

  1. #1
    Member
    Join Date
    May 2016
    Location
    United States
    Posts
    181
    Downloads
    0
    Uploads
    0

    Default So I bought a used Mikini...

    Knowing, more or less, what I was getting in to (thanks to the forum here).

    The price was negotiated down to budget for a complete retrofit. It was, frankly, quite a bit less than what SkyFire would charge to send me a 'bare-bones' no electrical/electronics mill. I bought it knowing it would probably be a project (but secretly hoping not so much). It even came with a 4th axis and a rather extensive collection of Royal quick change tool holders ($$$).

    Everything works so far and I have done some simple engraving, homing, axis moves. Lights and coolant containment have already been addressed.

    But... Spindle motor has the RPM dip mentioned here countless times. Not only does it dip a few hundred RPM, it also shuts off briefly (yellow tower light off) and comes back on while under a very slight load.

    Unfortunate, but not surprising. I've already contacted SWATH to see if he has one of those swanky custom boards to integrate a VFD/Induction motor with the Mikini panel. I'm not interested in spending a lot of time getting frustrated with broken cutters and botched parts before fixing this thing. I'm extremely new at CNC machining and I need to not have a machine fighting me since I'm perfectly capable of breaking things on my own.

    However, before I take the plunge, I'd like to hear some thoughts or advice on various options. Again, SWATH has been helpful and I've already put the question to him about options, but it occurred to me that maybe my first post on CNCZone after lurking forever should be a question for the Mikini folks. Here's how I see it:

    Option 1 - pitch BLDC and driver, fab a mount and install an open-loop 2hp or so 3ph motor & VFD. Manual spindle control outside of Mach3. Not a long-term solution, but would be the fastest route to glory. Upside is that the motor and VFD are unlikely to be pitched if/when I do other mods. Downside, of course, is manual spindle control, so no tapping even with a compression tap holder - I'm not that good.

    Option 2 - SWATH's REX84 board, plus PMDX 106 card, plus vector motor & VFD. More money than #1, but not by much. Upside is I have Mach3 controlling the spindle (open loop) - nice. Downside #1 is that the 106 card appears to be discontinued and don't know if the 107 card (or some alternate) is compatible with SWATH's card. Downside #2 is that if the Mikini panel dies I can't get another one as far as I know, and I'll have to pitch the two cards I bought. Being dependent on the Mikini panel is not ideal.

    Option 3 - Same as #2, but find a motor with encoder, and more expensive VFD. This is, I think, what SWATH has set up and he is perfectly happy with the arrangement. Upside is better spindle control (tapping?) Same downsides as above, plus a giant increase in price for the encoder motor.

    Option 4 - Gut it, more or less. This means pitching some combination, starting with the mikini panel & BOB.
    4a - keep the steppers & drivers, get an ESS & some BOB.
    4b - keep the steppers, replace the drivers, install ESS & BOB
    4c - pitch everything, upgrade to closed-loop steppers. Pull the column and hog out the base so longer motors fit. Yuck.
    4d - pitch everything, get some Nema34 servos. Robodrill rapids!
    4e - same as 4a-4d, but get a servo for the spindle instead of a VFD. I'm right next door to HGR Surplus, so big used servos are dirt cheap. Finding a compatible servo drive may be a bit trickier, but a new encoder vector motor & VFD appear to be quite a bit more than a 2.2kw servo and drive on the surplus market.

    So many questions.

    If I replace the Mikini panel & BOB, what do I go with? Is there a BOB or motion control board that permits me to use either steppers OR servos so I can keep the 4th axis stepper? KFlop? CSMIO?

    I suppose it boils down to money, time & effort. Like everyone, I'm not interested in pursuing an option if it means spending time & money only to pitch parts & start over because something didn't work or the mill sucked when I was done. Or doing a total retrofit with champagne parts and it doesn't really make any difference than if I'd stuck with the stock steppers & drivers.

    Obnoxiously long-winded, sorry; brevity is not my strong suit.

    Comments welcome.

    -Spumco

    Similar Threads:


  2. #2
    Member
    Join Date
    Feb 2009
    Location
    USA
    Posts
    2086
    Downloads
    0
    Uploads
    0

    Default Re: So I bought a used Mikini...

    Option 5 - Buy a BLDC driver only from Skyfire and replace the one on the Mikini. That's what I did. Unfortunately I haven't installed it yet, so I can't report if it works or not. For now, keep your RPM's at 80% of max or more and you should be fine. If you want to mill steel that can be a problem, but for aluminum, wood, plastic it works fine (the dips in power at that speed don't affect much).

    CAD, CAM, Scanning, Modelling, Machining and more. http://www.mcpii.com/3dservices.html


  3. #3
    Registered
    Join Date
    Jan 2005
    Location
    Australia
    Posts
    100
    Downloads
    0
    Uploads
    0

    Default Re: So I bought a used Mikini...

    Option 6 Get a proper cnc controller, drives and servo motors from the one manufacturer. I have a lathe equipped with a GSK controller, servo motors etc. The spindle motor on it is 5.5kW induction motor driven by a vfd. Now that I've seen it, and how it seems to be supplied to the lathe manufacturer with all the cables terminated, I don't think I'd muck about with anything else. It just works out of the box, It is strong and fast, and a bit scary to use when you are just learning like I am. The documentation that came with the controller is very good, and in real english. The lathe is a lot heavier than the mill, but cost the same $, so the controller and servo's can't be all that expensive. If you look at Defeng's latest offerings you will see he is using one of a different brand on the top of the range SVM2. Have a look on Alibaba.



  4. #4
    Member
    Join Date
    Feb 2009
    Location
    USA
    Posts
    2086
    Downloads
    0
    Uploads
    0

    Default Re: So I bought a used Mikini...

    You could get a whole kit from Flashcut...

    Tabletop & Minimill / Lathe / Gantry Kits | FlashCut CNC

    CAD, CAM, Scanning, Modelling, Machining and more. http://www.mcpii.com/3dservices.html


  5. #5
    Member
    Join Date
    May 2016
    Location
    United States
    Posts
    181
    Downloads
    0
    Uploads
    0

    Default Re: So I bought a used Mikini...

    Thanks very much for the input - much appreciated.

    As for running the BLDC as-is, it's not just the dips - it's the cutting out and dropping from 5k to 3k while essentially unloaded. Not encouraging.
    I do intend to do steel and other low SFM materials so even if the driver is replaced with a SkyFire, the torque curve (as I understand it) is not favorable for my planned projects. If you had installed yours (mcphill) and reported back that it was the bees knees, I'd maybe give it a shot.

    I found the GSK integrated controller site and it's looks sweet. Thanks for the direction. Same thing for Flashcut, but a complete kit from them with servos is north of 5k - that seems rather a bit much.

    SWATH has reported that the PMDX107 card will work with his kit, so that's encouraging. I think Option 2 & 3 are back on the table since I don't seem to be having troubles with the axis movements.

    I think I'll focus on the spindle for now and address axis components later. If the Mikini panel board dies, worst case I'm out a couple hundred and not TOO much time - and still have a working spindle motor and VFD.

    So maybe my next question is - any CAD files for a 145TC adapter available? Allen appears to have made a one-piece plate and cut the spindle cover. SWATH made a two-piece thing and pitched the cover.

    Do I need to stick with a 145 frame, or will a 182 fit? Other suggestions for a spindle motor?

    Thanks,
    Spumco



  6. #6
    Gold Member daniellyall's Avatar
    Join Date
    Sep 2009
    Location
    New Zealand
    Posts
    1856
    Downloads
    3
    Uploads
    0

    Default Re: So I bought a used Mikini...

    the other option is pokeys

    <img src="https://ivxo1q-dm2305.files.1drv.com/y4mENMmTr_Cabc7pR0FUdB6gtbADq2JbuG4_rGy0eBQvLJx19pTi6TqMUIJN0xgOyDIc0gWoxYhS38HpbSTFGdfaK-o42IOU6jczrhDpfpCOTNGL1X6hvZCbgj0y35gqmq1YGTrWwShYGV-C7lXA2esy0Pi_WfnBSyroDLSGXwce4uSr1U7op7srdi78rispHCa_K4aFlTlJPVkkNWMfgh_Tg?width=60&height=60&cropmode=none" width="60" height="60" />

    Being Disabled is OK CNC is For fuN


  7. #7
    Member
    Join Date
    May 2016
    Location
    United States
    Posts
    181
    Downloads
    0
    Uploads
    0

    Default Re: So I bought a used Mikini...

    Daniellyall,

    Thanks. Pokeys looks pretty impressive and not too complicated to implement.

    However, I've scored a nice motor with encoder from FleaBay and just bought a flux vector drive. Based on SWATH's suggestions, Option 3 is the path forward for now.

    Once the spindle is happy, I'll be able to better evaluate the motion control. If the axis moves are not up to snuff, I'll start looking at one of the suggestions here for a new controller and or stepper/servos.

    Thanks again to everyone. Wish me luck making the motor adapter.

    -Spumco



  8. #8
    Member
    Join Date
    Feb 2009
    Location
    USA
    Posts
    2086
    Downloads
    0
    Uploads
    0

    Default Re: So I bought a used Mikini...

    Quote Originally Posted by spumco View Post
    SWATH has reported that the PMDX107 card will work with his kit, so that's encouraging.
    Where is Swath's kit described/shown/sold? Got a link?

    CAD, CAM, Scanning, Modelling, Machining and more. http://www.mcpii.com/3dservices.html


  9. #9
    Member
    Join Date
    May 2016
    Location
    United States
    Posts
    181
    Downloads
    0
    Uploads
    0

    Default Re: So I bought a used Mikini...

    Via email. He's currently running his 1.0 'interpreter' card. He also has a v2.0 designed, but not built. He's not really selling a drop-in kit, but has discussed the various parts needed (his card, PMDX 106/7 card, VFD, 3ph motor, encoder is optional).

    As I understand it, the mikini encoder/drive work on a 6ppr signal, and the Mikini controller manages the spindle using PWM.

    The new motor and VFD operate at 1024ppr, plus use a 0-10v signal for RPM control.

    The PMDX106 or 107 convert the PWM to 0-10v, and SWATH's card converts the 1024ppm to 6ppm. Both of these are needed to permit the Mikini controller panel to operate & display the spindle properly.

    The difference between 1.0 and 2.0 is that 1.0 uses an axis alarm to trigger spindle halts or estops. The 2.0, I think, would permit Mach3 to see spindle faults directly instead of 'tricking' Mach into a stop. I'm probably missing quite a few details.

    He reports having two 1.0 cards printer but not assembled/soldered up. He has 2.0 designed, but not printed. The 1.0 was quoted at about $80, and the 2.0 he estimated at double that.

    We haven't discussed timing, but since he's busy I expect once we work out details to wait a couple of weeks for him to whip one up. I'll probably be requesting a 2.0 card despite the higher price unless it's going to take him months to get it printed and fabricated.

    Not sure if he monitors this site frequently, but he responded immediately when I emailed him through his War Machine LLC web site.

    Drop him an email. If you're interested in a card all three of us might be better off if we order two or three at once since I may order two just as a backup.

    -Spumco



  10. #10
    Member
    Join Date
    May 2016
    Location
    United States
    Posts
    181
    Downloads
    0
    Uploads
    0

    Default Re: So I bought a used Mikini...

    UPDATE:

    If anyone's watching this forum, here's the final results of my 7-month Mikini adventure.

    The deal with Swath to cook up a 'translator' board for the VFD fell through; no blame as what I asked for was slightly more complicated than we'd originally discussed. This forced me to essentially gut the Mikini and start from scratch. Here's what I wound up with:

    New PC and monitor mounted on swing-arms
    UCCNC software and a CNCDrive UC400ETH motion controller
    PMDX-126 and 107 spindle board
    Hitachi WJ200-15SF VFD driving a Marathon Black Max 2hp spindle motor
    Motor encoder for tapping (signal to both VFD and BOB)
    All new limit/home switches (12v)
    E-stop and all power circuits are based on 24vdc mechanical relays
    New control panel (all 24vdc - no 110/220 near the operator)
    All wiring inside rigid metallic conduit on back of machine.

    Coolant system hose now external to the enclosure
    2/ea 3" drain holes cut through base to a trough system that dumps in the OEM chip tray

    All wiring removed from enclosure except for X-axis conduit. Drag chain installed for all the crap going to the spindle head (encoder, motor wires, coolant hose, spindle index sensor)

    Lube pump moved to back of base (lower) to eliminate siphoning and the puddles of way oil

    This has been a serious pain, but the mill is now quite happy to make gobs of chips. Like 7000RPM, .125WOC, .375DOC @ 90IPM piles of aluminum chips, plus it can rigid peck tap.

    -Spumco



  11. #11
    Registered
    Join Date
    Jan 2005
    Location
    Australia
    Posts
    100
    Downloads
    0
    Uploads
    0

    Default Re: So I bought a used Mikini...

    Thanks for the update, much appreciated.
    John



  12. #12
    Registered
    Join Date
    Nov 2012
    Location
    United States
    Posts
    220
    Downloads
    0
    Uploads
    0

    Default Re: So I bought a used Mikini...

    It would be great to see some pictures of your build and if you don't mind, how much did Skyfire quote you for a machine with no electronics?



Page 1 of 2 12 LastLast

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


About CNCzone.com

    We are the largest and most active discussion forum for manufacturing industry. The site is 100% free to join and use, so join today!

Follow us on


Our Brands

So I bought a used Mikini...

So I bought a used Mikini...

So I bought a used Mikini...