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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > 1994-ish Minitech Mini-Mill/2 Resurrection?
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  1. #1
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    1994-ish Minitech Mini-Mill/2 Resurrection?

    Wow. This is quite the community! Here's hopin' I end up with a reason to be a part of it!

    I work in the IT department of a public high school. I recently was poking around in the back of the school's drafting room and FOUND A MINI-MILL/2, in a nice mdf/plexi booth, buried under some blueprints, balsa house-framing models, and a winter-blanket of dust. Upon finding a teacher who actually knew something about it, I was told it hadn't run in 9 years... wait for it... "due to software problems." *facepalm*



    The booth, thankfully, was closed up. The mill was still caked with chips and dust, but it was also still slimy with oil. Not a spot of rust on 'er. Okay, so given the situation, I guess I'm just here looking for answers--yes, answers to a few questions I've thought of, but probably more so the answers to the questions I wouldn't think to ask. I'm technically minded, a quick study, and very handy; but to quote the emc2 manual,
    "We learn from experience, if at all. Broken tools, gouged vices, and scars are the evidence of lessons taught. Good part finish, close tolerances, and careful work are the evidence of lessons learned."
    So yeah, I'm knee deep in forum searches and printed manuals, and I'm very eager to learn, but I have zero (0) CNC experience and zero (0) budget.









    __________________________________________________ ______

    Already on the agenda: estop, limit switches, home switches (has none of those now, and this is a high school). What I've done so far:

    --I've cleaned up the chips and such. I don't want to go to crazy removing the 'grime' though, since it's done a great job this past decade and I have no idea what anti-rust and lube to replace it with. I've read suggestions from painting on plain ol' WD-40 right up to packing with machine grease. Meh?

    --I haven't heard back from Minitech yet. In the meantime, anybody know the difference between Minitech Machinery and Minitech CNC? Same town, shared company name, some share model names. Different demographic, different phone numbers, and different staff?

    --The floppies that came with it are ©1994 and were corrupted. I hooked it up to a 2600+ AMD HP d325 tower running XP sp3 and installed the Mach3 demo. It clocked okay, but I couldn't get stepper motion. From this thread, I'm suspecting the opto-couplers are too slow. Even 'Sherline half-stepping mode' didn't help. I started from scratch with EMC2 and got each axis to come to life (didn't want to go far though pre-lubejob). I am, however, guessing at the pinouts and control specs. Does anybody have real specs or manuals for this older model Mini-Mill 2? They've changed over the years. A post elsewhere suggested the pins would match sherline style, so I hit that button but I don't have directional control.

    --While on that subject, no... I haven't tried to find specs on the steppers themselves yet. Just missing directional control though, I'm tempted to just try stuff until it works. Conversely, I'm hesitant to 'monkey with it' until I get the right pins and numbers locked in for fear of damaging it. I don't have the budget to get better controllers or a breakout board. I also don't have money for new motors if I fry these though. Should I be afraid of that, or are crashing and putting volts where they don't belong all I really need to worry about? Is choosing normal-hi instead of norm-lo or vice-versa going to fry anything?

    --Oh, and while I'm thinking of it, do I power on the PC or the mill first? As a computer guy, I'm used to thinking of old peripherals as devices you don't want to power up/down or plug/unplug while the host is running. That said though, if I turn on the [Astron RS-20A] power supply, then turn on the linux box, the Mill makes a bunch of fun, creepy noises I'm used to hearing from big honkin relays. That expected?

    --I know I should be asking most of this in separate posts, maybe in different forums, heh. If anybody reading knows EMC2 though, my monitor driver is missing and while everything looks fine over vnc, the physical lcd I'm using has everything 50 px or so low, including the hotspot for the cursor--have to be above what you want click! I read (in the manual?) that I shouldn't update Ubuntu, and can't have vendor graphics drivers. I'm not stuck at 800x600 like it said to expect, but it still stinks. Can I simply not go to 10.10 and the other expected LTS updates are fine?

    Okay! That's enough for now. Congrats if you read this far. I'm sure I'll be back with plenty more questions as things progress. Lots of high schoolers with the wonderlust, itching to get milling. I'm itchiest of them all, heh. Any advice or input appreciated!
    Cheers, Joel

  2. #2
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    Welcome to the zone. You are about to embark on a challenging journey. Fortunately today we have the internet. I too purchased a machine that had been used minimally and abandoned due to a very minor glitch of some form. I simply read the manual, cleaned the limit switch and the error code went away. Unfortunately the software is unavailable so conversion to Mach 3 and modern drivers was my choice after months of research and attempts to communicate successfully. Inevitably G code would still not have been able to be used but a coordinate system did work very well thru the controller. I did learn alot thru the late night reading though maybe it doesnt show yet. LOL. I dont know where the info will lead in the future, but the little room it is in, still has room for more! To me, you having an IT background should give you a leg up but then again we all have our challenges in this hobby/profession. You have come to a great site for pursuit of the answers, good luck and enjoy. Take lots of pictures. If you want to see how not to do it, read some of my posts. LOL Cya

  3. #3
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    Looking at your machine a little closer, wow, what a find. Sure it is OK to clean it with WD-40. I would use something else to protect it with though, I personally like to use gun wipes after cleaning with a shop rag and WD, might be a Texas thing? Just kidding, the wipes are like towlettes and are impregnated with some rust inhibitors/lubricant. Cheap and easy. The steppers are fine. Yes, they do hum when powered up and should resist if you try to turn them manually. They will heat up also, sometimes on the verge of too hot to touch but shouldnt get quite that hot with no load. It is also pretty durable in the sense of connections, but proceed with caution on the electronics just because its easier and better for those that have to unplug you(nuts). They might have better ones now but those will work for all intensive purposes. They will operate your machine faster than you can get to the E stop! Dont ask me how I know that. Also the leadscrews and some form of preloaded nut and linear rails on your carriage, again good stuff. The Sherline head is very versatile and if you are lucky that might be an ER16 spindle which has many sized collets available, if not it is Sherlines small morse taper (dont hold me to that spec) anyway the Sherline heads are available in may configurations and are relatively inexpensive (less than 200 bucks). The spindle looks like it is very solidly mounted for spindle of that size. I really suggest going to the software and electronics specific thread here on the zone. There are a few people you will see (very few for such a seemingly large world and they are the same people thru many forums, Thanks) who seem to be very knowledgable on the subjects needed. You might have to pm 1 of them and ask for specific help. Usually they will oblige you. Try the forum or thread first. I wont give you their names but in no time, you will see who they are for you. Btw the parts you might need breakout boards, power suplies, relays and the like are not very expensive at all and when you look around enough could be almost free from someones parts bins! Sorry to ramble and again good luck.

  4. #4
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    more tomorrow?

    Ha! Don't apologize for rambling! :-) I need all the info I can get. Thanks for the advice.

    Had no time with it today, but more pictures, trial runs, forum-diving, and question-asking are all on my plate for tomorrow. Anyone else with advice or input... the more, the better. Thanks!

  5. #5
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    Btw the spindle is a Sherline with its specific collets. Still very versatile you just have to purchase the collets from Sherline. I think 1/4" is the largest ID collet of theirs.

  6. #6
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    Thanks for reading and posting and PMing me, folks!
    Realized I didn't post any full pictures... (p.s. how do I use the in-built thumbnail embedding? Can't find it in help.)





    Remember, those thoughts that your thinking about it and what you would do... I don't know those thoughts! Heh. I'm utterly new to mill maintenance and operation. Give me a shout!
    Thanks again everybody. Really appreciated. Joel

  7. #7
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    Those old machines can do some amazing things. Mine is highly updated but here is a video of it ripping thru some plastic.

    [nomedia="http://www.youtube.com/watch?v=9_BhB9Wzrhg"]YouTube - Testing experimental spindle[/nomedia]

  8. #8
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    Quote Originally Posted by exitcode1 View Post
    Thanks for reading and posting and PMing me, folks!
    Realized I didn't post any full pictures... (p.s. how do I use the in-built thumbnail embedding? Can't find it in help.)





    Remember, those thoughts that your thinking about it and what you would do... I don't know those thoughts! Heh. I'm utterly new to mill maintenance and operation. Give me a shout!
    Thanks again everybody. Really appreciated. Joel
    At the bottom of the reply or new thread page it says manage attachments. Select that and link it to your photos. Should be a thumbnail then.

  9. #9
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    Talking Success! It Lives!

    Lots of questions still, but I'm happy to report I've gotten her conscious after her looooong nap

    [nomedia="http://www.youtube.com/watch?v=NI_GZ6mmd5Q&fmt=22"]YouTube - 1994 Minimill 2 Resurrected[/nomedia]


    Thanks again to everybody who reached out to me!
    Joel

  10. #10
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    I have the same machine, what were the pin outs for this?

  11. #11
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    Re: 1994-ish Minitech Mini-Mill/2 Resurrection?

    Pinout, output from PC, input to mill:

    Pin 2: output to PLC signal (it outputs in 24V)
    Pin 3: Pulse step X
    Pin 4: X direction
    Pin 5: Pulse step Y
    Pin 6: Y direction
    Pin 7: Pulse step Z
    Pin 8: Z direction
    Pin 9: Enable communication

    These are D0 to D7 parallels lines.

    It's the same parallel printer pinout, GND is present in various pins.

    There is one more pin, I'm not sure if it is pin 11, BUSY, that signals the PC it can start milling. Pin 2 & 11 drive signals to and from and external optional PLC connected to mill. The PLC tells the mill it can start milling, and the mill tells the PLC it finished milling. The mill transparently carry this signal back an forth to PC, only converting from 24V to 5V and back.

  12. #12

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    Re: 1994-ish Minitech Mini-Mill/2 Resurrection?

    I know that this is a very old thread, but I am trying to get a Minitech Mini-Mill up and running for a local middle school. I am trying to run it through LinuxCNC. I can't get the configuration right (or there is something wrong). The pinouts listed previously do not work. Is anyone else out there running this mill in LinuxCNC, configured with stepconf? Can you share configuration information? Sorry for the double-posting of a similar message here: https://www.cnczone.com/forums/bench...98704-cnc.html. No response from my posting there ... Thanks in advance!

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