New cnc Lathe build.

Discussion in 'CNC Machines and Conversions' started by blighty, Jun 27, 2013.

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  1. Jun 28, 2013 #21

    DICKEYBIRD

    DICKEYBIRD

    DICKEYBIRD

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    Sorry, been out in the shop working on my own electrical screw-up.;)

    Not sure about the 220/180vdc issue. I know the top speed/max voltage is adjustable on the KB but that seems pretty far apart for a simple adjustment. Like you noted, the KB specs do say max 180vdc. They know their product I'm sure.

    That's some motor you've got there and I guess it has a speed controller to match. I'm not an expert on this stuff, just a happy KB user. I'd hate to send you down the wrong path; maybe someone with professional experience will comment.

    I'm using CNC4PC's C-11 multi-function breakout board/speed control. I'm pretty sure the speed control section is the same as the C-6. It works fine, handles forward/reverse and speed control but I had a lot of trouble with the instructions concerning the isolation issue. I blew out a track on the board due to my lack of understanding but fortunately was able to repair it. I finally got it all working by adding a KBSI-240D Signal Isolator board between the C11 & the KB. Got it used on ebay for $25 and it fixed my problem.
     
  2. Jun 28, 2013 #22

    blighty

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    here you go... pic of the other end....

    IMG407.jpg

    IMG408.jpg
     
  3. Jun 28, 2013 #23

    blighty

    blighty

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    DICKEYBIRD........

    when i picked the treadmill up it was shown to be working, so that would imply all is well with the controller board. only problem with using its board is, it doesn't go backwards.

    i have a Boxford 240 TCL that was retro fitted by someone else. i'll have a look and see what hes put in it to run the motor. i've been in the back a few times and there is a C6 type board, a clear box with lots of wires and two sod off big relays.
     
  4. Jun 29, 2013 #24

    blighty

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    just been having a look on the old intermerweb net again for Reversing DC Motor Speed Controller (yes i did copy paste that) and noticed a bit of a trend.

    all the ones i found that i think are up to the job i.e. more than 11amps 3hp plus are all 240vac input and 180vdc output. maybe the motor didn't run on 240vdc when it was in the treadmill.

    i might hook it all back up and see what coming out of the controller and how fast the motor is going.
     
    Last edited: Jun 29, 2013
  5. Jun 29, 2013 #25

    DICKEYBIRD

    DICKEYBIRD

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    Sounds like a good plan!

    It's pretty easy to hook up a big 'ol DPDT relay controlled by Mach between your controller & motor to get reverse rotation but then you have to worry about blowing up the controller with reverse polarity spikes from accidently reversing while the spindle is spinning down to a stop. There's info on the web showing how to get around the problem but it's way over my head. I was working on it when I stumbled onto a steal on the KBCC....end of problem!

    By the way, you might also consider a 3 phase AC motor & VFD as well since they're getting pretty reasonable these days.
     
  6. Jun 29, 2013 #26

    canadianhorsepower

    canadianhorsepower

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    This is what you have to do to alternate your motor
    rotation you can also put a capacitor on the input

    dc reverse.jpg
     
  7. Jun 29, 2013 #27

    blighty

    blighty

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    thought about going the AC motor and VFD way. i have done this with the mill for a belt conversion..... still working on that one. price for the motor and VFD came to about £350 so i thought i would give the treadmill way ago:wall:

    if I can sort out this relay to reverse the motor that DICKEYBIRD/canadianhorsepower have suggested, then i can use all the stuff from the treadmill and as the treadmill cost me £74.... think it will be a bit of a bargain:)

    just out of interest, how does the relay know when to reverse the motor? does mach/C6 board turn that relay on at the M4 command effectively swapping the wires over.
     
  8. Jun 29, 2013 #28

    canadianhorsepower

    canadianhorsepower

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    [quoteif I can sort out this relay to reverse the motor that DICKEYBIRD/canadianhorsepower have suggested, then i can use all the stuff from the treadmill and as the treadmill cost me £74.... think it will be a bit of a bargain[​IMG]

    just out of interest, how does the relay know when to reverse the motor? does mach/C6 board turn that relay on at the M4 command effectively swapping the wires over. ][/quote]

    you don't have to use a relay just the switch will do. I use this set up (treadmill and switch) on my taig lathe, I chose a switch with a neutral
    position so it goes FWD OFF in the middle and REV.

    the way a relay works is the same thing then the switch when the coil is energise it will go in one direction, when de -energise it goes the other way.
    If your going with the relay I would suggest that your motor turn in the forward direction when the relay is off
     
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  9. Jun 29, 2013 #29

    vidio1

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    Assuming you will be belt driving the spindle, you probably want to run the encoder off the spindle. There's no sense scrapping a part because of a belt slip. FYI Mach uses a single pulse per rotation if I remember correctly. It works, but it's far from ideal. I've seen people use 2 encoders spaced 90 deg. from one another to improve upon that.
     
  10. Jun 29, 2013 #30

    vidio1

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    You would normally use a braking resistor to bleed off back-feed. There are dedicated circuits built for this:

    http://www.cnc4pc.com/Store/osc/product_info.php?cPath=64_77&products_id=335

    It might give you an idea of what you need to build one.
     
  11. Jun 29, 2013 #31

    blighty

    blighty

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    yep.. sensor will go on the back of the spindle. this well be the same set up as the Boxford 240 i have. been having good results using a G32 code for threading and semi ridged tapping...... no problems so far.

    i was threading with it the other day, 6mm thread 1mm pitch @600rpm. turned out well.

    for ridged tapping i made a floating tap holder that is mounted between two springs. as when the tap reaches depth, the Z axis stops, but the chuck will spin on for a few more rev's then stop. the same thing happens when the tap comes back out.

    seems to be working well with the one censor.
     
  12. Jun 29, 2013 #32

    blighty

    blighty

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    may of got the wrong end of the stick before.......

    this switch your on about is just a switch? i.e manually operated, when i want the motor to go backwards I flick the switch and Mach is none the wiser.

    if that is the case i'm might go with that. as the only time i need to reverse the chuck is when i'm tapping (G32).

    reason being, the boxford 240 runs CW (looking from tail stock at the chuck) this is because it puts pressure on the tool changer's stop. so when you have to drill something you have to revers the chuck.

    the tool changer i'm going to build for my lathe will load up the other way around and the tools will be mounted upside down, at the back of the lathe. so no need to revers the chuck for drilling.

    so unless im doing a tapping cycle, no need to revers the chuck.

    all needed now, is to find out where to hook up the C6 board to the controller :wall:
     
  13. Jun 29, 2013 #33

    blighty

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    just thought i would add..........

    i've been:wall::wall: for months trying to figure this lot out, with many, many nights on the net. In the space of 3 days you guys have got me one wire (ish) placement away from getting it going.


    thanks to you all!!:bow:
     
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  14. Jul 3, 2013 #34

    blighty

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    sort of hit a dead end with this controller problem. as i need the reversing bit, I'm not to keen on using the treadmills board and i'm not sure if a KBCC-225R will run the motor to its full. as it only kicks out 180vdc when the motor calls for 220vdc. at £150 and what ever Mr. Import Tax because we can tax Tax, adds on. is a bit to much on a maybe.

    I'm going to give the guy i got the boxford from (as he retrofitted it) a call, see what he uses for his conversions. with a bit of luck he'll have what i'm looking for....... not.
     
  15. Jul 3, 2013 #35

    canadianhorsepower

    canadianhorsepower

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    I will try to find the picture I have of a treadmill set up running a 3/4 inch press drill .....................the results will kick you on your but
    for 5o.00 Canadian can]'t beat it....never:hDe:
     
  16. Jul 16, 2013 #36

    blighty

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    this is turning into a nightmare :-(

    been looking some stuff up about the treadmill the motor came from. according to the tread mill specks it is 2.7hp and not 2.7kw (3.5hp) like the motor says. at 11amps.

    so going by that, the KBCC 225R rated at 3hp and 16amps sounds like it will do the job. that still leaves the 220dcv on the motor to worry about as the 225r is 180dcv. but saying that, all the dc controllers i have found are all 180dcv.

    next problem....price. there is one place in the UK i have found that sells them @ £195 don't know if thats vat inc.

    if this board will do the job, i have asked a mate who lives in the US to get one from flea bay and drop it off over here the next time he's on a works jolly.
    should save me self about £120.....but cost a pint in P+P.

    sound good to you guys ???
     
  17. Jul 16, 2013 #37

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    But the motor does say 2.7kW on the manufacturer's nameplate ;)
    (2nd photo in your original post)
     
  18. Jul 16, 2013 #38

    blighty

    blighty

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    Yep your right, it does say 2.7kw, but you could say I don't have to use all it's power and if I do go with the kbcc board at the 180dcv then it won't be.


    Or will it?
     
  19. Jul 16, 2013 #39

    salzburg

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    With the 180v dc drive you will end up with about 2.5 hp.
    I bought a 12"x30" used lathe that came with a 0.75 hp ac motor. Switched to a 2 hp ac motor and it worked great.
    so unless your lathe is bigger a 2.5 hp motor should do.
     
  20. Jul 16, 2013 #40

    blighty

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    the lathe i'm building will be swinging a 6"chuck at 3500rpm hence the 4000rpm motor. so it was going to get geared down any way. the size of the lathe would be like my 10 x 22. that has a 1.5hp motor in it, but because of the gearing at 2500rpm it more like 1hp.

    I'm beginning to think this board will do the job.

    a mate in the US is ready and waiting to click the "Buy it now" tab and he can drop it of to me in a few weeks.

    so guys........ should i get a KBCC 225R board??

    yes?
    no?

    you decide :cool:
     

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