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  1. #1
    Greetings to all, and thanks to many.
    I have been researching for a while now, and found many helpful and informed comments on MYCNC........ Many thanks for a great site and comunity.

    I have for many years wanted to have a cnc mill to make prototype parts, and possibly manufacture small runs to sell.

    After many failed purchace attempts on Ebay, I finnally bought an old Warco Major, made in Korea, and fairly poor condition, but at 125 I could not refuse.
    Found a man with a van (and tail lift) to deliver it for 40.
    Built a stand from 4x2.
    I stripped it for inspection ...... ooooo! ..... it looks like i was used to cut stainless mainly on the Y axis, no covers for the ways and lots of swarf embeded in them.
    There was a dip in the middle of travel, of approx 7 thou!, so I spent many, many hours with stones and then lapping paste and it is down to 1/2 thou dip. (just read of an enineering company in Bedford, who will recut the ways for 30 ish) ....we live and learn.

    The X axis was OK.
    Quill OK
    The spindle bearing are fairly worn and get hot at 2500 rpm, will replace those later.
    Motor (2HP single phase), was replaced with a 3 phase 2HP for two reasons:-
    1/ the single phase motor was the source of much vibration and fettling did not improve it (un-even air gaps)
    2/ I already own a VFD.

    For the conversion, I gleaned much of the spec. from here, Robin Hewitts post, but combined with info from Gary at Zapp and others.

    Ballscrews where purchaced from China (sorry to the English Companys) for 92 inc post and end machining. That is 2 x 1605 screws 400 and 600mm long, 2 x ball nuts + machining. They are single nuts and C7 rolled screws.
    Direct drive size 34 steppers (4.5 nm) from Arc Euro for X & Y, & A, size 23 (3 nm) for Z & C. (forgot to say, it is going to be 5 axis).
    Z screw from an aircraft breaker, (a flap screw I think) anyway it has a 1605 screw and rotating nut.
    Driver was one of the cheap 3.5A 36V, sorry 1.5A 24V boards from Ebay, but more on that later.
    Old 2.8Ghz computer and a 15" ELO touchscreen from a skip(thanks to my partner) which I repaired.

    The work:-
    Made blocks for the nuts, used the original bearing blocks and used a pair of angular contact bearings on each ballscrew, with the opposite end floating.
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    The motor mounts
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    Motors on
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    Having mounted the motors, I was keen to try it out, so I connected the motors to the driver 36v 11a PSU at min voltage of 32v and hey presto!
    Chuffed with my progress, I came indoors and did some more reseach.
    I read page after page saying that the driver board I was using was pants! Most blew-up at 30v or more (I had run mine at 35v with no problems {35v is max input for the 5v reg.}).
    More research, looked at modding the driver, then decided this was a waste of time and money. So i bit the bullet, phoned ArcEuro and ordered 2 x 9a and 1 x 4.2a drivers (for X, Y & Z). Bought an opto board from ebay, also found some IP67 micro switches for the limits (25 for 5)
    Using the 36v PSU (can go to 80v on the 9a driver) connected up and spent many hours, initially without any movment from the motors, then to one direction only (9a drives have switch for step/dir or CW/CCW orientation wrongly described) and finally working well.(Required 6uS setting in Mach3 for both step and dir.)
    Since this is never going to be hyper acurate, I have used 2000s/rev = 400 steps per mm.
    It runs at the maximum Mach3 can output in 35Khz mode which is 5250mm/min. so I am happy with that.
    Click image for larger version. 

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    Made sone covers for the ways, and fitted X & Y limit switches (one each).

    Found another bargain on Ebay, my fourth axis, apparently from a Swiss gear cutting machine.
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    Boy is it heavy, must weigh 40-50 kilos!, bit worried about the balance of the table, but with the trunniun table and end support it should be OK, I hope!?

    OK enough already, I will add more a I go.
    Last edited by Tweaky; 14-02-2010 at 08:55 PM.

  2. #2
    Should have said that this is my first post, ever, so I hope all is correct?.

  3. #3
    Tweaky, Drop the speed down a load, it's not a race and reliability is worth more than speed over such a short bed length,
    If you know it does 5250mm min, halving it will give you a 100% safety factor.
    Set the velocity in Mach to 2500.
    John S -

  4. #4
    Hi John, thanks for your coments.
    Should I increase the resolution, which will also decrease the top speed?

  5. #5
    I should add that whilst setting up, I set Mach3 to 45Khz, turned up the PSU to 40v and it ran hapily at 6000mm/min, so I thought I had some margin already.

  6. #6
    If you are happy at that then fine but 6 metres a minute over a bed length of this size doesn't give you much time to hit the E-stop.
    Another point is that Mach is more happy at lower kernel speeds less chance of errors and the base 25K is plenty for mills etc.

    The high speeds were brought in for routers and such with servo motors that require 2,000 to 4,000 steps per rev against steppers at 200 steps [ in full steps ] these were running out of steam.

    You don't really achieve much on stepper driven machines as the stepper drivers are the choke point and get egg bound way before the set maximum.
    John S -

  7. #7
    You are quite right, it leaves no time to hit the Estop, in fact whilst playing I found that the limit switch had to be set to be nearly 25mm inside the EOT to enable it to stop before *!?
    Last edited by Tweaky; 17-02-2010 at 11:33 PM.

  8. #8
    Here is my box for the electonics (ex alarm box from a skip). It is not tidy yet because I am still sorting it out.
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    and here is the Y axis limit switch.
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  9. #9
    Hi Tweaky

    Looking good but no pics of the Z, have you done that one yet? A honking plate? :naughty:

    On mine the pin that stops the quill turning had raised a burr down one edge of the groove it runs in. You can't see it, you can't even feel it, but when you do the Z you may lock the quill orientation and move the burr out of the groove it has cut for itself. If you have the quill out, easy job, look for a groove on the inside of the housing by the guide pin. If there, assume a burr and stone it off.

    Also, are you sure the spindle bearings are shot? l had a lot of clatter on the splined shaft and tried to fix it by liberal application of heavy grease, maybe a previous owner did the same to yours, it is an obvious fix :whistling:

    The grease eventually found it's way down in to the spindle bearings causing them to run hot at top revs, same as you've got.

    Might be worth running oil in at the top, with the spindle running, until it comes out oil coloured at the bottom. Changing that God awful original motor fixed most of the clatter for me, flushing the spindle bearings stopped the bearings running hot.

    best regards


  10. #10
    Hi Robin,

    Z is next, have a smaller honking plate than yours, only 25mm thick. It is a disk 150mm dia., with the quill bore offset.
    I have seen thinner ones, but when I saw your plate, I suddenly felt inadequate!. Do you think 25mm will flex?

    Thanks for your help with the quill (does this mean I owe you a Hobgoblin?), I did find burrs on the quill groove and the pin when I stripped it. The pin is quite worn.
    The bearings are marked on the rollers and the race, although once cleaned, it did tighten nicely ( no soft area), however, like you I would like more, 5-7000 rpm area. I have found some angular contact bearing that will fit, and they are rated at 14k rpm, dinamic load of 24Kn, do you think they would do the trick?

    Last question, for the mo' , as you can see my finish on ally is poor, I have not yet aligned the column, but have read much which suggests that finish is related to vibration. I still get some vibration at almost all speeds, feels to me like column flex. Does your do it?, have you filled the column with Epoxy Granite or balanced you pulleys (mine has 2 inters .....pain)?

    Thanks again.

    Last edited by Tweaky; 15-02-2010 at 10:31 PM.

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