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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > Weiss WMD30LV conversion project
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  1. #1
    Join Date
    Apr 2005
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    Weiss WMD30LV conversion project

    Or at least I think that's what this is. I bought this machine from TMTT on Ebay in the UK. As far as I can tell though, Weiss is the OEM for this mill.
    For more background, we were discussing the variants of this machine in this thread: http://www.cnczone.com/forums/showthread.php?t=88540.
    It is the larger version with the 840mm table and long X travel.

    I am planning to CNC this machine very soon, I will not be doing any manual work on it at all. I already have my converted X2 to make motor mounts etc, then the X2 will be sold on. The plan is to use 20mm ballscrews on X and Y, and possibly 25mm on the Z if there is space. I will probably add a second, removable lightweight Z axis to the side of the head to do small engraving work, using a high speed spindle.

    Here is a shot of the machine after I ripped 2 sides of the box off to check for damage. It is sitting in my garage.



    And here's one for size comparison with me standing next to it, I am 6'2".



    I was happy with the condition it was delivered in, which was very clean with no apparent surface damage. We'll see what it is like inside later. I can recommend this seller if you are in the UK, good communication even when the first delivery attempt was messed up by the courier. They showed up at my house with the machine on a truck and no way to offload it!
    I'll document the conversion process once I get going. I need to save up a bit more money before I can buy the screws, bearings etc. Also be interested to see any info from anyone else who has converted this machine.

  2. #2
    Join Date
    Oct 2009
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    5
    Nice
    I have read the other tread and i am looking forward to follow this one.
    Happy conversion!

  3. #3
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    Aug 2006
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    Congratulations LongRat - they look just as nice in Blue as in Warco Green

    I look forward to seeing the pics of the teardown and conversion. Just one question though - what is the advantage of 20/25mm screws over the cheaper 16mm ones? Do you get more mechanical advantage, or are they just stiffer?

  4. #4
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    As long as they are the same 5mm pitch, you don't get any more mechanical advantage, but the stiffness is a big plus. Especially on this machine's X axis, with the table all the way across to one side on the 840mm table length the machining forces in the X direction will be being taken by a long length of ballscrew. Both in compression and tension depending on machining direction of course. Basically I will fit the biggest screws I can fit in there, as long as they aren't out of my price range.

  5. #5
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    Quote Originally Posted by LongRat View Post
    As long as they are the same 5mm pitch, you don't get any more mechanical advantage, but the stiffness is a big plus. Especially on this machine's X axis, with the table all the way across to one side on the 840mm table length the machining forces in the X direction will be being taken by a long length of ballscrew. Both in compression and tension depending on machining direction of course. Basically I will fit the biggest screws I can fit in there, as long as they aren't out of my price range.
    Sounds sensible - though TBH I didn't have any trouble with 800mm long 16mm x 5mm pitch screws and 6000rpm/1.5Nm servos - well, other than trying to accelerate anything heavy is rather scary - does the machine move, or the room it's in?

    IIRC there might be issues with rotational inertia if your ballscrews get too big and heavy - but I can't remember where I read that, sorry.

    IMHO you might want to buy yourself an engine crane if you're going to have that thing in bits to do the conversion - I'd imagine the table and head are both in the order of 40kg each...

  6. #6
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    I'm going to borrow an engine crane tonight.
    This is just to lift the whole machine onto the stand so I can get a decent look at it from all angles. I see what you are saying about the inertia of the bigger screws, I'm not expecting the same dynamic performance I get out of my X2 though. Except in Z, which is why I am thinking about the auxiliary Z axis.

  7. #7
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    Aug 2005
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    180
    Hi,
    I see you "splashed the cash" on a shiny new mill - well done! TMTT were really fast and helpful when I was talking with them. Very interested to hear how you find the machine in use. I went up to Warwick ME show the other weekend to have another look at the Warco version, the SX3 by ARC (and the turnkey CNC version) plus the WABECO LF1210. Unfortunately Pro Machine Tools weren't there so I could compare the WABECO offering. Further inspection of the machine on the Warco stand has convinced me that the Weiss machine is the way to go in terms of size spindle speed cost and easy of CNC conversion, especially as you can get the longer table machine without a price penalty.
    20mm screws on X and Y would appear feasible and a good choice also agree with 25mm on the Z axis. Are you planning to use servos or steppers?

  8. #8
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    Apr 2005
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    862
    I'm planning to use 425oz.in NEMA 34 steppers. The X and Y leadscrews are dia 20mm as stock, so I am sure 20mm ballscrews will fit, and there seems to be plenty of space for nuts. I haven't opened up the Z yet.
    I don't know why but Pro Machine Tools don't seem to be going to many shows any more, possibly because the Wabeco machines are a bit out of most hobbyists' range. There's no doubt in my mind that the 1210 and 1410 are the best of this type of mill, but you just can't argue with £1100 for the TMTT mill - it is a bargain for what you get, and it is BIG.
    The Arc Euro machines are nicely done and reasonably priced as far as the competition goes, but are still much more expensive than a DIY conversion. I have to say I was impressed that they had 2 machines running under CNC control at Warwick. They are doing a good job at pushing the CNC cause, there were a lot of people crowded round.

  9. #9
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    I've got the machine craned onto the stand, and I ran the spindle bearings in a bit. The gearbox is pretty quiet. I tested the travels, X was 597mm and Y 207mm, but if you take the Z axis bellows bracket off you could get up to 238mm in Y! I'm very happy with that. I did a quick test cut in aluminium with a 2 flute 10mm carbide cutter, went through it like butter. From feel, I would say the removal rate is maybe 5 times faster than on the X2, and I expect it could have been pushed harder.

  10. #10
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    Have you had a chance to check how square the machine is? How easy was the lift on to the stand?

  11. #11
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    If by check, you mean read the inspection report - then yes. Otherwise, no. It is claiming to be trammed to 0.040mm in both X and Y. I'm not going to try to change the Y, I don't fancy shimming that out really. Obviously in X its pretty easy with the swivelling head. I can't remember any of the other values, but they did list table flatness, parallelism of T-slots to the X travel direction, and squareness of X to Y axis motion. All of those values were smaller than the 0.040 tram values, I remember that much.
    With a 1 ton capacity engine crane we managed to lift it onto the stand after shortening the hook chain to gain some height. I'm not going to say it was easy, because it wasn't. It wouldn't be too bad with 3 people, we did it with 2 and it would not be possible on your own. I don't have much experience working with very heavy stuff but my friend helping me has, this was a great help. He's always lifting engines out of cars and he didn't find it too bad.

  12. #12
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    I guess you may not have had much time to play with it yet, but how steady was it on the stand with the table or head cranked all the way out? I managed to wobble the whole machine at the Warwick show when cranking the head back down from the top, but I was hoping that was just due to the stand being on a wobbly pallet...

  13. #13
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    Well, my machine is solidly bolted to the stand. There's absolutely no motion between the two. The stand itself rocks and rolls on my uneven garage floor, but once it is moved into the final position I am going to bolt it to the floor too. It will be rock solid then.

  14. #14
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    Here are the values quoted from the test report. They are written by hand on the paperwork I received. Where there is a number reported like 0.01/300, I am assuming that means 0.01mm total indicated over a measurement distance of 300mm.

    1. Flatness of worktable surface - 0.03/300
    2. Parallelism of T slot to table longitudinal movement - 0.03
    3a. Parallelism of table to table movement (longitudinal) - 0.01/300
    3b. Parallelism of table to table movement (cross) - 0.01/100
    4a. Runout of spindle hole (at spindle nose) - 0.005
    4b. Runout of spindle hole (at 100mm distance) - 0.010/100
    5. Squareness of table longitudinal and cross movement - 0.01/150
    6a. Squareness of spindle axis to table (right & left) - 0.04/300
    6b. Squareness of spindle axis to table (forward & backward) - 0.04/200
    7a. Squareness of spindle sleeve movement to table (right & left) - 0.02/50
    7b. Squareness of spindle sleeve movement to table (forward & backward) - 0.02/50

    There's a small diagram explaining the meaning of each on the report.
    The report and manual generally have good English which leads me to believe they may be the work of the importer rather than the manufacturer. The plaques on the actual mill have the usual Chinese-English translation. I'm pretty happy with the documentation which is in a different league to the photocopied rubbish that came with my Chester X2.

  15. #15
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    Thanks Longrat. Those values look very good and suggest that the machine is good foundation for CNC'ing, unlike (in hindsight) the X2. Just need to convince Weiss to put on a 10k spindle for the same price!

  16. #16
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    I've had a chance to strip some of the bits off the machine and get some pics. Still good news all round, in fact I think the Z axis will be even easier to convert than I had thought. I'm pretty sure I can do it without even taking off the head. The rest of it looks very straightforward too, there's a ton of room everywhere.

    First I took off the motor cover and removed the motor and head top plate. This revealed the primary geartrain. Lucky I did this as some kind soul had left a stray locking washer in the gearbox, if I had done any cutting it could have easily vibrated into the gears and caused mayhem.



    All the gears are steel in this gearbox. It looks to me like the easiest way to increase the speed would be to get a larger pinion on the motor and switch the seconday gear to a smaller one. The gears are helical and the noise in operation is very reasonable, maybe not as quiet as a belt but much quieter than a stock X2 at full RPM. Switching to a 1-stage belt drive would probably mean losing the spindle tacho readout which would be a shame. You can see the tacho disc in the picture, it is a welded steel part ridiculously over-engineered for its purpose, but I'm not complaining!



    Here you can see the spindle itself and some of the steel gears. There are 2 thin steel cover plates to remove to get to see this. There was some grit and loose cast iron dust around here and near the gears, it is worth getting this far in just to clean out that crap. There is a decent amount of grease on the gears though.



    Looking down on the head towards the column, you can see how clearly the Z leadscrew is visible. Very simple design which I think will be simple to convert to a ballscrew drive. The stock screw is dia 22.0mm with a 4mm pitch.



    The top of the column removed, showing the z drive. The small bronze bush takes the axial loading in the 'up' direction. It would have been nice if they had used a thrust race here. The X and Y have thrust races paired up and preloaded. There was a ton of end float in the z thrust assembly causing 0.7mm of backlash. The problem is if you preload it up correctly, the plain bush inevitably imparts a lot of friction. I think if someone wanted to keep it manual, putting paired thrust bearings in here would be a very nice upgrade. As it is with a CNC conversion, they will be installed of course - probably angular contacts but I have used axial thrust bearings on the X2 with good results.



    Here is the column covering plate. They do use a thrust bearing for this side of the z drive. To give you an idea of the size, the ID of the bearing is 17mm.



    There's the z screw removed. Very simple. There is no constraint on the bottom end of the screw in the column. From a fully assembled mill to this stage takes literally a couple of minutes.



    Here is a view of the saddle sliding on the Y axis. Don't worry, that isn't rust, just looks that way in the photo. It's not the same as the red packing grease I've seen before, it is closer to an oil than that but very sticky. It has done a very good job of keeping the metal in good condition. Again the tail end of the Y screw is unconstrained, and there seems to be a good amount of space in which a ball nut could be fitted. Still might need a little grinding on the nut flange for the larger nuts. The stock leadscrews are dia 20mm in X and Y.



    With the X ramped over all the way to the limit you can see the surface of the ways, which appear to be hand scraped. The travel is certainly very smooth with no tight spots, and I can't detect any play whatsoever in the gibs or anywhere else.

    I've measured up everything, should be able to order some screws and nuts/bearings pretty soon. I've got a CNC router to build at the same time so I have to finalise the screws I want for that before I can order. I'm going to go with 'linearmotionbearings2008' on Ebay. I've heard good things about this seller and for the price it has got to be worth a try. Especially for the 20 and 25mm screws which are pretty expensive elsewhere. If anyone has anything to say about dealing with this person and his products, please post your thoughts. I've read a thread about the stuff on the zone with backlash reports ranging from zero to 50 microns. I was planning on double nuts. I'd like to aim for backlash under 25 microns if possible (0.001").

  17. #17
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    Excellent images and description. Do you think you can use the original nuts to mount the ball nuts? i.e. bore them out and thread them for the nut flanges? Or are going to make new steel ones? Looks like you'll have to support the Z axis screw, the Y will probably be ok.

  18. #18
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    Based on the nuts I *think* I will use, the existing nuts are probably not big enough to do that.
    I wasn't planning to support the free end of the Z screw. I don't anticipate I will be able to drive it at very high RPM. Any reason you say that? I hope I haven't missed something that might make it a lot more difficult...

  19. #19
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    Aug 2006
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    Hi Longrat - great pictures of the disassembly, and I'm glad to hear the head appears to be all metal gears.

    How does that Z-axis screw attach to the head? Is that round post on the acme nut tightly held to the head, or does it just rely on gravity to keep it in contact with the head assembly? I guess I'm just a bit worried that that connection could be another possible source of Z-axis backlash...

    As for securing the lower end of the Z-ballscrew - how would you actually go about it anyway? Is the lower end of the colum open enough for you to fit a bearing holder in from the bottom?

    Cheers,
    Joe.

  20. #20
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    The round post on the nut fits nicely into a round hole of the same diameter in a block screwed to the back of the head. This allows the screw a rotational degree of freedom with respect to the head. The post fits the hole pretty well, but this will be a source of backlash I am sure. I'm planning to solidly bolt this together when I make a ballnut carrier, so there won't be any movement then.

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