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IndustryArena Forum > MetalWorking Machines > Benchtop Machines > AMAT25LV Basically another PM25 clone :)
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  1. #1
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    AMAT25LV Basically another PM25 clone :)

    Finally made a start.
    Enclosure built except for the doors.
    PC, control box, steppers all tested.
    Machine is torn down ready for parts to be made on the X2.
    Going with double nut 1605 all round using AC bearings X,Y and thrust on Z.
    Could prob do with a 2005 on the Z tbf.

    I've been working on the oil system first while it's in bits. Took out the ball oilers and have threaded their holes to M8x1.0. Have some 4mm push-fit swivel elbows for those and some smaller thread size ones the same for the screws.
    Think I'll have to do the Y axis motion before I fit any tubing etc so I don't damage any fittings while the saddle is being tossed around.

    The stock design on the Y axis is crap. Table nowhere near centred and it's nut position means it can't go all the way back to the column. To get truly more than 165mm it needs a head spacer and then the table hanging off the front at least 50mm.
    Not a fan of that.

    The way I'm planning to go about things is to clean up the underside of the saddle and fit the nut further forwards.
    Z bellows are being removed and replaced with the roller cover mod attached to the head and the saddle so it moves with both.
    When this is all complete the saddle will go all the way back thus achieving a true 185mm with an overhang on the dovetails around 30mm in either direction.

    I'll get there eventually and I'll put a pic or 2 up soon.
    Enclosure doors will be the last job.

    Starting off basic.Steppers running off 36v & 60v.
    Using 1600oz/in Z and 425oz/in on the X,Y with Mach3 controlling.

  2. #2
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    Re: AMAT25LV Basically another PM25 clone :)

    It's very slow going.
    Nearly there with the Z Had a complete change due to the crap ballnut.
    My Z nut mount is made of 2 parts bolted together on top of each other. 2 single ballnuts are bolted either end. Tin foil is used as a spacer between the 2 nut mounts to spread the ballnuts to eliminate lash. It's a ballache of a design but looks like it will work.
    A couple of niggles need changing before I put a motor on.

    Almost done with the Y. I've opted to ditch the 425's and get some 1100oz instead.
    Reason being is I've put tin foil between the spacer and sleeve on the double nuts to spread them and minimise backlash. It's a little bit tight but spins and getting the AC bearings right is hit and miss.

    I just managed to get a test done on the Y axis and got a 0.025mm baclash reading (0.00098") I think that'll do.
    I really don't want to use the compensation in Mach if I can help it.
    Rapid moves had a stall at 2500mm/min so I'll leave it at 2000mm.
    It's pretty tight where bearings/nuts are concerned so It'll either go well or eat itself!!

    Been let down on material atm so I can't start on my X yet

  3. #3
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    Re: AMAT25LV Basically another PM25 clone :)

    That sure looks like a PM25 to me!

    To me, it seems like something is off if you need 1200 oz in motors on the X and Y and are only getting 100 IPM (2500mm as you noted). On my PM25, I have double nut ballscrews and I was using 400 oz in steppers and got more than double that speed easy. It also seems off if you are getting under .001" of backlash which means sticktion isn't really causing trouble.

    I would love to see some pictures if you have them!

  4. #4
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    Re: AMAT25LV Basically another PM25 clone :)

    Quote Originally Posted by shooter123456 View Post
    That sure looks like a PM25 to me!

    To me, it seems like something is off if you need 1200 oz in motors on the X and Y and are only getting 100 IPM (2500mm as you noted). On my PM25, I have double nut ballscrews and I was using 400 oz in steppers and got more than double that speed easy. It also seems off if you are getting under .001" of backlash which means sticktion isn't really causing trouble.
    I would love to see some pictures if you have them!
    I'll sort a couple of images later.
    I think I have the gib a bit tight for 1 and my ballscrew does have a bite in places as a result of my packing the spacer to eliminate as much lash as poss. Hence going with the bigger motor. (60V supplies).
    Pushing the carriage back and forth by hand without anything attached does show up a tight spot towards the front end of the ways.
    That is where I had the stall so a fiddle with the gib will be in order. Lapping/scraping is beyond me so hopefully it'll be better in time.

    I set the gib tightish to start with as the carriage had a wobble when overhanging the front end 30mm and above. Once the ballscrew etc were all fitted up it stopped doing it.

    I could in fact remove 1 piece of foil packer (0.03mm thick) and that will smooth out the ballnuts. But then the backlash will go up to around 0.05mm (0.0019").
    I would rather sacrifice some speed over increased lash and keep it at half that figure.

    I'll settle for 2000mm/min (80" ish) rapids it's still more than my small Sieg.
    With only max 3000rpm on the 25 I can't cut massively quick with a 6mm 3fl anyways.

  5. #5
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    Re: AMAT25LV Basically another PM25 clone :)

    I had some of these same experiences in my build. I used hybrid steppers if you haven’t done the purchasing yet.

    Much quieter and I’m able to wire in an alarm setup so it works well in that aspect.

    I do wish I had better ball screws.

  6. #6
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    Re: AMAT25LV Basically another PM25 clone :)

    Progress on enclosure. 45L coolant tank at bottom. Needs doors.

    PC near the roof. Monitor mount top right.Y slot cut as much as I wanted to go. Made new anchor points for the nut mount on the shelf area in front of where it originally was. Table rear travel now brings it closer to the column (15mm away). Means less overhang at the front. Unfortunately the easiest way of running the oil for me was to have the manifold located to the front. High pressure metal push fittings used all round.
    Bearing block was made wider to enable extra anchor points to be added at the sides to make sure it could hold the motor weight. Uses the 2* 8mm holes and 4* extra 6mm holes. My Seig gives a crap finish half the time. Be glad when this is running.
    Twin nut mount made for the X axis and recess cut in the saddle for clearance of nut and oil fitting. Nut will still need cutting down at the top.

    Built up the nut mount quite long to cover the DFU as much as possible. This should prevent any chance of nuts wobbling. Total travel measured in as 204mm using only a 59mm saddle overhang at the front. This means I have left myself the option of adding a 10mm head spacer to give a comfortable max travel of 200mm. Had to take it apart a few times to cut bits down here and there.

    I've ended up using only a 1605 screw with a twin SFU nut setup. Feels pretty solid and I'll upgrade to 2005 if needed. Drag chains for oil & coolant lines.
    There is a car roller blind mechanism been made for it using 0.5mm nitrile sheeting. Isn't fitted as I keep breaking the plastic brackets when knocking into it.


    With the roller unit fitted it will give a safe distance of 180mm from spindle centre to nitrile cover without material rubbing on it. That's about the distance I was looking for so I can cut a true 180mm sized square with the Z still protected.
    Attached Thumbnails Attached Thumbnails P1030895.jpg   P1030896.jpg  

  7. #7

    Re: AMAT25LV Basically another PM25 clone :)

    Very nice! Your enclosure is very similar, at least and size and shape, to the one I built for my G0704.

  8. #8
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    Re: AMAT25LV Basically another PM25 clone :)

    Adjusted this Y axis ballscrew way too tight me thinks. Too much friction. It runs o.k. but is speed restricted which is a little disappointing (2200mm/min).

    Backlash is stable at 0.025mm (0.00098") and it's repeating within 0.01mm over 170mm distance after many test runs according to the dial.

    What I did notice is that if I hit the soft limit point at more than 1300mm/min it throws the axis out by 0.2mm each time. I'll have to watch hitting them.
    Don't know whether to take some of the packing out of the DFU nut to loosen it a little. It should increase speed but will give a backlash of 0.05mm (0.002") affecting accuracy.

    What to do? I really don't like the stop/start business of the Mach3 lash compensation so don't want to use it if I can help it.
    I may just leave it all as is and see if bearings etc eat themselves or not.
    Only have the stock 3000rpm max spindle speed available so probably can't cut much quicker than 1000mm/min anyway.

  9. #9
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    Re: AMAT25LV Basically another PM25 clone :)

    To start with I have a question or 2.
    1. Should I remove the control box & arm and fit them outside the enclosure? I assume all it requires is extending the motor cables and doing something with the door switch to disable it.
    2. My motor & mounts on X table are quite weighty. Would you put a counterbalance on the slave end or not bother? I have put it's home position off center at the minute so it sits fairly balanced while not in use.

    So far the base / table are finally together.
    Tested X & Y.

    X repeats to within 0.01mm travelling over the entire distance. Backlash also reads at 0.01mm. Achieves a travel distance of 500mm.

    Y repeats the same. Backlash is now reading at 0.02mm. Achieves a travel distance of 203mm.
    Will put a 10mm head spacer in at some point so I can use the full 203mm.

    Column is on but haven't tested it yet. Starting on the head first tomorrow, need to fit some flood coolant attachments and some bits to use as tramming aids.

    I'm disappointed with rapid speeds overall but I have got all the mechanical parts set up quite tight. There is a fair bit of friction in the whole machine, screws, bearings etc. even with the gibs barely engaged.
    However I'm quite happy with the accuracy numbers.
    I reckon 80ipm is enough (2050mm/min).
    Hopefully it doesn't just chew up every bearing that's in it!!!

    Mach3 is set up as 2000/400 for the 5mm screws which is a resolution of 0.0025mm if I'm correct. In the motor tuning it shows a maximum velocity of 3750mm/min available. I will try 1000/200 soon for a resolution of 0.005mm as a test to see if speed torque changes/improves and I can get a speed increase.
    I don't think a mill needs much more than a 0.005mm resolution anyway tbf.

  10. #10
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    Re: AMAT25LV Basically another PM25 clone :)

    So the Nema34 and bearing blocks etc on the end of the X table weigh in at almost 4kg total.
    Question:
    Would you add something of the same weight to the opposite end to balance it?

    At the moment I've set home off centre where its COG is most likely to be.


    I still need to finish the head, build doors, attach the oil pump and tidy the cables.
    The X mounts are attached with 5 bolts for extra security. 3 extra were tapped into the table ends.

    Don't you just HATE it when you get a slightly bent ballscrew!!!








    Attached Thumbnails Attached Thumbnails P1030908.jpg   P1030909.jpg  

  11. #11
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    Re: AMAT25LV Basically another PM25 clone :)

    No. 4kg is nothing.
    7xCNC.com - CNC info for the minilathe (7x10, 7x12, 7x14, 7x16)

  12. #12
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    Re: AMAT25LV Basically another PM25 clone :)

    Back to the drawing board on the Z.
    The head totally stalled lifting at <1000mm/min.

    The twin SFU nut design I did is pretty impossible to get set properly. Nuts were mashed too tight making the screw almost jammed and there is no adjustment as such.
    Gave up and ordered some more actual DFU ones (hopefully some decent) and any play in there I can eliminate with some packing using the 0.01mm thickness alu foil I have.

    For now I've put in the awful DFU one I received originally just so I can get it all tried out. Head drop will be substantial with it by the feel of things.
    Tempted to leave it in bits for weeks until I get the new ones.

    When I thought about it afterwards I reckon I may have been ok using some gas struts as a counterweight while using the duff DFU screw. Tempting tbh.

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