Another build from Germany (ongoing)

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This topic contains 9 replies, has 3 voices, and was last updated by  Ryan 1 month, 1 week ago.

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  • #89438

    Alex
    Participant

    Hi all,

    first of all, I’d like to thank Ryan and his ‘crew’ for sharing all this. I have been reading through all the documentation and many posts. At first, I thought to add some modifications and build some hybrid of mpcnc and lowrider. But the longer I have been reading and thinking about all this it got more an more clearer how well designed everything is – so changing things will most probably make it worse 😉

     

    Here it is, after plotting the crown:

    myCrown
    sorry Ryan, cable ties not yet shortened on some axes (I wanted to wait until I’m sure tension is correct)

    But first things first:

    I spend yesterday building the table. I recognized that I could use 2 concrete walls, which should add a little stability to the table.

    table1
    table2
    table3
    This is 15mm OSB, and on top 18mm MDF (which will be cutted out in the mid for easy replacement later on.

    So, now I’m at hitting ‘order’ for the stainless steel tubes and ‘print’ on the printer; but I’m still a bit unsure… I plan to have 120x70cm working area, and this could be OK for the foam parts but too large for the MDF moulds I plan to mill. On the other side I think: try it out, if it is not ok I could then decide to resize the machine and build an additional lowrider 😉

     

     

    1 user thanked author for this post.
    #89478

    Ryan
    Keymaster

    I’d like to thank Ryan and his ‘crew’ for sharing all this.

    Which now includes you!

    #89566

    Bill
    Participant

    I plan to have 120x70cm working area, and this could be OK for the foam parts but too large for the MDF moulds I plan to mill.

    Just loosen the corners and end of axis and move them all in closer when milling the smaller designs. Only go out to the ends when you need to cut the big foam.

    #89634

    Alex
    Participant

    loosen the corners and end of axis and move them all in closer when milling the smaller designs.

    Ah, this is an interesting option!

    #93390

    Alex
    Participant

    Here is the mechanical assembly finished

    mpcnc1

    It took some time, as I had to replace all bearings, as the fist set was real crap. I ordered new ones, now everything slides smoothly.

    I already added the large spindle. A friend of mine strongly influenced me taking the larger one because of the collet size. I’m not so sure; I think I should have taken the 800W version. I could finally align the spindle vertical adding som extra small spacers in the mount. Should work.

    Attachments:
    #93419

    Bill
    Participant

    It is looking very nice so far. With those stainless steel tubes I don’t think the larger spindle will be a problem, unless you try to move everything really fast.

    #93424

    Alex
    Participant

    Yes, the stainless steel tubes a quite rigid.

    I was a bit disappointed at first because the roundness is not so good:

    put a micrometer gauge bottom up and rotate the tubes: the difference is about 8/10 mm. Quite large.

    This non-roundness however is constant along the tube -> sliding along results in variations of about 1/10 only.

    I was afraid that the spindle will hang through in the mid of the working area, but the effect is not so large (I decided to build the smaller machine).

    I plan to add mid-span supports when the electronics works.

     

    #94987

    Alex
    Participant

    I finally plotted my first crown, added a photo in the initial post

    1 user thanked author for this post.
    #96398

    Alex
    Participant

    I made some accuracy test today

    check1
    To recap: my working area is ~ 910mm x 570mm, I have endstops

    Repositioning even along the long axis ist mostly exact even when travelling far away and back again; someties 1/100 mm ‘inaccurate’. This is great!

    z-axis has backlash of 4/100mm (which is usual for the lead screw setup) – question: I once had a rigid semi-sized machine with ballscrews on all axes which had reversal backlash of some 1/100, which was compensated in software. This worked well. Something similar possible in marlin? (I dont think so).

    I the used a scale to measure the deviation from position when applying a pressure:

    400g -> 1/10mm

    1200g -> 1.5/10mm

    1500g <2/10mm

    Ryan stated somewhere milling of aluminum requires about 1.5kg -> I think (and this is astonishing to me) that leaving 2/10mm material for finishing, and then using 1 or 2 finishing passes could get better than 1/10mm for aluminum – I will believe this when I saw it 😉

     

    Attachments:
    #96444

    Ryan
    Keymaster

    A finishing pass is a marvelous thing!

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