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  1. #81
    Thanks routercnc for that stock-squaring video https://www.youtube.com/watch?v=tW8HNAlUXxU

    How serendipitous that I found your link to the video almost totally by chance. Enjoyed the presenter's humour also.

  2. #82
    Some overdue updates . . .

    To finish off the machining of the ballnut blocks. Chamfered 2 of the edges:
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    I swapped the 3 jaw over to the 4 jaw chuck and dialled it in using the bore I'd machined out on the CNC. Got it to within 0.05 mm, so pleased with that.
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    Drilled it out using a range of twist drills up to 25 mm, then bored it out to size
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    Three more to go:
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    Then used the CNC to spot out the 6 ballnut holes, then drilled and tapped then on the drill press:
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    Then onto the mounting holes on the underside. Again CNC spotting the holes, and then drilling and tapping the M8 holes on the drill press:
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    Checked it with a spare ballscrew - fits OK:
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    _________

    Then onto the side support plates - spotting out all the holes:
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    Drilled out, counter bored, and tapped:
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    __________

    Next parts are the tram plates. These connect the Y axis box structure (which contains the Z axis), to the Y axis bearing plates and allow the Z axis to be aligned in multiple planes to tram in the spindle. The adjustment will be made with M10 cup end grub screws before the main bolts are then tightened. I'll put a screenshot of the updated design in the future post.
    Cutting them out:
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    Spotted, drilled, counter bored and tapped:
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    Here they are trial fitted to the side support plates (which then sit on the bearing blocks).
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    ________

    Then onto parts of the Y axis box structure. Started with some eco-cast from aluminium warehouse. Nice and flat and in good condition:
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    Marking out the holes with a 3mm drill bit:
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    Then machined out the pockets which will take the 4off Z axis profile rails. I did a very fine finish pass with large overlap on the bottom of the pockets to get them as flat as possible. There is some adjustment when everything goes together but best to get it close as possible:
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    Quick check:
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    Cutout, drilled, counter bored, and tapped:
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    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  3. #83
    Next parts were the triangular supports. No photos of these being machined as I wasn't happy with first one. As the design was just a simple triangle I used tabs to hold it in place. But these left the usual witness marks on one edge which didn't look very nice. I tried to sand them out but wasn't happy.
    So I started again and added some internal cutouts to add a bit of style, but more importantly allowed me to hold the part in the middle while I machined all the perimeter away:
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    Still needs holes drilled and tapped in the sides, but decided to do a trial fit. It connects the tram plates to the side support plates:
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    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  4. #84
    A work of art, very nice :)

    It's very satisfying when you have made a pile of bits and they just all fit together perfectly :)

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  6. #85
    Great thread - always really interesting to see how people go about making the parts rather than just seeing the finished product.

    Super chunky looking parts there as well. I dunno what it is about a nicely machined chunky piece of alu but it's just damn tasty!
    Last edited by Zeeflyboy; 12-03-2017 at 12:18 PM.

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  8. #86
    Managed to cut another one out this morning:
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    Another trial fit showing both triangular supports:
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    Just 2 more to go for the other side.

    Here is the current design for the Y/Z axis. You can see the tram plates (small grey rectangular plates) I mentioned earlier which will allow me to tram the spindle relative to the larger green bearing plates underneath.
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    Initially I will put the WC spindle in the main housing and drive it direct. It might stay this way depending on how much better it is than today.

    But if not, the following pictures show the alternative full feature version. The parts will be made to accept either set up.

    Main feature is a home made spindle (Tormach TTS drawbar style with R8 collets), driven by the WC spindle via a pulley with different ratios, plus the addition of powered drawbar.
    Click image for larger version. 

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    Here is a rear view of the pulley drive from the WC spindle, which is connected via a sliding frame to allow the belt to be tensioned:
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    This view shows the Z axis with power draw bar. This will give a simple push button tool release. I don't have pneumatics in my workshop so this is electrically driven via a stepper, through a pulley reduction drive, and finally through a ballscrew. Quick calcs show this should have enough power/torque to overcome the pre-load on the belleville washers (part of the drawbar retainer) to release the tool. The whole PDB system floats on sliding bearings so that it squeezes the drawbar against the spindle shaft, rather than loading up the bearings.
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    Click image for larger version. 

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    Here is an underside picture showing the spindle which bolts in via the lower flange. It is also held in place with the clamps further up the main body, which are also used to hold the WC spindle in direct drive mode:
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    Here is a cutaway view of the spindle showing housing, bearings, draw bar and collet system. At the top you can see the pulleys for the drive and the belleville washers which hold the tool in place by pulling up the R8 collet, which in turn squeezes the 3/4" shaft of the tool holder. Google Tormach TTS for more info.
    Click image for larger version. 

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    (The power drawbar assembly is not shown in this drawing)

    Still some finessing to do (e.g. tube connecting AC bearings in nose to upper bearings not in correct alignment etc.), plus still have to convince myself that I am capable of machining the spindle in the correct steel (oversize by ~0.3mm), get it hardened, then grind the bearing journals and the R8 taper to all be parallel and aligned again as they will be distorted. I'll need to make a fixture for my lathe to hold a die grinder or some other idea.
    This is the biggest part of the project, the most risky, and the main reason I may just stick with the direct drive set up. But the attraction of big torque boost, the ability to run larger cutters, and the quick tool change keeps me interested.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

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  10. #87
    Very nice, look forward to seeing the spindle progress.

  11. #88
    Now thats the most out of the box z design i have seen recently. No shame in using 8x Hiwin bearing blocks and 4x rails plus a couple of motors apart from the Hf spindle. How would you align all that stuff in place? Each piece must be carefully machined to a tight tolerance.

    Ok. I know that you will patiently make it. Obviously not your first machine 2 questions:

    1. Wasn't it simpler and better using BT30 spindle and servo motor on a fixed gantry?

    2. So much effort in all places but gantry will slide on round open cage bearings? No square supported ones?
    project 1 , 2, Dust Shoe ...

  12. #89
    Boyan - in the first post ;)

    Quote Originally Posted by routercnc View Post

    X axis
    Twin beam gantry design using 60x100x5mm RHS steel sections. This sits on 16mm open bearings which are on 16mm simply supported rails. Cannot get finance approval for 1000mm profile rails so am re-using existing parts. I'm going to use 6 open bearings per side to get the most stiffness out of it. When the time comes there is only minimal work to adapt to profile rail.

  13. #90
    Quote Originally Posted by Boyan Silyavski View Post
    Now thats the most out of the box z design i have seen recently. No shame in using 8x Hiwin bearing blocks and 4x rails plus a couple of motors apart from the Hf spindle. How would you align all that stuff in place? Each piece must be carefully machined to a tight tolerance.

    Ok. I know that you will patiently make it. Obviously not your first machine 2 questions:

    1. Wasn't it simpler and better using BT30 spindle and servo motor on a fixed gantry?

    2. So much effort in all places but gantry will slide on round open cage bearings? No square supported ones?
    Thanks Boyan. This is probably about version 5 of the Y/Z axis design with all sorts of combinations tried out, some with single Z ballscrew, some with pulley driven ER straight shafts, and other options. Eventually the desire to have the option of pulley driven spindle (for lower speed, higher torque), much larger cutting bits, and the ability to add a PDB drove me to this design.
    I wanted to make the stiffest Z axis I could as it is all won or lost here. The 4 rails and 2 ballscrews is as stiff as it can be (in concept terms) so went with that. I thought a lot about the alignment of the bearings as you cannot just machine everything and bolt it together. The Y axis box structure has slip planes to allow it to be pre-loaded up to the bearings to squeeze them together. I'll let you know if this plan works !

    1. I agree fixed gantry would be even stiffer, but I needed to maintain a very large cutting area for wooden panels. If it was just smaller metal parts then you are correct. So this requirement has forced a compromise. Fixed gantry would have a very large working footprint and I don't have that space.
    I also looked at lots of spindles including buying off the shelf BT30 etc but they are very expensive with PBD. In the end I decided to allow fitment of direct drive WC spindle (the hole is 80mm diameter), with the option of making a spindle later.

    2. As Zeeflyboy has pointed out this has already cost a lot to make, plus there is more cost to come (more Z axis rails, more aluminium plate, more steppers and drivers, pulley hardware etc.) so the ~200 profile rails on X will have to wait. Agree it is a weak point, and will also give some loss of accuracy. For now they will have multiple blocks per side, not the usual 2, to get the best out of them. But the rail supports which they run on has already been spot drilled ready for profile rail. A simple adapter plate to the gantry will then allow the upgrade.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

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