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  1. #1
    Hi folks
    I would like to show my design before fabrication in case you spot something not wright.
    Machine itself is tiny - working area 320x320x100. Reason for that is that I am limited with my Mill.
    I will not use epoxy for any leveling, base for linear rails will be machined.
    My mill with 2.5" head can do pass 450mm long along longest travel.
    Both base on bed will be done from one fix - that is why frame is 360mm wide excluding base for rails and rails itself.
    Profiles 50x25x2.5. I had them very cheap considering UK prices for steel.
    THK 15 rails with two blocks on each rails
    RM1605 ballscrew on X and Y
    RM1204 on Z
    Nema 23 3.1Nm stepper
    Belt drive HTD 5M 15T-20T - height of profile determine that, gear 30T is greater than 50mm and sticks out from bed
    Spindle - Kress 1050
    Design is nearly done - only home/limit switches are mising, cable carriers and few cosmetic item - brackets etc.
    Any comments welcome

    Cheers
    Tom
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    Last edited by Tom J; 19-09-2015 at 10:36 PM.

  2. #2
    Still trying to decide if this a moving gantry or Fixed gantry machine.? In both cases I'd change a couple of things on the main frame but will wait until you clear up which it is.!

    On the Z axis I'd switch the rails around and have them on the front plate with bearing on rear plate. This will give you a variable length lever depending on extension compared to the fixed length one now at any extension.

    I also wouldn't use a Kress router has it will be letting a nice stiff little machine down. Either 1.5 or 2.2Kw water cooled spindle is the right tool for this machine and won't cost much more than a Kress. It will last 5 times longer with much more power and lots quiter and I mean lots.!!
    Last edited by JAZZCNC; 19-09-2015 at 10:33 PM.

  3. #3
    Hi Jazzcnc
    It is movable gantry type as can be seen from every picture. Posted two version of gantry, but will use that with vertical orientated profiles - last 4 pictures.

    Reason for using blocks on spindle plate is simple - less cutting chips on rails as they are higher - means Z plate.
    I am not quite sure how you can have variable length lever? Unless distance on bearing blocks can be adjusted accordingly.

    I have both 2.2Kw water cooled spindle which seems to be massive for this particular design. This will be engraver - mickey mouse machine, but precise enough for my needs. I might go for 1.2KW water cooled but is hard to find, 1.5KW no problem

    Thanks for reply
    Tom

  4. #4
    Quote Originally Posted by Tom J View Post
    Hi Jazzcnc
    It is movable gantry type as can be seen from every picture. Posted two version of gantry, but will use that with vertical orientated profiles - last 4 pictures.
    The fact it doesn't have any legs or way for the gantry to clear the bench made me wonder if it was sat on the bench and the table moved.?

    Quote Originally Posted by Tom J View Post
    Reason for using blocks on spindle plate is simple - less cutting chips on rails as they are higher - means Z plate.
    I am not quite sure how you can have variable length lever? Unless distance on bearing blocks can be adjusted accordingly.
    Your design is like a spring board with just one fixed length. The distance from the bearing block to the end of the plate is constantly that length no matter where it is on the rails. So if say the front plates deflects for argument sake 1mm it will do so at any extension along the rails.

    If you swap them around then this spring board is variable depending on how extended the rails from the bearings. So at full extension you'll have 1mm deflection but if only extend down half way then deflection halfs.!! . . . . Does that make sense.?



    Quote Originally Posted by Tom J View Post
    I have both 2.2Kw water cooled spindle which seems to be massive for this particular design. This will be engraver - mickey mouse machine, but precise enough for my needs. I might go for 1.2KW water cooled but is hard to find, 1.5KW no problem
    1.2 or 1.5Kw hardly much in it both miles better than Kress.
    Last edited by JAZZCNC; 19-09-2015 at 11:36 PM.

  5. #5
    For a machine this size I'd go for the fixed gantry option.

  6. #6
    doing miter cuts on the gantry frame is going to be a mission, unless you got a very accurate machine to cut at 45 degrees ...

    agree with the rails on the plate ...

    my thoughts :D

  7. #7
    Blackrat

    Mitre cuts is no problem doesn't need to be so accurate - 89-91 deg will do as I leave the gap for welding bead.
    Big problem is to keep control distortion - cooling/pulling after get cold. I bought HD clamp 45 each to keep the angle.
    Heat treatment is important as well - annealing (releases tension in welding joints)
    Last edited by Tom J; 20-09-2015 at 01:58 PM.

  8. #8
    Sorry, should say that, legs are missing - got adjustable stands 40mm with M8 stud on each corner, high enough so gantry can slide without touching leg surface.
    All will stand on table top or designated bench with enclosure - all depends the noise from spindle (Kress or 1.2-1.5Kw water)

    I will swap over blocks with rails on Z - in spite of travel of Z being 75% of distance between blocks and spindle plate overhanging length is 3 times the thickness of that plate.
    Thanks for pointing that - this will help me to reduce the Z plate overall length by Z travel which is 110mm:)

    I will try both spindles, only problem is that water cooled is heavier what cause the CoG move forward and is not in middle of sliding blocks on the gantry like is now with Kress.

  9. #9
    Quote Originally Posted by Dragonfly View Post
    For a machine this size I'd go for the fixed gantry option.
    This will reduce already short travel of 320mm to 220mm. Was considering that as is much simpler build

  10. #10
    Quote Originally Posted by Blackrat View Post
    doing miter cuts on the gantry frame is going to be a mission, unless you got a very accurate machine to cut at 45 degrees ...

    agree with the rails on the plate ...

    my thoughts :D
    Here is how I did welding before I got those HD clamps - previous design - travel 900x400x150
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