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  1. #1
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 2 Hours Ago Has been a member for 9-10 years. Has a total post count of 1,839. Received thanks 192 times, giving thanks to others 5 times.
    After much weighing up the pro/cons of going the mill conversion or router from scratch route, I've pretty much decided a well made router is the way to go for now.

    I want at least 300mm x 300mm work area, with enough height to add a 4th axis at some point in the future. Main initial use will be plastic, but I want good aluminium capability for some future items, so designed to allow use of coolant i.e. rails/screws well protected from anything on the table.

    So, current notepad doodles have come up with the following.

    X-axis has about 400mm travel, with 200mm wide gantry sides.
    Y-axis has about 350mm travel, with a 150mm wide/200mm high Z-axis mounting plate.
    Z-axis has about 200mm travel, with bearing rails on spindle mount plate.

    As I'd like to use profile rails, the main construction will be Alu plate and extrusion.
    The main table will be U-shaped with open ends. X-axis rails will be mounted on the outside along with the twin ballscrews to give maximum protection. I'll probably go for twin steppers, as it's far simpler from a design/build point especially since I'd like to keep the ends clear.

    Height from table to gantry I've currently got as 200mm, but I may drop this to 150mm once I consider 4th axis options.

    Current plans are 20mm profile rails for all axis, along with 1605 ballscrews.
    I've priced the bits from Zapp to get an idea of costs, but need to explore the other options.

    As for the sides, I'm not sure whether to go for 15mm or 20mm thick plate. Price wise there's not too much difference, but will there be much difference in stiffness?


    I'll try and get some time this week to get some drawings done in Sketchup.

  2. #2
    As for the sides, I'm not sure whether to go for 15mm or 20mm thick plate. Price wise there's not too much difference, but will there be much difference in stiffness?
    the gantry sideds?.... 20mm! even if the flex isnt much better the added weigh will help dampen resonance
    im convinced every single bit of weight and stiffness you can get will earn its keep over and over
    i guess the weight has to be watched if you want good acceleration but id go for quality of cut over speed if i had a choice

  3. #3
    Want to cut aluminium? FWIW could I suggest a different way to make the machine?

    Start with a good solid base, a couple of thicknesses of beech worktop sounds good. That's your anti-vibration inertial lump.

    Put an aluminium plate, side to side, across the middle. About 8" wide sounds good. It's only a washer so it doesn't have to be too thick.

    Bolt the gantry to the plate and base. Butress it. Get a good solid Y axis.

    Bolt profile rail blocks facing upwards on the plate to hold 2 rails 8" apart. Screw the rails to the bottom of a 12 x 20 bed plate. You now have a good solid X axis. Your cutter will never be more than 4" from 2 carriage blocks in Y and 4 carriages in X.

    Because the X bearings are only 8" apart you can use one screw up the middle, it isn't going to twist. Don't make life difficult trying to drive 2 motors together.

    Make the sides of the gantry too tall so you can move the whole Y,Z assembly up when you come to do your 4th axis.
    I'm expecting to be told I am out of my tiny mind, let's see what they can come up with

  4. #4
    Quote Originally Posted by Robin Hewitt View Post
    I'm expecting to be told I am out of my tiny mind, let's see what they can come up with
    Your out of your tiny Mind. .

    No seriously I see where your coming from robin with this size machine but SORRY can't agree on the choice of material for the base and foundation of the machine.?
    A living and breathing material like wood is not a good idea for the foundation of machine IMO.

    The rest I can agree with on this size machine.

    I'd say make it a fixed gantry if you want it strong and have the space.!

  5. #5
    Quote Originally Posted by JAZZCNC View Post
    can't agree on the choice of material for the base and foundation of the machine.?
    A living and breathing material like wood is not a good idea for the foundation of machine IMO.
    But beech is so much more acceptable for her indoors than the bloke alternatives.
    It just wants a good solid lump connected intimately to the workings

  6. #6
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 2 Hours Ago Has been a member for 9-10 years. Has a total post count of 1,839. Received thanks 192 times, giving thanks to others 5 times.
    mmm...never thought about going fixed gantry. Biggest issue I can see with that is if I do end up running coolant. I know misting is an option, but flooding is easier to contain.

    Adjustable height gantry could be possible, but I'd probably just leave it at whatever height it would need to get a 4th axis, so wouldn't really be any benefit.

  7. #7
    It was only a concept suggestion, it's your machine, make it any way you want

    I don't quite see how a fixed gantry precludes flood coolant though, doesn't it make it easier?

  8. #8
    Quote Originally Posted by m_c View Post
    mmm...never thought about going fixed gantry. Biggest issue I can see with that is if I do end up running coolant. I know misting is an option, but flooding is easier to contain.

    Adjustable height gantry could be possible, but I'd probably just leave it at whatever height it would need to get a 4th axis, so wouldn't really be any benefit.
    Nah the fixed bed doesn't make it any harder to have coolant, It's just the same has a milling machine but with the bed moving in only one Axis and the column becoming the 2 fixed gantry sides. Just sit the whole thing in a collection tray or metal enclosure.?

    I prefer blown mist cooling for aluminium anyway. Flood is ok if it's proper massive flood but you can't see what's going off where has with mist you see every thing and the cutter is mostly chip free so not re-cutting.
    Not saying it's better than Flood just it's my pref unless real big flood so all chips are washed away and this can get very messy so enclosure very much needed.!!
    Last edited by JAZZCNC; 10-09-2012 at 06:32 PM.

  9. #9
    Quote Originally Posted by JAZZCNC View Post
    Just sit the whole thing in a collection tray or metal enclosure.?
    Maybe m_c doesn't have the space required for the bigger enclosure required to accommodate a moving bed machine? I think the inconvenience of having a large enclosure is negligible compared to the advantages of having a fixed gantry.
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  10. #10
    Quote Originally Posted by Jonathan View Post
    Maybe m_c doesn't have the space required for the bigger enclosure required to accommodate a moving bed machine? I think the inconvenience of having a large enclosure is negligible compared to the advantages of having a fixed gantry.
    Possibly but that still doesn't make having flood cooling harder on a fixed gantry and that was the point.! . . . Plus the tray wouldn't need any more space than the machine requires anyway.!

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