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  1. #1
    Hello All.
    I'm certainly learning a lot as I read through the posts so thank you very much to the people that answer the questions but also ask the questions that I don't even know I want to ask.

    I have come up with my design in sketch Up after finding I can't yet work out Autocad 3d (Although I guess it will come along as I progress)

    I haven't as yet finalised my design but thought I would just see if you guys think that I am on the correct approach for my needs

    I was a little silly and bought the rails and screws as a kit but i'm happy with the quality of everything I would have probably gone larger but it has its own problems so i'm going to use what I have.

    at the moment the design is to use 50x50 Box section with the option of using 100x100 as the top for the rails and the screw next to each other. but I'm not sure whether I really need this ?

    The bed is movable for creating a movable table for other things than sheet material and mould making. but I have capped the ends to that I don't have to use the bed as strength as much. It could be an issues if I put long material in but think I'm OK.

    I'm using SBR20 rails for everything and SFU1605 screws all round

    The project plan is to be able to cut a range of materials from Perspex , Wood & Aluminium, I also want the ability to end mill which is why the rails go right to the front of the machine giving the option to clamp to the frame but still working on that.

    The plan is to use a 2.2kw Water cooling system and haven't really though what electronics to go fo as yet but thought I would see the weight of the machine first.

    I think Sand in the box section is likely to dampen down any vibrations

    I have made the gantry wider than the rails because I didn't think when I ordered the rails that I would be loosing some for the actual plates (Which is why I would have gone bigger)

    The rails are 1100mm x 600mm x 280

    I have put a design that I think I'm on the right road with but before I get too far thought I would ask you kind people if I am in the right road or if things should be changed ?

    I thought I would put this as a build log because it will turn into one sooner or later anyway.

    Thanks for looking

    Rob Grain
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  2. #2
    I have though Mounting of the rail mounts on a 10mm Steel plate that is tig welded to the box section (Maybe Bolted for a little movement) ? and this way I can have the actual frame as wide as I like but just the cutting will then still be the same but this way I could put larger material on the frame and move it around if I ever wanted to e.g for cabinet doors at the moment I thing I would struggle to fit it on. and yes it is all because I bought before I thought ( I might use that saying again I like it)

    I am still unsure if putting the gantry SBR20 rails would be the strongest design for the top and bottom or both on the front, or maybe have the one rail at the top and then the lower rails on the front.

    I am really sorry I haven't used the X,Y,Z because I think I get it wrong when I say it, I thing Y is the movement of the whole gantry and the X is the movement of the across axis e.g. moving of the spindle left and right and I know I get the z Right 1 out of 3

    If someone could confirm this or tell me I'm and idiot and have it wrong that would be much appreciated.

    I have chosen the have a sliding Bolt through for the bed in the middle with a bracket tig'd on the box section and then I can bolt through to give extra strength but then at the ends just go through the actual box section of the base although I'm not sure if this will take away a lot of strength from the base.
    also I though I would be best to mount the screw blocks on the outside of the gantry to stop dirt getting into the screw. there will be screws on each side to stop any problems however I am currently leaning to using 2 motors and not a timing belt but you might tell me differently.

    Any comments would be very much appreciated

    thanks for looking through and listening to my ramblings

    Rob Grain

  3. #3
    Take a look at this diagram, you can see that in your design the spindle would hang out from the gantry well past the bearing blocks.


    It's usually regarded as X being the rails mounted on the frame, Y being the rails mounted on the gantry, Z where the spindle mounts.
    Two motors on X works fine, just remember you would then need to, rate your power supply accordingly, purchase another stepper driver, add 2 home switches. It's generally regarded as advantagous to connect the motor to the ball screws using timing belts, the pulley sizes can also be selected to increase or decrease speed so that your stepper motor is working in it's optimum range while the cutting speeds are also optimum.
    You might need this as you indicate 1605 screws all round, I'm using 1610 on X and Y which seems right using 1:1 ratio of pulley
    Last edited by EddyCurrent; 25-09-2014 at 05:15 PM.
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

  4. #4
    Rob Welcome to the forum. Please don't buy anymore kit until you have your design finished its the biggest mistake people make. Ask as many questions as you can (a few at a time is better) and expect a bit of leg pulling but you will get all the advise you need on here.
    There are generally two ways to drive the x screws either with one motor and a belt going to the other screw or using two motors one for each screw, there are for's and against both system. But they both function ok.
    You will need more bracing of the frame that what you have. ..Clive
    Last edited by Clive S; 25-09-2014 at 05:53 PM.

  5. #5
    Thanks guys for that, I have put the spindle so that it will go past the frame so that I can cut on the end of material for letting on the sides of work, Although I suppose I am stopping me from being able to cut sheet as long as I would otherwise be able too. I have thought about moving the rails back a little and then making a clamp so that I could lamp it to the internal 'Y' support beam.

    I thought I might be under building on the supports. Because I am going through the centre vertical beam I will have to have a change to get the support in. would it be best to brace from corner to corner or is it as strong if I triangle off the corners

    I seem to buy the stuff and then learn and I have after many years started to come out of that routine things always work out but always a more difficult path and more stuff for the spares box.

  6. #6
    Hello I have been doing a spot of re-design for the bracing Hopefully I haven't gone the other way with it now. I was trying to use a little less steel to keep the cost down but I would certainly rather have a stronger machine.

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  7. You don't need cross bracing at the ends, a single diagonal will suffice, run it in the opposite direction at the far end. One in the middle might be beneficial too.
    Last edited by irving2008; 27-09-2014 at 06:33 AM.

  8. #8
    Hey Irving2008 great thanks for that. I have made the change I haven't as yet put the middle support in, which I'm guessing that you mean through the centre of the base ?

    that will be handy too im so close to being able to use x3 7.5 metre lengths so hopefully if I don't mess up cuts and welds I might get away with it. (So we all know I wont and will need more )

    I'm leaning more to the timing belt option because it give me more options on configuration but I'm not sure How I will do that as yet.

    Thanks very much for the advice so far it is really appreciated.


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  9. #9
    If you put a brace in the centre you lose the ability to have a movable bed. ..Clive

  10. #10
    There's loads you could shave off this structure most those bits at the bottom are not needed. Something along the lines of this but narrowed down will work. You'll use less steel and still be plenty strong.
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