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  1. #1
    Hi everyone, after lurking on here for a short while, its time to bite the bullet and get something done about it.

    My initial thoughts are to use mdf to make up the framework. Then once I have worked out all the sizes, got it working, made mistakes, and fixed them, I'll stiffen it all up by repalcing the mdf with aluminium/steel plate.

    Ideally I want it to be able to cut softwoods, plastics and maybe rarely aluminium. With a bed size of around 700 x 700 x 100.

    My first ideas were to use supported rails on X and Y with round rail on Z. Im also torn between leadscrews or ballscrews. Is the extra cash worth it?

    Im not after anything that can cut in miles/min, but I also dont think the neighbours will appreciate it being run 24hrs a day.

    Not thought about the electrics/motion side of it yet, any advice would be greatly appreciated.

    This weekend's task is to come up with a design as a starting point. Im quite lucky to have access to solidworks (albeit only basic knowledge).


  2. #2
    The best and cheapest way to, "work out all the sizes", is to use Sketchup (or Solidworks if you have it) then you can go right to the metal. If you've had a good read on this forum you will see that it's supported or profile rail all round and ball screws. Obviously there are MDF machines with all sorts of arrangements out there and they seem to work but also they are inaccurate, slow, and can't cut much of anything with a decent depth of cut.
    Personally I don't have time to waste and neither should anyone else so just go for the right stuff from the outset.
    Oh and welcome to the forum.
    Last edited by EddyCurrent; 06-03-2014 at 09:31 PM.
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

  3. #3
    Eddy thanks for the vote of confidence, I think I might have those first cut worries. I've never made anything on this scale before.

    Is there such a thing as a 'plug and play' electricals available? Im quite mechanically minded but not electrically.

  4. #4
    To be honest not many of us have done anything like this before thats why a forum like this is important as it allows questions and answers to be posted.
    Bite the bullet.

  5. #5
    Eddy's correct about MDF it's false economy and while yes it may seem good for learning but reality is it's not that much harder to build one in steel and the learning is just the same but without all the hassle you'll have chasing accurecy and flex etc.

    Electrics are easy really and with a little guidance you'll do it no problem so don't be afraid. There are a few products out there that make it easier depending on the size of the machine but I won't mention them yet as your many steps away from that yet and it will only serve to cloud the vision.
    When the time comes we'll help you choose the correct electrics and guide on how to wire etc but first you need to start with the design style and size plus materials it will be built from. Then other things like linear motion components ie ballscrews, rails etc can be decided then from this lot the electrics can be choosen.

    So first step design or Nick some others design then go from there.!!. . . . . . Ask anything your unsure about, no matter how silly you think it may sound ask rather than be unclear and get it wrong.

    Good luck.
    Last edited by JAZZCNC; 07-03-2014 at 04:32 PM.

  6. #6
    Just a quick one for anyone, I presume the bf12 can go either way round, but which way does the bk12 go?

  7. #7
    Can go either way but like this is most common. Click image for larger version. 

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    Quote Originally Posted by qwertyjon View Post
    Just a quick one for anyone, I presume the bf12 can go either way round, but which way does the bk12 go?

  8. #8
    Funny you should say that, here's my recent findings about the similar FK12
    Spelling mistakes are not intentional, I only seem to see them some time after I've posted

  9. #9
    Quote Originally Posted by EddyCurrent View Post
    Funny you should say that, here's my recent findings about the similar FK12
    FK bearings are slightly differant but same applies they can go both ways around. Then only thing with FK is that you can only use one side of the flange but which way it fits on the screw doesn't matter.
    When I've fitted them I've always found it best to fit the flange to outside of bracket or plate holding then this way it makes removing screw easier.
    If you put it on inside it's trapped and makes removing harder and means taking brackets or plates off to remove which then means you have to realign again when replacing. Where if you machine brackets accurate so nice fit for bearing then removing screw for what ever reason is simple and goes back in same place without disturbing anything.! . . . . If that makes sense.??
    Last edited by JAZZCNC; 08-03-2014 at 10:13 PM.

  10. #10
    As promised, I've been working on my design. I've decided to go slightly larger as it works out at only a few more. So overall size is nearer 1100x1100mm now.

    Can anyone point out any obvious faults before I carry on? I've designed it with twin X ballscrews, probably going to be belt driven. I'll apologise now that the screws, don't look like screws. And I've not worked out the Z axis yet. Hopefully its a good starting point though.

    The base runs on 20mm supported rail, and the gantry on 16mm. The brackets that I will need to make are out of 12mm aluminium. Will that be strong enough?
    Click image for larger version. 

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    Click image for larger version. 

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