1. #1
    I am trying to think out the box here so that I can move away from using steel for the frame. Having read a fair bit, I have concluded that steel is far from ideal for cnc rails due to the following.

    1. Resonance
    2. Thermal stability

    As a result I have looked at casting the rails using epoxy granite and reinforced plastic beams. Both of which will have excellent damping. I am waiting on the tech literature for the recycled plastic beams as I am not sure what the thermal stability of them is.

    http://www.lankhorst.co.uk/hst/l18a1...K?open&lang=UK

    Interested to hear your thoughts on this.

    Thanks

  2. #2
    As a result I have looked at casting the rails using epoxy granite and reinforced plastic beams
    im assuming when you say "rails" you mean the frame or rail beds ?

    i like the idea of epoxy granite, i dont like the idea of casting around the plastic I beams.... if your going to the trouble of casting a base anyway why go to the bother of using the I beams..... if its about keeping the "volume to weight" ratio down id be tempted to just cast around foam or polystyrene blocks
    Last edited by blackburn mark; 19-10-2011 at 11:14 AM.

  3. #3
    Quote Originally Posted by blackburn mark View Post
    im assuming when you say "rails" you mean the frame or rail beds ?

    i like the idea of epoxy granite, i dont like the idea of casting around the plastic I beams.... if your going to the trouble of casting a base anyway why go to the bother of using the I beams..... if its about keeping the "volume to weight" ratio down id be tempted to just cast around foam or polystyrene blocks
    Sorry, but having reread my post it was not very clear. I was thinking of

    a) casting the rails using epoxy granite

    b) using the plastic i beams for rails

    Both a and b would then have a 50mm * 40mm machined aluminium section attached which has been precision milled to hold the linear guide rails.

    The other option and I would love to explore it, would be to make the rails using composite materials. eg foam which has been layered with carbon. Carbon is super stiff and I suspect you would end up with a very stiff and light rail ?

    Thanks

  4. #4
    The plastic beams you are referring to in that link is the same thing as plastic decking. Have a look here
    http://www.ebay.co.uk/itm/Recycled-s...item5adfe7aa65

    This stuff still flexes but good over short lengths. Might give some a try myself.
    If the nagging gets really bad......Get a bigger shed:naughty:

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