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  1. #11
    check your PMs

  2. #12
    Quote Originally Posted by fvfdrums View Post
    I was looking at the prices on there and to be honest by the time I have added up the cost of shipping the lengths I am looking at and added the chance of VAT on top its looks like I could buy the same from Zapp for about 25 more but new (thats based on what they have on their eBay store at the moment) probably better to go new I would have thought.

    I am assuming 4 blocks on the z axis is a must for a machine like this? This was the original plan but i thought i better check.
    Definitely 4 blocks. The problem is you're just looking at buyitnow listing, which are obviously going to be more expensive than waiting and bidding. Via bidding and negotiation my friend and I have got the following:

    Hiwin: New, Two rails and 4 blocks, 15mm*640, 80
    Hiwin: New, Two 15*760mm Two 15*1150mm, 10 blocks, 360

    THK: New, Two rails and 4 blocks, 25mm*760mm, 100
    THK: Used, Two rails and 4 blocks, 25mm*300mm, 80

    ...etc, you just have to be patient and I need to stop buying them all!

    All of those prices are significantly less than the eBay listing linked to in post #7... than one isn't a good deal.

    I still want to get two 2120mm rails for my X-axis, but ones that long don't come up very often at all and postage is of course very expensive.
    Last edited by Jonathan; 28-10-2012 at 06:36 PM. Reason: Typo infestation
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  3. #13
    Quote Originally Posted by Jonathan View Post
    Hiwin: New, Two rails and 4 blocks, 15mm*640, 80
    Hiwin: New, Two 15*760mmw Two 15*1150mm, 10 blocks, 360
    Probably Stolen goods. . Lol

  4. #14
    Forgot to mention, those are all rails/blocks with 4 rows of balls which is what you want since their load rating is equal in all directions and the moment load is greater. Two rows is still fine if they're quite big and clearly still far superior to supported round rails.

    Quote Originally Posted by JAZZCNC View Post
    Probably Stolen goods. . Lol
    I better keep them locked up else they will be!
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  5. #15
    Quote Originally Posted by Jonathan View Post
    Forgot to mention, those are all rails/blocks with 4 rows of balls which is what you want since their load rating is equal in all directions and the moment load is greater. Two rows is still fine if they're quite big and clearly still far superior to supported round rails.
    I very rarely see 2 row bearings for sale.! Where do you see them.?

    Quote Originally Posted by Jonathan View Post
    I better keep them locked up else they will be!
    Better still get them working and earning there keep.!!

  6. #16
    I found them to be a good seller. About 3 weeks to arrive and reasonably packaged in a thick cardboard board with lots of bubble wrap. Would buy again if building another machine (!). My parts were clean and ready to use.

    For info I see alot of machines using supported rail on the Z axis and whilst there is nothing wrong with that I would recommend new builders (or upgraders) to have a look at these used profile rails. Putting aside all the advantages of profile rail, their compact size makes for a neat installation in an area of the machine that benefits from compactness. And these short lengths (typically 300mm in a 15mm width) make it good value at about 80 all in.

    I know what you are saying about the longer lengths. For my X axis (1300mm) I went with new supported rail from linearmotionbearings2008 (ebay).

    Since the Z axis always has an unavoidable overhang I would personally go for 4 blocks.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  7. #17
    Ok I'm going with profile rails on all x,y & z 4 blocks on each rail.

    My thoughts are going towards a low level gantry eg minimum deflection in relation to the x axis with the adjustability of the bed. I have access to a fair bit of 100mmx100mm off cuts and was thinking of using this as the base for the machine. Would this be too extreme for the gantry?

  8. #18
    Quote Originally Posted by fvfdrums View Post
    My thoughts are going towards a low level gantry eg minimum deflection in relation to the x axis with the adjustability of the bed. I have access to a fair bit of 100mmx100mm off cuts and was thinking of using this as the base for the machine. Would this be too extreme for the gantry?
    Excellent. Nothing's too extreme. The worst that will happen is you might need bigger motors, or have to accept lower feedrates (which is irrelevant for aluminium cutting). Design the machine then select the electrics to suit. Don't start trying to make things lighter to optimise the feedrate since a rigid slower machine is much better than a fast weak one.
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  9. #19
    Quote Originally Posted by Jonathan View Post
    Excellent. Nothing's too extreme.
    Quote Originally Posted by Jonathan View Post
    Design the machine then select the electrics to suit.
    Completely 100% agree on both counts. . . . If you then filled it with concrete you still wouldn't be extreme, Infact if you mainly intend cutting Aluminium I recommend you do exactly that has it makes a big difference to resonance and quality of finish.!!

  10. #20
    Right I have had an hour to play in solidworks so this is not very detailed its just an outline of the idea I am thinking of once I have ironed out any potential problems I will go in a bit more detail.

    So once again 1200mm x 800mm bed current z axis 200mm ? good bad ugly?

    z axis is based on 4 blocks sitting on a 200mm square footprint eg one on each corner of a 200mm square.

    Adjustable bed for altering depths of material / things to machine.

    twin ballscrew on the x axis, single on the y and z

    concrete/ sand etc in the box section taken on board I will give that a go.

    Click image for larger version. 

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