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  1. #61
    Quote Originally Posted by Clive S View Post
    If I am not mistaken
    You're not mistaken :)
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  2. #62
    Thanks for the replies, I also had one from Chai and confirmed the same thing I am actually planning on using the bk12 on both ends so wanted to make sure where the ball screw ended in relation to the placement of the bearing blocks.

  3. #63
    Whilst i am here, this machine will have an adjustable bed, I was wondering what peoples opinons are on a sensible distance between adjustment holes? 50mm 100mm? That is how far the bed moves up and down between one set of holes and the next

  4. #64
    Quote Originally Posted by fvfdrums View Post
    Thanks for the replies, I also had one from Chai and confirmed the same thing I am actually planning on using the bk12 on both ends so wanted to make sure where the ball screw ended in relation to the placement of the bearing blocks.
    There's two reason to use angular contact bearings (bk12) on both ends of the screw. One reason is it increases the axial stiffness of the screw, since you have twice the number of bearings supporting it. The other reason is it raises the critical speed of the screw, so you can spin it faster without it whipping. For the vast majority of DIY builds, the stiffness of the screw is at least an order of magnitude greater than other parts in the axis, so you're unlikely to see a tangible gain from doing so. The critical speed however is important, but for the 1610 screw you've chosen you'll be able to get good feedrates so long as the screw is no longer than 1500mm. According to an earlier post ('1200x900 footprint area with approx 1000 x 800 cutting area'), your machine is well below this length so using two BK supports on each screw will only increase cost with no useful gain.

    (Search on google for 'Ballscrew stiffness calculation' and 'ballscrew critical speed calculator' if you want a reference for the above.)

    Quote Originally Posted by fvfdrums View Post
    Whilst i am here, this machine will have an adjustable bed, I was wondering what peoples opinions are on a sensible distance between adjustment holes? 50mm 100mm? That is how far the bed moves up and down between one set of holes and the next
    It depends on your Z-axis travel. Also no need to have them evenly spaced, why not have more holes nearer the place you expect to be using the bed most often and less at the limits? In the past I've gone for 60mm spaced an 50mm spaced, simply because that what the size of the box section I used. You'll probably only move the bed about once a year anyway! I'm not sure I've even moved mine that often, and the latest machine is so much stronger that it doesn't matter where you put the bed.
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  5. #65
    Hi
    Quote Originally Posted by fvfdrums View Post
    Thanks for the replies, I also had one from Chai and confirmed the same thing I am actually planning on using the bk12 on both ends so wanted to make sure where the ball screw ended in relation to the placement of the bearing blocks.
    Glad to hear that you have restarted your project. So have I and I've just ordered my aluminium plate for it. I noticed that you are going to use BK12/BF12 bearings - I have 2 pairs surplus to my build as I am using FK12 and FF12 instead on the Y and X axis. If you are interested, pm me andwe can come to some arrangement.

    I will be officially opening my build log soon!

    Regards
    Mike Campbell

  6. #66
    Ok, so today started with me making a 5 mile trek with these linear bearings on my shoulders all the way across nottingham becuase the other half has the car and is away for a week and there was no one around to grab a lift from (I know I could have got a taxi but that would have been some of the cnc fund ;) ) Anyway I would not recommend it.

    Having said all that when I finally got back home and inspected the package it was extremely well packaged and I would not hesitate from ordering from FA Systems from ebay again or recommending them. They were extremely easy to deal with even had a bit of negotitations with them for a better deal on price and postage and they arrived in 5 days from Korea. I got stung for a little Import duty but overall it was a great deal.

    The bearings themselves hardly look used, they are well greased and run smoothly up and down the rails which also are mark free so all in all very happy indeed.

    @ Mike - Thanks for the offer but I have just placed an order with Chai so I already have these parts on the way otherwise I would have been in touch. I look forward to seeing your build come together.

    So due to the dimensions of the rails it has meant we have a slightly different sized machine now, its 1130 x 1060 with a cutting area of 940 x 940. The redesign of the machine is going well and even though I would have rather had the original files to work from its bee refreshing to tackle the design from the ground up and incorporate some of the great ideas people have come up with over the last year since I put the original together.
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  7. #67
    More ordering done from overseas!!

    We got a great deal on the motors and drivers so now we have 1 x nema 34 and 2 x nema 23 plus 3 of the 7.8amp drivers coming in the next 5 days or so.

    Also the order from Chai has been processed now and is also enroute so once everything is here and checks out I think its time to get on to Aluminium warehouse and start the gantry build!

    btw: Chai was extremely patient and helpful even pointing some things out I missed and I did not feel the language was a barrier at all. Hopefully what arrives is as good as the service

  8. #68
    Quote Originally Posted by fvfdrums View Post
    btw: Chai was extremely patient and helpful even pointing some things out I missed and I did not feel the language was a barrier at all. Hopefully what arrives is as good as the service
    Chai is a top bloke and he's saved my bacon a few times when ordering stuff because I've forgot to add BK/BF bearings and he's sent them anyway. Suppose that's because he knows I always buy them together but still good to know he's got my back.!!

  9. #69
    Quote Originally Posted by JAZZCNC View Post
    Chai is a top bloke and he's saved my bacon a few times when ordering stuff because I've forgot to add BK/BF bearings and he's sent them anyway. Suppose that's because he knows I always buy them together but still good to know he's got my back.!!
    Ha ha! exactly the same things with me, so concerend with getting the sizes right of the ballscrews that I didnt even put the BK on the order low and behold the quote came back with the relevant number of bearing housings on the list! The guys great

  10. #70
    Another question?

    In peoples experience what is the best size bolts for joining 20mm 6082 plate together in this case for the gantry of the machine? I am thinking of fitting dowel pins in place once the whole assembly is together to aid with reassembly should it need taking apart in the future?

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