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  1. #71
    The flat bar was as well as sort of taps are spiral flute a load on ebay from China they're cheap as chips. Most taps are made for steel, even the cheap black spur ones they sell in pound shops. If you've a good printer, a decent centre punch and a hand drill you can make a decent gantry. Sure a mill helps but ultimately care and attention to details and hand tools are enough if that's all you've got and you want to make a CNC router ;)

    Sent from my Galaxy S5


  2. #72
    Anyone got a SW file for the bit of a ballscrew that is bolted to the gantry? 16mm...I googled the dimension to make one myself but each picture seems to show slightly different dimensions...Why arent all thee bits generic across the board -.-

  3. #73
    Its not that milling would be a problem, My taid (Wlesh for grandfather) has a workshop for model engineering...he builds those little steam engine that pull 20 people... Also I dont mind getting a few parts done on a laser either... my budget can go up a couple hundred which i can use some for parts to be made...allot of company quotes to come haha. If they all turb out to be stupid in price then ill do it myself.

  4. #74
    Quote Originally Posted by FlyHighRC View Post
    When the epoxy is applied to the steel and sets, to bolt on the rail im assuming you just drill and tap? otherwise that must be a very fiddly job getting all them nuts down there haha
    I used 5mm box section and drilled and tapped through the epoxy post 6 here:- is the epoxy being poured. Eddycurrent has used a similar system but he glued a flat plate with gorilla glue inside the box section to give more of a bite for the threads. ..Clive

  5. #75
    Quote Originally Posted by FlyHighRC View Post
    .. How far should i keep the bearing carriages apart? ..
    With a single ballscrew in the centre then racking becomes a problem whereby the gantry can rotate or twist if you are cutting anything towards the edge of the gantry. To minimise this you can space out the bearings further, but there is a compromise on travel.

    With twin ballscrews all these problems go away, which is why it is highly recommended. The gantry cannot rack as a ballscrew holds it at each end. Your considerations then come down to placing the bearings so that the centre of gravity of the gantry (which will be somewhere behind the spindle centre line) and the cutting tool centre line both lie within the region between each bearing, as viewed from the side. If you need to deviate from these positions then don't worry as the profile linear bearings will take quite a load.

    As I guide I would say between 100-200mm is about right, probably going closer the 200mm end of the range, giving you maximum travel.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  6. #76
    for a good machine what is recommended, A router or spindle? cant see any bvious advantage or disadvantages to either... Yet to see anyone give a preference on any of the build logs

  7. #77
    Also bear in mind that the deflection of the axis, due to the linear bearings, for a given cutting force is inversely proportional to the square of the bearing spacing. A relatively small increase in the spacing you choose can therefore make a big difference, assuming the stiffness of the system isn't dominated by another weaker part. The reason for this is that the force on each bearing decreases with their spacing and the deflection of the tool also decreases for a given bearing deflection if their spacing is increased, so overall you get a quadratic relationship.

    Quote Originally Posted by FlyHighRC View Post
    for a good machine what is recommended, A router or spindle? cant see any bvious advantage or disadvantages to either... Yet to see anyone give a preference on any of the build logs
    Simple answer is get a proper spindle. But please read the build logs more - people have already linked to some good ones in this thread, yet all the questions you've asked so far are already answered in the logs.
    Last edited by Jonathan; 06-06-2014 at 10:01 AM.
    Old router build log here. New router build log here. Lathe build log here.
    Electric motorbike project here.

  8. #78
    Quote Originally Posted by FlyHighRC View Post
    for a good machine what is recommended, A router or spindle? cant see any bvious advantage or disadvantages to either... Yet to see anyone give a preference on any of the build logs
    I don't think you will find many routers on here being used. They are very noisy. The popular spindle is the 2.2Kw water cooled they run very quiet and will run at speeds up to 24,000 rpm. ..Clive

  9. #79
    So I have nearly completed the first draft of my design, Im very comfortable with being able to make this machine with the tools and equipment I have access too. The gantry im happy with and the way in which the gantry is mounted to the rails. Im also happy with the location of the rails, steppers and mounts etc... the ball screw support blocks have yet to be mounted to a plate(next job) then onto the z axis :)

    The frame is mostly 60x60x3mm box section with the gantries vertical section and support section being 40x40x5mm, Hopefully you guys approve this which case I start my budget plan to make sure it can be built within my budget. Then progress to the parts list and DXF files for the laser cut stepper mounts and then go from there :)

    Added some colour to give it a bit of life...

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  10. #80
    OK Mike, sorry I'm going to be blunt here. Jazz has said to go through the build logs as have myself, Jonathan and the others I still think you need to go back and do some reading as the design you have put here has been done before (or designs nearly identical to this one) and commented on.

    Again being blunt:

    Quote Originally Posted by FlyHighRC View Post
    Do you have a link to these linear rails?

    I dont know much about CNC but i know how to incorprate strength into a design. If there is one thing Im good at its designing...dont get me wrong...i have seen builds on this forum which to me seem fine but people who have been there and done that have pointed out aspcts of designs that didnt show up to me...but all their critisims and expertise has been written down on my Pukkapad to bear in mind when designing my machine, which will be posted so others can tell me what needs improvong and whats ok etc etc.

    Really appreciate the help :)
    The design you posted is anything but strong...people will have pointed out things in other builds which to you don't show up because they have experience of building the machines, normally by making the same mistakes and regretting it. My brief comments on "first draft"

    • Bed does not have enough support and will vibrate and bounce giving poor finish.
    • X axis bearing mount to gantry is too thin and flexible.
    • Mount the steppers with belts to reduce resonance, not essential but preferable.
    • Gantry has no bracing or support so will bend/bounce/twist giving poor finish.
    • 40x40 box (for the gantry) isn't strong enough as Jazz said before.

    The above assumes that you will be cutting some aluminium at some stage.

    Sorry my reply might come accross as being unfriendly and harsh but I can see you going down a route as Jazz said that will leave you dissapointed if you're not careful and if you're not careful you'll waste money prodcing a machine that won't cut what you want to cut.


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