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  1. Exactly right John.. the issue, George, is that you are not applying engineering pragmatism and and element of real-world experience to the problem. A really hot stepper gets to 80degC max.. but is easily able to radiate that heat... your heat gun is easily 3 - 4 times hotter then that and is heating the air around the test piece too, so your test isnt representative... apart from the points John makes

  2. #12
    ecat's Avatar
    Location unknown. Last Activity: 08-02-2014 Has been a member for 6-7 years. Has a total post count of 157. Received thanks 5 times, giving thanks to others 8 times.
    Firstly, temperature (kinetic energy) does not equal heat (the transfer of energy). A stepper motor generates X watts of energy ( J/s ), the heat gun generates Y watts. X is probably less than 100w (?). Y is probably in excess of 1kw.

    Secondly, I look at these mounts as a metal studded rod mount with MDF spacers, the metal rods (in tension?) provide a lot of stability, the MDF (in compression?) doesn't really have any where to expand into.

    Third, the shaft coupler should take up any small variation.

    Feel free to correct any of this, as if an invitation was required lol.

  3. #13
    Tom's Avatar
    Location unknown. Last Activity: 30-11-2016 Has been a member for 7-8 years. Has a total post count of 172. Referred 1 members to the community.
    Small print:

    * attack by paint stripping gun may degrade performance.
    * attack by paint stripping gun may not degrade performance.
    * may contain nuts.

    Thanks for the interest everyone! lol
    Any suggestions from people who need other MDF bits made? Send me a PM. (Suggester / first user / beta tester gets their parts for free....)(within reason).
    Last edited by Tom; 08-08-2010 at 02:17 PM. Reason: spelling

  4. #14
    i think most people know that if they build a machine out of MDF it`s not going to be 100% accurate

  5. #15
    Secondly, I look at these mounts as a metal studded rod mount with MDF spacers, the metal rods (in tension?) provide a lot of stability, the MDF (in compression?) doesn't really have any where to expand into.
    Correct, which begs the question is all that mdf needed? I would have just used the front and back plates and then spacer tubes on the threaded bar. But as John said, I think analysing MDF to this degree is unnecessary as it will typically be a first build.

  6. #16
    Hi Tom,
    Nice little units - and love the small print, made me chuckle. Some people eh?

    Personally I would use plywood, just because I don't like MDF dust, but the concept is sound. My first machine did use 4 spacer tubes as Ross suggested, but if you have limited hand tools it can be tricky to cut 4 tubes exactly the same length. There are ways of course, but the spacers guarantee a pretty square mounting surface.

    George,
    Think, then type, not the other way around .
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  7. #17
    Tom's Avatar
    Location unknown. Last Activity: 30-11-2016 Has been a member for 7-8 years. Has a total post count of 172. Referred 1 members to the community.
    Quote Originally Posted by Ross77 View Post
    .... is all that mdf needed?
    I really like the design process. Now you mention it Ross, it probably isn't. I like bolting through a wide face of MDF because it adds plenty of torsional stiffness, but there probably isn't the need for 3 closed sides. If I made the spacers separate (2 on each layer) it'd save some raw material, a tiny bit of cutting time, and some weight. Mk3 on the way... :)

    Thanks for the complement Barry...

  8. #18
    I like the closed sides it gives stiffness, the problem with spacers is that there is no torsional stiffness and it looks like grandads mantlepiece clock.
    John S -

  9. #19
    Hi Tom
    My coment wasnt a dig at your design and is more a reflection on my bad posting, I was meaning it as a way to reduce any expansion in the mdf due to paint striping gun :heehee:

  10. #20
    Tom's Avatar
    Location unknown. Last Activity: 30-11-2016 Has been a member for 7-8 years. Has a total post count of 172. Referred 1 members to the community.
    I appreciate the comments, Ross - all positive input! On balance though, I think laziness wins (I can always say it's for improved torsional rigidity, a-la-John S)(I don't like mantelpiece clocks either).

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