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Type: Posts; User: CaptainVee

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  1. Replies
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    Re: Mold release + EG + vibration => problems?

    I have done a few molds using mdf with only wax.
    These released very well but I have only done smaller parts, that are not cast but molded in to place using drier mixes.

    But I think that the...
  2. Re: Epoxy-Granite machine bases (was Polymer concrete frame?)

    Keep in mind that epoxy percentage by weight can be deceiving.

    A 4% mix by weight with 2 mm aggregate will be covered with a layer epoxy roughly half the thickness compared to a 4 mm aggregate.
    ...
  3. Replies
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    Re: Passivating Stainless Citric or Nitric

    Question is 10 years old and counting, I found it in researching the topic.

    So far I found that citric acid is often better.
    Requires 4% solution, between 70 and 160 dgr F and more than 120...
  4. This was before opening any gcode, just opening...

    This was before opening any gcode, just opening the .py file of gcoderipper.
  5. Re: G-Code Ripper - Scale, Rotate and Split G-code

    I thought to give gcode ripper a try but I get this error:

    ERROR EXP-3: Unable to evaluate expression: [/2]

    For all the versions listed on your website.
    In this case on a virtual machine with...
  6. Replies
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    2,683

    Re: building large CNC on budget

    If you cannot provide details of what you are in need of accomplishing, I will not provide ideas.
  7. Replies
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    2,683

    Re: building large CNC on budget

    1: Don't
    2: There are good cnc machines and cheap cnc machines. There are no good and cheap cnc machines.
    3: What may help if you are very, very technical, both on the software side and the...
  8. Re: Has anyone seen these anodizing blemishes before?

    If these lines were more across rather than straight I'd have to say yes.

    I had black lines appearing on uncolored anodisation.

    I think what happened then was that I got a bit of material (10...
  9. Replies
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    56,594

    Re: Large Epoxy Granite Vertical CNC Mill

    This guy knew what he was doing and he had the right kind of epoxy.
    And lets be clear, to get this kind of curve the shrinkage is absolutely minute.

    All this means is that there is some...
  10. Replies
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    56,594

    Re: Large Epoxy Granite Vertical CNC Mill

    Indeed, polyester shrinks.
    So does epoxy, but by very tiny amounts.
    A friend of mine built a EG gantry with steel on one side to later connect the rails to.

    Even with setting up the cast on a...
  11. Replies
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    Re: Epoxy granite in metal frame.

    It seems to me there is a bit of a mix-up in theories here.

    - You can add EG to a steel frame. That will increase stiffness and it will reduce the amplitude of vibrations. It will probably also...
  12. Replies
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    Re: Importance of ball screw pitch size

    I wrote what I think is right because of the second part of your post.
  13. Replies
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    8,322

    Re: Importance of ball screw pitch size

    Unless you are a super experienced metal worker when you start the first cnc, I think no one will notice the difference in resolution when you choose 16 mm pitch over 5 mm pitch.

    But you will...
  14. Replies
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    9,392

    Re: Large Format 5-Axis Gantry Router

    Ah, hadn't thought of that one, good one. So you put the glass on the outside then?

    Another thing, did you plan for some kind of straightening the surfaces for the linear rails?
  15. Replies
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    9,392

    Re: Large Format 5-Axis Gantry Router

    In reading through this post again, what is the point of using glass AND carbon fiber in the gantry?
  16. Replies
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    9,392

    Re: Large Format 5-Axis Gantry Router

    That surly is an ambitious build, especially for a first machine!

    Do you work in composites? Both the machine and method of construction suggest so.

    I look forward to its completion.
  17. Replies
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    Re: My carbon fiber CNC Gantry

    This video is about completely irrelevant to the cnc discussion. Or do you plan to make your own ballscrews from large diameter carbon fiber?
    The reason why CF is used for drive shafts is that...
  18. Re: Epoxy Granite In Practice (Mineral Casting, Polymer Concrete)

    From what you write you seem way more experienced in releasing epoxy than I am.

    But me being crytical is not about the release agent.

    "the easiest parts to release are from flat smooth surfaces...
  19. Re: Epoxy Granite In Practice (Mineral Casting, Polymer Concrete)

    Forgive me for being critical but do you actually release cast epoxy granite from surface plates?

    But very good info nevertheless, thanks!
  20. Re: Epoxy Granite In Practice (Mineral Casting, Polymer Concrete)

    I would never (as in NEVER, EVER) cast EG on a surface plate directly without having someone next to me, looking me in the eye and telling me he has actually done that and was able to release, no...
  21. Replies
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    Re: Why aren't portal mills more popular?

    With this design you introduce some overcomplication.

    To get the z-axis go up and down straight you need to get the gantry square to the bed and before that you need to get the cariage vor the...
  22. Replies
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    Re: Vacuum matting in Oz?

    If you mill pcb's you do not put any force on the work piece.
    If you want to do serious work with a vacuum table PE is useless, as is a single hole for bigger work pieces.

    The hole point (pun...
  23. Replies
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    Re: Techno Vacuum Table Help

    That suggests that the location on the table does not make a difference.

    I find vacuum tables a bit of black magic.
    But the basics are quite simple:

    There is an absolute maximum of clamping...
  24. Replies
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    8,723

    Re: Techno Vacuum Table Help

    Is the plywood not totally flat then?
    What happens when you turn the sheet 180 degrees?
  25. Re: I need advice on this design. EG mill head with spindle.

    Can you explain?
    This is the first time I read that you can dampen machine vibrations with light weight foam
  26. Replies
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    Re: Underwater machining ?

    I seem to remember that grease attracts diamond, as in, olive oil is used to coat cutting wheels for diamond so that the diamond dust adheres to the wheel.

    I think that using oily compound as a...
  27. Replies
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    Re: Levelling CNC Work Area

    If the rails are not flat/straight, the work area, and the result will never be flat either.
  28. Replies
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    Re: All aluminium 1250x1250x250 router

    With help from Dabit, I have added the 4th axis:

    http://www.cnczone.com/forums/attachment.php?attachmentid=359146&stc=1

    12 Nm closed loop stepper at 230 volt, running as lathe as well as for...
  29. Replies
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    Re: Steel / aluminum CNC router design

    Most of it is pretty good as far as I can see, except I find the setup for the Y-axis too complicated.

    Takes too much energy and time to get it working propperly and then it will still be less...
  30. Replies
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    56,594

    Re: Large Epoxy Granite Vertical CNC Mill

    Nagging about updates is also not nice.
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