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Type: Posts; User: RotarySMP

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  1. Thread: Concrete VMC

    by RotarySMP
    Replies
    135
    Views
    6,837

    Re: Concrete VMC

    Very impressive build. Thanks for sharing it.
  2. Thread: Concrete VMC

    by RotarySMP
    Replies
    135
    Views
    6,837

    Re: Concrete VMC

    Great to see you back in the saddle. Look forward to seeing your progress. It is a really cool machine you are making.
    Mark
  3. Replies
    4
    Views
    316

    Re: Epoxy granite

    There was a reference in a german language book on epoxy granite (the book is listed in the mega E/G thread), which stated that the ideal largest agregate size is 1/5 the smallest feature thickness....
  4. Re: Are the Mini Lathes sold by HarborFreight worth the $500 price tag?

    I have hada Sieg 7x12 for about 10 years. All the 7x cheap chinese lathes are made by SIEG, and except for the motors/driver are pretty much the same. The only reason to get one is if you do not...
  5. Re: Epoxy-Granite machine bases (was Polymer concrete frame?)

    Variable frequency drive otherwise known as an inverter. The one I used was 1 phade 240v in and three phase 240V out.
  6. Re: Epoxy-Granite machine bases (was Polymer concrete frame?)

    Yep. I used one of them, with a VFD to look for resonant frequencies.
  7. Re: Epoxy-Granite machine bases (was Polymer concrete frame?)

    I bolted one of those grain silo vibrators to the mould, and used a VFD to tune the frequency till I find one to help it sag. I would not expect anything less to be effective.
    Mark
  8. Thread: Concrete VMC

    by RotarySMP
    Replies
    135
    Views
    6,837

    Re: Concrete VMC

    Forger the o-ring. It is common in industry and also building to thread holes into the top matching plate, and use screws to get the gantry aligned and then inject an epoxy grout into the gap. Just...
  9. Re: Epoxy Granite In Practice (Mineral Casting, Polymer Concrete)

    The only way to mould a flat surface is to mould against a surface plate.
  10. Re: Epoxy Granite In Practice (Mineral Casting, Polymer Concrete)

    What are you using to vibrate your mix? I used a three phase concrete vibrator on my 8% mix, with a VFD on it so I could look for a resonant frequency to help it slump. My mold was pretty small,...
  11. Re: Epoxy Granite In Practice (Mineral Casting, Polymer Concrete)

    Even if you start with a perfect mixed fuller curve of aggregate, if you add 25% epoxy, the different aggregates will separate with the large particles settling out as you fill and vibrate the mould....
  12. Re: Epoxy Granite In Practice (Mineral Casting, Polymer Concrete)

    ISBN 3-478-93273-4 "Mineralguss für den Maschinenbau".

    Trying to get optimal ~8% epoxy mixes to flow is rather differcult, but that is what you are aiming for. If you had 1/2 wall thickness...
  13. Re: Epoxy Granite In Practice (Mineral Casting, Polymer Concrete)

    These are all very "wet" samples. Industrial experience shows that you need:
    - to get the epoxy down to 8-12% for decent stiffness.
    - a near fullers curve packing density.
    - plenty of...
  14. Thread: MAHO 500W

    by RotarySMP
    Replies
    3
    Views
    831

    Re: MAHO 500W

    Have you contacted DMG? I have found them to be extremely helpful.

    Not sure if they'l help, but here are the parameters of my 1986 400E with a 432/10. You really need to specify your machine more...
  15. Replies
    2
    Views
    1,097

    Re: Building a Wiener90, Mendel90 derivitive

    Woops, forgot to document most of it. It is now up and running with a DuetWifi. After the initial test peices of Unicorn cookie cutters and mermaids, I printed of some parts for the pattern of a...
  16. Replies
    40
    Views
    1,805

    Re: Small, aluminium cutting mill

    I have bought all the bits to make a copy of BrainRights controller, but still waiting for the 37pin D-Sub connectors to arrive.

    In the meantime, I finished my 3D printer:...
  17. Thread: THE GRIZZ

    by RotarySMP
    Replies
    704
    Views
    37,796

    Re: THE GRIZZ

    What about hogging a new saddle out of durabar cast iron. It is not a huge chuck of iron, and there are not that many features on it.
    Mark
  18. Replies
    154
    Views
    2,708

    Re: ENCO RF45 Clone CNC Conversion - LinuxCNC

    Thanks for your response Kurt. Not long winded, as it is experience and insight from guys like you who have such a project that make this forum so useful. By the way, congratulations on getting...
  19. Replies
    154
    Views
    2,708

    Re: ENCO RF45 Clone CNC Conversion - LinuxCNC

    Excellent, clleanly designed and well thought out conversion you have done. Thanks for posting the model files. I have imported them to Onshape, and they converted perfectly.

    Interesting in your...
  20. Thread: Concrete VMC

    by RotarySMP
    Replies
    135
    Views
    6,837

    Re: Concrete VMC

    Great start to the show. Subscribed and getting popcorn
    Mark
  21. Replies
    19
    Views
    3,296

    Re: Epoxy granite or UHPFRC Concrete 5 axis CNC

    Do you have any information on the shrinkage of those products. I didn't see anything in those broshures.

    Do you have the provisions to vibrate a ton of epoxy granite in a mould?
    Mark
  22. Sticky: Re: WidgitMaster's Largest Steel Router Table Project 9ft x 5ft x 8" Water Cooled Spi

    Glad you are still with us. I hope you can regain full motion with you foot. Please get a helmet when you ride Big Red again.
    Mark
  23. Replies
    19
    Views
    3,296

    Re: Epoxy granite or UHPFRC Concrete 5 axis CNC

    Are you designing based on compressive strength, and not youngs modulus? Normally strength is pretty irrelevant to tool frames, other than certain features like not wanting threaded anchors to pull...
  24. Replies
    74
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    7,117

    Re: SIEG C6 Retrofit [Ongoing]

    I used a similar encoder on my Boley
    Boley 4L
    Post #18
    I planned for three sensors, but also only have two connected. ~50 tooth rev seems to work fine under LinuxCNC.
    Mark
  25. Replies
    19
    Views
    3,296

    Re: Epoxy granite or UHPFRC Concrete 5 axis CNC

    Aren't you mixing up polyester resin (which shrinks badly) with epoxy (which is more stable after curing). An optimal 8% epoxy mix is very dry and needs significant, tuned vibration to compact....
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