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Type: Posts; User: badhabit

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  1. Replies
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    Re: Yet another epoxy granite mill

    A lot of talking to my self here, but i just ordered a couple of accelerometers. I'm going to see if something can be concluded from that...

    /Thomas
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    Re: Yet another epoxy granite mill

    Maybe an acceleration sensor, fix the sample in one end and "hit it with a hammer" in the other? I'm unsure if the damping is frequency dependent or not? If frequency can be ignored then length and...
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    Re: Yet another epoxy granite mill

    Yeah, well, i have a lot of stuff, but high speed cameras is sadly not on the inventorylist :-( Apart from this, the deflection will be very small with these sample-sizes...so i don't think this is...
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    Re: Yet another epoxy granite mill

    Yeah, i'll see if i can order the stuff for a test af that...it will take a couple of weeks since i have a lot of traveling in the upcoming weeks...

    Maybe i should figure out a (simple) way to...
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    Re: Yet another epoxy granite mill

    Yeah, when i see cutouts of "professional machinebases" they usually have very large aggregates embedded(guess: size=50-80mm!) within them. But it also makes sence, less flexible epoxy=stiffer. The...
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    Re: Yet another epoxy granite mill

    Yeah, i could, but not sure if there could be anything interesting to figure out in the process?

    PS: I've been thinking that i should try adding larger aggregates to see what it changes. The...
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    Re: Yet another epoxy granite mill

    So...the results are in...short answer: 22-23Gpa...for a 12% by-weight Silimix282 with R&G ResinL + GL2 Hardner. Cured for 2 weeks at 30c, no postcure treatment.

    I've attached an excel spreadsheet...
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    Re: Yet another epoxy granite mill

    The biggest size is 4mm in the Silimix282...if this works out fine, i think i'll cast a couple more, but with some larger aggregates in...

    I'm not sure if i can calculate anything that will tell...
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    Re: Yet another epoxy granite mill

    Yeah, i made a spreadsheet that does the calculation:
    504506
    Its just a calculation for a midspan load on a beam supported between to points. So with a guestimate of E=20Gpa a load of 100N will...
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    Re: Yet another epoxy granite mill

    How much weight did you use in your tests and what sort of deflection did you measure at what distance? Did you do a cantilever test or at 2-point setup with load in the middle? I'm planning on doing...
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    Re: Yet another epoxy granite mill

    504468
    ...casting done... i tried the blue die this time:cool:

    They've been placed to cure in the furnace room at around 27-28c...so demolding in a couple of days i think...

    ...i think i'm...
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    Re: Yet another epoxy granite mill

    I had some spare phenolic plywood laying around, just enough to make two forms for 40x40x800mm test bars:
    504088
    ...i'll cast some billets with my EG very soon and post the results here...
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    Re: Yet another epoxy granite mill

    Defently :-)
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    Re: Yet another epoxy granite mill

    I was planning on making 40x40mm square billets for testing, 800mm long... does that sound reasonable or ? I think my largest aggregate is around 4mm, so i'd figure 10x in size.... i was planning on...
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    Re: Yet another epoxy granite mill

    Yeah, well, i've never been fully convienced about the dry-stacking idea for EG, however i don't think this is even an option with the Silimix282 ayways. Some of the aggregate is very fine, like VERY...
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    Re: Yet another epoxy granite mill

    I was going to build a chamber for this. Some Ø150mm steel tube with flanges on the ends and then compressed air. And before the internet police arrest me, yes, i know it is "a bomb", but heavy duty...
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    Re: Yet another epoxy granite mill

    Impressive planning! I've used soooo much money on shipping because i almost ordered each part individually...and sometimes the same part twice because i broke it the first time ;-)

    Apart from the...
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    Re: Yet another epoxy granite mill

    https://www.youtube.com/watch?v=24e8sDDS0ag
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    Re: Yet another epoxy granite mill

    Got the controlpanel wired up:
    503516 503518

    ...now i just need the mounting arm for it...and attach the backplate :-)

    ...on to the next part: finish wiring the main electronic enclosure!
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    Re: Yet another epoxy granite mill

    Waiting for CycleStart/FeedHold and potentiometers(for feed/spindle overrides) in the mail...everything else got mounted:
    502244
    ...its starting to look like something now :-)

    A couple of...
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    Re: Yet another epoxy granite mill

    The controlpanel starts to take shape:
    502186 502188 502190
    ...next up: buttons and a ton of wires!
  22. Re: Advice needed for parts selection for new DIY CNC Mill

    ...not sure i understand you correctly here, but isn't the floating end of the ball-screw really "floating"? Mine is resting inside a bearing which sits in a housing with no(!) axial limits at...
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    Re: Yet another epoxy granite mill

    No, not yet :-( But i have moved it around many times since it arrived because it is always in the way of something ;-) But hopefully VERY soon as the electronics is almost done and i'd like to test...
  24. Re: Advice needed for parts selection for new DIY CNC Mill

    I'm sorry to "hijack" your thread here, but I'm curious if you have any pictures of the setup doing this? I'm about to do the same with my EG mix to compare and i'd like the tests to be somwhat...
  25. Re: Advice needed for parts selection for new DIY CNC Mill

    I think this is quite telling regarding EM difference:
    501564
    (from: https://www.rampf-group.com/en/products-solutions/details/ultra-high-performance-concrete-epudur/ )
    ... not sure about the...
  26. Re: Epoxy-Granite machine bases (was Polymer concrete frame?)

    I haven't done much research into EG vs. UHPC, it mostly seems like a "religious war" and in my opinion there is not a clear "winner". The biggest downside to UHPC (as far as i've research!) is that...
  27. Re: Epoxy-Granite machine bases (was Polymer concrete frame?)

    Yes and no:-) I didn't get the institute to do the testing. Mostly because the ones i talked to usually "just" test concrete and their main focus is compressive testing, which isn't very usefull for...
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    Re: Yet another epoxy granite mill

    As part of getting the electronics in order, i'm trying to figure out how i'd like the control interface....and honestly...i have no clue :-)

    So, i'm making a simple "version 1" and then i'm not...
  29. Re: Advice needed for parts selection for new DIY CNC Mill

    Thats about what i/we did to mine. A friend of mine is a professional welder, the sort of guy that other welders call when they either don't know what to do or have messed something up. So i beveled...
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    Re: Yet another epoxy granite mill

    A little progress on the electrical part of the project:
    501228
    ...might look a bit messy without the covers on, but looks very tidy when they are mounted:-)

    The panel is like 95% done. I'm...
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