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Type: Posts; User: ckelloug

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  1. Re: Epoxy-Granite machine bases (was Polymer concrete frame?)

    Hi Gang,

    While looking for something totally different, I came across this excellent open access paper on polymer concrete.
    http://dx.doi.org/10.4236/wjet.2013.13009

    I think anybody who is...
  2. Re: Epoxy-Granite machine bases (was Polymer concrete frame?)

    Hi Konobi,

    I have a very small test machine so the sizes I can handle are limited. The test I can do is ASTM D-790 flexural strength and modulus. This isn't as definitive as compressive stength...
  3. Some Quick thoughts responding to PM's

    Hi Thread,

    I'm dropping in 'cause I got a few PM's. Tenter asked if my aggregate simulator is available. I can make it available if somebody wants to maintain it. It's a pair of linux...
  4. Re: Epoxy-Granite machine bases (was Polymer concrete frame?)

    The recipe above is exactly what I used. #600 silicon carbide is dust. G200 zeeospheres are measured in microns.
    http://i161.photobucket.com/albums/t202/ckelloug/Egsamples.jpg
  5. Re: Epoxy-Granite machine bases (was Polymer concrete frame?)

    Hi all,

    I can see I'm not going to get back to this topic for a long time so I'm going to post the last formula I tested.

    In general, an optimal recipe is based on characterizing exactly what...
  6. Re: Epoxy-Granite machine bases (was Polymer concrete frame?)

    LowAlloy,

    I've emptied my PM box. I don't seem to have modeled the starblast ultra but I liked it because it had a wide variety of sizes and since it is a disposable product, ought to be...
  7. Re: Epoxy-Granite machine bases (was Polymer concrete frame?)

    In general, epoxy, even with reactive dilutants, should not have appreciable volatiles content. A liquid amine hardener is somewhat volatile however a few minutes at 29.x inches won't hurt it a bit....
  8. Re: Epoxy-Granite machine bases (was Polymer concrete frame?)

    The amount of epoxy needed is highly dependent on the size distribution of the aggregate that you are using. If your aggregate are sized in a suboptimal way, they won't pack together very tightly...
  9. Re: Epoxy-Granite machine bases (was Polymer concrete frame?)

    Hi Thegolfer,

    I find that you really need to get about 29.9 inches of mercury to fully degas epoxy. A venturi won't get to this level but it might be enough to help with your problem. Also,...
  10. Re: Epoxy-Granite machine bases (was Polymer concrete frame?)

    Aaron 1975,

    That info on using PET as the bonding agent sounds interesting. A mix that can be dry blended and then melted has a lot of advantages in terms of capillary action working for you...
  11. Re: Epoxy-Granite machine bases (was Polymer concrete frame?)

    The golfer,

    Your block looks pretty nice. I'd suggest vacuum deairing the epoxy before mixing the material up. If possible, a few percent of BYK 525 deairing agent will also help. In about 30...
  12. Hi John, That's on a volume basis as that's...

    Hi John,

    That's on a volume basis as that's what the Isahi-Cohen equation uses. Epoxy is very close to 1 gram per cc and quartz 2.6 g/cc therefor the mass of 1 gram of the mixture is .88*2.6...
  13. Greetings and Updates

    Hi E/G'ers,

    I wish I had more time to spend on this thread. I've been busy with some commercial work on something else and I hope I can tell the story about it here some day. I've been thinking...
  14. Hi Rocketflier, For commercial castings, my...

    Hi Rocketflier,

    For commercial castings, my research suggests vertical only vibration is better for compacting E/G than circular vibration from an ordinary table like the one pictured....
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    I'd suggest finding a diamond bit if you have to...

    I'd suggest finding a diamond bit if you have to do more than a few of these. I've seen the much thicker 1/8 thick carbon fiber take teeth of a bandsaw blade.
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    Thoughts: 80 mm is way more than you can do in...

    Thoughts:

    80 mm is way more than you can do in one pass but you already knew that.

    If you're having surface finish issues, how rigid is your setup?

    Are you using carbide or hss? Carbide is...
  17. Rocketflier, Mixing in hardener after...

    Rocketflier,

    Mixing in hardener after aggregate is strange. I didn't see that video. In my opinion, that's probably a sign that they are using a high percentage of a catalytic hardener like a...
  18. Hi Alex_ku, The aggregate percentage I gave...

    Hi Alex_ku,

    The aggregate percentage I gave are in percentages of the total aggregate weight.
    The epoxy percentage I gave is in (weight epoxy+hardener)/(weight aggregate+weight epoxy+weight...
  19. HI Alex_ku, I'll start by saying John Ohara's...

    HI Alex_ku,

    I'll start by saying John Ohara's advice and link to Roach's post are good advice.

    I ran the aggregates you said you had available through the model and it suggested
    the following...
  20. Hi alex_ku, My suggestion would be to see if...

    Hi alex_ku,

    My suggestion would be to see if that supplier has any material with a larger maximum size. You can probably make a usable mixture with any of these but it will tend to have a higher...
  21. Hi Jestah, Congratulations on the design of a...

    Hi Jestah,

    Congratulations on the design of a really sweet looking machine.

    Sorry to be late noticing your post and saying something. Bruno is right that 22mm is a bit excessive for a small...
  22. Hi Rocketflier, Interesting suggestions on the...

    Hi Rocketflier,

    Interesting suggestions on the mixing methods, especially the ice cream maker. E/G is very abrasive and is certain to erode mixing paddles although I can't say I'm sure whether...
  23. Hi Roman, I must admit that my test samples...

    Hi Roman,

    I must admit that my test samples have been a bit small but the only exotherm problems I have ever seen have involved poor choices of hardener. TETA, TEPA, and AEP are very exothermic...
  24. John, I salute your practical work and wish...

    John,

    I salute your practical work and wish that the others who are doubtlessly build stuff would post their work. Work like yours is why I assume we are here. It doesn't detract in the least. ...
  25. John, I am impressed with your work on the...

    John,

    I am impressed with your work on the Worden and think you are doing a great job realizing it in E/G. I don't think anyone here should be allowed to detract from that.

    In all honesty,...
  26. I'd suggest looking on e-bay for an industrial...

    I'd suggest looking on e-bay for an industrial convection oven. I got a used Grieve convection oven that is 48x36x36 for around $2000. It will go up to 375F. It has large heating coils at the...
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    Take a look at PTM&W Epoxy, aeropoxy, vartm,...

    Take a look at PTM&W Epoxy, aeropoxy, vartm, rapid prototyping, and urethane tooling resins. to see what's available in filled epoxy for industrial purposes.

    They make all sorts of filled epoxy. ...
  28. Hi Jeff, I can't speak for everyone here but...

    Hi Jeff,

    I can't speak for everyone here but I'll answer for myself.


    My original objective was to thoroughly understand the science involved in E/G and be able to design materials as I...
  29. Hi Guys, Roach definitely did teach us a lot...

    Hi Guys,

    Roach definitely did teach us a lot of useful information. My own work has been mainly theory although I have been working on catching up in the lab to get sufficient properties. I'll...
  30. Because the base of a machine is designed...

    Because the base of a machine is designed primarily on the basis of displacement under the design loads, the strength differences and modulus differences aren't major problems in an actual machine. ...
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