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Thread: Concrete VMC

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  1. #101
    Join Date
    Jan 2005
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    15362

    Re: Concrete VMC

    Quote Originally Posted by stef110 View Post
    @ Mactec54
    If you gone pay the transport and the machining i would really like to do it that way...

    I know machining will be the easiest way and the best way but those parts are to heavy to move around easily for me. Let me first try i with epoxy and if that fails or not giving the right result i can always consider machining.

    I have ordered a straight edge and epoxy few days ago. My plan is to use the way
    Markus Müller did on his huge EG milling machine.
    He pressed his straight edge in the epoxy to get an almost flat surface an from there he scraped and sand the surface to get it perfect flat.
    I ordered the same epoxy as him, that one is special designed for this applications in machine building environments.

    Stef
    The problem with the epoxy it is to soft and as you torque the rail capscrews to the correct torque the rail will sink into the epoxy, if you new you where going to do this then you should of machined them first and then just scraped them after

    A lot are doing this but it is never going to be as good as a machined surface
    Mactec54

  2. #102
    Join Date
    Jul 2012
    Posts
    97

    Re: Concrete VMC

    Here we go again with the ridiculous claims... "epoxy is too soft".

    I did some FEA experiments with a 25mm rail mounted with a M6 bolt, tightened at 9.2Nm (Hiwin datasheet), on a 50mm large steel strip coated with 2mm of DWH 310P epoxy.
    The difference of deformation vs bolting directly into steel is less than 1 micron (or 0.00004").

  3. #103
    Join Date
    Aug 2004
    Posts
    780

    Re: Concrete VMC

    Agree completely.
    Epoxy is more than hard enough - industrial epoxy.

    Quote Originally Posted by jackjr-123 View Post
    Here we go again with the ridiculous claims... "epoxy is too soft".

    I did some FEA experiments with a 25mm rail mounted with a M6 bolt, tightened at 9.2Nm (Hiwin datasheet), on a 50mm large steel strip coated with 2mm of DWH 310P epoxy.
    The difference of deformation vs bolting directly into steel is less than 1 micron (or 0.00004").

  4. #104
    Join Date
    May 2016
    Posts
    108

    Re: Concrete VMC

    Im pretty sure the epoxy will be way good enough for me. I gone use the DWH 310FL.
    Don't forget its just a hobby machine and in any case it will be way better then my current machine and i don't have to fly to the moon with it.
    I hope the epoxy and parallel will arrive soon cant wait to try it.

  5. #105
    Join Date
    Jan 2005
    Posts
    15362

    Re: Concrete VMC

    Quote Originally Posted by jackjr-123 View Post
    Here we go again with the ridiculous claims... "epoxy is too soft".

    I did some FEA experiments with a 25mm rail mounted with a M6 bolt, tightened at 9.2Nm (Hiwin datasheet), on a 50mm large steel strip coated with 2mm of DWH 310P epoxy.
    The difference of deformation vs bolting directly into steel is less than 1 micron (or 0.00004").

    My clams we can back it up with real life testing FEA with I have and use will not give you the correct numbers

    So your numbers are total Bs We did the testing in real examples and compared 3 different epoxy's even the hardest Moglice ( Expensive ) that they use for rebuilding machine way's and there was deforming of .0004" to.0006" with a 18" rail mounting, the other epoxy's that you suggested where even worse, with having this amount of deforming is to much for any quality linear rail mounting, at every SHCS mounting point ( every 60mm ) there was deforming of the rail it's self


    The max hardness of flexible epoxy's is 35-60 D shore hardness

    Rigid Epoxy's is 70-90D shore hardness still a soft working surface


    https://theepoxyexperts.com/shore-hardness/
    Mactec54

  6. #106
    Join Date
    Jul 2012
    Posts
    97

    Re: Concrete VMC

    Your statements are contradictory. Moglice P and DWH 310P have the exact same shore hardness and E-modulus. How can one perform worse than the other?
    I don't know how you performed your tests, but the epoxy thickness and bolt tightening torque have obviously a huge influence.

  7. #107
    Join Date
    Jul 2012
    Posts
    97

    Re: Concrete VMC

    Quote Originally Posted by stef110 View Post
    Im pretty sure the epoxy will be way good enough for me. I gone use the DWH 310FL.
    Don't forget its just a hobby machine and in any case it will be way better then my current machine and i don't have to fly to the moon with it.
    I hope the epoxy and parallel will arrive soon cant wait to try it.
    Of course it is. Markus proved it with his 5 tons, micron precise VMC.

  8. #108
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    Jan 2005
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    15362

    Re: Concrete VMC

    Quote Originally Posted by jackjr-123 View Post
    Your statements are contradictory. Moglice P and DWH 310P have the exact same shore hardness and E-modulus. How can one perform worse than the other?
    I don't know how you performed your tests, but the epoxy thickness and bolt tightening torque have obviously a huge influence.
    Yes correct I should of said the epoxy that most use is way softer than the Moglice we tried was the best, what number do you have for your shore hardness because we can test that

    2mm to 2.5mm was the recommended thickness for testing which did not change the out come, there is another builder doing a very large 5 Axes machine who is an epoxy expert will tell you the same as I have
    Mactec54

  9. #109
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    Jan 2005
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    15362

    Re: Concrete VMC

    Quote Originally Posted by jackjr-123 View Post
    Of course it is. Markus proved it with his 5 tons, micron precise VMC.

    He has not proved anything, I'm sure it is moving as I write this, it will never be stable no matter what he say's, it's all about the lack of compressive strength, with a shore of only 88D your bones in your body have a shore of 100D to give you a comparison
    Mactec54

  10. #110
    Join Date
    May 2013
    Posts
    480

    Re: Concrete VMC

    Quote Originally Posted by jackjr-123 View Post
    Here we go again with the ridiculous claims... "epoxy is too soft".

    I did some FEA experiments with a 25mm rail mounted with a M6 bolt, tightened at 9.2Nm (Hiwin datasheet), on a 50mm large steel strip coated with 2mm of DWH 310P epoxy.
    The difference of deformation vs bolting directly into steel is less than 1 micron (or 0.00004").
    i believe that. but my comment regards my own experience of bolting a 20mm rail to about 1/8" or 3mm of system 3 mirror coat.

    under a 20mm rails there are only two, about 5 or 6 mm wide contact patches.


    and you have to figure the bolt torque is only going to be spread out at a 30degree cone away from the bolt. it won't be evenly spread out across a 50mm wide area. also you have the surface roughness of the epoxy to compress.

    anyhow, its totally acceptable for some applications but not for others.

  11. #111
    Join Date
    May 2016
    Posts
    108

    Re: Concrete VMC

    Can we end this endless discussion about epoxy will be fine enough or not. It will be my choice and my decision is made.

    Didn't make a lot of visible progress last week. Today i moved the base to its final place where it will be put together.
    I ordered the 12krpm servo spindle and some measuring tools also arrived this week.
    The design of the column is also almost done so i can start making the steel inserts and base plates this week.

    Stef






  12. #112
    Join Date
    Mar 2014
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    1131

    Re: Concrete VMC

    This is going to be a nice machine.

    Is the 12k servo you ordered for the spindle?

    Sent from my MI 5s Plus using Tapatalk

  13. #113
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    May 2016
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    108

    Re: Concrete VMC

    Yes it will be powering a bt30 spindle which is limited to 6000rpm but maybe in the future i will change the spindle to higher rpm.

    Stef

  14. #114
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    May 2016
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    108

    Re: Concrete VMC

    This weekend machined the steel inserts for the column. Hope to start building the mold next weekend and have it casted in 2 weeks from now.

    Stef




  15. #115
    Join Date
    May 2016
    Posts
    108

    Re: Concrete VMC

    This weekend made the mold for the column, this week i want to wax it and put the PVA coating on and then try to have it casted on Thursday and if all goes well i can have it baked on Sunday already.
    Welded some small improvised rebar on the bottom off the column to reinforce the mounting feets.

    Stef








  16. #116
    Join Date
    Dec 2015
    Posts
    46

    Re: Concrete VMC

    That's a really clever way of doing your column mold. None of those angles have to be butted up because your only doing the inside. Here I was thinking of a much more complicated method for a column mold but yours is ingenious.

    Look forward to your casting. Your project is looking really good. Thank you for the updates and taking us on the journey with you.

  17. #117
    Join Date
    Aug 2009
    Posts
    291

    Re: Concrete VMC

    Man, you rock'n it!! What is the grove down the back for? I'm assuming the tubes are for counterweights?

    I don't recall that you've touched much on the molds. Cutting with tablesaw? How are you affixing the thinner offsets (like on the front face to make the rail supports stand proud).

    Any take aways from demolding the base? Seems like the inner section didn't want to release?

  18. #118
    Join Date
    May 2016
    Posts
    108

    Re: Concrete VMC

    I really like to keep you guys updated with pictures also for my self so i can look up later and see my own progress.
    About the mold, the 2 tubes are just for cables and coolant hose. The cutout in the middle will be for the pneumatic cylinder acting as a counterweight.

    Making the actual mold is really fun to do. The wooden sheets i use are in the size 9mm and 18mm thick so in my design i used for all dimensions a multiply of 9 so i can just simply stack those pieces of wood to make the right shapes.
    For the steel strips i just bold them down to a base plate which forms the base of the mold. Then take the 9mm sheet and fill all the space around it which forms the bottom of the actual casting mold.
    After all the wooden sheets are stacked to gather i plaster them and give them a quick sand with sandpaper and then 2 layers of white paint so the release agent wont get sucked in the wood right away.
    The wood i use already has a special coating on it so i only have to paint the edges the rest is already almost watertight. The edges i use some silicon to make them and round and make sure the epoxy wont go to places i don't want it to be.
    And for cutting the wood i just use a circular saw with a guidance rail.

    About the release, i was really surprised how easy most of the mold came of. The one part on the inside of the mold that didn't came lose at all i think i might forget to put the release agent on that part...
    Since the rest of the mold came lose pretty well.


    Maybe you can get an idea with those 2 pictures.

    In this photo album you can also see all the pictures with bigger size:
    Powered by jGallery2-stable

    Stef




  19. #119
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    May 2016
    Posts
    108

    Re: Concrete VMC

    Today the base have been casted, total of 258kg of silimix and 28,5kg epoxy. Its about 7kg less then what went in the base.
    Now while its curing i can start on leveling the rails on the base of he machine.


    Stef















  20. #120
    Join Date
    May 2008
    Posts
    1185

    Re: Concrete VMC

    Looks nice.

    I see you added a few bits of steel to some of the high pressure points.
    youtube videos of the G0704 under the name arizonavideo99

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