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Thread: Concrete VMC

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  1. #109

    Join Date
    Jan 2005
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    9838

    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

  2. #110
    Junior Member
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    May 2013
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    470

    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.

  3. #111
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    May 2016
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    53

    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






  4. #112
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    Mar 2014
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    929

    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

  5. #113
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    May 2016
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    53

    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

  6. #114
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    May 2016
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    53

    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




  7. #115
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    May 2016
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    53

    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








  8. #116
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    Join Date
    Dec 2015
    Posts
    42

    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.

  9. #117
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    Aug 2009
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    288

    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?

  10. #118
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    May 2016
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    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




  11. #119
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    May 2016
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    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















  12. #120
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    May 2008
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    1156

    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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