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  1. #221
    Member peteeng's Avatar
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    Default Re: Milli a new composite mill kit

    If your going to fill with filler then pour, the epoxy will be perfect. The recent interest in river tables and epoxy casting has resulted in non thixotropic resins becoming available... The CSA grout will be lower cost and heavier and stiffer. I have found swarfs do not pack well if you are aiming at high filler ratios. But if they are free then all good, they do need washing/degreasing. Don't tell your other half that you put it through the washing machine....

    Humidity is not a problem for CSA. Its the recommended concrete for marine environs over portland... Class C CSA's expand about 0.6% so gets squished into the form and mechanically keys so macro/micro cracking not a problem and not expected. Epoxy shrinks 0.5% so it depends on its great adhesion to the form to stay coupled. I'd go with CSA as its stiffer and denser, both on your wish list. If you use CSA wrap in plastic to stop water evaporating from the surface or keep the surface wet with a towel or similar for several hours. Haven't used it yet so new territory for me. Keep us informed!! Do a little test paperweight first and report back....I won't have any CSA here until new year. Regards Peter


    https://www.ctscement.com/product/ultraflow-4000-8 this maybe better. The local chemist talked more about grouts then cements



  2. #222
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    Default Re: Milli a new composite mill kit

    Peter,

    Thanks again. Looks like I'll be trying out the CSA and getting some fibers. I'll report back when I have some results.

    -Ralph



  3. #223
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    Default Re: Milli a new composite mill kit

    Evening all - I've been doing some more FE work and its been interesting. In simsolid you can make a part "rigid" ie it will have infinite stiffness. This is handy to establish what is moving and what is not. So I made the arm column and base rigid and and only got to Z 23N/um which means this is the absolute to stiffness the design can achieve and 20 is my target. Using the cast value I get 9N.um so I'm going to land somewhere in the middle but won't get to 20+ so the column has to be bigger.... I'll rethink its geometry. Peter

    Attached Thumbnails Attached Thumbnails Milli a new composite mill kit-x-axis-jpg  


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    Default Re: Milli a new composite mill kit

    Hey Pippin - I just came across "aircrete" forget about styrene balls look at aircrete if you want lightweight concrete its also DIY. Peter



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    Default Re: Milli a new composite mill kit

    Morning All - I have read thru all of the participants comments in the thread. Thanks for all the input it has been helpful. I also read through the thread to figure out if I'm going in circles or not. On some issues I have. I set out to design a lifting gantry mill and it turned into a moving column design. I started out wanting to do fibreglass parts now they are CSA. Now I'm struggling to get a column stiffness I want and I see way back a Mazak configuration that looks good. Millis current column is tending to grow backwards trying to prevent its X axis getting wider. If I go the fixed table, moving column in XY (but it has a saddle) then it gets back to what I wanted in the first instance. stuck again. But the CSA thing is really good so that's been a great discovery in this thread. Peter

    Attached Thumbnails Attached Thumbnails Milli a new composite mill kit-mazak-vtc-200-jpg  


  6. #226
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    Default Re: Milli a new composite mill kit

    All just reflects the fact there is no perfect design, just a series of priorities and compromises!

    I note there are three Y axis servos and no X or Z axis servo on that diagram.... They didn't proof it very well...

    7xCNC.com - CNC info for the minilathe (7x10, 7x12, 7x14, 7x16)


  7. #227
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    Default Re: Milli a new composite mill kit

    Hi Pippin - Should we send a little red mark up to Mazak? The struggle to find machine Nirvana continues...Are we having fun yet? Peter



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    Default Re: Milli a new composite mill kit

    Hi All and Sundry- I put together a moving XY machine. Its actually a little smaller footprint then the moving column design. It gets the motors and screws out of the crud which I like and the job does not move which means the motion system can be optimised for structure as the load does not change with the job mass. It still suffers from lack of torsional stiffness but its no different to the others. I can see a couple of things to fix. It scores in N/um X 16 Y 39 Z 26. if I make all parts aluminium. I'll adjust the arms subplate that definitely needs attention then come back to a CSA model. Nirvana must be around the next corner.. Peter

    Attached Thumbnails Attached Thumbnails Milli a new composite mill kit-milli-15-1-jpg   Milli a new composite mill kit-milli-15-2-jpg  


  9. #229
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    Default Re: Milli a new composite mill kit

    Hi- I fixed a couple of small things and made the main parts CSA with an E=40GPa. The chemist says it will get there easily. I have been conservative and been using 30GPa. So now its
    N/um (1 N/um = 0.001mm) X 14 Y 38 Z 28. So creeping X up. Need a 6 more in X and I can smile... Peter

    Attached Thumbnails Attached Thumbnails Milli a new composite mill kit-milli-15-jpg   Milli a new composite mill kit-milli-15-b-jpg   Milli a new composite mill kit-milli-15-c-jpg  


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    Default Re: Milli a new composite mill kit

    Hi Peter, while searching for more info about CSA found this: https://www.targetproducts.com/PDFs/DS-machbasegr.pdf
    Don't know if it's any good but thought I share it with you.



  11. #231
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    Default Re: Milli a new composite mill kit

    Thanks Klaas - Its very well specified. But its Portland which has residual reactions over a long period of time. It probably has CSA added to it as a shrinkage compensator. I'd go 100% CSA grout vs anything with Portland in it. Peter



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    Default Re: Milli a new composite mill kit

    Hi All - I've been worrying about having to use 200x200 solid aluminium (or stiffer) to get to the stiffness required. So my mind cast doubt on simsolids results. My other FE system Strand7 I've been using for 20 years and have been involved in many testing programs that proves its statistically accurate, So I built a test model in simsolid and in S7. Results are within 6% of each other. I expected it to be closer. Both software systems have NAFEMS benchmarks which means they have been applied to many standard problems with analytical answers to calibrate correctly to. So I suppose this may represent the range of analysis. I did linear and none linear runs and answers were the same in both so no non linear effects here. SS being a boundary value analysis (vs std FE) could be more accurate. But no worries, SS is good enough it seems. I made an E=40GPa column 200x200x700 high. It has a 250mm arm and I applied 1300N torsion to it. SS says 0.0520mm and S7 says 0.0489mm. In simsolid I ran an 8 adaption solution which should be really accurate... so back to the grindstone... Peter

    Attached Thumbnails Attached Thumbnails Milli a new composite mill kit-ss-1300n-jpg   Milli a new composite mill kit-strand-1300n-jpg  


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    Default Re: Milli a new composite mill kit

    Evening all - We've arrived. I made the column bigger and bigger until the magic appeared. That magic was 250x250mm. The saddle is 75mm thick CSA. at 200x200 the stats are in N/um arm 55 column 19 saddle 16 then feet 14. These numbers represent constraining the bearings at each bit. So the arm loop is stiffest then you can see the column is the main offender. So next is to make a tapered column, adjust the envelope then start making it practical, like how are the bolts for the bearings and sub-plates going to work? I think the saddle will be 50mm thick aluminium or maybe steel (I don't like steel) I suppose I could cast in inserts.... got to get practical now. Then there's the Q of can I make it big enough so can make Milli parts on Milli...Peter

    Attached Thumbnails Attached Thumbnails Milli a new composite mill kit-milli-15-27n-um-jpg   Milli a new composite mill kit-deflection-jpg  
    Last edited by peteeng; Today at 05:59 AM.


  14. #234
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    Default Re: Milli a new composite mill kit

    Everytime I read this thread , my head hurts afterwards.....



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    Default Re: Milli a new composite mill kit

    Hi Sterob - At least you've been consistent since I "meet" you. Are you a Bex generation? Peter



  16. #236
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    Default Re: Milli a new composite mill kit

    You gave me some good tips in my EG thread so I thought I'll return the favour. I might have missed it but was there any particular reason you decided against a fixed double column gantry and a moving table?

    https://image.made-in-china.com/202f...nup-Tq1611.jpg



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