Epoxy-Granite machine bases (was Polymer concrete frame?) - Page 246


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Thread: Epoxy-Granite machine bases (was Polymer concrete frame?)

  1. #4901
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    Default Re: Epoxy-Granite machine bases (was Polymer concrete frame?)

    The cheapest stable structure I can think of off the top of my head would be 12" cement blocks with machined aluminum plates bolted in between them (and maybe steel ones on the ends).



  2. #4902

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

    I would like to continue this conversation at the frequency of 2007-2008, anyone interested?



  3. #4903

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

    I was hired by a newborn ONG here in South Italy to build an affordable CNC milling machine able to cut tactile maps. The budget is extremely tight. I am considering building the frame in polymer concrete (to avoid casting iron and welding/annealing steel) and use DWH resin (from Diamant) for squaring (to avoid milling, surface grinding and/or shimming).

    Looking around on youtube videos, forum threads (including this one), thesis and scientific pubblications (most of all were already cited here), blog posts (ike CNC cookbok - which remainds here)... I'm just getting more and more confused.



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

    an affordable CNC milling machine able to cut tactile maps. The budget is extremely tight.

    Step 1: realise that you did not make that budget decision, so you do not carry the responsibility for any problems coming from that budget decision. If the company wants to play real cheap, they get real cheap. You do the best you can and don't lose any sleep.

    Cheers
    Roger



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

    Quote Originally Posted by scipione205 View Post
    I was hired by a newborn ONG here in South Italy to build an affordable CNC milling machine able to cut tactile maps. The budget is extremely tight. I am considering building the frame in polymer concrete (to avoid casting iron and welding/annealing steel) and use DWH resin (from Diamant) for squaring (to avoid milling, surface grinding and/or shimming).

    Looking around on youtube videos, forum threads (including this one), thesis and scientific pubblications (most of all were already cited here), blog posts (ike CNC cookbok - which remainds here)... I'm just getting more and more confused.
    Part size, material, needed precision are all factors in recommendations. On the cheap(er) I'd point you to kit or plan wood cnc routers. You don't have to design and rework design when something doesn't fit.

    I'd also suggest getting with local metal working clubs, maybe someone would be interested in a team project. Maybe they weld, you pick up scrap steel and 2 units get build.

    One epoxy/granite project was started but the guy found he could get a granite slab fairly cheap and drilled and epoxied in inserts.

    Which your location made me think of. Maybe hunt for stone drops, sink cutouts, defective tombstones.



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

    defective tombstones.
    The Mafia hit failed. The guy is not yet dead.

    Cheers
    Roger



  7. #4907

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

    Quote Originally Posted by rocketflier View Post
    Part size, material, needed precision are all factors in recommendations. On the cheap(er) I'd point you to kit or plan wood cnc routers. You don't have to design and rework design when something doesn't fit.

    I'd also suggest getting with local metal working clubs, maybe someone would be interested in a team project. Maybe they weld, you pick up scrap steel and 2 units get build.

    One epoxy/granite project was started but the guy found he could get a granite slab fairly cheap and drilled and epoxied in inserts.

    Which your location made me think of. Maybe hunt for stone drops, sink cutouts, defective tombstones.
    Every kit and/or built machine I looked for just sucks... I know that I'm used on HAAS, Hermle and Matsuura machines... but paying 10,000$ for a machine which vibrates like hell doing a dry routine (with even the motor disabled)...

    "Metal working clubs" ? Nothing. Only an old man who can to do the face milling for cheap on his large, old cast-iron milling machine in his huge all-manual shop.

    I also considered using granite slabs, like this guy did:

    But the costs went in the sky (we need a minimum working area of 600x400) trying to use scraped granite plates.



  8. #4908

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

    Has anyone tried using those hand held pneumatic or electric concrete vibrators?



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

    es, I have tried about anything you can think of with polymer concrete. It is important that the vibration compacts the material and does not induce air. You can manually compact the material using a tamper (a 2X4 and hammer).



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

    Tried the concrete vibrators like the "rod style".. dont work, EG is to sticky. Best sucess has been with one of those grain bin vibrators that is bolted to the outside.



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

    Very simply 2 bearings, shaft, pulley, adjustable offset weight





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

    That could work, my experience is that you wanna shake the aggregate to a point where it is basicly fluid tho. While shaking you should be able to press your hand or a roundbar or something down into the bottom of the container with no effort.. And i mixed in the epoxy during this state of shaking, make it dispearse and really cover all the aggregate properly.



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

    Looks like a job for a mallet and a wide tamping bar to me. It's solid stuff.

    Cheers
    Roger



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

    I bolted one of those grain silo vibrators to the mould, and used a VFD to tune the frequency till I find one to help it sag. I would not expect anything less to be effective.
    Mark

    Regards,
    Mark


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

    The inside of those silo vibrators is a motor and 2 offset weights. That's what gave me the idea for using a grinder with 2 pulley's to which you could bolt panels. But I didn't think the grinder's bearings would be sufficient. Started me thinking about the axle and offset weights when I found some uTubes of concrete block forming and a couple showed the same setup.

    Epoxy-Granite machine bases (was Polymer concrete frame?)-sfl_6-jpg
    Epoxy-Granite machine bases (was Polymer concrete frame?)-diagram-electric-vibrator-png







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

    Yep. I used one of them, with a VFD to look for resonant frequencies.

    Regards,
    Mark


  17. #4917

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

    Quote Originally Posted by RotarySMP View Post
    Yep. I used one of them, with a VFD to look for resonant frequencies.
    What do you mean for VFD ?

    However, we are about to start building the machine and I still don't know where/how to find the needed materials... We are in South Italy, does somebody knows where we could source the pebbels and sand?



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

    Variable frequency drive otherwise known as an inverter. The one I used was 1 phade 240v in and three phase 240V out.

    Regards,
    Mark


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

    Quote Originally Posted by RotarySMP View Post
    You need pretty violent vibration. I used a 3 phase concrete vibrator which weighed about 15kg to compact the M/G I used on the head support for my mill and it still took a fairly long time to compact. Also I still had some air bubbles. To do the vibrating accoustically, you would need to borrow the The Who's PA system.

    If you have a nearly ideal packing density, this stuff is really still. An orbital sander won't impress it at all.
    Mark
    Hi Mark
    Do you still have the excel sheet from Thomas?
    I can't find it unfortunately

    Thank you

    @all: thank you for all your efforts. I'm going to poor the first batch of test in May I hope. let's see what happen
    I really struggle to find zeeosphere, I think I will use crushed sand of abarasive glass balls instead...



  20. #4920

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

    Quote Originally Posted by vib View Post
    Hi Mark
    Do you still have the excel sheet from Thomas?
    I can't find it unfortunately

    Thank you

    @all: thank you for all your efforts. I'm going to poor the first batch of test in May I hope. let's see what happen
    I really struggle to find zeeosphere, I think I will use crushed sand of abarasive glass balls instead...
    I do. Send me a PM



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