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IndustryArena Forum > Mechanical Engineering > Epoxy Granite > Quartz Counter top for Mill Base
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  1. #21
    Join Date
    Dec 2013
    Posts
    33

    Re: Quartz Counter top for Mill Base

    I have finally started this build. Here is what my almost finished design looks like.
    ATTACH=CONFIG]350452[/ATTACH]
    I am working to finish the X and Z axis before I finish with the frame and Y axis.

  2. #22
    Join Date
    Dec 2013
    Posts
    33

    Re: Quartz Counter top for Mill Base

    Some pictures of the build

  3. #23
    Join Date
    Jun 2010
    Posts
    4252

    Re: Quartz Counter top for Mill Base

    I have often thought it could be interesting to collect a few discarded granite tombstones and to work with those. The mfrs can polish them very flat - the customers do not want ripples in Dear Grandpa's headstone. Our local monumental mason assured me it would be very possible.

    Cheers
    Roger

  4. #24
    Join Date
    Dec 2013
    Posts
    33

    Re: Quartz Counter top for Mill Base

    I believe the manufactured Quartz is superior to natural granite. No cracks to worry about and there are dealers setup to water jet the pieces to very close tolerances. I spent $67 for all the quartz for my upper Z and X axis. Aluminum would have been five times as much. The vibration damping is superior to anything else and I am sandwiching carbon fiber cloth in between layers to improve that and stiffness.

  5. #25
    Join Date
    Jun 2010
    Posts
    4252

    Re: Quartz Counter top for Mill Base

    I don't think you will find cracks in the granite used for tombstones. Most unlikely! The mason would send it back immediately.

    However, the vibration damping bit is a very good point which I had not thought about. Thanks for that.

    Cheers
    Roger

  6. #26
    Join Date
    Dec 2013
    Posts
    33

    Re: Quartz Counter top for Mill Base

    One other thing I will show with my design is that use if the 30mm sections I can bring the flatness and parallelism for linear rail mouthing surfaces to 0.0001 using jack screws and epoxy with no machining.

  7. #27
    Join Date
    Dec 2013
    Posts
    33

    Re: Quartz Counter top for Mill Base

    One other thing I will show with my design is that use if the 30mm sections I can bring the flatness and parallelism for linear rail mouthing surfaces to 0.0001 using jack screws and epoxy with no machining.

  8. #28
    Join Date
    Dec 2013
    Posts
    33

    Re: Quartz Counter top for Mill Base

    Sorry for the double post. I have finished machining the cross support and have set it up on the surface plate to dry test the assembly with the carbon fiber sandwich. It looks like I have 0.0045" bow with the center high.
    This is actually not bad considering the pieces were cut next to each other so I should see the same twist so the ends will have to have more pressure applied. I also measured the deflection with a load to see if that corresponds with what inventor is telling me.I have 0.0003" of deflection with just over 17 pounds of load. This is before I double the section and add the carbon fiber. I will do the dry test of the carbon fiber tomorrow to see if I can meet the 0.0001 linearity. If that goes well then I will do the wet layup. If I have time I will do the Inventor defection to compare my results.

  9. #29
    Join Date
    Dec 2013
    Posts
    33

    Re: Quartz Counter top for Mill Base

    Ran a quick test with Inventor to compare my test results with their stress results.
    Attachment 350970
    I am using concrete for my material and it looks like I am seeing close to the amount of deflection I should see.
    Attachment 350980
    Here is the same test using 6061 Aluminum as the material. Test shows about 1/3 the defection as the concrete.
    Attachment 350982
    This test is with mild steel as the material. Test shows about 1/8 the defection as the concrete.
    So by itself its not as good as the other material that have been used as far as stiffness. Adding the carbon fiber should help with the stiffness and I will do that when I have some time to the model. I will also do a modal analysis which I think is where this material will do well.

  10. #30
    Join Date
    Dec 2013
    Posts
    33

    Re: Quartz Counter top for Mill Base

    So yesterday I did the dry run to assemble and straighten my X axis beam. I ran into a few problems.
    Attachment 350992
    This is the eight layers of carbon in place, 0.011" per layer.
    Attachment 350994Attachment 350996Attachment 350998
    I mounted the top piece and started to run my indicator back and forth to find how far out I was and found I was way out of parallel. When I checked the thickness of the material it was 0.025 different from end to end, not good. If I had flipped ends I could have balanced out the difference but it too late now. The good thing is that I had planned to align this axis at assembly so how the back side aligns doesn't matter.
    Attachment 351000
    I decided to make some ball jacks to get the top plate in plane as close a possible so I could use the jack screws to get the surface flat.
    Attachment 351002
    Last problem is I reach the torque limit of the bolts before the surface becomes aligned. The carbon fiber just does't compress in a linear fashion. I get maybe 0.002" of movement before the bolt is tight. So my next move is to disassemble and try 3d printing some compression washers that will keep me just above the carbon fiber and allow compression for the alignment.

  11. #31
    Join Date
    Dec 2013
    Posts
    33

    Re: Quartz Counter top for Mill Base

    I did another analysis of the x axis beam using carbon fiber layers on the top and bottom.
    Attachment 351244
    The first run was with two layers of cloth set at 0.5mm in the test. This improved max deflection from 0.000284 to 0.0001894 cutting the defection almost in half.
    Attachment 351246
    When I added 8 layers the defection was reduced to 0.000091 which is less than the aluminum test. The carbon fiber looks promising. Price for the carbon fiber was $22 a yard and was 60" wide so not too bad.

  12. #32
    Join Date
    Dec 2013
    Posts
    33

    Re: Quartz Counter top for Mill Base

    I had good results with my testing today. I made some 3d printed washers with 25% fill and reassembled the X axis to see how they would compress with the jack screws. Most of the surface I could get within a couple of tenths, but one area is still out 0.0015. I plan on reprinting a taller washer for that area.

    Attachment 351332Attachment 351334Attachment 351344

    I also setup my X axis rail risers on my mill and added JB weld on the back side. I clamped the finish side down to eliminate any bow and when the JB Weld sets I will mill the backside flat. This doesn't have to be perfect because I will be using jack screws to level it but it need to start out close.


    Attachment 351336Attachment 351338Attachment 351342

  13. #33
    Join Date
    Dec 2013
    Posts
    33

    Re: Quartz Counter top for Mill Base

    I was able to do the carbon fiber layer today. I had to wait for some new epoxy, what I had didn't look good.
    Attachment 352862
    I didn't want to get anymore epoxy into the inserts then I had to so I taped over the holes. As I inserted the bolts to clamp the pieces together, the tape pushed out of the way. I also covered the bolts with petroleum jelly to keep any epoxy from sticking.
    Attachment 352864
    When I did the dry fit for the washers I used feeler gauges to see what the gaps would be. The ends were about 0.070" while the middle was 0.100. I found where the curve hit 0.088" (eight layers) and then cut additional fabric from scrapes to make up the gap in the middle of the layup.
    The layup of the carbon and indicating in the surface went good, not perfect but close enough. The linear rail mounts will be bonded next and will need to be as close as I can get them, hopefully 0.0001"
    Attachment 352866
    While I was waiting for the epoxy I picked up the rest of the quartz that I needed and the tubing for the base. Cost for the piece was $200 so a total of about $270 for all quartz. This should get me very close.
    Attachment 352868
    I purchased this harbor freight saw which was rated fairly good but I had problems the first time I used it. I don't think it was meant to cut 30 mm material. The suggested 4 1/4" blade didn't quite cut all the way through so I pickup a 4 1/2" which should do the trick. The other problem was there was no guide to use and when you are cutting there is a cloud of dust. I found some scrape aluminum and mounted it to the front by welding a couple of threaded couplings to the saw base. The other problem was I didn't cut 90 degrees, just too weak for the material so for now I jammed a wood wedge between the motor and the base to hold it solid. Need to test this on some scrape next.

  14. #34
    Join Date
    Jun 2010
    Posts
    4252

    Re: Quartz Counter top for Mill Base

    I found some scrape aluminum
    Scrap?

    Was that an actual stone saw with diamond blade? If so, it should run WET!

    Cheers
    Roger

  15. #35
    Join Date
    Dec 2013
    Posts
    33

    Re: Quartz Counter top for Mill Base

    Quote Originally Posted by RCaffin View Post
    I found some scrape aluminum
    Scrap?

    Was that an actual stone saw with diamond blade? If so, it should run WET!

    Cheers
    Roger
    Wish I could Roger, it makes a mess. Saw is dry only. I have a wet saw just need to get the pieces small enough to use it.

  16. #36
    Join Date
    Jun 2010
    Posts
    4252

    Re: Quartz Counter top for Mill Base

    I believe that the reason for using water is to keep the metal blade cool so you don't rip the diamonds out.
    Just a thought.
    Cheers
    Roger

  17. #37
    Join Date
    Dec 2013
    Posts
    33

    Re: Quartz Counter top for Mill Base

    So I am working on three things in parallel on this project. The frame, which I have all of the steel for except the guards. The quartz frame which I have cut up and found that I am short the pieces for the side supports and the table and the X axis gantry. The gantry I am taking slow because that is where I will get the accuracy for the mill. I have also been working on the design, which I feel pretty good about except for the upper enclosure.
    Attachment 354248
    The mill will have guards with a gap of 50 mm all the way around which allow the chips to fall into the blue chip pan shown in the rendering. I still need to finish this design but the pan will pull out for disposal of the chips. I am thinking of 8020 for the enclosure but have not locked in on this yet.
    Attachment 354250Attachment 354252
    I am trying a 25% fill 3d print of PLA for a crushable spacer to allow me to adjust the surface of the linear way. The jack screws come up from the bottom (shown in the right picture) and allow me to adjust to within 0.0001. My original test failed as I couldn't get the crush I needed to level the way mounts. I removed the outer parts of the 3d spacer and reassembled and was happy with the results, I was able to get my 0.0001" but ran into two problems.
    https://youtu.be/UGj_wwMff3I
    I did a two minute time lapse and found that I was getting about 0.0001 creep. I re-zeroed the indicator and went to the bar for a few hours, guys gotta have fun, and found the creep is 0.00035". So I am still not to the point I want to commit with JB Weld to lock in the 3d spacer. In the mean time I will work on the tube frame and quartz frame.

  18. #38
    Join Date
    Jun 2010
    Posts
    4252

    Re: Quartz Counter top for Mill Base

    At that level of accuracy, you could be getting either creep in the PLA material or a thermal change. It gets difficult.
    Cheers
    Roger

  19. #39
    Join Date
    Mar 2004
    Posts
    1306

    Re: Quartz Counter top for Mill Base

    Cool alternative method of building.

    Why did you put the carbon fiber in a sandwich wlong the neutral axis? I would have add much more stiffness out on an outer surface wouldn't it?

    To get really flat, have you considered epoxying strips of cast iron to the granite, and then scraping it in?
    Mark
    Regards,
    Mark

  20. #40
    Join Date
    Dec 2013
    Posts
    33

    Re: Quartz Counter top for Mill Base

    All of the exterior surfaces will be covered in carbon. The reason for the sandwich was to set the mounting surface for the linear rail riser as flat as possible which it did. I have bonded two 1/8" x 3/4" angle iron pieces to the cross pieces for a new jack screw arrangement I will use. I have decided that I can't use 3d printed spacers for setting the surface so I will be using another jack screw system in opposition to the rear system currently used. I will have pictures with a diagram explaining shortly. I need to let the epoxy set and do the new carbon layup before I try the new jack system. More to come.

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