Pre-build: YAGGM (Yet another granite gantry mill)


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Thread: Pre-build: YAGGM (Yet another granite gantry mill)

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    Default Pre-build: YAGGM (Yet another granite gantry mill)

    Wanted to post my basic design for a moving gantry mill/router that I'm planning on building over the next year or so.
    Base/mill table is a 36x64x6" granite surface plate, linears are 35mm NSK's and the spindle is a 120 lb, 16 HP (I'll need to derate for single phase) Colombo with 7 ft-lbs torque. Projected work envelope is 41x19.5x~14.
    Other materials are 6", .25" wall square tubing, .5" and 1" plate. Other than the granite, spindle and linears I'm completely open to using different materials, those are just what's available at reasonable prices around here.
    Haven't put too much into linear motion control yet. Probably do ball screws for gantry and Z and end up with R&P for the long axis.
    Primarily plan to cut aluminum, but other nonferous, composite and plastics will see time on the machine as well. Would be able to do light steel work occasionally. This won't likely be a production machine, more for prototyping and short runs of my designs.
    I've already got the spindle and am planning on picking up the surface plate soon, the linears are automationoverstock and seem like a steal, so I'd like to stick with them. The rest of the design is wide open. Plan to weld the 2 6" square tubes together and weld on the 1/2" strips for the rails to sit on. Will probably need to do epoxy leveling for the gantry as I don't have any other way to make them flat (and I can use the base as a reference surface.) The rest I plan on using a zillion bolts to hold together, so I can modify the design easily later on.
    Fabrication of the plates will be some multi-setup work on my CNC converted RF30. (about 7x18 travels.)
    Rails will be held to the surface plate by core drilling and epoxying in threaded inserts. Work holding will be similar. Right now the plan is to get some 4140 prehard rod, core drill 1" holes on a 4x4" grid (with a small drain hole at the bottom of each) epoxy in the rod, then drill/mill in place 5/8" dowel pin holes on top of thread milled 1/2"-13's.
    Pre-build: YAGGM (Yet another granite gantry mill)-granite-mill-png
    Thoughts? Any glaring issues? I haven't done any simulations yet, but will, and I'm sure some of the design will change when I do.

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    Default Re: Pre-build: YAGGM (Yet another granite gantry mill)

    Pneumatic counterbalance I assume?

    Where are you going to mount your gantry ballscrew?

    Workholding? Spoilboard? Are you going to mount any vises?

    Just questions really.



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    Default Re: Pre-build: YAGGM (Yet another granite gantry mill)

    Yes, planning to use a pair of pneumatic cylinders connected to a reservoir.
    Ballscrew would go in the normal place between the rails. May need to thicken the plates for the rails to make room but I think I can squeeze a 25mm screw in that space by machining a pocket for the nut in the moving plate.
    Was planning to use fixture plates/spoilboard for any flat machining, never mounting items to be machined directly to the bed. Do plan to mount a vise or several depending on the work. Might put down some aluminum sheet to cover the granite over unused areas to protect from accidental drops and chips.



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    Default Re: Pre-build: YAGGM (Yet another granite gantry mill)

    Quote Originally Posted by skrubol View Post
    Yes, planning to use a pair of pneumatic cylinders connected to a reservoir.
    That's what I'm doing. I haven't got it done yet. I should be working on it now. I procrastinate too much . I ended up ordering mine online from Aliexpress. One thing you can do is to to get the cylinders that have a magnet in the cylinder and then use two cylinder prox sensors attached to a cylinder for your Z limits. I think most of the cylinders have this magnet by default.

    Linux_fan used a single pneumatic cylinder in his build. He's got some pics of the bracket he made in his thread.

    Quote Originally Posted by skrubol View Post
    Plan to weld the 2 6" square tubes together and weld on the 1/2" strips for the rails to sit on. Will probably need to do epoxy leveling for the gantry as I don't have any other way to make them flat (and I can use the base as a reference surface.)
    You can see some pics of what I did here:

    http://www.cnczone.com/forums/cnc-wo...-forum-24.html

    In post #113



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    Default Re: Pre-build: YAGGM (Yet another granite gantry mill)

    I've actually been catching up on your build. Only up to late June though.



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    Default Re: Pre-build: YAGGM (Yet another granite gantry mill)

    Quote Originally Posted by skrubol View Post
    I've actually been catching up on your build. Only up to late June though.
    That's not my build, I just happened to post a couple of pics in that thread when we were discussing machining costs.



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    Default Re: Pre-build: YAGGM (Yet another granite gantry mill)

    Ah, ok, sorry. Anyway, following that build.



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    Default Re: Pre-build: YAGGM (Yet another granite gantry mill)

    Well, a bit of a change of plans already.. Went to pick up the granite this afternoon, and neither of the pieces he had were in great condition. They had a lot of threaded inserts already in them and some significant cracking between inserts.
    But.. as it turns out these plates are from PCB drill/mill routers that had been stripped down, and he had another partially stripped one that I asked him if he'd part with as-is. Most of the stuff valuable to him was already stripped, but still had a full gantry (fixed) with motion components and some of the Y axis, but I'll probably need to scrap all of it as it's very light duty (air bearings that ride on the granite.)
    Now I just need to figure out how to transport and unload the thing. He estimated the weight at 5k lbs, but I think he's way off. The plate should be around 1300-1400 assuming the measurements are right and it's not some super dense granite, and there just wasn't that much to the rest of the thing to have more than another 1000 lbs I don't think (mostly the frame underneath, a couple transformers and that gantry.)

    So anyway, design has changed to a fixed gantry, I may upgrade the linears from the 25mm ones on there to 35, but I dunno. Will still need to build Y and Z though, and figure out what to use for a table. X-Y travel should end up around 19-24x30-34.



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Pre-build: YAGGM (Yet another granite gantry mill)

Pre-build: YAGGM (Yet another granite gantry mill)