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Thread: Granite and steel gantry router

  1. #1
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    Default Granite and steel gantry router

    I am putting this in the wood router forum even though I plan on cutting metal and wood with this machine. Here is my progress so far.

    I started with a 24x36x4 granite surface plate. It came from KBC tools and cost about $370 including shipping. I built a stand for it out of 2x4 wood and 3/4 inch particle board. The surface plate is supported at 3 points only. This forms the base of the machine and it was used to lap the other parts flat. I also indicated against this plate to straighten the linear rails.
    .Granite and steel gantry router-img_20181107_193442-jpg

    The gantry is built from a piece of 8x8x27 inch steel tube with a 1/2 inch wall. I bought ground strips of mild steel and grouted them to the gantry tube with a mix of epoxy and 220 aluminum oxide grit. The ratio was about 75 percent aluminum oxide and 25 percent epoxy by volume. The mix was a little thicker than chunky peanut butter. The ground steel strips were placed against the surface plate to force them to be flat. Spring washers were stuck in the epoxy to provide uniform force to hold the steel strips flat to the surface plate. I used xylene to clean all surfaces to be grouted and roughed them up as well with a sander. I added concrete blocks to increase squeeze out.

    .Granite and steel gantry router-img_20181119_192530-jpg Granite and steel gantry router-img_20181119_193820-jpg

    After the epoxy set I flipped the tube and measured the flatness of the steel strips with an indicator. It was out by about 0.002 inches. I decided to lap it the rest of the way. I tried using a small surface plate and two sheets of sand paper but the flatest I could get was about 0.0015 inches probably due to my technique. I decided to lap the gantry against the big plate to get it flatter. I glued four sheets of 100 grit paper to the big plate and lapped for about 20 minutes. This got me to better than 0.001 inches of total flatness. I finished lapping with a sheet of 220 on the smaller plate (not pictured) and got a nice finish and about 0.0007 inches to total flatness error. I decided to stop at this point.

    Granite and steel gantry router-img_20181124_190457-jpg Granite and steel gantry router-img_20181124_221915-jpg

    Next was mounting the X master rail. I moved the tube to the floor and brought the drill to it. I temporarily clamped the rails to the tube and used a transfer punch to mark the hole locations. I drilled and tapped the holes in an afternoon. The drill needed to be sharpened a few times because of the aluminum oxide and epoxy layer. I used 5/16-18 bolts to mount the HSR30 rails.

    Granite and steel gantry router-img_20181125_175453-jpg

    Once the holes were tapped, the tube was put back on the granite table and the master rail was indicated in. I got it straight to better than 0.0003 inches. Once the master rail was attached I verified its flatness with the smaller grade A surface plate. The needle on my 0.0005 inch indicator did not move much at all.

    Granite and steel gantry router-img_20181126_183600-jpg Granite and steel gantry router-img_20181126_183631-jpg

    Continued in the next post because I hit the 8 image limit...

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    Attached Thumbnails Attached Thumbnails Granite and steel gantry router-img_20181107_193442-jpg   Granite and steel gantry router-img_20181119_192530-jpg   Granite and steel gantry router-img_20181119_193820-jpg   Granite and steel gantry router-img_20181124_190457-jpg  

    Granite and steel gantry router-img_20181124_221915-jpg   Granite and steel gantry router-img_20181125_175453-jpg   Granite and steel gantry router-img_20181126_183600-jpg   Granite and steel gantry router-img_20181126_183631-jpg  

    Last edited by multivactubes; 12-05-2018 at 02:44 PM.


  2. #2
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    Default Re: Granite and steel gantry router

    Next I indicated the second X rail using the master rail as a guide. I got these parallel to about 0.0002 inches I estimate.

    Granite and steel gantry router-img_20181126_194138-jpg

    With the X axis rails mounted I moved on to the the Z axis mounting plate. I used 1 inch thick cast tooling plate to build the Z assembly. The plate is flat to about 0.002 inches over its 16 inch length. I may lap it at a later time but I have yet to see it cause any problems. I printed a paper template and glue it to the plate. I then used a punch to mark each hole and drilled all the holes with a drill press. My drill press has a reverse switch and a momentary run switch so I can easily power tap. The Z rails are NSK LH25 rails and mount with 1/4-20 bolts. I used a gun tap to thread the holes.

    Granite and steel gantry router-img_20181128_184722-jpg Granite and steel gantry router-img_20181128_195719-jpg

    I mounted the Z axis plate to the X axis rails and then mounted then Z axis linear rails to the plate. I used the smaller granite surface plate to indicate the master Z rail in then indicated the secondary rail in from the master. Like the X rails these Z rails are quite straight. I squared the Z to the X axis at this point using a ground angle block and my indicator. I did this by rotating the Z plate slightly and sweeping the indicator back and forth against the angle block. I acheived a squarness of about 0.001 inches over 6 inches and decided this was good enough. I then tightened the Z axis plate against the X axis trucks.

    Granite and steel gantry router-img_20181128_200516-jpg Granite and steel gantry router-img_20181128_203755-jpg

    At this point I tried sliding the Z assembly along the X rails and noticed no binding. You can feel the preload in the rails though and it takes a little force to move across the X travel.

    I then started on machining the spindle mounting plate. I made a paper template once again and drilled and tapped the needed holes. This plate required counterbores and machining as well which was done on my X2 mill. I ended up breaking a plastic gear in my X2 and had to rebuild the spindle during this job. I replaced all the gears with metal and swapped the bearings to sealed versions as well.

    Granite and steel gantry router-img_20181201_164841-jpg Granite and steel gantry router-img_20181201_185045-jpg

    I mounted the spindle plate to the Z axis rails and checked for binding but did not find any. I made another paper template and drilled the holes in the spindle clamp. The back of the spindle clamp was lightly lapped and then the spindle was attached to the spindle mounting plate.

    Granite and steel gantry router-img_20181201_185853-jpg

    Continued in next post....

    Attached Thumbnails Attached Thumbnails Granite and steel gantry router-img_20181126_194138-jpg   Granite and steel gantry router-img_20181128_184722-jpg   Granite and steel gantry router-img_20181128_195719-jpg   Granite and steel gantry router-img_20181128_200516-jpg  

    Granite and steel gantry router-img_20181128_203755-jpg   Granite and steel gantry router-img_20181201_164841-jpg   Granite and steel gantry router-img_20181201_185045-jpg   Granite and steel gantry router-img_20181201_185853-jpg  

    Last edited by multivactubes; 12-05-2018 at 02:48 PM.


  3. #3
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    Default Re: Granite and steel gantry router

    Nice work.

    Gerry

    UCCNC 2017 Screenset
    http://www.thecncwoodworker.com/2017.html

    Mach3 2010 Screenset
    http://www.thecncwoodworker.com/2010.html

    JointCAM - CNC Dovetails & Box Joints
    http://www.g-forcecnc.com/jointcam.html

    (Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)


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    Default Re: Granite and steel gantry router

    Here is what the gantry looks like with the spindle test fit.

    Granite and steel gantry router-img_20181202_171743-jpg

    I had a small company machine the ballscrew mounts for me as well but his tollerance was very loose so I am having to remachine many of the important surfaces and use some shims. I may recut all these parts with the machine once it's made. Here is a test fit of the X asis screw. The X and Z screws are THK 2005 ground ballscrews. The fixed end supports are Kuroda FK15 preloaded angular contact bearings.

    Granite and steel gantry router-img_20181205_075800-jpg

    I sent a drawing of the gantry support legs to a fabricator as well and am waiting for them to be made.

    Granite and steel gantry router-screenshot_20181205-115445-jpg

    Attached Thumbnails Attached Thumbnails Granite and steel gantry router-img_20181202_171743-jpg   Granite and steel gantry router-img_20181205_075800-jpg   Granite and steel gantry router-screenshot_20181205-115445-jpg  


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    Default Re: Granite and steel gantry router

    Your machine is going to be awesome mate, keep up the progress!



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    Default Re: Granite and steel gantry router

    Here is where I am at on the Z ballscrew assembly. I finished the machining on the mounts. I also cut the ballscrew to length which was not easy. I tried to part it off on the lathe but it was far too hard. I tried a carbide tool as well but that did not make much progress either. I ended up grinding through it and used a damp rag to keep it cool.

    I used the indicator again to align the screw to be parallel to the rails to within about 0.002 inches. I tested the Z axis by driving the ballscrew with a drill and did not detect any binding.

    Granite and steel gantry router-img_20181209_194259-jpg
    Granite and steel gantry router-img_20181209_194220-jpg

    Attached Thumbnails Attached Thumbnails Granite and steel gantry router-img_20181209_194259-jpg   Granite and steel gantry router-img_20181209_194220-jpg  


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    Default Re: Granite and steel gantry router

    I completed the mounting of the X axis ballscrew.

    Granite and steel gantry router-img_20181216_161054-jpg

    The welded support columns came in as well and I am getting ready to turn them flat.

    Granite and steel gantry router-img_20181216_161040-jpg

    Attached Thumbnails Attached Thumbnails Granite and steel gantry router-img_20181216_161054-jpg   Granite and steel gantry router-img_20181216_161040-jpg  


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    Default Re: Granite and steel gantry router

    I had some time off for the holidays so I made a decent amount of progress on this machine. The columns were put in the lathe chuck and the end plates were skimmed flat and square to the 5x5 inch tubes.




    I lapped the ends of the columns as well so they will make good contact with the granite machine base.



    I machined a custom tool to tighten the nuts that hold the ballscrews to the angular contact bearings.



    Next I worked on the motor mounts. There are turned aluminum spaces 2.25 inches long. The couplers are Oldham style.

    Granite and steel gantry router-img_20181223_003126-jpg

    I tapped holes in the gantry tube to mount the columns as well and I did a mock-up to see how it looks assembled.



    I am getting missing steps at some speeds maybe due to resonance issues. This will have to be fixed before I use the machine. I have had it up to 120 IPM even with these issues and it does not seem to be binding. I may order some hybrid stepper motors and boost the voltage to see if I can stop the missing steps. Right now I have 415 in/oz steppers which don't produce much torque at speed.

    Attached Thumbnails Attached Thumbnails Granite and steel gantry router-img_20181223_003126-jpg  


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    Default Re: Granite and steel gantry router

    Next was the hard part- drilling 38 holes in the granite plate. I used a 14mm sintered diamond drill I bought on eBay. After 38 holes it still has plenty of life left. I made a hole in a piece of tile not pictured and used it as a guide to start each hole. I used the HSR 25 rails as a guide for a transfer punch to mark each hole location on the granite.

    Granite and steel gantry router-img_20181229_165434-jpg

    I drilled each hole submerged in water. I took a pvc fitting and machined one side flat and stuck this cup to the granite with grease for each hole. The cup was then filled with water.


    Granite and steel gantry router-img_20181229_194520-jpg
    Granite and steel gantry router-img_20181229_205550-jpg

    The rails and clounms seem like they will fit.

    Granite and steel gantry router-img_20181230_190540-jpg
    Granite and steel gantry router-img_20190101_195421-jpg

    I turned 28 of these inserts so far. They are 1/4-20 coupling nuts that I turned mostly round and knurled to increase grip. I am not any good with knurling so some of the inserts have a course pattern and some are fine.

    I left some of the hex intact on each insert to provide resistance to pull out and twisting.

    Granite and steel gantry router-img_20190101_195520-jpg

    Attached Thumbnails Attached Thumbnails Granite and steel gantry router-img_20181229_165434-jpg   Granite and steel gantry router-img_20181229_194520-jpg   Granite and steel gantry router-img_20181229_205550-jpg   Granite and steel gantry router-img_20181230_190540-jpg  

    Granite and steel gantry router-img_20190101_195421-jpg   Granite and steel gantry router-img_20190101_195520-jpg  


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    Default Re: Granite and steel gantry router

    Nice work. Where did you get your granite slab?



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    Default Re: Granite and steel gantry router

    Quote Originally Posted by 1Jumper10 View Post
    Nice work. Where did you get your granite slab?
    Thanks. The granite came from KBC tools. It cost about $370 including shipping. Grizzly is a good option too for about the same price but they were out of stock at the time I ordered.

    Here is a progress update:

    I cleaned each hole in the granite with a vacuum, then water, then acetone, then vacuumed again.

    I put 0.03 inch thick fiber washers between each insert and the mounting holes on the machined surface of the gantry support legs. The washers are used to force the inserts to sit below the surface of the granite.

    Granite and steel gantry router-img_20190102_201155-jpg

    I then mixed up some epoxy and added about 50 percent aluminum oxide power by volume. This mix is about like creamy peanut butter in that is will slowly flow and roughly self level.

    The process of epoxying in the inserts is done in two stages. First, a small amount of epoxy is put in each hole and the support columns and insert assembly is set in the holes. The amount of epoxy in the holes is limited so that there is no squeeze out to accidentally stick the support legs to the granite. After this first round of epoxy hardens the bolts are removed, the leg is removed, and a second batch of epoxy is applied to fully secure the insert.

    I clamped 123 blocks to the granite to help get the columns in the right place.

    Granite and steel gantry router-img_20190102_201215-jpg

    I also used a piece of angle iron to align the columns. At this point there is a small amount of epoxy in each hole and the inserts are hanging down into the holes.

    Granite and steel gantry router-img_20190102_212313-jpg

    Here it is the next day and I am applying the second round of epoxy from the top to fully secure each insert. I bought some syringes from McMaster to make applying the epoxy easier. The mix is the same as before - 50/50 epoxy and Al oxide grit.

    Granite and steel gantry router-img_20190103_200025-jpg

    Here is what an insert looks like with all the epoxy added.

    Granite and steel gantry router-img_20190104_233909-jpg

    At this point I loosly mounted the columns and set the gantry on top to see what the machine looks like. You can see I am starting to get the Y axis rails in place as well.

    Granite and steel gantry router-img_20190105_195137-jpg

    Finally I set up guides, installed inserts, and poured the first round of epoxy to attach the Y rails.

    Granite and steel gantry router-img_20190106_200837-jpg

    Attached Thumbnails Attached Thumbnails Granite and steel gantry router-img_20190102_201215-jpg   Granite and steel gantry router-img_20190102_212313-jpg   Granite and steel gantry router-img_20190102_201155-jpg   Granite and steel gantry router-img_20190103_200025-jpg  

    Granite and steel gantry router-img_20190104_233909-jpg   Granite and steel gantry router-img_20190105_195137-jpg   Granite and steel gantry router-img_20190106_200837-jpg  


  12. #12
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    Default Re: Granite and steel gantry router

    This is really awesome work.



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