Posted: 3/11/2014 6:51:00 AM EDT
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We recently got a HMC with pallet changer and 2 tombstones. Whats the best way to locate the tombstone on the pallet for repeatability?
Someone here posted a photo of their shop with a massive pallet change system. Cant remember who. |
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First I am assuming that the pallets only have t-slots.
When I ran one we had sub-plates with precision placed bushings on them. You would use pins in the bushings to locate the fixtures or tombstones. Worked great. You can basically make them on your cnc. If you can afford it, and your pallets are easily changeable you can get other pallets and never remove the tombstones. This is very general but I would need to know how the machine is being used for a better answer. I really miss machining. |
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Quoted:
First I am assuming that the pallets only have t-slots. When I ran one we had sub-plates with precision placed bushings on them. You would use pins in the bushings to locate the fixtures or tombstones. Worked great. You can basically make them on your cnc. If you can afford it, and your pallets are easily changeable you can get other pallets and never remove the tombstones. This is very general but I would need to know how the machine is being used for a better answer. I really miss machining. We have multiple pallets at my shop and we use these precision bushings and pins to locate the entire pallet, rather that just a tombstone. It's very, very rare that we ever have to indicate a tombstone in when using the pins. Our repeatability is well within .001" If you don't have pins, you will have to indicate the tombstone in just like you would a vise. Bolt one corner down and tap it until it's straight. Good luck, I love running our Mazak horizontal. You can do quite a bit more in a horizontal that a vertical. Be cautious if you haven't had experience on one though, they can be a little bit tricky to figure out at first! |
| Right now we have our zero at center if rotation. We mount jig plates on either side of the tombstone. Currently we are using only one tombstone and it is keyed, but the repeatedly isnt good. Im trying to put bushings in the pallet and tombstone then use a pull dowel to locate but my boss doesn't think that will locate any better. |
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Quoted:
We recently got a HMC with pallet changer and 2 tombstones. Whats the best way to locate the tombstone on the pallet for repeatability? Someone here posted a photo of their shop with a massive pallet change system. Cant remember who. TZLVredmist has a couple horizontal Makino's with a pallet pool http://www.ar15.com/member/member.html?id=47383 |
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We purchased both Kurt towers, as well as blank tomb stones. The towers and blanks are both pinned and bolted to the pallets
The blanks are nice, because you can stab pin holes, and bolt locations and change your fixturing as needed. Build the fixturing, change it out, and it's repeatable. |
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Snapped some pics for ya...
This is the blank tombstones, with some fixturing we made. It makes the pallet universal, as well as very scaleable based on production. We can yard that fixturing off, and pin on a new blank and cut. Put it back on, and continue production. You can see the Makino pallets bolt to the sides of the tombstones as well. 
And the Kurt towers..... these are damn expensive, but the jaws are nice for easy parts. 
Whole system, You can see some lowers fixtured in the upper left. 
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Snapped some pics for ya... This is the blank tombstones, with some fixturing we made. It makes the pallet universal, as well as very scaleable based on production. We can yard that fixturing off, and pin on a new blank and cut. Put it back on, and continue production. You can see the Makino pallets bolt to the sides of the tombstones as well. https://lh3.googleusercontent.com/tS0iHQqHv1eK0hDxPgzOF-7I2HWld9jdk8tERjwuXds=w557-h836-no And the Kurt towers..... these are damn expensive, but the jaws are nice for easy parts. https://lh3.googleusercontent.com/-d0roGIPFfNE/Ux9EOhhahZI/AAAAAAAAAuk/VQyPRde4w8w/w557-h836-no/IMG_3324.JPG Whole system, You can see some lowers fixtured in the upper left. https://lh6.googleusercontent.com/-iFbNZSOjNkw/Ux9ENkffdWI/AAAAAAAAAuQ/GnmWuqv9gUg/w843-h562-no/IMG_3325.JPG Thanks a lot. I appreciate it. Hopefully I can talk my boss into doing it the way I want to. |
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We use tombstones on our CNC horizontal milling centers all the time, the only problem is; I've never gotten to run one. So sadly, I don't know the answer yet, OP. I usually run one of the CNC VTL's.
Maybe if I get time today I will ask on of the operators who run them. |
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Subplates with Jergens ball lock system. http://www.jergensinc.com/site/wsg_quick_change_fixturing/ball_lock%C2%AE_mounting_system/ball_lock%C2%AE_components This is highly repeatable, within 0.001 usually if you pay attention to cleanliness. I have subplates on most of my machines with ball lock bushings. Even have vise plates set up this way for use on vertical mills. Well worth the investment for the amount of time saved if you change set-ups frequently. |
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The shop next door uses a full size tombstone base on their two Kitamura's. Both of them have the blocks like the ones in the TZLVredmist pics, that are bolted to the sides of the pallet, and tombstone base.
On their new Okuma they are running a smaller tombstone base that is just bolted down to the pallet. They are using this machine for shorter runs, and quick change overs. Changing out the Chick Jaws instead of swapping tombstones. |
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The shop next door uses a full size tombstone base on their two Kitamura's. Both of them have the blocks like the ones in the TZLVredmist pics, that are bolted to the sides of the pallet, and tombstone base. On their new Okuma they are running a smaller tombstone base that is just bolted down to the pallet. They are using this machine for shorter runs, and quick change overs. Changing out the Chick Jaws instead of swapping tombstones. Thanks. I have bushings and pins ordered. Hopefully I can get it close .Id like to get away from having different origins for each set up and have them all a known distance in Z from center of rotation. |
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heres the table <a href="http://s542.photobucket.com/user/jm0502/media/20140311_114843_zps7d4e4b89.jpg.html" target="_blank">http://i542.photobucket.com/albums/gg415/jm0502/20140311_114843_zps7d4e4b89.jpg</a>  http://youtu.be/eMM4EhtPYLEI wish my work had some machines like this. 
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TZL that looks a lot like the pallet system we had at Edelbrock.. Worked CNC repair there.
The cylinder head line was pretty awesome.. 16 station pallet system and storage racks.. Though cylinder heads have pretty long cycle times so it wasn't moving all the time.. We had around 120 vertical and horizontal Milling stations. Big mix of HASS, Mori, Makino, Matsuwa, ext... Had an awesome tombstone grave yard out back.. We fenced off a small area and put the really bad crashes on display.. Wish I still had pics.. They slowly got recycled back and cut down to make smaller fixtures.. But it was awesome while it lasted.. |
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TZL that looks a lot like the pallet system we had at Edelbrock.. Worked CNC repair there. The cylinder head line was pretty awesome.. 16 station pallet system and storage racks.. Though cylinder heads have pretty long cycle times so it wasn't moving all the time.. We had around 120 vertical and horizontal Milling stations. Big mix of HASS, Mori, Makino, Matsuwa, ext... Had an awesome tombstone grave yard out back.. We fenced off a small area and put the really bad crashes on display.. Wish I still had pics.. They slowly got recycled back and cut down to make smaller fixtures.. But it was awesome while it lasted.. Ouch!!! Any crash is bad, we have yet to have a major crash at all.... I would like to do some turning work for Edelbrock and have been trying to get some work from them for a while. we have some 8-Axis Nakamura's for those kinds of fun parts. |