Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: derek on December 27, 2012, 11:48:04 AM
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Well like so many people after seeing Dave DeCaussin's ATC on you tube I had my “I want that!” moment.
The thing that put it over the top for me was being able to regrind the r8 to work with the BT30. I settled with using the 4 ball gripper design and Belleville washers for the drawbar pressure. My quill is locked and I use the knee for the Z axis so that made things a little easier. All of the drawbar parts are A2 that I hardened and tempered. The drawbar has about 1000 lbs of pressure. I’m using a 4” Bimba flat multi power cylinder. I needed the multi power as I don’t have a ton of travel on my Bellevilles. I’ve been using the drawbar setup since July and have had zero problems. I took it apart about 2 months ago and it looked perfect.
When I started working out my design for the ATC I was going to have the carousel on the end of the table and have the X axis bring it over to the spindle. I had a job come up where I really needed some sort of changer so I knocked together a quick tray type. One thing became immediately apparent was that I was running the crap out of the X axis. So out went that idea and I settled on a more traditional “fly it in” design. Over the course of time I settled on a 3 stage system. One stage down to line the forks up with the tool. one stage to engage horizontally and one stage to bring the tool down out of the spindle. There are proximity sensors at the end of each travel. The M6 macro is written so that it operates in a follow the leader fashion. When the first stage proximity activates it triggers the next stage. This works really great and is very safe. I opted to use slides from cncrouterparts. They are inexpensive, well built and really versatile. They are designed to work with 80/20 extrusion and 1/4” CRS flat bar. I’ve used them in a couple of other projects and I was really happy. The carousel is driven by an extra servo motor I had and is designated as a C drive. Spindle indexing was supposed to accomplished with the new Delta VFD-M I purchased but unfortunately it didn’t play nice with my 2 pole motor. I ended up going with a shot pin arrangement until I can afford a new motor.
Terry (BR549) wrote really slick macro for me that makes it all work. He has the spindle stop then turn slowly to the index signal. It then kills the spindle and shoots the pin. Another neat thing he did was instead of having a fixed position for the tool change he uses the “tool change position” DROs on the setup screen. This allows me to position the tool change at the most efficient spot for each setup.
I’m a big proponent of working out designs in 3D before committing to actual construction. The first thing I did was model my mill as closely as I could. I included the table and a couple of Kurt vises. You can download 3D files of the vises directly from Kurt. This allowed me to run the table through it’s motions and get a better idea of what kind of envelope I had to work with.
(http://i1086.photobucket.com/albums/j459/Datsunworks/tool%20changer/millonly.jpg)
Then I proceeded to model the rest of the components as I worked out all the motion and clearance issues. Although his kind of modeling takes time I find for me the end product is so much cleaner. Plus I build it a few times in the computer so when it’s time for actual construction I have a good idea of what I’m doing. Most of the purchased components offered 3D files so this made things a lot easier.
(http://i1086.photobucket.com/albums/j459/Datsunworks/tool%20changer/Full.jpg)
Even 3D files of the pokeys were available.
(http://i1086.photobucket.com/albums/j459/Datsunworks/tool%20changer/close.jpg)
The build was fairly straight forward. Most items were made from .5” thick 6061. I have a small anodizing line so I anodized everything. The extra holes in he parts are for mounting things if necessary. When I prototype I put extra drilled and tapped holes all over the place so that if I have to add something it’s not a big deal.
(http://i1086.photobucket.com/albums/j459/Datsunworks/tool%20changer/DSC_0003.jpg)
I opted for a traditional fork design with tension spring to retain the tools. It took a few designs to get it to slide over the balance holes drilled in the tool holders.
(http://i1086.photobucket.com/albums/j459/Datsunworks/tool%20changer/DSC_0001.jpg)
I also engraved the tool slot numbers in the edge of the carousel. Not sure how well this will work when I get the cover on.
(http://i1086.photobucket.com/albums/j459/Datsunworks/tool%20changer/DSC_0002.jpg)
Using the 80/20 extrusions and cncrouterparts slides made designing things like brackets much easier to build. They have 3D models available for all their components.
(http://i1086.photobucket.com/albums/j459/Datsunworks/tool%20changer/DSC_0007.jpg)
(http://i1086.photobucket.com/albums/j459/Datsunworks/tool%20changer/DSC_0010.jpg)
I’ve done a few thousand tool changes in an actual machining environment and only had a few bumps and those were caught by the proximity system.The things I’m going to change are pretty minor. The main vertical movement is too short. The tools collide with my splash guard mounted on the table. I have plenty of height and the higher I can get the tools the less chance chip contamination there will be. Coincidentally I didn’t model the splash shield in my original model and now I’m paying the price. I also have a bit of tidying up to do but I’ll do that after the vertical mod.
Having an ATC has opened up a whole new set of things I can bid on and has already paid for the price of the parts in the few jobs I’ve done with it. Plus it was a gas to build and that in itself made it worth it.
Here's a couple of videos. The first one is a normal change with a 6000 rpm spindle speed and spindle indexing. The second one is an earlier macro before the indexing was hooked up but it shows the speed of the change.
Thanks for looking
Derek
http://youtu.be/Zcv-ej45Ka0 (http://youtu.be/Zcv-ej45Ka0)
http://youtu.be/kxhk0KC6UjI (http://youtu.be/kxhk0KC6UjI)
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Very nice! But I'm wondering why you don't use your quill? I ran my knee mill for about 18 months using the knee as the Z axis, and, besides being painfully slow (50 IPM, compared to 250 on X/Y), I saw significant wear on the leadscrew and bevel gears, and it's not hugely accurate, due to lead error in the leadscrew. I added a quill drive, which has been wonderful. Now I use the knee to apply tool length compensation, so I always have full quill travel for every tool.
Just finished my own 10-tool ATC: http://www.youtube.com/watch?v=54s0aoAT37o
It's great fun watching it work for the first few days, isn't it?
Regards,
Ray L.
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Very nice! But I'm wondering why you don't use your quill? I ran my knee mill for about 18 months using the knee as the Z axis, and, besides being painfully slow (50 IPM, compared to 250 on X/Y), I saw significant wear on the leadscrew and bevel gears, and it's not hugely accurate, due to lead error in the leadscrew. I added a quill drive, which has been wonderful. Now I use the knee to apply tool length compensation, so I always have full quill travel for every tool.
I have gas springs on the knee so I have no trouble hitting 120 ipm with the knee. For the work I do it's plenty accurate. 15" of travel comes in pretty handy doing pattern work.
Just finished my own 10-tool ATC: http://www.youtube.com/watch?v=54s0aoAT37o
Oh I've been following your exploits! I actually thought about the swing arm arrangement but because of space issues it didn't go very far for me.
It's great fun watching it work for the first few days, isn't it?
You got that right! For me it's been more of a "holy crap it actually works!!!" kind of thing.
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What are you using to move the knee? I've had, at various times, up to four gas springs on mine, but never got above 75 IPM, using an 850 oz-in DC servo driving through a 48:1 reduction: 5-pitch leadscrew, plus original bevel gears, plus a 4.8:1 belt reduction. I assume you have a ballscrew on the knee?
Kinda funny.... I considered an approach similar to yours, but ruled it out due to space issues! :-) It would've required extending the table enclosure at least a foot further to one side to make room.
Regards,
Ray L.
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What are you using to move the knee? I've had, at various times, up to four gas springs on mine, but never got above 75 IPM, using an 850 oz-in DC servo driving through a 48:1 reduction: 5-pitch leadscrew, plus original bevel gears, plus a 4.8:1 belt reduction. I assume you have a ballscrew on the knee?
I'm using an old Pacific Scientific treadmill motor and a Rutex 2020 drive. If I run it at 120 rapids the motor gets a little warm so I keep it at 100 so I have a little overhead. I'm not in that much of a hurry. I've been running it like this for at least 6 or 7 years. you can tell by the pictures the mill get's a lot of use. Other than replacing the springs every so often it's been fine. I plan on changing over to pneumatic cylinders and a reservoir tank at some point.
Kinda funny.... I considered an approach similar to yours, but ruled it out due to space issues! :-) It would've required extending the table enclosure at least a foot further to one side to make room.
It's absolutely what works for one won't work for another type of thing.
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great atc, looks very similar to the denford system. One observation though, you will need to cover the gear drive on the carousel as it will hold swarf and jam up relatively easily, a geneva mechanism was introduced to get past this problem.
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great atc, looks very similar to the denford system. One observation though, you will need to cover the gear drive on the carousel as it will hold swarf and jam up relatively easily, a geneva mechanism was introduced to get past this problem.
Covers??? we don't need no stinkin covers!!!
Actually they're next on the list. I have a vacuum forming machine so I'm going to knock out a set from ABS.
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That is a nice changer, much prefer the motorised rotation myself :)
Hood
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i hate the geneva mechanism, but it does do the job when there's swarf about. The motor / gear drive is much nicer.
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Looks looks a great thing. Did you have to regrind the spindle to fit the bt30 gripper in?
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Looks looks a great thing. Did you have to regrind the spindle to fit the bt30 gripper in?
Thanks.
no there was enough room after grinding the taper for the gripper to fit.
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The reason I ask is I have a bp clone with a nt30 and would love a tool changer but didn't think I had enough room for a gripper without modding the spindle.
Also how did you get your mill to 6000rpm. Did you use an inverter and turn up the hertz?
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The reason I ask is I have a bp clone with a nt30 and would love a tool changer but didn't think I had enough room for a gripper without modding the spindle.
Also how did you get your mill to 6000rpm. Did you use an inverter and turn up the hertz?
I run my knee mill up to 8200 RPM. It's a 2-/4-pole AC motor, and I run it up to 90Hz in 2-pole mode, and 160Hz in 4-pole mode. Been running that way for years with no problems at all.
Regards,
Ray L.
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IF you have a QC30 or nt30 spindle and switch to bt30 tool holders the tool holder will be shorter and should give you plenty of room up top for a gripper. Just make sure if it is a QC30 spindle that the center hole is present in the spindle shaft not all QC30s have the center hole
Just a thought. (;-) TP
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The reason I ask is I have a bp clone with a nt30 and would love a tool changer but didn't think I had enough room for a gripper without modding the spindle.
Also how did you get your mill to 6000rpm. Did you use an inverter and turn up the hertz?
I have a 2 pole motor that's rated at 3450 so I overdrive it a bit. In hind sight I wish I had bought a 4 pole and drove it a 120 or more hz to get the rpm. The 2 pole motor made indexing tricky and it has no guts in low rpm situations.
If you don't have a drawbar hole in your spindle then your dead in the water. If you do then I would measure the bore of the area above the taper, Check it for run out, and then measure the distance from the base of the bore to the face of the spindle nose (not the dogs). If you give me those figures I can quickly tell you if there is room.
I'd like to know myself. My neighbor has that spindle but without the drawbar hole and there didn't seem to be enough room above it to hold much.
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Looks like 14.2mm then opens up to 17.5mm to accept the shank of the nt30 (17.00mm)
Are you guys running those sort of revs with the vari speed heads or pullies? I have turned up my inverter 10hertz above standard and to be honest thd vari head doesn't sound like it enjoys it to much so turned if back down.
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Hi!
Really good worked, look really nice! I´m building my own ATC and BT30 gripper system right now so input for you would be great.
Regarding the drawbar and gripper, did you make it yourself and do you have picture of it? What ballsize do you use?
I have build a 6x5mm ball gripper but I get dents on the pullstud (using 45deg) and don´t know if this is normal since it could affect runout I assume.
I´m using about 800pounds of force from bellevilles springs.
I also have a VFD with 2 pole 3-phase engine and planing to use index signal to orient the BT30 holder. Can you provide more detail about the shot pin, picture of it would be super?
BR/Andreas
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Looks like 14.2mm then opens up to 17.5mm to accept the shank of the nt30 (17.00mm)
Are you guys running those sort of revs with the vari speed heads or pullies? I have turned up my inverter 10hertz above standard and to be honest thd vari head doesn't sound like it enjoys it to much so turned if back down.
No, mine is a step-pulley. I think you'd be pushing your luck running a VariSpeed that fast.
Regards,
Ray L.
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Sounds like its time to put a bushing kit in the varispeed.
(;-)TP
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I've had a few requests for the M6 Macro.
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Regarding the drawbar and gripper, did you make it yourself and do you have picture of it? What ballsize do you use?
I have build a 6x5mm ball gripper but I get dents on the pullstud (using 45deg) and don´t know if this is normal since it could affect runout I assume.
I´m using about 800pounds of force from bellevilles springs.
I also have a VFD with 2 pole 3-phase engine and planing to use index signal to orient the BT30 holder. Can you provide more detail about the shot pin, picture of it would be super?
Nothing special on the gripper. Just the same 4 ball that everyone else has done. I'm using .187" balls and about 1000 lbs of pull. I just checked my pull studs and I have no signs of wear.
My mill has a step pulley. I'm using a small pancake cylinder. It was double acting so I took it apart and added a return spring. No chance of it coming down unless it's told to. The rod came drilled and tapped for an 8/32 bolt. I cut the head off of the softest screw I could find and screwed it in the cylinder rod. That way it MAY shear off if there is a problem.
(http://i1086.photobucket.com/albums/j459/Datsunworks/tool%20changer/DSC_0005.jpg)
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Looks like 14.2mm then opens up to 17.5mm to accept the shank of the nt30 (17.00mm)
Are you guys running those sort of revs with the vari speed heads or pullies? I have turned up my inverter 10hertz above standard and to be honest thd vari head doesn't sound like it enjoys it to much so turned if back down.
I don't think 14mm is a large enough diameter. The pull stud head is 11mm. It may be possible though. If you give me some complete dimensions I'll plug that into my model and see how it looks.
I'm using a step pulley.
Derek
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What type of pull stud do you use with ball gripper? 45deg?
I'm using 45 deg from ctc toolz and have clear marks with less force than you.. Hmm
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What type of pull stud do you use with ball gripper? 45deg?
I'm using 45 deg from ctc toolz and have clear marks with less force than you.. Hmm
I'm using a 45 degree. I mostly use the ones from Mari tool
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Thanks for your answers, how about the shot pin arrangement for spindle orientation? Pictures would be great, since i can´t see it on the other pictures?
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That small cylinder next to the aluminum rod in the picture above is it.
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how does the shot pin idea work ? thanks Mark Moog madness