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Phil
Originally Posted by R.DesJardin
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Has anyone just made a static tool exchange that say holds four tools? We just bought a new EDM at work and it has a rack of forks on the left end of the travel that holds 4-5 electrode holders. Seems like a simple setup for the Tormach. I've only had my Tormach a couple weeks and do like it, but most my projects relly only need a few tools.
RAD. Yes those are my initials.
Idea, design, build, use. It never ends.
http://www.hossmachine.info/Videos8.html
Phil
There seem to be some developments, one of them the ATC that is also being dicussed in this forum. They all come up with nice solutions to find the tool - the challenge with the most question marks seems to be "how do I lock the tool in the tormach spindle" - a question that would also have to be answered by a static TC.
Tormach TTS style holders with 3/4" R8 collet and powered drawbar.
Phil
I was aware of the TTS.
I would be a little uneasy about the "powered drawbar" portion
benji
Why?
Phil
I would be a little uneasy about the "powered drawbar" portion
benji
Look at your post #61 in that thread.
If the designer wants the tools in and out of the spindle automatically (look at all the adjustments he makes) and wants enough rigidity for "the real men's stuff" than there will be a lot of torque on drawbar and a permanent corresponding side pressure (-z direction) on the bearings. The bearings are made for -z cuts and take the +z pressure - but do they stand the double pressure (extra power by powered drawbar + cut to -z)? Only time will tell since bearings wear out slowly.
Involuntarily I took a look at a spindle and its bearings - not tormach but very similar. To my mind they are not made for a long term pressure of this kind of force. (I know with tormach it is all different)
I would not be able to proof this, it is just my gut feeling.
The last thing I want to do is discourage the genius that develops that thing.
benji
Seems like a person could build a fairly simple ATC for 5-6 tools. For an R-8 spindle you would have to work without the key. I would use a 3/8" butterfly air wrench mounted above the spindle with a deep socket over the end of the drawbar. A push-pull solenoid would operate the forward-reverse. The socket could be set so that when the drawbar is loosened it would travel up into the socket until it bottomed out, once it could no longer move up, then the force would push the tool out of the spindle. I would make a drawbar with a piloted end so the threads would not get crossed up. For the holder, you could make a simple rack on the end of the X Y table that would hold the tools. Each tool would be coded, and when you want to change, your program would move the table so that tool "A" would drop out of the spindle back into its empty slot and then the table would move tool " B " under the spindle and the quill would move down to engage the drawbar. Those air wrenches should hold up under high speed spindle RPM, and they are really so cheap you could toss them after a while if they wear out. Seems like the whole thing could be built for a few dollars.
I do R&D work for a living, designing machinery for new processes and I think at first glance the collet release looks to be the simplest part to design. But that's at first glance so don't flame me, since I don't know the background on what's been tried. I'll be looking into it after I get more accustomed to running the mill. Having it operating making my parts is first priority right now. I try to follow what to two guys building tool changers are doing because I am intrigued.
Merry Christmas and God Bless,
RAD. Yes those are my initials.
Idea, design, build, use. It never ends.
The vanilla power drawbar, with spring washers and air cylinder, only applies a load to the spindle bearings when you activate it. With some compromise you can limit this load to acceptable limits. It is possible to design a "floating" activation arrangement with an air cylinder that never applies any load to the spindle bearings and does not limit the load you can apply, other than the spindle shaft tensile strength. Also the "air wrench" design doesn't apply any load to the spindle bearings during activation.
None of the above systems apply any load to the spindle bearings when the spindle is running. The drawbar, as per manual use, is pulling against it's own bootlaces.
Phil
Look at your post #61 in that thread.
If the designer wants the tools in and out of the spindle automatically (look at all the adjustments he makes) and wants enough rigidity for "the real men's stuff" than there will be a lot of torque on drawbar and a permanent corresponding side pressure (-z direction) on the bearings. The bearings are made for -z cuts and take the +z pressure - but do they stand the double pressure (extra power by powered drawbar + cut to -z)? Only time will tell since bearings wear out slowly.
Involuntarily I took a look at a spindle and its bearings - not tormach but very similar. To my mind they are not made for a long term pressure of this kind of force. (I know with tormach it is all different
I would not be able to proof this, it is just my gut feeling.
The last thing I want to do is discourage the genius that develops that thing.
benji
I guess we will have to see what the designers come up with. Let us take a look at the final product and then have a discussion with a real life example. How many ATC's with a draw bar system do we know? I have yet to experience one, but I am looking forward to see it.
I'm probably showing my ignorance but I thought a powered draw-bar was kinda the standard for this class of machine, and most other classes too.
Phil
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