Ray, Scotts piece was a real work  of art  I have a picture of it on the wall in the shop as inspiration.  What is really the heart of ANY tool changer is going to be a workable spindle WITH the tool change claw to hold the tool holder. There are ISO20 tool changers used on routers and then you could do cat30 type.

There are also some R8 adaptors that MIGHT be able to be adapted to a working solution. They have lugs to keep the tool locked and use tool holders NOT collets.

STILL though the claw mech is the bogie bear to any good tool changer.



AS to the spindle I would use a quality steel and have it NITRIDE hardened on the surface. Then do a deep cryo cycle to stress relieve and then finish grind to spec. You would also need to make sure the area inside the shaft where the claw mechanism would work is hard as well to prevent wear. Make sure to harden the spline area as well.

(;-) TP

Terry,

   Thanks for the chops........  (btw, did you like that hotswap I sent your way.........?)

Ray,

      I was building it for an aftermarket "Plug and Play" ATC for the tormach. But, the guys on the CNC zone in the tormach thread, said, that it must be able to cut
a 1" depth of cut, with a high flute 1/2" AL mill bit with out pulling out.......   Just like a video on Tormach web site shows there tool holders doing.

I was cutting ok at 3/8" no problems.  But at a 1" depth of cut it was a no-go.  I was unwilling to take the liability risk in selling it as is, even with the statement, dont cut
past 3/8", because sure enough, someone would, and then here comes the lawyers.......

Greg had given me a "Price Point" that he did not want me to exceed of max 3k per unit (1/2 the cost of the Tormach). To get it to hold reliably my opion is that I would
need to add a Pull Stud on the R-8 collet, and a locking Cam as well. That would have added another level of complexity to the system. Realistically, it would have pushed up the price past Gregs price point, since I would have to factor in, Support, warrently, insurance etc.

The one I build was targeted at the "Industrial/Commercial" client, not the hobbiest, thus the high price point. It was build to industrial standards, the PLC and ATC controls
where in a Nema 4 enclosure, there was a DL06, BOB, stepper amp, SMC manifold/with solinoids, Proxes on the physical ATC for error cheaking/movements.

Tell you what, I will sell mine to you including the I.P. for 8k, (includes the M6 and other macros/brians), you can then add the Pull stud system...  heheehe

scott

Terry,

   Thanks for the chops........  (btw, did you like that hotswap I sent your way.........?)

Ray,

      I was building it for an aftermarket "Plug and Play" ATC for the tormach. But, the guys on the CNC zone in the tormach thread, said, that it must be able to cut
a 1" depth of cut, with a high flute 1/2" AL mill bit with out pulling out.......   Just like a video on Tormach web site shows there tool holders doing.

I was cutting ok at 3/8" no problems.  But at a 1" depth of cut it was a no-go.  I was unwilling to take the liability risk in selling it as is, even with the statement, dont cut
past 3/8", because sure enough, someone would, and then here comes the lawyers.......

Greg had given me a "Price Point" that he did not want me to exceed of max 3k per unit (1/2 the cost of the Tormach). To get it to hold reliably my opion is that I would
need to add a Pull Stud on the R-8 collet, and a locking Cam as well. That would have added another level of complexity to the system. Realistically, it would have pushed up the price past Gregs price point, since I would have to factor in, Support, warrently, insurance etc.

The one I build was targeted at the "Industrial/Commercial" client, not the hobbiest, thus the high price point. It was build to industrial standards, the PLC and ATC controls
where in a Nema 4 enclosure, there was a DL06, BOB, stepper amp, SMC manifold/with solinoids, Proxes on the physical ATC for error cheaking/movements.

Tell you what, I will sell mine to you including the I.P. for 8k, (includes the M6 and other macros/brians), you can then add the Pull stud system...  heheehe

scott

Scott,

1" DOC with a 1/2" endmill seems a bit over-aggressive to me....  But I normally rough with a 1/2" 3-flute, 1/2" DOC, 30 IPM for a full slotting cut.  Do you think it'll do that safely?  If you've followed this thread, it appears to me that at a 2000# drawbar tension, the torque capability of the Tormach holder is at least 10X the worst-case actual continuous cutter torque, which seems to me plenty of margin for handling any impact loads and other transients.  But, if your experience says otherwise, I'd like to understand the limitations as well as possible, before sinking any more time and money into this.

Regards,
Ray L.

Ray,
 just wondering if you ever considered the impact wrench type powerdrawbar for this? If you did was there a reason you decided against it?
Hood

Ray the problem you wil run into with the  tool moving in the collet holder is from 2 things .One is the short taper of the r8 and 2 is the impact load of each flute .

The tool sets up a resonate vibration which causes the taper to hinge on itself. This when the frequecy is right will allow the holder to release the tool microscopicly in stages. Over a short period those stages add up and the tool has moved under the directional  load of the helix.

SCOTT, the hot swap is a cool tool.  I will NOT be converting the BOSS over to a tool changer but I will use a carrasel to hold the tools needed. I will be the robotic arm (;-) so it is still very usefull as a tool platform to present the tools for each program. That in itself MIGHT be an interesting product. A tool carrasel to hold and present the tools needed for each job powered by Mach3. Just load up the tools and mach will present you with each tool AS needed.  (;-) Simple to make and HANDY as all get out.  The HOTSWAP would make it very practical to boot as when you changed out the tool the new tool would take the place of the old tool (;-)  The Hot Swap TOOL carrasel is a marketable product with little to NO liability(;-)

We are still looking for a good donor VMC to do a complete retrofit complete with tool changer, that coupled with the new Version of Mach M3v4 will be the cats meow.

On the THC we went ahead and bought a kit from Tom C. , needed to get it done and working. SORRY :-(

(;-) TP

Ya know, another approach occurs to me....  Let's assume we do require even 5000# of drawbar tension.  This is trivial to achieve with Belleville washers.  The only "gotcha" is how to generate the even larger force required to release the drawbar.  Getting 5000# force with pneumatics is difficult - it requires either very high pressure, and/or a very large (and $$$$) cylinder, and/or some major mechanical advantage.  However, a simpler approach just occurred to me - Compress the springs using a scissors arrangement (like I already have), powered by a screw, driven by a stepper or servo with a very high mechanical reduction.  After all, speed is not an issue.  The torque required would, I think, be easily generated by a stepper with a large reduction.  With the existing mechanical advantage (6:1), the torque on the screw would be only about 5 foot-pounds....

Regards,
Ray L.

Ray have you check inside the spindle to see how much room is in there above the toolholder?? May be room enough to setup a claw mech and just use an R8 with a pull stud. May have to shorten the R8 to have room??? I would work towards that end for simplicity. R8 tool holders are low cost compared to ANY Other solution.


BUT before you give up TRY what you have (;-) You may be surprised. The grip on the tool holder can be effected by the surface finish. A turned holder will NOT have the grip a ground holder will (;-) do to the actuall surface contact area.  DON"T stop developing intill YOU see it as NOT good enough OR the large lady with horns on her hat sings.

I also would run as large a diameter for the tool holder stub as I could. Largest collet holder 3/4 or 1" ??  I think if you stayed in the 3/8" tool range it would work just fine After all it is a cnc and you can take as many smaller cuts as needed. It is not like you are standing there CRANKIN the handles all day (;-)

I saw earlier that one of the small Xseries 2,3,4,5 etc of bedmills is using a simalar setup with a large diam stub and a slot for the changer grip arm. Look on You tube I think X4 tool changer

GIT_R_DONE DAWG 

     SIDE note:  NEVER stop a developement project JUST because someone said it won't work (;-)  I have done a LOT of things in the past that weren't suppose to work. (;-)

Just a thought, (;-) TP

RAY here is the Youtube example

http://www.youtube.com/watch?v=6CChUHOAknc

With you upper mech and this lower setup I believe you will be just fine (;-)

Just a thought , (;-) TP

I think I will add a pull stud with lock on my project as time/money permits.......

scott

RAY here is the Youtube example

http://www.youtube.com/watch?v=6CChUHOAknc

With you upper mech and this lower setup I believe you will be just fine (;-)

Just a thought , (;-) TP

Terry,

First, I haven't given up yet, but I'm close.  And not because anyone else said it wouldn't work, but because I have other things to do, and this project has already taken far more time and money than I had hoped.  I originally considered both this approach, and the impact wrench approach.  The impact wrench had the advantage of being dirt cheap ($50?), though it seems crude to me.  This approach had the (apparent) advantages of simplicity and elegance.  However, the decision was based on the assumption that the required drawbar tension was in the 1000# range.  This assumption was wrong - the required tension is as much as 5X that, which gets very difficult to deal with.  Had I known that at the outset, I would never have gone down this road.  Getting above about 2000# becomes quite difficult.  What I have, even in it's original incarnation, would work just fine on a small mill, like and X2 or X3, with perhaps 1000# tension, but is not up to the loads of a full-size knee mill.  I am running production, so going to smaller tools/more passes is REALLY unattractive.

That one in the YouTube video is an X3, and I'd be willing to bet the owner considers a 0.100" cut with a 3/8" endmill to be *really* heavy.  I run all day long at 1/2" DOC, or more, at fairly high speed (30+IPM), so having a tool pull out would be a very bad thing, in terms of scrapped material, lost time, and potential danger. 

In retrospect, I tend to think the impact wrench approach is the simpler, cheaper, and safer, way to go.  But I still think it's crude.  Adding a pull-stud does nothing to mitigate the problems with this approach, unless I give up collets entirely.  It is the very high drawbar tension requirement that is the issue, and that is just a fact of life with R8.  I am going to consider this approach - in fact, I did very early on - but it presents a different set of problems.  For one, I don't know how you make an ATC to swap R8 tools.  At a minimum, it would require removing the alignment pin, which I'm not real keen on.  It greatly increases the vertical room needed to make a toolchange - though at least alignment would be easy, since the "mouth" of the spindle is so large compared to the top end of an R8 tool.

Regards,
Ray L.