The new unofficial ATC idea thread

[ihavenofish]

Originally Posted by smallblock As far as these tool changers go, its the same principle- look at how they are done by companies that have been around for many years. Chances are they have tried every style and design before and know what works and what doesn't.

while there something to be said for not repeating the mistakes of others... if all anyone did was copy designs because "everything else must have been tried already" we would never have a new product.

we would have no tormach TTS, or HSK, or Mach3... cause thats not how everyone else did it.



as for the atc... has anyone noticed these:
http://www.kelinginc.net/CNCSpindleandController.html

toward the bottom theres BT30 spindles. water cooled, 15000 to 24000 rpm, 1.5 to 10hp and have pneumatic drawbars release. by the specs and sizes they look to be very good matches for machines like the tormach and kx3/novakon/smithy.

if i recall the tormach cartridge dimensions correctly, the 85mm models could be given a nice steel mounting plate and replace the tormach spindle with no modifications. just remove the old one, its motor, and belt assembly. the kx3 has a smaller spindle bore, so it would need more modifications to use it.

seems like an interesting option for those who want an atc, as well as higher speed and/or power. of course its more money than just using the r8 collet and tts style tooling.

[digits]

Originally Posted by ihavenofish while there something to be said for not repeating the mistakes of others... if all anyone did was copy designs because "everything else must have been tried already" we would never have a new product. we would have no tormach TTS, or HSK, or Mach3... cause thats not how everyone else did it. as for the atc... has anyone noticed these: http://www.kelinginc.net/CNCSpindleandController.html toward the bottom theres BT30 spindles. water cooled, 15000 to 24000 rpm, 1.5 to 10hp and have pneumatic drawbars release. by the specs and sizes they look to be very good matches for machines like the tormach and kx3/novakon/smithy. if i recall the tormach cartridge dimensions correctly, the 85mm models could be given a nice steel mounting plate and replace the tormach spindle with no modifications. just remove the old one, its motor, and belt assembly. the kx3 has a smaller spindle bore, so it would need more modifications to use it. seems like an interesting option for those who want an atc, as well as higher speed and/or power. of course its more money than just using the r8 collet and tts style tooling.

Those spindles look nice, and to my mind not insanely priced, but they don't look great for cutting metal - except perhaps Aluminium. According to my calculations, the 4.5kW/6HP one only has about 1.8Nm of torque - which isn't going to drive a 25mm drill through steel! I would also like to see the load rating of the bearings - my guess is they're high speed but lowish load.

[digits]

Originally Posted by philbur There ya go, and if you fixed the upper sleeve in the spindle the mechanism would automatically release on the down stroke, without the need of a "separation" spring. Assembling it in the spindle with the balls might be a bit of a challenge though. What does the arrangement of a commercial equivalent look like. Phil

I would have thought you could tape/glue/clingfilm the balls in place and then dissolve out the glue, or pull out the tape once it's assembled.

Have you seen this excellent thread on building a BT30 spindle from scratch?

http://www.cnczone.com/forums/showthread.php?t=41200

It shows the components of a working ball gripper - though according to HO, the gripper appears to be causing some runout by not pulling evenly on the pull stud

I did see something else interesting on Practical machinist recently - an advertisement for a multi-part spindle, which had a removable taper!

http://www.cnczone.com/vb....html?t=181519

I don't know if they're any good, but check out the picture - the taper is just a component of the spindle, so in theory, it might be possible to bolt a new taper on the front of your R8 Tormach one, and use the space left for the R8 toolholder's shaft to install a drawbar gripper. Obviously the taper would be further out from the spindle bearings, but it might be interesting!

[ihavenofish]

Originally Posted by digits Those spindles look nice, and to my mind not insanely priced, but they don't look great for cutting metal - except perhaps Aluminium. According to my calculations, the 4.5kW/6HP one only has about 1.8Nm of torque - which isn't going to drive a 25mm drill through steel! I would also like to see the load rating of the bearings - my guess is they're high speed but lowish load.

well, most high speed spindles tend to be geared to small tools and aluminium or plastics. steel with 25mm drills dont need it. but yes, i agree that they might not be a suitible all purpose single spindle for certain people. - but since tormach offeres a bt30 option for low speed, a "one tool changer for all" could work here.

as for 1.8nm torque. thats at 24000rpm - and likely intermittent duty. continuous stall at 1000rpm-ish drilling steel is assumably much higher, but no way of knowing without a curve. torque needed to drill steel with a 1" bit at 1ipm is about 6nm or so says my calculator - which may be wrong. it likely doesnt have 6nm at stall though but who knows.

but at the same time... why drive a 1" drill through steel? why not a 1/2" end mill in helical interpolation?