School me on air collets

[Jim27]

Picked up a benchtop mill with an air hose coming off the top of the spindle. R8 collet. It has a drawbar with flats on the top for tightening that looks like a conventional drawbar. From what I have read I think that springs (beleville washers?) keep the collet closed and air releases it. Does that sound right? How do I tell how tight to tighten it?

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[machinedude]

Picked up a benchtop mill with an air hose coming off the top of the spindle. R8 collet. It has a drawbar with flats on the top for tightening that looks like a conventional drawbar. From what I have read I think that springs (beleville washers?) keep the collet closed and air releases it. Does that sound right? How do I tell how tight to tighten it?

an R8 collet is just 1 form of collet. what you are talking about is a power drawbar which come in a few different flavors. the only two options for a R8 i can think of is what Tormach uses with a special R8 collet with a flat on the face to register a TTS holder which is what actually holds all your tooling and the shank fits the special R8 collet. Or an impact wrench style power draw bar that screws the drawbar from the end of the R8 collet so you can use a different size R8 collet.

only way to know for sure is to tear into it and see what makes it work.an air line alone does not mean the mill has any kind of power drawbar system for all i can tell someone could have had a mist coolant system hooked to the machine and what your seeing is the remains of the air supply connection? i would pull the drawbar out and see what is attached to it if anything?

[Jim27]

I have used the a Tormach so know about that collet system although I don't know exactly how the drawbar works and it's been a while. This one has a R8 collet with taper on the lower end like a typical one although it may not be original to the machine.

This is a stock system as far as I can tell. Don't see how it could be for a mist system. The drawbar isn't attached. Once loosened it pulls right out just like a simple, manual drawbar. It has a plastic cover (again that looks stock) - will have to see if that can be easily removed. I may apply some air pressure and see what happens. The mill has a Yuasa tag with no model number. I sent a request to them with pictures for more info but it looks like about 1980 vintage and nothing like it is on their web site so I may not get anything from them.

Here's a pic. It looks like if the hose is removed the cover can be removed to see what's inside.

[machinedude]

I have used the a Tormach so know about that collet system although I don't know exactly how the drawbar works and it's been a while. This one has a R8 collet with taper on the lower end like a typical one although it may not be original to the machine.

This is a stock system as far as I can tell. Don't see how it could be for a mist system. The drawbar isn't attached. Once loosened it pulls right out just like a simple, manual drawbar. It has a plastic cover (again that looks stock) - will have to see if that can be easily removed. I may apply some air pressure and see what happens. The mill has a Yuasa tag with no model number. I sent a request to them with pictures for more info but it looks like about 1980 vintage and nothing like it is on their web site so I may not get anything from them.

Here's a pic. It looks like if the hose is removed the cover can be removed to see what's inside.

this machine looks like a scratch build honestly. i have never owned a Tormach so i just have a basic understanding of what they have done, with the TTS they use a master collet that never comes out of the machine the drawbar has a spring stack of B.W. and you have an air cylinder mounted over top of the drawbar controlled by a switch to control the air cylinder when the ram on the air cylinder extends it makes contact with the end of the drawbar and compresses the spring stack to release the collet to where it unclamps the tool holder. i guess you could set the system up as a one switch control or have a two switch system to clamp and unclamp depends the design. the impact style i have used were a aftermarket add on for a Bridgeport style mill set up with a switch for clamping and another one unclamping. i would lean towards it being a impact style draw bar if you got a set of R8 collets with it?

i would pull the drawbar out and see what's attached if you have a spring washer stack then you have something like a Tormach TTS system, if not and you see something that would act like a socket to engage to the end of the draw bar i would say it's an impact style power drawbar.