4331
General Mach Discussion / Re: A Power Drawbar Like No Other....
« on: May 17, 2012, 05:17:57 PM »
As a GENERAL rule YES they share the basic geometry.
ON a R8 the drawbar force and the clamping force of a collet are 2 different things. I solid tool holder is easily held with light drawbar force. A collet type on the other hand would slip the tool easily with the same light force you can use on a solid.
To calculate the drawbar force one needs to the know the angle of rotation of the drawbar, thread pitch and the size and type of steel used for the drawbar. Torque really does not come into play.
The angle of rotation X the pitch tells you the stretch of the drawbar .
Torque is not an accurate way to determene the amount of stretch. Yes it acan get you into the ballpark(;-)
When Dave Dec did his ATC he wanted to KEEP the R8 spindle as a cost option. He modify the Cat30 holder by Regrinding it to the SAME angle as an R8 and used a gripper to pull the holder tight into the taper. BUT that is also NOT a Bridgeport type type spindle he was working with.
I'll look up the Utube page for you.
(;-) TP
ON a R8 the drawbar force and the clamping force of a collet are 2 different things. I solid tool holder is easily held with light drawbar force. A collet type on the other hand would slip the tool easily with the same light force you can use on a solid.
To calculate the drawbar force one needs to the know the angle of rotation of the drawbar, thread pitch and the size and type of steel used for the drawbar. Torque really does not come into play.
The angle of rotation X the pitch tells you the stretch of the drawbar .
Torque is not an accurate way to determene the amount of stretch. Yes it acan get you into the ballpark(;-)
When Dave Dec did his ATC he wanted to KEEP the R8 spindle as a cost option. He modify the Cat30 holder by Regrinding it to the SAME angle as an R8 and used a gripper to pull the holder tight into the taper. BUT that is also NOT a Bridgeport type type spindle he was working with.
I'll look up the Utube page for you.
(;-) TP