BT30 Drawbar Screw - for tightening or depth adjustment??

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madebymccoy
Posts: 27
Joined: Tue 13 Dec , 2016 23:36 pm
Hardware/Software: Novamill
- in process of upgrading controller to Mesa I/O and LinuxCNC
- retrofitting head with power drawbar
- and next year, raise column by 70mm

Microrouter V3

Micromill 2000

BT30 Drawbar Screw - for tightening or depth adjustment??

Post by madebymccoy » Thu 29 Mar , 2018 17:35 pm

Hi,

Can anybody confirm the purpose of the screw that's fitted to the bottom of the BT30 drawbar?

On the drawings there's no mention, other than the thread size.

From my understanding, its purpose is to give you something to hold when tightening the Bellville spring compression nut at the top of the shaft. Simply stick a screwdriver up through the toolholder and into the screw head, and use a pin-spanner to turn the top nut. (Holding onto the toolholder won't help, as that is actually independent of the shaft and BT30 petal).

However, I've heard some people claim it's for adjusting the how much the petal holds onto the pull stud. I think that's nonsensical, as every other BT30 petal I've seen and mechanism relies upon the drawbar pulling the toolholder into the taper as tightly as possible. Doesn't make sense to limit how much the pull stud is gripped by, as the pull stud is designed to be latched and pulled.

Any input welcome!

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