dgfoster
Diamond
- Joined
- Jun 14, 2008
- Location
- Bellingham, WA
In a another current thread a poster mentioned tha Beaver mills used pins to positively locate nod and inclination of their mill heads. I have long mused about adding such tapered locating pins to my BP head. I thought I’d start a new thread here rather than derail that thread
First a couple questions:
1) I assume that taper pins are used in that application.
2) What size pins are used?
3) In actual practice how accurately do they tram the head?
I am wondering if pins would provide the degree of accuracy that I like to achieve when face milling things like straight edges. I find that the difference between a nice crosshatch flat pattern from my face mail versus a slightly concave pattern can be a matter of only maybe 5 thousandths of movement of the Facemail when measured against the table as I pivot the head slightly. I wonder if that tiny increment of rotation would be locked in that accurately by a pin or not. Or does the pin provide a pretty close approximation of trim which in the final analysis has to be touched up a bit anyway to get really accurate tram?
I suppose one disadvantage of the pin might be that in the event the cutter encounters unexpected resistance, a pin would prevent slight rotation which can prevent a more serious crash should such pressure-relieving rotation not be possible.
Anyway, I’m interested in pertinent thoughts and experience on the subject.
Denis
If my math is correct, rotating the head enough for a .005” deflection on a roughly 20” arm is a 2 arc-second rotation. A common precision level uses a 20 arc-second vial.
First a couple questions:
1) I assume that taper pins are used in that application.
2) What size pins are used?
3) In actual practice how accurately do they tram the head?
I am wondering if pins would provide the degree of accuracy that I like to achieve when face milling things like straight edges. I find that the difference between a nice crosshatch flat pattern from my face mail versus a slightly concave pattern can be a matter of only maybe 5 thousandths of movement of the Facemail when measured against the table as I pivot the head slightly. I wonder if that tiny increment of rotation would be locked in that accurately by a pin or not. Or does the pin provide a pretty close approximation of trim which in the final analysis has to be touched up a bit anyway to get really accurate tram?
I suppose one disadvantage of the pin might be that in the event the cutter encounters unexpected resistance, a pin would prevent slight rotation which can prevent a more serious crash should such pressure-relieving rotation not be possible.
Anyway, I’m interested in pertinent thoughts and experience on the subject.
Denis
If my math is correct, rotating the head enough for a .005” deflection on a roughly 20” arm is a 2 arc-second rotation. A common precision level uses a 20 arc-second vial.