my build from the start

[mmcp42]

Ahh just realised. My method can easily be extended to the general case for n bolts. You just need to know half the angle interior angle of the particular polygon. Then do cosine of that to get the factor...

3 = Triangle, 60/2 = 30, so cos(30)
4 = Square, 90/2 = 45, so cos(45)
5 = pentagon, 108/2 = 54, so cos(54) = 0.5878 (!)
6 = hexagon, 120/2 = 60, so cos(60) = 0.5

The formula to find the interior angle is 180(n-2)/n.
So that means, given n bolts with spacing x.

r=cos(90(n-2)/n)
PCD = 2*cos(90(n-2)/n)

enjoy!

my question is - none of these formulae use x - I'm sure they should somewhere?!?

r= x/(cos(90(n-2)/n))
PCD = x/(2*cos(90(n-2)/n))

[m_c]

should be x/cos(whatever), as you're working out the hypotenuse from the adjacent.

[mmcp42]

fair do's
I've updated by guesswork...

[Jonathan]

should be x/cos(whatever), as you're working out the hypotenuse from the adjacent.

Yes it is, sorry ... was rushing and missed that

[h4ppy-chris]

big time backlash on the z axis so time to investigate and here's what i found.



and here's how i sorted it there was play between the bearings so skimmed 0.76mm of the end cap no more play backlash now down to 0.003

[h4ppy-chris]

well my ally turned up so made a start on the z motor plate
all i could think of when making it was, if the mill was finished i would just be watching it being cut.

[Jonathan]

well my ally turned up so made a start on the z motor plate
all i could think of when making it was, if the mill was finished i would just be watching it being cut.

Similar to how I did it except I mounted the motor plate 90 degrees clockwise to yours, and lathed a bit of 3" aluminum bar to act as a spacer and give a bit more surface area for the motor plate to bolt on to. Doing it that way enables me to use the handle for manual drilling without removing the stepper - I think yours would collide?

[h4ppy-chris]

good point jonathan, i will wait till it's all working then make a new one.

[Jonathan]

good point jonathan, i will wait till it's all working then make a new one.

Here's a couple of photos of mine, pretty self explanatory...

[h4ppy-chris]

cheers mate that's give me some think to think about.