Fourth Axis replies

I have posted three files to the file section of this list.
They are called 4th axis.jpg - 4th axis1.jpg and Helical.jpg
The first two are of a 4th axis I built using a rotary table converted to
vertical mounting.
This was a 120:1 ratio with the fast release mechanism to free the worm off
for manual moves. I adjusted this as carefully as I could to remove the
backlash. I found one tight spot and freed that off with Brasso as a
lapping compound.
I have driven it by toothed belt drive with a reduction drive to convert it
to 90:1 ratio.
This is because at 400 steps per rev 120:1 didn't work out to a dead figure
of a degree. It was 0.002777 degrees per step.
90:1 works out to 0.01degrees per step, less chance of error.
The first picture show the general layout without the timing belt cover.
Centre hight is just short of 7 1/2". In this photo is also the layout I
have chosen for the Ahha retrofit as regards screen and keyboard. Also
shown is the setup I use on all the millers as regards the vise. These are
always put in trays to stop the coolant filling my boots <g>
It also makes it easier to clip a plastic screen around the tray to act as
an enclosure for flood coolant. There are three holes in the tray all in
line with the tee slots. Two are for the vise and the third is the drain.

The long shaft leaning up against the machine is a 3 metre ball screw off a
laser cutter. The rest of the controller is on stilts to get it out of the
way
The last photo called helical.jpg shows a brass helical gear being cut
using this setup. The cutter is a shaped 'D' bit cutter as my CNC cannot
swing the head over to the helix angle to allow a normal gear cutter to be
used.
Normal use of this setup is just for dividing as part of the CNC program
but I have cut quite a few gears with it. The Ahha setup has a very good
macro language with it so you can automate a lot of these process's like
gear cutting and keyways.
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Regards,
John Stevenson
Nottingham, England