[fastbike]

... time flies by ....
I got the X axis set up using a 20mm x 5mm pitch ballscrew I'd bought cheap. I attached the ballnut to the carriage as detailed above, and used a modified BK15 support on a new end plate I machined for the left hand side from some 10mm steel plate. This has been ok for a 2D partial CNC, but I need to get the Z Axis conversion done and then I can make some improvements to the X axis adaption to address some of the shortcomings:
- increase X travel from 300mm to closer to 360mm by moving the dovetail shield curtains further out
- support the free end of the ballscrew to allow higher rapid speeds without the possibility of whiplash
- decrease the distance the stepper sticks out on the left side of the machine
- making a new endplate on the right side to tidy things up, currently the hole from the original acme screw bearing is covered by gaffer tape.

I'll attach some photos that I took while converting the X axis. I will do some more design and upload some sketches over the next month to show further changes I want to make on this mill.

[fastbike]

Here's the ballnut screwed into the carriage. The original endplate at the left end of the carriage has been removed along with the dovetail curtains.

[fastbike]

Here's the replacement endplate with the BK15 support. This bolts into the end of the carriage and the stepper motor is then attached using stand offs and an Oldham style coupler
Attachment 474484

[fastbike]

And a final photo before the motor was attached. This shows the chip tray reattached - the original fastening posts were too long with the additional thickness of the endplate (from 3mm on the original to 10mm) so had to be remade in a shorter length. The original endplate is sitting on the mill table. The dovetail curtains have been refitted.

[fastbike]

One of the improvements I'm designing is to locate the main thrust bearing at the other end of the carriage, and use a floating bearing to support the end connected to the motor.
I found an interesting thread on why a floating bearing is still required at the motor end. My initial though had been to just rely on the coupling, but on reflection a bearing is still required.