Thanks for that. Impressive build log.

Thanks for that. Impressive build log.

Looks very good and I'll need to thing about the ball joint connection . My extruder is gimbal mounted but I think the bowden I'm using is currently too long to allow it to move freely. Can' t adjust the length until the print is complete!

For anyone interested I have added a link showing the extruder in operation. I had read that a long bowden compromised performance of printers but am amazed at how much better the printing is with this arrangement.
https://youtu.be/Y3GZLjHfz48

My machine is largely based on David Crockers blog. I have had significant problems with blobbing and stringing which I have been unable to reduce to an acceptable level. Hence the decision to reduce the length of the Bowden by implementing the 4th column.

I have adopted a slightly different approach using a counter balanced linear actuator mounted in the centre of the machine with the extruder and motor attached to the bottom of the actuator.
The arrangement is working well and I have all but eliminated the stringing and blobbing thus far on quite challenging prints.

The downside: when the actuator is at its home position it projects well above the top of the machine which is already 1m high.

Next iteration will be to replace the actuator with a telescopic arrangement again counterbalanced and mounted in the centre but driven with a stepper and capstan wound with 3mm dyneema cord. The stepper will pull the column up but will not drive it down. When stepping down the weight of the counterbalance will lower the column but will be controlled by the stepper. This will significantly reduce projection of 4th column above machine.