I have done lots of testing and have found the following.
The bed on my delta is made from 6mm aluminium plate with a 280mm diameter piece of 6mm float glass on top. The plate is secured to the printer floor in 3 places corresponding to the 3 towers using 6mm bolts. Between the floor and the bed plate are 3 heavy springs. This means I can adjust the plate up or down easily using the bolts whilst keeping a constant upward force on the bed plate. The advantage of being able to adjust the bed manually is it means there is less tweaking with the end stops during calibration. I much prefer each end stop to need the same amount of adjustment in the firmware.
I started with off with a MK2B 24Vdc heater for my bed but unfortunately the time taken to get to 110ºc was nearly 50 minutes, and that is even with insulation on top of and under the bed. This pre-heat time was just too much for my liking so I have changed over to a 220vac 500w silicone heater pad form Keenovo. It will get the bed to 110ºc in just over 4 minutes which is much better. Yes you have to be more careful with mains voltage but with the correct wiring and precautions there is no problems.
Testing the bed for movement whilst heating.
To my surprise even with the full aluminium construction, 30x30mm extrusions, 12mm linear rods and additional supports the frame still flexes when printing as confirmed buy putting a dial gauge on the bed and pushing the frame. It's not much but enough. To fix this I am going to fold a 0.9mm sheet steel skin that will be fastened to the frame. This skin will tie the whole printer together and should stop all flex. to my understanding the flex was causing small ripples in the prints as each ripple always followed the same plane.
Bowden Tube Extruder
After watching the bowden tube in action I am going to suspend the extruder above the hotend to give as shorter tube as possible. I have found that the retracts are very hard to get precise and there is far too much fiddling involved to get this right, or should I say nearly right.
Once the enclosure has been complete I am going to rig up a fume and particle extraction system. the idea is to recirculate the air within the chamber so as to not pull the heat from it which will affect the ABS prints. There will be a turbo mode that can be turned on just before the door is opened to scrub the last of those pesky smells that we love to hate.
this is where I am still on the fence. I have had great results with Cura and Kisslicer but haven't fallen in love with either. Each have there pro's and con's but Simplify 3D has caught my eye but not being able to download a test version it is a concern given the outlay if I don't like it or it doesn't suit my printer. I have seen it in action at my CAD software vendor and heard good things but I am still on the fence.
I have been working on a dual extruder end effector in CAD but it is still very much in the thought stage but something I want to get going. Even if it just to print soluble support it would be great.
Anyways, just a quick update but will try to add more post sooner rather than later.