@David_Moorhouse Now that you mention it, the truss design is interesting, I imagine it not only gives load bearing against gravity, but provides robust torsional rigidity as well, much more so than a standard cube frame. Are the top and bottom just MDF? I’m still messing with a new design, and debating on kinematics, framing, and flat plane material. You sir, have made the decision even tougher. Super clever design, totally thought out of the box, pun intended
The Tinkercad pages for the top and bottoms bits for a simple truss are
At present it has poles at 30 degrees from vertical but I think 20 - 25 degrees to make it a bit taller may be better. I’m getting my prototype done first 
It is indeed very rigid, I have aligned telescope mirrors within 0.1 mm using these sort of trusses and they just stay put, no vibration, zero flexure and cheap to make
Hmmm… I may need to borrow the truss frame design for some fixtures at work
Thanks for those extra insights @David_Moorhouse and welcome to the community :). As @Sanjay_Mortimer mentions, synchromesh might be a worthy candidate to replace the spectra.
Over on the reprap forums, @Dale_Dunn came up with the bright idea of using the Y-stage design for a Z stage drive too. That would mean you can use only 1 motor with a pulley and 6 idlers to drive a Z stage without the need for printed gears and drive shafts as I’ve used in my Ingentis design.
I am thinking of using that idea but putting the motor at the top so I only need 5 pulleys. I got mine on ebay
20pcs 624VV V Groove Sealed Ball Bearings Vgroove 4 X 12.6 X 6mm 1.7mm deep
@Tim_Rastall hmmm… Sounds very interesting. Can you post a link to the thread please?
Excellent, Thanks!
I hope to have a Z stage using this cable idea done in the next few days.
@David_Moorhouse Excellent, please post plenty of pictures
It is being harder than I hoped to get the Z stage done, a few failed prints and solids where I needed holes for cables. I love design work 
@David_Moorhouse tell me about it. Of course, the awesome thing for us is that once you’ve fixed it, you can just press print and wait for new parts
hahaha that’s true. I’m trying a bit to hard in that I’m combining the lower Z axis pulleys with the truss tube mounting point. I should model the entire thing to make sure things work. Printing Mk2 test parts right now, it is starting to look good actually.Biggest issue now is exact alignment of the holders for the two vertical rods so that they are square and parallel to each other. I only have flat baseboard and top plate with no real reference points to go from.
It seems Richrap has taken this idea to a full working model, pity I didn’t get any credit for bringing this idea to the 3D printer world from him. However good on him for making a working model that others can now easily copy. I still definitely feel this is a good XY design and should make very smooth prints. I got lazy and my main printer broke so I never got one actually functioning but I got it moving nicely.https://www.youmagine.com/designs/sli3dr-pronounced-slider-3d-printer#!design-information
@David_Moorhouse Apologies for not mentioning your work on the same system, It was not at all intentional.
I excitedly started working on the concept from the Sketch @Tim_Rastall posted when this was all being talked about last year. The Sli3DR design was finished around March time, but has taken me a while to get the drawings clean and release all the source files so everyone who likes the idea can benefit.
I have corrected the @YouMagine page and my Blog posts about Sli3DR (both of them) and included you and links to G+ - I have also included a link to your blog about cablebot. I can also link to any source files if you have released them?
I do all my designs simply for the RepRap community and fun of doing it. I don’t expect anything in return for releasing my files into open source. Apologies again if you felt you didn’t get credit for bringing this into the RepRap world, I have done my best to correct that.
And please contact me anytime if you have any questions or want to collaborate on anything, 3D printing or otherwise.
Cheers,
Rich (RichRap)