I understand that the Z-axis carriage is supported by the rails rather than the ballscrew, my concern isn’t the vertical force needed to support the carriage, it’s the horizontal force delivered by the ballscrew.
With the screw above the two linear rails like that, whenever the carriage is moved, the X-axis rails are going to be subject to a moment on the same plane as the Z-axis carriage.
Maybe it is a problem, maybe it’s not (probably not), I’m just curious how it ended up like that.
This is the machine I built last year. Exactly same design. SO3 rail is only 80mm high and there’s so little space between the linear rails to fit the ballscrew.
You can attach the ballscrew nut to the side of the Z-axis assembly without using a nut housing/bracket but then you’re slightly limiting your x axis travel - on the machine that has already limited cutting area.
You can mill a more elaborate z axis mount, that incorporates mounting points for the linear rail carriages and ballscrew, similar to what Nomad uses but then it takes much longer to convert the machine, there’s also more room for error.
Finally you can attach the ballscrew above the rail which is the simplest solution. all you need to do is cut one plate that the linear rail carriages bolt to at the same plane as the screw’s nut. Can’t be any simpler than that.
Look how close the screw is to the linear rails. On the machine of this size and the quality of the components (most of which are Chinese knockoffs) used to do the conversion I can bet anything, that the location of the screw has no adverse effects on the cut quality what so ever.
Find it hard to believe that he would have any other reason to do his conversion as he did. It’s all about keeping it as simple as possible, especially that he reused the Y axis plates, so he had to adapt his design to the existing bolt pattern.
The bit that matters (pun intended) is the collet or cutter tip which is already some distance away from the centre of the linear rails. So there’s going to be leverage in the system wherever the ballscrew is located. The only reason to care about deflection in the machine is how it relates to the cutter / workpiece alignment.
That said, the idea of the linear rail bearings is to only have one degree of freedom and they don’t rotate or deflect much for the forces you can create on a Shapoko. The distance between the bearing blocks requires a sideways deflection for a rotation of Z which they’re very good at resisting and that distance is likely dominant in the deflection for any given force.
With the X ballscrew above we have the driving force on one side of the pivot and the opposing cutter force on the other which is a ‘worst case’ so, in theory putting the ballscrew below the axis would minimise the leverage around the pivot point but, deflection is low for the bearing blocks anyway…
Nice model.
Have you taken measurements on the machine of the various deflections, slack and backlash to find out where it’s good and where it could be better?
Now that you’ve exterminated the V wheels I would suspect (but without measurement it’s no more than that) that the deflection due to leverage on the vertical plates at the front / back of the machine may become a significant part of your overall movement.
I think some people feels my Shapeoko is not Shapeoko enough… it has gotten as far as direct messages… weird thing isn’t it?
Is like i should’t be allowed to post on the facebook group… well… i guess i have to add more toys to feed their feelings!!! oh i want to see their eyes when i get the new enclosure finished, or the granite epoxy filled extrusions, oh!!! and the 5ft axis!!! hahahahaha
You always have a place here! Love following the build.
I’m hoping that eventually this becomes a kit like the HDZ did.
Haters are going to hate. I for one love the ingenuity, it gives people a lot of ideas about what they could do to their machines, even if they only choose to do 5% of what you’ve done. Options are always a great thing to have.
Zuckerbergs tracking software does seems to be rather like YouTube comments…
I would say it’s like a car, so long as the original chassis plate with serial number is still there you get to call it a Shapeoko.
Which brings me to ask, can we order replacement S H A P E O K O stickers from support if we have to remove them for some reason?
Respond to these people asking whether their philosophy paper definitively resolving the Ship of Theseus thought experiment has been published yet 
Contact us and let us know the specifics and we’ll see what can be done for stickers/badges/build plates
Like FB, that group is largely disinteresting. I appreciate this forum for its inquisitive and creative participants, and subsequent content. I am glad that it is nothing like those groups, and I hope it stays that way. I appreciate and enjoy your contributions, please continue, at least on this forum.
Where’d you end up ordering from? Looks like you found a single place with a bunch of goodies.
An AliExpress store which is highly recommended by a bunch of users on mycncuk as selling the real HiWin and other decent quality parts at pretty fair prices. He does the rails, ballscrews and the range of linear motion parts. They all came in a big heavy HiWin box, seem to be in decent condition and didn’t cost much more than the non-HiWin generics on Amazon or eBay.
Not sure what the rules are here about mentioning which seller?
You can. The forum rules say “no commercial activity” as in “don’t come and self promote your products here”, but buyer tips are welcome (e.g. Drillman1 on eBay has been referenced countless times for endmills, G-penny spindles, Elaire for collets, etc…). Also, I’m dying to know 
Thanks Julien,
His store on AliExpress is BST Automation here are the rails I ordered which they cut to custom size for you and even ask if you want them cut with even spacing from the last bolt hole to the cut ends of the rails.
They seem to be pretty decent quality, there’s a little lumpiness as the bearings slide but that feels like heavily greased up races.
If there’s anyone with more experience of what they’re looking at here’s some pics of the blocks and rails;
Now I’m off to make a couple of mods to Dan Storey’s HDZ adapter design and then either send that to 3D Hubs or find a local CNC machinist who can bootstrap me with the main mounting plate.
I was looking at online CNC shops and found Xometry to be much cheaper than 3DHubs FWIW.
I checked that out and…
With Xomentry in the USA, delivering to the continental US the $ price was about the same in $ as 3D hubs in £ (so about 80% of the price), the made in China option delivered to the USA was about half the price of the made in the USA version.
But using Xometry.de the European version, the price is slightly higher than 3D hubs for the basic part and additional things like anodised finish are way more expensive than 3D hubs and there’s no made in China option on their European site.
So, it’s the usual, US has more choice and better prices story 
