Wyvern – Information – Day 11

I’ve been adding a bit to the design over the last day or two but I’ve been struggling a little with the diagrams provided by Chai (linearmotionbearings2008 on eBay). They look like scans of scans of badly taken photos and are only just readable if you squint. I thought, therefore, I’d try and track down the manufacturers and see if there were original diagrams to be had and for the most part I think I’ve been successful.

Note: I might be wrong with some or all of these manufacturers as I have nothing but what Chai sends through to go on. The art work is a good match in each case and the numbers all line up so I’m pretty sure these are the correct (original) manufacturers – I don’t doubt some of the stuff is a local copy.

Ballscrew Supports

Chai sells BK and BF style mounts which appear to be identical to the ones manufactured by a Japanese company called THK. If you dig around on their site a bit you’ll find information for a wide range of products including the data for BK/BF support units (under ballscrews) or you can download a cached copy here. I’ve checked the figures and as far as I can see they are the same.

Ballnut Mounting Blocks

Manufactured by a Russian company called Aketon and unfortunately their site doesn’t have an English version. Google translate does a fair job though so you can just about navigate around. You can download a cached copy here.


I wasn’t able to track this one down for absolute certain as Chai sends through a Word document with some drawings and a table but no identifying information. They are very close to the ones drawn in the Aketon PDF available in the Ballscrew Mount Blocks section above and I suspect they are local copy.

There are a couple of minor differences to be aware of: the L dimension is generally a millimeter or two longer in the Aketon PDF and the ball diameter varies. Chai’s screws almost all use 3.175mm balls but Aketon Form B use 2.778mm on 1610 screws. From a modelling point of view this shouldn’t be a big issue just make sure you take the L dimension from Chai’s ballnut figures.


I wasn’t able to track down the manufacturer of the ballscrews. There’s quite a few likely candidates and Chai doesn’t offer any information to go one other than the diameter and pitch of the screw. The implication from the ballnut data is that most of the screws use 3.175mm balls but even that doesn’t really help narrow things down much. I doubt anyone will be drawing the thread on their ballscrews though.

End Machining

This is generally supplied as a PDF which means the quality is quite good. The company the PDF comes from is Korean and called SBC Linear. I’m sure if you dig around their site a bit you can find the document but I couldn’t, you can download their whole catalog including the machining apendice from here though (note, it’s about 45MB and comes over a slow connection) – there’s some other good information in the catelog too.


There are some really good models of the supported rails in the Sketchup library so there really isn’t any reason to draw your own. Here are the Chai rail figures.