I finally sorted out the screws for holding the o-rings in place. The previous ones I purchased were a little too sort to hold three o-rings at once. I was using 4g x15mm and instead I found some 6g x18mm. I had to sleeve the shank as the threads go quite far up the screw and could cut through the o-rings, or at least damage them.
The 6g screws were slightly too big to fit on some K&S 5/32" brass tube, so I held them in a collet chuck int he lathe and filed them down a little,
I little reduction in the screw size and the sleeves fit over pretty well,
I needed a dozen or so sleeves and needed to come up with a quick way of cutting short lengths of brass tube accurately. I grabbed another short length of 5/32" alumnium tube and used it as a stop inside the cordless drill chuck. I cut it just long enough that the brass tube could be inserted in front of it and then cut off flush with the drill chuck jaws to make the correct length.
I cut the brass tubing into the 8.5mm lengths using a Tajima heavy duty box cutter while the drill is spinning. I cleaned the ends up with a needle file in the same drill to remove and burrs.
And here is the difference in the screw sizes. The sleeved screws have a larger bearing area for the o-rings to sit on.
With the o-rings installed.
Little jobs like this seem to take up a lot of time, especially when the specified hardware seems to be unobtanium!
