first attempt at end covers

well its my first attempt at a end cover hope to improve with the next one bolts for holding in lathe

Willie, that looks damn good to me. Nice and flush to the cylinder, double O ring...very good indeed.


Richard

very neat what size is it and where are you going to get your o-rings from

the  size is to fit 58mm id tube  made it from20 mm thick  Perspex  I cut out blanks with a 73mm hole saw  2 from 105mmx150 mm Perspex blanks which I go 2 off  on e-bay for just over £6 also ordered 53mm id x3mm o- rings off e-bay      the main sizes are outer od 63mm inner od 58mm  6mm lip the slots are in 2mm  from the end 3x2.5mm then 3
mm space then 3x2.5mm slot

up at b&q today picked up some O-rings to give it a try 35mmidx3mm fitted with a wee struggle  to the cap but very nice fit in the tube

Hi Wilte,
Are you saying that the o ring grove is 3mm wide and 2.5mm deep,and the o ring section is 3mm,if this is correct you need to open up the sides of the grove to allow for the expansion when the o ring is compressed otherwise you not get the end cap out when the have been in place for a few days,personally I would open the grove to around 4mm, but the width is not of any importance to the sealing,when I do piston tanks I would make the grove 2mm wider than the section of the o ring this causes the o ring to roll in the grove and that action breaks the initial grip that the seal has on the cylinder, the same principle applies with your end caps you need the o rings to roll in the grove slightly to break the seal when you pull them out.

thank you nigele, I am still thinking of the old days when I use to machine and fit o rings to hydraulics use to work out the area of the seal and leave a mm for compression

your welcome sir,there is a formula for radial o rings I have it somewhere but it really don't work on acrilic tube it's a bit trial and error,the tube is so rippley and the tolerances are all over the place I have seen a 2mm tapper in a tube 12 inches long,its worth looking at silicon o rings they are much softer and are more forgiving,
anther tip make sure you sand the ends of the cylinder so there are no marks or scratches if you don't I have known the tube to crack all the way along it,Richard has had this happen to him,it is one of the problems with radial seals,and why I use compression seals instead but that comes with it's own set of problems.

took nigele advice and got some silicon O-rings I got then from polymax 53mm id x2.65 mm they are25 pence each but your order must be above £10 but below £15 and free postage

a robbe pump fits ok just a plate  and bracket to make now