Type-VII o-ring question for David

[pjdog]

I had purchased a type-VII S/D kit some weeks ago. I recently assembled the kit and removed the hardware (adf, receiver, Lipo guard, snort) from my broken type-VII S/D and placed that hardware in the new S/D. When I went to press the battery end bulkhead of the new S/D into the cylinder I had a hell of a time keeping the o-ring in its place. I kept trying to slide out of the o-ring grove. I thought that all the o-rings where the same size and never took any time to look them over. Was I right in assuming that the o-rings are all the same size? Or did assume get me again.

Jack

[He Who Shall Not Be Named]

Not all lots of 2" o.d X 1/16" wall thick Lexan extruded tube is of the exact same dimensions. Hence the need for me to custom cut the o-ring groves in the bulkheads to suit the specific diameter of cylinder I'm dealing with -- that's why a bulkhead from one cylinder may not fit another cylinder of supposed like dimensions. The industry tolerance for dimensions of Lexan tube is very large.

I sometimes accommodate this disparity of tube size from one batch to another by varying the tension on the o-ring itself: I may use a 1.75" on an over-sized cylinder, and a 1.5" O-ring on a tight fitting bulkhead. Often, when you're swapping bulkheads between different cylinders you'll find that one bulkhead will fit just fine in one cylinder, but might not fit at all to another; just the situation you find yourself butting your head up against right now.

If your O-ring is too tight you have two choices: either go in there and file the bulkhead grove a bit deeper, or substitute a smaller diameter O-ring.

Welcome to the wonderful, sometimes chaotic and tail-chasing, world of SD production.

David,

[Rick Teskey]

Hi Dave
I concur with the inconsistent size of tube.
My cure is too go deeper and shim the o ring with 1/8th pin stripe, cheap and easy .
I know shut the f up dam squid throwing so and so
Rick

[He Who Shall Not Be Named]

Hey! Who took the Canadian block down!? Mike and I had worked so hard to block posts from that hated nation.

Anyway, the evil north has somehow punched through our elaborate security filters.

And I have to admit, I never thought of that cure for a loose o-rings. Good one, Rick. In the past I have used Teflon anti-seize tape to fatten up the groove to tighten the fit between O-ring and cylinder. The pin-striping idea is far superior. I like it.

Oh, and don't be put off by Mike's shot at RCABS. We're secretly working with a stunningly small solenoid and related miniature devices in support of a 'special project'.

Thanks for the tip, Rick.

David,