Hi, I know this may well be mission impossible, but I am seeking an oil pressure indicator button that was used in the civilian m20's from 1937-1939, it was mounted in the fuel tanks instrument cluster.
Would anyone have a spare ( for sale ) or know if there is anyone remanufacturing these?. I thought I would ask before I start the process of making one.

Rgds Dave

Gerard van Putten from the Netherlands made drawings to make them. Gerard made a very good working replica and parts proved to be interchangeable with an original.

Henk.

email (option): ahum@quicknet.nl

They're written in them funny measurments, they're not in that new fangled "Metric" are they??

email (option): davmax@ntlworld.com

Metric and Euros, that's the future

Hi Henk, thank you for the drawings thats very good. I now have an option to make if I can not source the real item. Thank you very much for your help.

Do you know if Gerard is making them, or did he just make the one?

Rgds Dave

tommy the way things are going at the moment i don't thing there is much future in the euro

email (option): roger.beck@node6.com

hi,can someone who speaks german decipher the parts legend in the bottom right corner,then we may know whats what
cheers rick

email (option): richardholt@rocketmail.com

Rick I think you mean Dutch! Ron

email (option): ronpier@talk21.com

email (option): ahum@quicknet.nl

Hi Henk, I have E mailed you off forum...

Just out of interest on the metric thing I'd like to draw your attention to the following conversion chart that some European forum members may find useful, I notice that some of the dimensions are non standard imperial sizes (I'm pretty sure that the tell tales were made in imperial measurenments)so it may come in handy when doing engineering drawings. I know that a lot of imperial sizes of metal are "non preferred" but they are still available with only just a little bit of hunting. It appears that the only materials that are harder to get in imperial sizes are tubing. Anyway, heres the link http://www.hamuniverse.com/antfrac.html

email (option): davmax@ntlworld.com

email (option): n.gentner@bigpond.com

Hi Neale, I have sent you a PM.

Rgds Dave

email (option): d.weston@virgin.net

Hi neale

Could you please e mail me with information / details

Many thanks

Jo'b

email (option): Jonnyob1@googlemail.com

Where do they get their feed takeoff from?

Douglas,

BSA OIL PRESSURE BUTTON, FOR TANK TOP PANEL, 14 individual parts, originally made by Rotherham (also made “Bonniksen” instruments). Fits many pre WWII BSA models.“Nitrile” oil proof diaphragm material. Machined from solid brass, as original. Stainless spring & pivot pin. All parts interchange with original. Individually pressure tested to 100Kpa.

Replaces BSA part # 66-8234. $300.00 AU.

Plus postage from Australia

Weight is 92g. plus packaging.

WARNING!

Do not insert anything except low pressure oil into BSP threaded orifice.

The most critical part of this indicator is a fabric reinforced Nitrile diaphragm of 0.008" thickness.
(Original diaphragm was waxed pig skin)

These indicators are assembled and dismantled from the button end only!



Have PM'd Dave and John

Rick
1 & 9 = main body, NOTE: originally machined in one piece, as mine are.
2 = support ring
3 = diaphragm
4 = piston/pusher, movement limited by major dia (this prevents diaphragm rupture)
5 = combined button guide and spring retainer NOTE: originally formed from brass sheet, as mine are.
6 = spring
7 = washer/thrust-plate, pushed from beneath by lever, spring above returns.
8 = locknut below panel.
9 = see 1, thread is 1/4" BSPP
10 = button/indicator, originally hard rubber (washer/thrust plate is screwed to bottom of button)
11 = top nut (chrome)
12 = combined retainer, guide and pivot for lever
13 = lever (amplifies small movement of diaphragm into greater movement of button)
14 = Pivot pin, retains lever 13 in 12.
Not shown: countersunk screw, (fixes washer/thrust plate to bottom of button)
Not shown: oil baffle, presses into bore of BSPP union, restricts oil and destructive tools from accessing fragile diaphragm (I don't replicate these)



My combined button guide and spring retainer, cut from brass sheet by water-jet, pressed with special tooling, underside shown.

Operation:
The oil pushes against the diaphragm 3 which lifts only approx 2mm before movement arrested by support ring 2 and piston/pusher 4.
The piston/pusher 4 lifts the lever 13 approx 2mm at about mid-point.
The free end of lever 13 pushes against outer edge of washer/thrust-plate 7, which causes black button to emerge from top nut (chrome) 11 by about 5mm.

Yes I can be considered a rivet counter and proudly wear the T shirt!

email (option): n.gentner@bigpond.com