The Steamboating Forum

Does anybody have or know where I can get engineering drawings of Penberthy injectors as I would like to have a go at turning up a couple of spare parts such as the threaded cap and tails and the steam jet for a 1/2" BSP standard pressure AA injector.

Thanks - Keith

Tunneltug wrote:Does anybody have or know where I can get engineering drawings of Penberthy injectors as I would like to have a go at turning up a couple of spare parts such as the threaded cap and tails and the steam jet for a 1/2" BSP standard pressure AA injector.

Thanks - Keith

Save yourself a lot of heart aches and trouble. Buy the parts from Penberthy or get them from someone else. Simply Google "penberthy injector" and see what comes up. But unless you have the manufacturer's design drawings don't even try to make parts. Some dimensions are CRITICAL!

Thanks for the advice but I have already seen the prices of the new jets. The steam jet inparticular is a very basic component that should cost about £2.50 (considering their batch size and the versatility & accuracy of CNC machine tools) but I think from Penberthy's distributer in the UK it was an outrageous £125.00. If I can't find drawings I will copy an existing jet that I have in another identical injector, I did this for my 3/4 Penberthy and it worked fine although I have lost the sketches I made at the time, which is a shame. I don't have the caps and tails for a 1/2 Penberthy but I'm sure I could borrow one from Philip Martino (SN Adamant) just to measure up.

Regards - Keith

Once again, Google penberthy injector. There are some detailed drawings online - unless of course you like to re-invent the wheel. I tried that a couple of times; best I could do was four corners and very uneven rotational speeds.

I'll back artemis in saying that the jet dimensions are absolutely critical.

Yes it is critical - but thats the fun!!

If you have time and easy access to live steam near/in your shop just try it out.

Do all changes in smal steps and discuss the results with yourself or others and you will win.

There is no feeling better then making this bitches work!!!

Thanks for all your comments, I have borrowed a similar AA injector from a friend who uses it at pretty much the same pressures that I intend to (150psi). This is the third Penberthy steam jet that I have had the opportunity to examine and it is amaizing the variation in the cone angles between the BB, AA and high pressure models.

The AA that I have borrowed is exactly the same as mine, the only difference is that unlike mine it has a steam jet. This is a very basic bit of machining and I think phosphor bronze will be fine. I will have a go at making a replacement jet, even if I make numerous attempts I should be able to sort it out in the end. I won't be able to test it until the spring but I will let you know when it is working, or not whichever the case may be.

The only thing that might make it difficult is setting an accurate angle on a Myford.

Regards - Keith