Rescuing a Stuart Triple Expansion engine

[wgreeley]

I have obtained a Stuart Triple Expansion engine by an unknown builder. The problem I am having is locating replacement hardware The engine was built with 4-36 hex head machine screws. Does anyone know of a source for these.

Thanks
Bill

 

[WOB]

To get hex head, you will likely have to machine blanks from hex bar stock and buy a 4-36 die( ebay).

WOB

 

[SmithDoor]

Here place sell 4-36
https://www.fastenal.com/products/details/0174021

Odd are it old thread
Taps are still made

Dave

 

[kvom]

I wouldn't use slotted screws myself.

 

[abby]

Are you sure that the screws are UNS 4-36 ? as you will have found out this is by no means a common thread.
It would be a crime to fit anything but scale hexagon head screws to your engine and a possible solution might be to re-tap the holes M4.
This will be a few thou larger on the screw diameter but screws are available with a size smaller head so that scale appearance can be maintained.
The same can be said for BA threads which I use for all my hexagon head screw modelling requirements , still easily obtainable here in the UK , but I have the stock of several long departed model engineers which will last me for my lifetime and leave plenty to pass on after.

Dan.

 

[10thumbs]

4x36 taps are available from Brownells', for use in gunsmithing. Across the pond, but available.

 

[abby]

Yes the taps are available in the UK too , but how does that help ? Bill is looking for a source of suitable hexagon head screws .
Dan

 

[Drillrod]

I might be able to help, as I have that size thread tooling and a (limited) supply of 11/64" (.176" a/f) steel hex stock to produce a small batch of 4-36 screws. If .176" across the flats will work for you, let me know the length and quantity required.
Drillrod (nyc)

 

[Apprentice707]

I recently bought a very nice set of American small size taps and dies from Chronos, about £32 if I remember rightly.

 

[john_reese]

Forget Fastenal. On my last visit I saw a sigh that they were only selling business to business.

 

[wgreeley]

Thanks All
It looks like the screws were machined from 3/16 (.1875) hex stock. The same as an H.E. Boucher engine I am also working on. Looks lie the die approach is the best choice.

 

[eifion]

Hi. May not be relevant. I recently helped a friend get a Stuart engine sorted and that had been put together using 3, 5 & 7 BA bolts which had quite low profile hexagonal heads. This was a bit of a nuisance as being primarily an aeromodeller I use even numbered BA nuts, bolts etc.. Just not cricket using odd numbers!!!