Scott vacuum engine (flame gulper)

[Sanjay F]

Thanks all still a lot of soldering knowledge to learn 

[Sanjay F]

Made some tiny fiddly bits, the small end and its screw; the design doesn't call for a nut, but a 6BA fitted perfectly on the 1/8" x 40 thread and I feel a lot more confident about it not coming apart under load

[Michael S.]

The connection between the connecting rod and the piston looks good and stable 👍

[Sanjay F]

Question & ideas: Soldering bosses

I've made the valve rods and need to solder the bosses to the ends (see photo). I want to keep them together using a 5/32" pin through both boss and rod to get the alignment, but how do prevent the pin getting soldered?

Any ideas greatly appreciated? Maybe align them using the pin, pull the pin out and hope everything doesn't shift during soldering, that doesn't sound good tbh!

[Sanjay F]

Maybe it will work if I prevent the pieces from moving as I withdraw the pin or in this case the a 5/32' drill bit?

[uuu]

Fit a pin made of soft metal - e.g. brass - with centre drill mark and/or recessed in the boss, then drill it out after soldering?

Wilf

[Jasonb]

If you turned the bosses with a short spigot to fit inside the hole that would locate them while soldering.

You can then hold the boss in the lathe chuck and provided you have enough room to swing the rod proceed to drill the hole.

Wilf's method will save having to remake them this time

[Sanjay F]

Excellent ideas - however, I had started on the journey before I read them, the bosses shifted marginally when soldered them using my random method so I had to run a reamer through and it seems to be okay .....

[Sanjay F]

Back to the gupler today and made the little lifter arms for the valve.

Next is the cam follower arm and pin and this time I'll solder the boss onto the arm and then drill so to avoid the alignment issues  I presume I can't see the cam follower boss on the GA drawing as its tucked away under the cylinder or am I missing something?

[Sanjay F]

The drawing states 3.050" between ctrs of the holes either end, but to check on assembly; I presume I don't make the hole at the other end (non-boss end) until once I have completed the bending? Also I dont' know how much allowance to leave for the bending?

[Jasonb]

get the bending and the bush doen then offer it up to the engine, just leave the bar long like you have it then there is no real need to worry about how much to leave though looking at the shallow angles I would think 1/16"

[Sanjay F]

Blimey, I wasn't reckoning on as much as a 1/16", I'm glad I've left the arm long, thanks

[Jasonb]

It is unlikely to be as long as a 1/16 but allowing that much would make sure you did not come up short.

As no length is given for the bend positions, it will just depend on how far apart you place them.

[Sanjay F]

I'm confused by the bearings on Bill of Materials and drawings

It states:

2 x 686ZZ for the main shaft - check (see photo)
2 x MR105ZZ for big end and follower - check for the big end (see photo), but the follower?

Haven't I just made the follower and there's no bearing in the drawing?

There is also some random huge bearing which doesn't belong!!

[Sanjay F]

Hang on maybe this is it? Why can't it just say bearing!