Scott vacuum engine (flame gulper)

[Sanjay F]

Thanks Wilf

I thought as much, they must have changed it at some point, but I think that I'll use some primer filler to tidy it up it should be ok. I'm very much interested in getting this one going over the looks at the moment and have seen an interesting and simple way of lessening the tension on the springs which seems to be a recurring issue with these engines (see photo).

These neat little extension linkages look simple enough so if I experience the similar issues may go down that path. Also there is no indication of how the flywheel is attached which isn't a problem a grub screw or keyway, either will do?

[uuu]

I've got a grub screw - it's not listed - there are just two listed, one each for the crank and cam - they supplied a length of 4BA studding, for you to cut your own.

The spring drawing has the comment "Note: - spring as supplied may be too strong stretch slightly so that valve is just held to port face"

Perhaps the extra link is better as you can change it if you make it too loose.

Wilf

[uuu]

Here's mine - you can see the grubscrew hole in the flywheel.  I never did paint it - and it's a bit grubby from storage - but it still turns over OK.  Copper wick tube is not fitted.

20250814_103453 by Wilf, on Flickr

Wilf

[Sanjay F]

Nice - I'm moving onto the crank and cam next, you've made a nice job of those 

[Sanjay F]

Mistake

I made the flywheel centre 1/4" rather than 6mm (0.236"). This wouldn't be a problem if it weren't for the bearings which are made for 6mm instead of 1/4". However I have not made the crank and cam disks yet so will make them 6mm and then thinking I make the crankshaft with one end 1/4" for the flywheel and machine to 6mm for the bearings and both crank & cam - hopefully that'll work 

I have very little metric kit and this has measurements in both metric & imperial!

[uuu]

Perhaps you could carry on boring it out, past the damaged section, and then fit a bush.  Solves two problems at once.

Wilf

[Sanjay F]

That's a great idea, but I've now made the cam to the right spec  , but that's reminded me to get the good ole JB Weld out to patch the annoying holes before priming

[Sanjay F]

Finished the crank disc as well today, glad to get those pieces done, a lot of messy filing!

[Sanjay F]

Today was spent making the conrod - quite a delicate little thing which has a bearing at the big end. I overran the decorative groove which runs along the middle, I think that'll be hidden by the piston and cylinder.

I think I'm finally getting somewhere with the silver soldering, but only on small items ....... larger bits are still proving a challenge

[Sanjay F]

I couldn't finish in the workshop without making the crank pin and joining the 2 pieces I made over the weekend together 

[PaulR]

Looking good! Didn't you clamp or otherwise fix the conrod parts together for soldering?

[Sanjay F]

I did, I had the bar and the round end lifted on some little pieces of scrap so the solder would run underneath, and a heavy piece of stock pushing against the round end to hold it against the bar.

I did think about clamping it, but couldn't of a way to do it?

[PaulR]

Could make a jig like this but you'd have to be careful not to solder it as well!

[uuu]

But you'd have to get the jig hot as well, so it slows down the heating process.

For some fiddly bits you can use gardeners wire to tie them up.  Theoretically the solder won't stick if the wire is rusty.  But It always sticks to mine, so I then have to cut and file it off.

Setting aside some small toolmakers clamps for soldering duty is a good idea - but not really useful for this particular job.

Your method seems to have worked just fine.

Wilf

[crueby]

Brush some Wite-Out on the jig around the area where it contacts the part and let it dry. That will keep solder from sticking to the jig. As Uuu says, keep the mass of the jig down to keep it from be8ng too much of a heat sink.