Scott vacuum engine (flame gulper)

[Sanjay F]

I figured it, bearing slips over the follower pin! 

Made a modified mainshaft which is Imperial on the flywheel end and metric the rest of the length due an earlier error assuming I could use 0.250" instead of 6mm; won't be doing that again! 

[Sanjay F]

Help

It was all going so well, made the shafts fixed the bearings to the main shaft and that's ready to be loctited into position. Problem is with the cross shaft the holes are out of alignment and this need to rotate freely so there's no jamming it in? 

I noticed that bogstandard on his build, used ball races (see last photo) instead of just of the plain shaft into the holes and wondered if that was the way forward? He used 7mm wide x 2.5mm width and presumably 4mm diameter as the shaft is 5/32" or 3.96mm

I think these would do the job: https://bepltd.com/products/smr74-zz-4x7x2-5mm-miniature-stainless-steel-deep-groove-ball-bearing?

[Jasonb]

You don't have a lot of play with ballraces so would still need to get the larger holes to line up.

You could just open up one of the holes in the lron and make a brass or bronze bush that can be JBWelded into place with a shaft through the two holes to keep it lined up while the JBW sets.

[Sanjay F]

That's a good idea, I presume I have to use the 'good' hole as the guide for drilling the bush. I'm just concered that I don't misalign that operation again. Or are you suggesting that I make the bush a loose fit which will set in the correct postion whilst the shaft going through both holes?

I'm not sure how it happened the first time to be honest, I was careful and used a long spot drill to make a a dint before using a specially bought long drill bit which passed through the 1st hole and went on to drill the second -

[Jasonb]

yes have it a loose fit so the shaft can align it

[Sanjay F]

I made a .300" diameter hole in the upright and had to make the plug .254" in order for the pin to rotate freely! I think using a long thin drill bit to go through both uprights didn't work, not for me anyway.

Time to cut the plug to length and get JB Welding

[Sanjay F]

That seemed to have worked very nicely, thank you. I'll leave it another few hours before filing it clean:

https://youtube.com/shorts/SjuIuM9Q7E4?feature=share

The major components are now completed apart from the strange looking graphite block which looks like the obelisk from the end of 2001, A Space Odyssey.

I then have to make the flame part of the engine and decided to go with the gas tank, something new and you know how safe I am with flammable fuel  . Looks like a trip down to the plumbing supplies shop is needed ........

[Sanjay F]

What an absolute horrible job the valve is - basically machining a large pencil lead which feels like it's going to shatter at any moment and covers everything a fine black powder.

I managed to get all the way to the end and then got a chipped edge  - luckily not on the business side so all is good. Finally lapped it with some 1200 grit (even more mess) and have a nice surface.

Right now to tidy up, maybe I need a large pencil eraser 

[Sanjay F]

Made a start on fire production apparatus of the build with diffuser which fits into the end of the pipe; luckily for me my mate is a plumber and he had all the standard elbows, pipe and bendy bits needed - thank you Keith!! 

[samc88]

Looking good, nice work on that graphite, looks a tricky material to machine

[Sanjay F]

And another soldering question

I take it plumbers solder won't cut the mustard for this piece due to temperature? The build I'm following suggests the following:

"The joints were set up with Tenacity 5 flux and 1/16" easyflo silver solder. Thicker solder than normal was used because the joint cavities will take a bit of filling".

[Jasonb]

Probably not but which bits are you soldering?

[Sanjay F]

It’s the elbow to the end angle bit and the elbow to the straight piece of pipe - see photo. It’s not the diffuser as that’s a push fit

[Jasonb]

Yep silver solder those. My usual rod is 1/16th anyway so would not have given it a second thought as to gap.

[Sanjay F]

Made some progress today and bent the cam follower arm between 2 parallels and that worked out well. I've never managed to successfully make holes for taper pins so drilled straight through the spigot and the valve shaft so they can be locked together with an 8BA bolt.

This is where I've got to so far and there's a few more fiddly bits to go and hopefully this week I'll solder up the gas burner

<a href="https://www.youtube.com/watch?v=qnftxjKFW-s" target="_blank">http://www.youtube.com/watch?v=qnftxjKFW-s</a>

Any advice on taper pin drilling gratefully received