Scott flame licker build

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lordedmond:
Thanks John for the explanation and CoC

More like a manual pop rivet with a tapered pin to expand the part outside the joint

Bogstandard:
That's OK Stuart, sorry for the confusion, just me using my old terminologies again rather than the correct ones.

John

arnoldb:
Once again, good progress John.

And thank you for the explanation on the rivets; I was also wondering about those.

Would it be correct to say that one can adjust the amount of play between the pivoting parts of the riveted joint by just punching it a bit more ?
I've not seen rivets used a lot in model builds of late, and I'm wondering why, as it seems a good method to use for many things...

Kind regards, Arnold

Bogstandard:
Normally Arnold, you use a rounding over type of punch to make it look slightly like a dome head rivet, but a taper punch is plenty good enough for what I am doing, in fact I will be using a 90 degree centre punch end so the swelling is more towards the surface, so leaving the parts turnable loose rather than clinching them together.

The depth of hole plays an important role, too deep and it swells inside the rotating parts and locks them up, and yes, the easy way is to gently punch until you get the correct side float (not sloppy) and still have nice fairly free rotation.

If you want to get very technical and work it out with a calculator, there are charts about to give you starting points. But really it isn't necessary, I just drill down to depth until the drill tip reaches a point the same thickness as the parts being joined, and put a supporting washer on the opposite side of the head. I leave about 1/16" protruding from the washer.

http://www.doidge.com/english/semitub.html

John

Bogstandard:
Tonight's little exercise turned out to be a bit of a dirty job.

One of the most important parts on the engine, the flame valve.

This is what it is made out of, a lump of graphite that has been rough sawn on all six sides, with not one side flat, straight or square.

When working with graphite, the dust can get everywhere. You can spray with fine mist of water, but the dust is even worse to clean up.
Not really recommended, I taped paper towel down to the vice and table to attempt to stop it going everywhere, and I kept the air blower well away from the machine. NEVER use anything other than easily torn paper like this, cloths and rags are a definite no-no.

I had to go thru the whole routine of getting the part all flat and square, and I used a razor sharp flycutter to do it. The dust just stayed in the local area, and was wiped away very gently from the parallel's surfaces at the change of face.

I used the flycutter because it gives a highly smooth and flat surface (as long as the machine is in tram), and will save me having to lap it flat later.

Once it was to size, by gently pecking away with the drill running a lot faster than normal, 1500 rpm, I got the drill thru the part very accurately.

Using a 90 degree countersink, the three bevel edges were added.
Everything while handling this material is done very softly, finger pressure to set down onto parallels, just using the weight of the vice handle to tighten the vice up, and of course slow steady cuts. You can easily shatter edges or even break it in half by being even a little heavy handed with it.

Spot on size and not a chip in sight, and the valve face was as flat as though I had surface ground it.

This is the face it will operate against, opening and closing the port so that flame gets sucked in at the right time.

This is the state of my hands just by handling the stuff, and I haven't even touched the dust hardly, so you can imagine what state the front of my t-shirt is in. That is one I will have to sneak into the washing basket.

I am still a little undecided about the springs supplied for holding this valve onto the face, they look decidedly heavy, so I will try them, but if they are too much, a redesign will be called for.

Bogs

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