It's Stuart Hammer time......

[Sanjay F]

Ah yes, of course, that makes sense to modify the spigot; I'll only reduce it sufficiently to get the piston moving so there will still be some contact between the  spigot and the cylinder 

[john mills]

set it up in the correct position and remachine the spigot it wont clean up but make what does fit and let the cylinder line up

[Chipswitheverything]

Hi Sanjay, the lever looks nice... 
The possibility of a discrepancy between the piston and the cylinder bore is what I was getting at a few days ago, when I was chipping in an idea about machining that spigot on top of the piston rod in relationship to the actual position of the cylinder bore when that was running true, rather than necessarily being in the centre of the piston rod section.

[Sanjay F]

Yep, I thought I’d resolved it by clocking the spigot to the inner part of the mouthpiece but clearly not! Interesting though, I’ve realised how much trouble a ‘square’ hole can cause 🙂

[Sanjay F]

This took quite a bit of sorting.........

Firstly huge credit to Michael S who came up with a simple and elegant solution which was to open up the hole(s) in the piston and reduce the size of the bolt thereby allowing the piston to float into the correct position within the cylinder before being screwed into place (see photo 1) .... a back of a fag packet drawing as we like to say!..........thank you Michael that worked an absolute treat 

As with all these things I then discovered the piston flange was now out of alignment with the mouthpiece (see photo) so instead of opening up the nice square hole I reduced the diameter of the flange as the whole of the internal cavity will be packed with graphite yarn; and by goodness it took some filling, that's 5mm square yarn and a couple of complete turns of it around the piston rod.

The rod and piston are moving nicely with a good seal, it's making that lovely chuffing noise we like to hear and I feel the air being pushed out of the ports.  There's no packing around the piston, no cylinder cover or gasket between the mouthpiece and cylinder...............

https://www.youtube.com/shorts/DRL67tPJ2pI

[Michael S.]

I’m glad it worked. My idea was that this would allow the piston to shift into the correct position. If the misalignment had been somewhat variable, the piston would have needed to be mounted in a "floating" manner—similar to how a piston ring can slide without excessive play. Limiting the screw's threading would allow for that sliding movement. After all, the piston only exerts downward force, and the screw only has to lift the piston (using a hammer); so, the load on the screw would remain well within safe limits.

Michael   

[Chipswitheverything]

Some serious looking graphited yarn in the picture!  Michael has come up with a good way to get things running here, and the arrangement should cope OK with the mostly downward force of the hammer action, and a very intermittent load at that. 
 
 One of the things that has struck me about most model engineering builds of this sort, is that generally, the builder is having to do some quite tricky processes with the emphasis on needing to get the whole lot right first time ...   We haven't usually got any "spares" to do a bit of experimenting with, castings are expensive or difficult to obtain ; and even procedures using stock material take up a lot of investment in time, so the pressure is "on" to get things right at the first attempt, and perhaps to live with what emerges.
I have quite often thought when doing some operation , making some component, that if I had been armed with the knowledge of what I encountered the first time, then I would have been able to do a bit better subsequently, maybe come up with an improved way of going about it.  In most activities, one doesn't really expect to have a one -off thing of perhaps a new sort turn out right first time !    But I suppose that the mistakes, bits of bother and odd disappointments of the hobby over a long period do feed into a background of gaining general experience which helps to avoid some of the snags.

[Sanjay F]

I agree with your thoughts regarding making errors especially while learning; they can be both painful and expensive! As can be seen with many secondhand sets of castings, builders have made an attempt then abandoned them when something has gone awry - this steam hammer being a case in question.

I have previously bought a really nice 'partially built' engine which luckily I could send back as it was so far gone it would have meant buying individual castings which again works out very expensive.

Another thing for a beginner to be aware of, having been there myself, is knowing your own skill and experience level. I have projects under my bench which I don't feel comfortable attempting at the moment; hopefully, given time and with some more completed projects under my belt they will be brought into the light! 

[Sanjay F]

Just making some little bits at moment; this is the lever stop which bolts to the side of the standard restricting the lever movement

[Dave Otto]

Hi Sanjay

Don't know if you had seen this or not, he is wound a little tight but entertaining never the less.
There are seven videos in the build of the hammer.

Dave

<a href="https://www.youtube.com/watch?v=TIixXTsG6dU" target="_blank">http://www.youtube.com/watch?v=TIixXTsG6dU</a>

[Sanjay F]

Hi Dave

Yes, I have come across it, and yes, the chap presenting can be a bit 'annoying' however the content and build is good. He made a simiilar error to me with piston rod being rotated incorrectly through 90 degrees 

I'd like the room and kit he has.........

[Twizseven]

Have you watched his videos of refurbing his various full size hammers.  I must admit his frustration and exuberance when he is struggling to get something apart and then finally succeeds are a little off-putting.
But it is interesting to see how some of this old hardware was assembled.

Colin

PS I have a Stuart Steam Hammer sat in a box waiting.