mickoo
Western Thunderer
There are many ways to achieve this, I've not seen them all or even attempted the ones I have seen, but the few that I have tried always ended up total failures involving intricate work and tolerances well beyond my skill and more importantly enthusiasm level.
First off I apologise if this method has been done before, but it's how I've worked out how to do it and do not claim world breaking news.
The objective was to make self contained buffers with the simplest of hand tools, reliably and in as basic form possible, though I did use a lathe for a couple of the operations they are also easily achieved with a pin vice and a little more patience. I also wanted to be able to remove the buffer head later for painting or servicing, something many self contained buffer systems lack, especially if there is no access from the rear (behind front buffer beams whose rear is exposed and detailed).
Ingredients required:-
One Slaters LNER/SR Step parallel buffer.
One length of thickwall 3 mm brass tube (3.0mm OD x 2.0mm ID).
One 12 BA cheese head screw - Steel preferred, 10.0 mm long minimum.
One 12BA washer - Brass preferred.
A 3.0mm drill.
A 2.4mm drill.
A 1.0mm drill.
A 12BA tap.
There is no requirement for a oven or gas mark 4 in this mix.
This is image heavy and not a particularly short post, so a cup of coffee might be a good companion.
So to start, first an assessment of what we get in the package from Slaters.
First off the brass housing casting, salient points here are a 2.5 mm bore at the rear (approx) and a 4.0 mm bore for the buffer head shank at the front.
Second the steel buffer assembly with a 4.0 mm shank and 2.2 mm stub threaded 8BA with associated brass nut.
Finally a steel spring approximately 3.8 mm OD and 3.4 mm ID
Clearly when the buffer compresses the nut on the rear outside will protrude through the buffer beam.
The conversion.
Step 1:
Open the rear hole up to 3.0 mm dia and trim the stub to roughly the thickness of your buffer beam. I used a lathe for this as it was just quicker than hand balling it.
Step 2:
Take your 3.0 mm tube and bore the inside out 2.4 mm or just enough to clear the screw cheese head, 12BA is nominally 2.3 mm. I bored a depth of 5.0 mm but it's not overly critical right now and you can bore deeper by mistake and not need to panic.
Next I cut it off around 5.5 mm long which is way over length but we'll be trimming it later anyway. This gives me two bores, one at 2.4 mm 5 mm long and one at 2.0 mm 0.5 mm long. I found the small bore just a touch to large for the 12BA screw, so as added insurance to stop the head pulling through, soldered the washer on the end and trimmed to the same OD as the tube. The important bit is that when you cut it off some of the original smaller bore is still at one end.
In reality you could drill right through and just add the washer, but the tube wall would be thin and the solder joint less resilient. In truth I suspect just the plain drilled bore would be fine, we're not going to be pulling on it, just compression.
Screw passed through the (what I call the retention cup) showing washer soldered on.
Step 3:
Converting the buffer head, this vexed me for some considerable time, how to drill the hole in the base whilst holding the buffer by the head straight and square, in the end the eureka moment came and I simply drilled from the front right through and then tapped 12BA right through. Fret not all will become clear later.
Once all the parts are made it's time to assemble them
The above view gives an idea of the basic assembly order. Below is what it would look like if the outer casting was removed, though the screw would be wound in more and not visible from the rear end of the tube.
Step 4:
The 3.0 mm OD tube was a smidge over size for the drilled hole in the rear of the buffer casting, which is good as it will give it a nice tight interference fit when fitted, I ran it in the lathe and gently held a #4 flat file on it to give a slight taper as well.
Insert the tube from the rear with the washer (narrower bore) end toward the front, the depth isn't actually that critical but for those wanting to know it's about 4.5 mm from the top lip. The excess on the rear will be trimmed later. The friction fit means you'll probably need to use a vice to push the tube in but if yours a bit loose a dab of solder once in position will secure it nicely.
Looking inside you can see that the new retention cup comes up above the internal 4.0 mm ID base and creates a rim to locate the spring.
The 3.0 mm OD tube fitting inside the ID of the spring.
Step 5:
Pass the steel screw in though the base and simply screw the head on.
The 12BA steel screw will pass right through the head and protrude from the front....perfect.
Adjust the screw so that at full compression the head sits flush or just below the mounting spigot on the rear.
Finally flip the assembly over and add a dab of solder on the exposed screw thread and buffer head and then trim flush, being steel the joint will be near invisible.
I've not soldered this solid or trimmed this as in part two (only 15 images per post) I want to be able to remove the head later so soldering this in will simply lock the unit as one. But if your happy to not worry about removing the head later or masking for painting then this is as far as you'll need to go.
Total time to this point was about 15 minutes work, to photography and write up, 45 mins.
That concludes the sealed unit.
MD
First off I apologise if this method has been done before, but it's how I've worked out how to do it and do not claim world breaking news.
The objective was to make self contained buffers with the simplest of hand tools, reliably and in as basic form possible, though I did use a lathe for a couple of the operations they are also easily achieved with a pin vice and a little more patience. I also wanted to be able to remove the buffer head later for painting or servicing, something many self contained buffer systems lack, especially if there is no access from the rear (behind front buffer beams whose rear is exposed and detailed).
Ingredients required:-
One Slaters LNER/SR Step parallel buffer.
One length of thickwall 3 mm brass tube (3.0mm OD x 2.0mm ID).
One 12 BA cheese head screw - Steel preferred, 10.0 mm long minimum.
One 12BA washer - Brass preferred.
A 3.0mm drill.
A 2.4mm drill.
A 1.0mm drill.
A 12BA tap.
There is no requirement for a oven or gas mark 4 in this mix.
This is image heavy and not a particularly short post, so a cup of coffee might be a good companion.
So to start, first an assessment of what we get in the package from Slaters.
First off the brass housing casting, salient points here are a 2.5 mm bore at the rear (approx) and a 4.0 mm bore for the buffer head shank at the front.
Second the steel buffer assembly with a 4.0 mm shank and 2.2 mm stub threaded 8BA with associated brass nut.
Finally a steel spring approximately 3.8 mm OD and 3.4 mm ID
Clearly when the buffer compresses the nut on the rear outside will protrude through the buffer beam.
The conversion.
Step 1:
Open the rear hole up to 3.0 mm dia and trim the stub to roughly the thickness of your buffer beam. I used a lathe for this as it was just quicker than hand balling it.
Step 2:
Take your 3.0 mm tube and bore the inside out 2.4 mm or just enough to clear the screw cheese head, 12BA is nominally 2.3 mm. I bored a depth of 5.0 mm but it's not overly critical right now and you can bore deeper by mistake and not need to panic.
Next I cut it off around 5.5 mm long which is way over length but we'll be trimming it later anyway. This gives me two bores, one at 2.4 mm 5 mm long and one at 2.0 mm 0.5 mm long. I found the small bore just a touch to large for the 12BA screw, so as added insurance to stop the head pulling through, soldered the washer on the end and trimmed to the same OD as the tube. The important bit is that when you cut it off some of the original smaller bore is still at one end.
In reality you could drill right through and just add the washer, but the tube wall would be thin and the solder joint less resilient. In truth I suspect just the plain drilled bore would be fine, we're not going to be pulling on it, just compression.
Screw passed through the (what I call the retention cup) showing washer soldered on.
Step 3:
Converting the buffer head, this vexed me for some considerable time, how to drill the hole in the base whilst holding the buffer by the head straight and square, in the end the eureka moment came and I simply drilled from the front right through and then tapped 12BA right through. Fret not all will become clear later.
Once all the parts are made it's time to assemble them
The above view gives an idea of the basic assembly order. Below is what it would look like if the outer casting was removed, though the screw would be wound in more and not visible from the rear end of the tube.
Step 4:
The 3.0 mm OD tube was a smidge over size for the drilled hole in the rear of the buffer casting, which is good as it will give it a nice tight interference fit when fitted, I ran it in the lathe and gently held a #4 flat file on it to give a slight taper as well.
Insert the tube from the rear with the washer (narrower bore) end toward the front, the depth isn't actually that critical but for those wanting to know it's about 4.5 mm from the top lip. The excess on the rear will be trimmed later. The friction fit means you'll probably need to use a vice to push the tube in but if yours a bit loose a dab of solder once in position will secure it nicely.
Looking inside you can see that the new retention cup comes up above the internal 4.0 mm ID base and creates a rim to locate the spring.
The 3.0 mm OD tube fitting inside the ID of the spring.
Step 5:
Pass the steel screw in though the base and simply screw the head on.
The 12BA steel screw will pass right through the head and protrude from the front....perfect.
Adjust the screw so that at full compression the head sits flush or just below the mounting spigot on the rear.
Finally flip the assembly over and add a dab of solder on the exposed screw thread and buffer head and then trim flush, being steel the joint will be near invisible.
I've not soldered this solid or trimmed this as in part two (only 15 images per post) I want to be able to remove the head later so soldering this in will simply lock the unit as one. But if your happy to not worry about removing the head later or masking for painting then this is as far as you'll need to go.
Total time to this point was about 15 minutes work, to photography and write up, 45 mins.
That concludes the sealed unit.
MD
The only new thing might be the hidden rod to act as a screwdriver blade to allow removal of the head in units fitted with no rear access.
hence my quest for a more tiny tots club approach 
