Potty Simpson and Shipton Short Stroke Engine

[sbwhart]

I ,,, but Stew ,,,,,,,will it be ready for Harrogate 

Rob

PS ,,,,, cracking job by the way 

It will be darn close ready for Harrogate, it may be a bit rough but it will be close.

Any way got the base soldered to the cylinder, it took two goe's my first atempt the nozzle was a bit small and I wasn't getting enough heat into it, swapped to a bigger nozzle and it went like a dream, at the first attemp I tought should I swap to a bigger nozzle, but I was to lazey and went with what was fitted, came out ok in the end its slightly skiwiff, but a light skim of the base should sort that.



Next up the covers, I'm making these out of 1/8" thick brass, first job cut then off the bar and square the ends, then carfuly drill the centre holes 3mm to take dowels and a couple of 1/16 for brass pegs to locate a thickening peice.



Then cut out the thickening peice square them up and drill them for the 1/16 pegs



File a rad on each end



And this is how they fit on the cover for silver soldering



Job done:- the pic doesn't do it justice its a very neat joint.



The covers have a curved slot that the piston rod runs in this has to be on a 75mm rad, and the covers have to fix centraly on the cylinder bore. so I made a fixture to hold the covers on.

A 10mm hole was drilled and reamed in the jig 75mm from this two 3mm holes were drilled to take 3mm dowel pins, and a hole drilled and tapped to take a clamp. I also made a 10mm clamp bolt with a 10mm register dia a neat fit in the 10mm hole in the fixture, this bolt screwed into the surface plate that I made some time ago to increase the capacity of my RT.



and how it all fixes together.



Stew

[doubleboost]

Stew
You are making it look easy again
John

[Stilldrillin]

Stew
You are making it look easy again
John

He does that, doesn't he, John! 


I like your "surface plate" extension Stew. I use the lathe's faceplate.

Keep on, keeping on....... 

David D

[sbwhart]

Cheers John/David

I can now start treating the cylinder like a casting, the trouble with this design of engine is that its so weird, its difficult getting your head round feature that are important.

I figured that it will be important getting the slot that the piston rod moves in central with the cylinder hence the fixture I've made.

So to mill the slot first centre the RT on the mill spindle zero things up then, using the bolt secure the fixture to the table, but first clock it up level with the Rt set on zero deg.



Then index 75mm bolt the cover to the fixture and with a 8mm slot drill mill the slot.



Next drill the 2mm holes on the PCD, both ends



Onto the cylinder centre it up on the mill zero the dials. and using a boring head bore out the cylinder vertically down, advancing 1mm vertical down again advance 1mm etc etc until its long enough.



Did this for a couple of rouging cuts, then to finish advanced it 0.5mm/cut , this left a slight ripel in the bore but that will soon clean out with a bit of fine emery cloth wrapped around something flat.

Then on the centre line drill a couple of holes each side to take 3mm dowels.



Locate the covers on the dowels and spot through 2mm followed through with M2 tapping drill.



Centre the jig back up on the RT and radius the end of the covers.



And this is what the covers look like on the cylinder, only got one finished before domestic duties called, I'll finish the other off tomorrow.



Hope things are starting to look a bit clearer.

Stew

[Stilldrillin]

Hope things are starting to look a bit clearer.

Stew

Now, it reminds me of a cross between a mantel clock, and a diver's helmet.........   


Thinking I might be getting some idea....... Is the cover on upside down, in your last pic, Stew? 

Or, is it a test to see who's paying attention? 

Or, is it just an optical illusion?

Or, should I just sit here, quietly?

David D

[sbwhart]

You win the coconut for observation Dave, yes the cover is on upside down

 

Stew

[Stilldrillin]

You win the coconut for observation Dave, yes the cover is on upside down

 

Stew

  YAY!!   

I might be getting the hang of it....... 

David D

[saw]

The building is coming along very nicely  ,
still I have hard to understand how it works despite that I was looking at the drawing and the animate picture. 

[sbwhart]

Thanks Dave/Bennie

Her's a pic of the covers the right way round, I think it looks happier the other way 



With both covers fitted i put a length of 8mm silver steel through the slot and measured the height side to side and front to back, and it was within 0.06mm:- not alf chuffed with that   



Back on the mill and drilled and milled the air ways, and drilled m2 tapping for the valve chest.



Then tapped the holes M2 using the tapping stand to get them square, these holes are on both side of the cylinder, on the model they don't do anything, but on the origonal the cylinder sides were spring loaded to take up wear hance covers both side.



On with the valve chest now, first square it up to size, then centre spot where the bore is to go for the spool valve.



Then in the four jaw chuck clock up a wobble bar centred on the spot centre.



Centre drill then drill and ream 8mm.



Swap it round clock the centre spot up on the face.



Drill through into the 8mm bore and face the boss for the air coupling.



Over onto the mill using centre the work and with the DRO drill the holes on the PCD for the coupling.



Flip it on the back find the centre and drill the feed ports and 2mm for the studds



That was a good morning work 

Any one know where I can buy some M2 studding in the UK.

Stew

[Stilldrillin]

Thanks Dave/Bennie

Her's a pic of the covers the right way round, I think it looks happier the other way 



Any one know where I can buy some M2 studding in the UK.

Stew

Yer right Stew! It does look a little sad, now...... 



Studding? Try here.......   http://www.modelfixings.co.uk/metric_studding.htm

David D

[sbwhart]

Thanks Dave

Got some ordered 

Stew

[Rob.Wilson]

Hi Stew ,,,,  the cylinder looks GREAT  ,, cracking bit of machining 


Rob

[sbwhart]

Thanks Rob

Got the stream chest finished off, today.

Drilling the holes for the sealing gland.



Next up the little top hat to take the graphite cord.

Turned the OD and reamed through 3mm parted off flipped it round then used a slot drill to cut the flat bottom hole.



Then turned up the spool valve from some silver steel bar,
Drill and tap and acuratly turn the gap and over all length as these are important to the valve timing.



Camera went flat at this stage, and couldn't be arsed to get the spare out of the house.

Finished of the rest of the bits for the gland, this is how they all fit togethere



Then onto the valve cross head bar, made this from a bit of 1/4 square bar, so in the four jaw self centring chuck, rough out the steps.



Then with a thin tool and with the compound slewed over 5 deg turn the taper bits.



Over onto the mill and find the midle of the bar and drill though 3mm index to the outside bits and drill these through 3mm as well.



Then with an end mill thin the end bits out.



Time for an hows it looking.



Stew

[arnoldb]

Time for an hows it looking.

  It looks GREAT Stew; you've certainly upped the pace now 

 , Arnold

[sbwhart]

Thanks Arnold 

Things will slow down over the next week as I'm on domestic duties 

Decided the cross head would look better with the end bits rounded off so made a filing button and nibbled away with files, I think that looks better:-- less clumsy.



Used the rest of the morning making the link bars.

First cut off a length of bar enough to make all three links, then drilled some pairs of 3mm holes 12.5mm apart, the DRO on the mill gets the pitch for each one very accurate.



Cut each link from, then turn a 3mm mandrell on the lathe, bolted each link to it and faced it off to form the arm.



With the same filing button finished the ends off, then drilled and tapped M2.5 for a grub screw.



Job done





Stew

[saw]

Looking good Stew, it's so very nice to see how you easy do your work 

[Stilldrillin]

I love the way you deal with the fiddly bits Stew! 

David D

[sbwhart]

Thanks Guys

Started back on the engine for a little while at least.

Finished off the rest of the linkage



Stew

[Rob.Wilson]

  your the man Stew 


Rob

[Stilldrillin]

That's a great looking assembly Stew! 

Purposeful...... 

David D

[doubleboost]

Words fail me 
I like the way you can make tiny bits look big
John

[HS93]

I recently got to hold the drain taps that Stew had made , now I thought they where quite big for something like a 3" tractionnengine until he handed me one it was TINNEY  I was very very impressed with them,   even my wife who normally just says yea lump of metal had to have a look and was impressed  (I think a first for heir)    also this engine is one Heavy piece of nicely machined brass, I think l I know how it works now !

Peter

[sbwhart]

Thanks Chaps

Peter it was nice meeting up with you and you'rs, its a shame it was in such sad circumstances

Well made the piston today its a job I've been putting off don't know whyi I guess I just had a funny for doing it.
I liked the idea of making the piston out of PTFE, the main reason is its slippy plastic and quite soft, and I figgured that if I made it just a coulple of though longer that the cylinder it would act as a good air seal against the covers  we'll just have to see how it works out the bottom line is to change it for steel if it don't work out.

I used very sharply honed tools it cut like butter with a great finish.



Set it up in the mill and drilled the off set holes.



Back on the lathe and resessed the faces.



Then parted off a length of 8mm silver steel (drill rod) and put a rough straight knurl into the middle.



Sorry its such a crap pic

Then gently tapped the rod into the cylinder the straight knurl acting as splines to give it grip.

Mounted it back in the lathe a carfully skimmed the cylinder to width

The cylinder covers wern't sitting flat so gave them a bash wif me ammer, and a rub on emery cloth on a flat surface.

This is how it looks in the bore



Stew

[saw]

You are doing a fantastic jobb, nice to see that you are coming along very fine. 

[sbwhart]

Cheers Benni

Had a couple of sucessful days in the shop.

Made the crank webs, they are of the pinch clamp type so you can get them on and off due to the design of the engine.

First drill the holes 2 with 8mm crank pins 2 with 6 mm crank pins



Cut off with slitting saw



With two drill through the holes across top of vice, mill off so they are central, for the two cranks with the 6mm crank pin holes had to use a drill imm smaller



Drill and tap and open up half with a clearance drill



Cut the split.



Then with filing buttons file to shape, they still need a bit of tidying up and a rub with emery, but her they are with the buttons



Think they look a bit on the heavy side may thin them out a bit.

Next up the con rods the engine has four using 9/16 free cutting mild steel first cut off to length face them up so they are all the same and centre drill and turn up a lost centre.



With a part off blade put a couple of grooves into them to show where to stop and to give some clearance to the turning tool.



The with a running centre chew the meat out of the middle.



Slew the compound over a couple of deg and with a radius tool form taper toward the chuck, swap it round and tune the other end to form the barrel.





Cut the centre pips off then over on the mill cut the flats.



Called it a day at that and went for a brew and a snooze.

Stew