# triple expansion engine



## peatoluser (Nov 29, 2010)

although my long term goal is to build a loco, like a lot of model engineers, i'd also like something to put on the shelf as it were.
And after flicking through some of the free download books (thanks to Pat J's postings) i decided to build a marine steam engine.
After looking at Brunel's and Stuart's sites, the price of the kits are way out of my league, but i purchased the plans for Brunel's triple (to O.B. Boltons design published in M.E. in the 50's) anyway with the intension of seeing if i could scratch build it ,but put them to one side.
Months later, i ran into an ex work colleague (long retired, the lucky so and so) and we got talking etc. and to cut a long story short, a couple of days later he called round with a set of Newnes Marine Engineering books from the 50's.
this wetted the appetite again, so plans dusted of , and time to see if i could buid it from stock materials. But, as i'm not using castings, i thought i'd try and base it on some of the illustrations from Newnes.
Building the model would also be a good excuse to build some tooling and jigs i would probably need for the loco. So i think this is going to be a long build.

first up was to make the base. Decided to make this in 3 sections , fabricated box construction. (i'd post a photo of the page but don't know if it would infringe copyright), but with the main bearing housings made from 3/8.

milling slots for main bearing bolts







and these are the parts for the high pressure part of the base




with the end part cut to shape using manually operated multi tooth cutters. with the intermediate and low pressure to do, like i said it's going to be a long post.


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## Artie (Nov 29, 2010)

Hi, looking forward to your progress, as for long posts.... uhm... id be the last to critise ;D Im sure its going to be worth waiting for... ... enjoy!


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## peatoluser (Nov 30, 2010)

Bit more hacksawing and filing today. Finished the 3 base platforms. Here's a photo of them together with part of the main bearing housings and some of the platework for the box sections resting in place. When i've finished filing the rest of housings and started soldering the box sections i'll post some more pictures.


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## NickG (Nov 30, 2010)

Peter,

This is going to be quite a project! A heck of a lot of work goes into the triple expansion engines, I'm sure it'll be a great family heirloom. I'll definitely be watching, thanks for sharing.

Nick


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## swilliams (Nov 30, 2010)

I have an ambition to build a triple one day, so I'll be following this with interest. 

Best of luck with your build Peter

Cheers
Steve


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## peatoluser (Dec 2, 2010)

Well, finally finished filing the main bearing housings




now i have to make sure that the depths of the slots are all the same, so clamp them together and using a scrap piece of 5/8 bar, engineers blue and some riffler files (now I know what they're for!) make sure that i'm getting decent contact on all 6 and that they are level, although i dare say i'll have to repeat this operation after i've completed the bases. 








Pat, you make a good point about pushing the envolope when scratch building. I think when i come to solder this lot up i'll soon find where about on the scale from "over-optimisticaly ignorant" to "knowingly competent" my skills lie. At least doing the job should keep me warm. In this weather (in England)after about an hour in an unheated garage my -er- 1/2 whitworths soon become a pair of 1/4 BSF's :big:


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## peatoluser (Dec 2, 2010)

seem to have messed up posting photos. hopefuly here they are.


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## 4156df (Dec 3, 2010)

Thanks for taking the time to post your project. This looks like it'll be a great one to follow along with.
Dennis


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## m_kilde (Dec 3, 2010)

Hi peatoluser

I'm really looking forward to follow your project, I have had the joy of building a Triple Expansion Engine my self :


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## peatoluser (Dec 3, 2010)

Thanks for posting the video Mogens, if (when!) the going gets tough I know where to look for inspiration. Thm:


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## peatoluser (Dec 6, 2010)

Well, I've cut all the plates for the box sections, so it's time to solder them up. I'm always nervous about clamping so many parts together only for something to move or joint gaps to disappear. Therefor in one respect I 'bottled it' a little, and welded then filed square some of the plates so as there would be less to go wrong when I light the torch. Veed the joints and used 1.6mm rods at 40 amps.




Even with the plates welded and less to go wrong, I still tend to overheat the job, and i don't want to calculate how much solder I fed in, but I did eventually get everything stuck together.




the small webs (1/4 by 1/4 16g) are a pain to hacksaw and file, so I need to make a slitting saw arbor and a jig to cut them on. (there's 32 on each block). I've also realised that the best way to procede with the other two bases is to use a length of 5/8 square bar to align all the bearing housings up before I bolt them to there respective bases. If I make each base individually, when I come to bolt everything together, there's no guarantee that the bearing slots would be in-line. So some bar ordered along with more supplies of solder. I think I'll be doing well if I can get all 3 the bases finished by Christmas.


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## peatoluser (Dec 7, 2010)

Pat, 
I think line boring is the best way , but with a tiag lathe it's not an option. I intend to make a faceplate fixture and bore them individualy. So long as i mark which way they go into it, and assemble them the same way, I shouldn't have too much misalignment. Although i do fully expect to have to use shim to get them aligned given the construction method of the base. hopefully sketch gives the idea. Got the method from 'Simple Workshop Devices' by Tubal Cain.


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## swilliams (Dec 7, 2010)

I like the way you're going about this peatoluser. Seem to be achieving a lot with the minimum of equipment. So I guess your model is quite a bit smaller than O.B. Bolton's one? The Bolton triple expansion is pretty big right?

Cheers
Steve


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## peatoluser (Dec 7, 2010)

Not really Steve. The dimensions of O.B.Bolton's are cylinders 7/8 , 1 1/4 , 1 3/4 by 1/14 stroke. All slide valves. Connecting rod 2 11/16. Stands 8 3/8. I'm sticking with the cylinder and stroke sizes. may increase the con rod size.Toying with the idea of having one set of columns for forward and reverse instead of the crosshead being guided between two columns , but that may be beyond my machining capabilities. most of the changes i will be making are largely cosmetic as i'm not using castings but fabricating.
yours 
peter


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## peatoluser (Dec 7, 2010)

Pat, 
thanks for the link to Sotherns. managed to down load 8th edition (1916) where some of the foldouts have been scanned. 
yours 
peter


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## swilliams (Dec 7, 2010)

Sounds like a good size Peter. I really like this project :bow:


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## peatoluser (Dec 9, 2010)

Bar arrived, so drill some holes to bolt everything together.




turn over and drill tapping size, clearance and countersink all at one setting before moving onto next hole. Generally I don't like to use c/sk screws to bolt parts together. No waggle room if things go wrong.




then it's just a question of assembling each base and soldering up. If its possible I tend to tack weld parts together.
All brazed up. Just the webs to fit, but i'll use soft solder to fit them. The 1/4 plate at the end will be used as a drilling jig for the enfd plates.




I now need to machine the bases for the columns so they are all at the same hight, and file/scrape the ends of each base to make sure that when they are bolted together they don't pull the main bearing slots out of alignment. Probably have to fettle the slots again to make sure that they are still at the same hight.
peter


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## peatoluser (Dec 11, 2010)

At last some machining. Although I still have the webs to solder, as i'll be using soft solder, there should be no distortion.
Clamp each base to the vertical slide and skim the pad of the column. Lock the saddle in this position and then as each base is milled they will all be the same hight.




I also relieved the centre part of the vertical faces of the bases. This was to make it easier to fit them together.




Two bases are slid towards each other located on the bar and feelers are used to check for gaps. It's a case of filing so both sides are touching. This is easier to do with the centre portion slightly recessed.




You know it's right when you can clamp both parts together without jamming the bar.


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## swilliams (Dec 11, 2010)

This is fast becoming an impressive piece of fabrication Peter. Nice work

Cheers
Steve


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## peatoluser (Dec 16, 2010)

Found it quite fiddly trying to hacksaw and file 1/4 by 1/4 webs , so used the situation as an excuse to make that slitting saw arbor i'd been promising my self for some time. Simple jig on the cross slide and soon had them done.




I found soft soldering these almost as difficult as silver soldering the bases. I ended up tinning the base and then sweating the webs on.
Managed to get them bead blasted and although they looked O.K. , on closer inspection I could see where some of the solder had not run down on some of the webs, and that some of them needed re-aligning. When you drown the job in the amount of flux like me, it's difficult to see if everything is O.K. but i'll fix these hiccups later. at this moment don't want to spoil the finish.
next job was to use the drilling jig to drill the end flanges of the bases. If the jig is marked sides A and B, you clamp A to one face and then B to it's corresponding face, then every thing should line up.




Then it's a case of bolting everything together.




once i've checked the alignment of the slots, it's a question of making all the chock blocks and then hopefully I can start on the main bearings.


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## swilliams (Dec 16, 2010)

Very impressive Peter :bow::bow: Hell of a lot of webs in that

regards
Steve


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## Deanofid (Dec 16, 2010)

That's an impressive fabrication, Peter. I like watching a fellow use the machines he has on hand.
(I have a Taig lathe, too.)


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## peatoluser (Dec 30, 2010)

well, between the snow, cold weather, getting dragged round the shops and general festivities, i managed some shed time.
as the material for the base blocks hadn't arrived I decided to make the main bearings.
because i'm milling the slots on the lathe, and the cross slide only has 1 3/4" travel, I made them from 1 1/2" lengths of 1 1/4" dia. bronze bar, first squaring the bar to 13/16 by 9/16 cross section in the 4 jaw chuck.

I have a collection of various thicknesses of 4" by 2" flat bar, brass and plastic shim , so I can set work on the cross slide with some degree of accuracy as regards it's hight. To align the material with the cross slide axis, I generaly screw on the faceplate and hold the work flat against it while I clamp it down , or align it using a square. I check it with a DTI and its very rare that it needs adjustment.





when i came to slice the bar, I found that the slitting saw arbor I had made didn't give me enough depth of cut, so had to remake it but this one is just held in the 4 jaw.




the next job was to put them in the boring fixture I had made and bore them all out to 3/8"


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## peatoluser (Dec 30, 2010)

Heres a photo of them in thier slots




i need to make the bearing retainers and bolt the bases down to fully check the alignment. As 3/8 bar is nominaly one and a half thou down on size, a piece should go through without binding. If it's tight i'll need to fettle the slots. trying to lap in the bearings would leave me with oval and over size journals. which brings me to a question. I intend to use a built up crank. If i use 3/8 BMS (CRS) will this give me too much clearance? or should i use 3/8 precision ground BMS and lap the bar down were the bearings are to give, say, half thou clearance?
thanks for reading the post
yours 
peter


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## Seanol (Dec 30, 2010)

Peter,
All I can say is WOW!

I learned how to add webs and what a difference it makes to the look of the model!

Thanks,
Sean


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## Ken I (Dec 30, 2010)

Use silver steel for the shafts - it is precision ground and generally better quality - its obviously a bit more expensive.

Ken


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## peatoluser (Jan 24, 2011)

managed to do a bit more to the engine this past week.
first up, I decided to make the chock blocks that the base stands on. As there's 84 of them I wasn't particulary looking forward to the job, but at least they are now out of the way.

first I made a simple L shaped jig to cut them to size (3/16 sq. bar by a 1/4 long)





didn't make a jig to drill them, but with hindsight probably should have. i used scrap pieces of 3/32 and 1/8 plate to mark the centres , drilled and tapped to 6BA. here they are in place




 I then gave the bases a coat of white primer to protect them and also removed the webs on the vertical parts of the bases. Don't know why I fitted them in the first place as they dont appear in the illustration i'm basing them on. They just made it an utter pain to bolt them together.




I decided to make the crankshaft next. This is a built up affair as I think that turning it from solid would stretch me and the Tiag too far :-\

I had already made a fixture for turning eccentric sheaves, so adapted this to bore out the crank webs




The drawings i'm using show plain square crank webs, but I came across a video clip on youtube that showed a (smallish) fullsize triple with nicely curved webs, so out came the files and I gave them some bling




I took Kens advice and used silver steel for the shaft. to set the 'web angle' I placed the shaft on 2 blocks, and the big ends on two smaller blocks. If my maths is right the difference in hight is just half the crank throw. Used loctite but undecided whether to pin as well.




On the original drawings , because the shaft is solid, the inside eccentric sheaves have to be split. But as i'm using a built up design i figure i may as well make all the sheaves solid and slide them on the shaft before fixing on the final crank. So next job is to make the sheaves.


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## NickG (Jan 24, 2011)

Wow, that's an incredible amount of work  Great stuff and making brilliant use of the peatol lathe there. :bow:

Nick


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## peatoluser (Mar 10, 2011)

foe various reasons didn't get much shed time in february, but hopefuly i can now get back into the engine.
next up to make are the eccentrics. for these i was able to use the 'V' faceplate i detailed on another thread. 
here it is drilling the holes at .140" offset.




these are held onto the shaft with grub screws and to drill these centraly i first drilled and reamed a hole in some angle




then it was a simple job to calculate the height of a spacer bar to place the eccentric on the lathe axis when located with a pin to the angle




I decided to try and give the eccentrics a bit of 'polish' by drilling and filing a couple of lightening holes in them , like their full size counter parts.




the trouble is, although i don't mind filing, i kinda hate using needle files, so i cobbled together a needle filing machine to fit the peatol




it works quite well. so much in fact , i've ordered some proper type B (1/8 shank) machine files. although i'll probably have to modify the design somewhat. when they arrive i should be able to make short work of the rest of them
peter


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## peatoluser (Apr 28, 2011)

After messing up the first set, I had to remake the eccentrics, but finaly managed to finish them.
The next job was the straps. as I wasn't using castings I used slices of phosybronze bar.
these were faced off and rough bored 7/8




I located them on a peg on the cross slide so I could mill a flat on them




This aloud me to atleast split them all the same, if not directly on centre. they locate against a strip of metal bolted to the slide




they were then soft soldered together and
I then centred them on the faceplate and finished bored them 29/32 with a central locating groove of 31/32 for the eccentric.




It was then a case of filing them to profile. I also decided to drill the eccentrics for two dummy bolts (9BA) to make them look like there full size counterparts


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## compspecial (Apr 28, 2011)

This project is so inspirational Peter! wonderful workmanship, and all done with a minimum of sophisticated equipment, good luck with your progress.
                Stew.


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## peatoluser (Apr 28, 2011)

Thanks for the compliment stew, but my workmanship is probably only marginaly better than my photography!
yours 
peter


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## nfk (Apr 28, 2011)

:bow: :bow: :bow: :bow:
Wont say any thing else!


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## bearcar1 (Apr 28, 2011)

I applaud you for demonstrating so excellent and well thought out fabrication work. And all with the tooloing you have available at hand. BRAVO!!! :bow:

BC1
Jim


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## peatoluser (May 17, 2011)

Thought i'd make the bigends and connecting rods next.
the big ends were straight forward split bearings , but I thought i'd give them some bling
(my apologies for the crap photos. the compact seems to have a mark on the lens- i had intended to treat myself to a new camera but blew the budget on tooling at the harrogate show)
I milled out 2 recesses on the sides of the bearing, turned up some barrel shapes , filled these in half using my filing rest and then soldered them into the recesses so they look more like full size practice. after spliting i bored them out using the same jig i used on the eccentric straps.




the connecting rods i made from 1 dia bar
first turned the profile




the next step was to square the stock. I thought about using my filing rest, but there was an awful lot of metal to remove, so decided to remove to the bench vice, hacksaw most of the waste away and use my bench filing jig to bring to size.




by the way, the jig i initialy made to help in filing thin sections. here it is as initialy concieved with some loco spring buckles. By filing down to wear strips, it saves a lot of time in continualy measuring and checking progress. when the strips (just pieces of scrap plate) get too 'filed down' just fit 2 new ones.




the rest of the work was just drilling and basic filing. here are the three stages of production in glorious three-quarter blur-o-vision so nobody can spot all the mistakes or out of squareness :big:




thanks for looking
peter


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## peatoluser (May 31, 2011)

before making the eccentric rods I thought i'd make the bushes for them as well as the bushes for the reversing links as these are almost identical.
heres a brief sketch of whats required




used the 4 jar to turn some pieces of round phosy bronze to 3/8 by 5/16 square, then sliced off 12 off 5/32 pieces and 12 off 3/16 using slitting saw and cross slide table.
thought about making a drilling jig to drill the holes, but discounted this method as they are quite small and fiddly, and came up with this method instead that somepeople may find interesting:-
filed up a piece of 3/8 bar so it was about 1/16 below lathe centre hight then clamped this, edge on, to the milling table (actualy a block of 2 * 4 * 1/2 steel). i then skimmed the top with a 5/32 cutter, set up the cross slide stops i'd made, then it was a case of clamping each of the first 12 blocks on top of the bar and drilling the 1/16 holes. because the bar was the same width as the blocks they were easy to align.
heres the photo of the first stage, centre drilling the 1/16 holes




I then skimmed the top with a 3/16 cutter, drilled the next 12 blocks, and finaly used a 5/16 cutter to skim the bar and drilled 3.9mm (i'll finish holes with hand reamer) in all 24 blocks. I think it was a lot quicker than trying to use the drill.
here they are all done




the 3/16 ones have bosses machined on the front. I just used loctite to fix 4 of them onto pieces of 5/32 bar, turned one face, removed from collet, and as long as i then removed it and loctited a new block on, by the time i'd done the other 3 (repeating the process) it would have cured enough to machine the next.
i guess the next job is the eccentric rods.
thanks for looking
peter


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## steamer (May 31, 2011)

Blurry or not, still looks great!  Nice set ups!

Dave


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## ShedBoy (May 31, 2011)

Mint looking engine. You really get every ounce out of that little taig. Every post has that Taig doing something different. :bow: :bow:
The filing attachment is great. I will follow with much interest.
Brock


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## peatoluser (Jun 8, 2011)

with the little bearing blocks made, time to start on the eccentric rods.
the drawings show these in 2 parts, the 'fork' being separate and screwed onto the rod, but I decided to make them as one piece so as to look more like their full size counter parts. although the sketch I used (from Newnes Marine Engineering) as a basis was probably more for crossed rods whereas the engine I'm building is open roded.
used a similar method of manufacture as for the connecting rods, but to make sure that I could file the fork on, I had to turn turn the shaft so it was off centre otherwise I would've had to make them from 1 1/2" bar and as the stem is 5/32" dia. tapering to 1/8", that would've been an awful lot of metal to remove for the peatol!
the photo shows the stages of manufacture. 3 down and 3 to go. hopefully should get them finished this weekend. the 2 pieces of grooved bar at the front are just a simple filing jig to help me round off the edges of the blocks while keeping the top and bottom faces square.
the rods are 2 3/8" high and all the nuts are 10 BA 




thanks for looking 
peter


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## peatoluser (Jun 21, 2011)

After filing the eccentric rods decided to have a go at the expansion links and die blocks. Although the links looked like a straight forward filing job, the drawings showed the die blocks having a straight slot. For some reason I can't fathom now, I wanted these to have a curved slot and I'd had enough filing for the time being, so decided to try and design a curve milling fixture for the peatol. well, I say design, but I just grab what's available and make it up as I go along.
this is what I ended up with: disassembled




and assembled




as you can see, it's just a plate that can pivot on a fixed back plate. I used my beam trammels to mark out a series of arcs (1/4" spacing), then centre poped these on a centre line with the swivel hole (reamed 10mm). In use I line up the nearest hole with a pointer held in one of the collets, and if the radius (as in this case, it was 3 3/16") isn't a multiple of !/4", I adjust the cross-slide with the help of a DI, as here




here it is being used to mill a bronze disc that will become part of the die blocks




and here, some gauge plate for the expansion links (i used my cross slide stops to control the thickness




did it work? well, yes and no. I did eventualy get all the parts made, but not without going through some cutters, fortunately I'd only paid a pound each for them, but it still irked nonetheless.
I had hoped to get away without making a lead screw for it, relying on friction (the pivot is tightened with a nyloc nut) and a long allen bolt as a handle to control the cutting rate, similar to the small rotary tables i've seen here to round of the end of rods etc. (appologies for not remembering who posted the original idea). I think with the cutter being so far from the centre I had a great deal of trouble trying to control it when it was breaking through. cutting the slot was fine. I had the same problem when I was milling on an edge. but i did eventually end up with this




that became these




was it worth it? I could have filed them quicker than the time it took to build the jig, and by the time i'd filed up the die blocks...well... i could only _see_ the curve in them because i _knew_ it was there... but the expansion links would only fit in them one way round and they were all the same thickness. So i think i will carry on developing it. I just need to make a lead screw for it. also i think the scapper plate (stops me ploughing into the swivel plate with the cutters) would be better if it was bolted from the back. and i think I could do with drill/reaming a hole in the pivot bolt. this should enable it to be able to mill arcs centred on a hole. anybody got any suggestions about the best way to go about these or other improvements will be gratefully recieved  ..oh.. and my appologies for this last photo.... the kid in me couldn't resist it :big: :big:






thanks for looking
peter


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## peatoluser (Jul 26, 2011)

The longer pivot arms in the curved links have a collar on the end to hold the reversing link bearings in place. decided to use taper pins (1/16") to hold these in place. not having much luck with cross hole drilling in the drilling machine, I decided to mill a V-block to fit the lathe. used a combination of 6 flute countersink & 1/16" slot drill to produce a vee groove in a block clamped to the cross slide.
here's the block beeing milled





and the small journals (5/32" dia.) being cross drilled .I loctited the collar onto the shaft to hold it in place, then after I'd drilled and reamed the hole disassembled with heat, before soldering onto the link.




the v-block worked so well that i ended up making another, but used a 1/2 countersink to produce a bigger vee.
With all the valve parts made, I thought I'd have a trial assembly of the shaft and base. here it is.




Instead of making round oil cups for the main bearings, I decided to try and make them square. A bit like the large oil boxes on full size engines.
Forgot to take photos, but I milled an oval slot in some brass bar using a similar set up to the way I'd drilled the reversing link bearings.
the lids are only a push fit. I tried milling these from solid using the vertical slide. got into all sorts of difficulty with size depth of cut etc.
so bought some solder paint and made them from scrap pieces of 18g brass. It may be an expensive way to buy solder , but a touch of the flame and they were done. I guess it pays to at least think of a couple of ways to do a job before cutting metal
I guess the next job is to make a start on the columns, but befor that, I've agreed to walk the coast-to-coast route. the daft things one agrees to do when drunk ;D. 2 weeks without any shed time. how will i cope!
thanks for looking 
peter


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## peatoluser (Sep 4, 2011)

Finaly finished the columns. well except for cleaning and fitting to the base. these were fabricated from 1/8" plate.
first was to hacksaw and file the sides




then tack weld the front and back pieces on




then I welded them up




but making sure i had built the edges up enough to allow filling and emerying to shape




I then tacked up a simple jig




to allow the top,front and base to be soldered on. i was concentrating on clamping everything up square forgot to take photos, but this should give an idea of how it turned out




as I've decided to try and make an open front engine instead of the closed column design, I tacked a piece of 1/8" plate to the centre of the jig to give me the slope for the front columns




the tool makers clamp is only just nipping the bar. In fact, I probably could of left it out. In situations like this, I usualy use a small chisel or centre punch to raise a couple of burrs either end of the bar. These tend to hold it in place while maintaining the joint gap.
and here are the columns ready for cleaning and fitting





thanks for looking

peter


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## steamer (Sep 4, 2011)

Nice fabrication work!  I made a cross drilling fixture like that that mounts to my QCTP

Works Great!

Dave

http://i164.photobucket.com/albums/u27/mcandrew1894/P7100003.jpg


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## Deanofid (Sep 5, 2011)

Great job you're doing, Peter. You've sure poured a lot of ingenuity into making so many parts with 
the lathe. I have the thought that you could do it all by hand!
Good stuff, this thread.

Dean


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## peatoluser (Sep 5, 2011)

Gentlemen, thank you for the compliments, much appreciated

Dave, I like your stop on the QCTP . I must fit one on mine.

and Dean, I must admit that there are times when all I seem to be using are hacksaw and files, that it feels like I'm doing it all by hand :big:

yours

peter


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## JorgensenSteam (Sep 5, 2011)

Great work Peter, it is interesting to see it start to come together.

Will be watching and waiting for a run.

Great project.

Pat J


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## peatoluser (Oct 26, 2011)

Slow progress, but progress nontheless
to make the crossheads I first squared up some mild steel and then used the lathe to drill the pivot hole and tap the piston hole at 90 degrees, as I can't trust my drill to drill that square. the profile was then filed to shape. the 'foot' was made from phosy bronze and used the vertical slide to mill a locating groove in it. it was then soldered on to the crosshead. heres a photo of the stages





I hacksawed and filed 3/8 strips from some 3/16 plate to make the guides. these were clamped to the cross slide at the right hight and a step was milled in them to suit the crosshead

milling the step





I bolted these to the columns, but instead of using a few countersunk screws , I decided to make them look like full size practice and used 10 ba bolts instead. more by luck than design , the connecting rod and crosshead just miss them although I had to chamfer the guides to stop them fouling the connecting rod.

here they are assembled





Yep, it's deffinately comming together at last.
next stop are the brackets for the reversing shaft and linkages and then i can finaly start thinking about the cylinders

thanks for looking

peter


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## pete (Oct 26, 2011)

Peter,
A awesome and very well done project that makes me feel more than slightly guilty for what I have in my shop. Before your post was started, I wouldn't have believed that a engine of this type could be done with the limited equipment you have. Once your engine has been completed, You really should contact Taig and provide a link to this thread. Your engine would be a super advertising example for them. I'd guess that Jerry Kieffer made a nice amount of spare cash from Sherline some years ago when they used some of his work as an example of what can be built using Sherline equipment. To be honest, This whole thread should be slightly rewritten as a long running multi part artical for one of the hobby machining magazines.

Pete


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## Jasonb (Oct 26, 2011)

Yes thats certainly comming along nicely. Talking of magazines the latest issue of ME has a nice scratchbuilt triple expansion on the cover with accompanying article.

http://www.model-engineer.co.uk/

J


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## Shopguy (Oct 26, 2011)

Peter

Looking good. When done you'll certainly have a fine looking model.
Ernie J


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## SBWHART (Oct 26, 2011)

That's comming together very very well Peter.

It will be a real nice engine when completed.

Stew


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## ShedBoy (Oct 26, 2011)

Nice, real nice. Love the detail, keep up the great work.
Brock


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## pete (Oct 26, 2011)

Jason,
Here in Canada our mail delivery is two behind that magazine. I'm looking forward to it.

Pete


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## steamer (Oct 29, 2011)

Very well done Peter! :bow: 

The next few steps are critical...getting the cylinder/crosshead/crankshaft to all line up correctly....take your time.

And a Karma for you for bravery! ;D

Dave


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## swilliams (Oct 30, 2011)

really looks fantastic Peter. Very nice job :bow: :bow: :bow: :bow:


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## kye (Oct 30, 2011)

wow!! 

surely im not the only one thinking that that will be hypnotic to watch as the crank is turned over!!!

 kye


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## Harold Lee (Oct 30, 2011)

Peter - That is beautiful work. I think to tackle that on the equipment you have is outstanding. I'll be following this with interest.

Harold


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## Ken I (Oct 31, 2011)

I'll second what Harold said, I am so impressed with what you are doing.

Can't wait to see this finished.

Ken


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## ref1ection (Oct 31, 2011)

I'm really impressed with the authentic look of this engine. It leaves no doubt that it's based on a real engine.

Ray


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## peatoluser (Dec 21, 2011)

Well, it's been a while since I posted, so thought it was time for an update. but first, can I say thank you for all your kind comments - they've certainly helped keep me focused on the task in hand and not drift into other projects! - although looking at other peoples build logs I feel I don't deserve half the praise.

the next parts were the reversing shaft brackets and arms which were straight forward soldering and/or filing jobs





the next bit was the operating mechanism for the shaft and this caused a bit of head scratching. the drawings show a worm and wheel arrangement but give no guidance as to number of teeth or pitch etc. I thought about trying to generate a wheel using a tap held in the 4 jaw.
I found this site that gives advice on this method,
http://www.atmsite.org/contrib/JSAPP/wormgear/wormgear.html
but felt i wanted something that would give a faster movement. So I settled on the idea of using a screw and nut similar to the one on imation's paddle engine posted on this board here
http://www.homemodelenginemachinist.com/index.php?topic=16548.0
but it was Zephyrin's comment about the scew that got me thinking. unfortunately.
I've always wanted to try thread cutting on the peatol by the follower method, and figured this would be a good a starting point as any. 
I had a 3/4 whit nut and bolt and thought about using these to produce a 10 TPI square thread but I really liked the look of that 8 TPI twin start.. 6 turns and the nut moves 1 1/2"...but how to produce a 4 TPI nut and bolt. In an act of ignorant optimism over intelligent experience I gave it a shot.
the first thing to do was to produce the screw. I chucked a piece of 1" bar in the 4 jaw, centred it , and scribed 8 axial lines down it's length. I then scribed across these in 1/32" steps to give me a spiral pattern around the bar as here




then, using first a 3 corner needle file, then a six inch one, I attempted to file a thread around the bar, but not after re-chucking the piece to bore both ends 5/8" and drill right through with a 6mm drill (this way it gives me 2 bites of the cherry to get a good fit on the lathe spindle, and makes it easier to thru drill the 6mm hole) . why I didn't just cut a card template of one helix and use this to mark the thread I don't know.
here's the bar with a plug loctited in for turning it




for the nut, I bored a 1" hole in a piece of 1 1/2 by 1/2 bar and drilled it to accept a 5mm bolt that i had turned a cone on the end.that's all that was going to be pulling the saddle along , but that bit worked surprisingly well. A scrap piece was welded on to it so it could attach to the bar that is bolted to the saddle




and here it is on the end of the spindle




I turned a suitable blank for trying out then set up for cutting the thread. then what could go wrong did go wrong.
i initially had it supported by the tailstock, but the tool easily deflected the work, so made a quick and dirty travelling steady and bolted this to the block i had bolted to the saddle. it's in use here cutting the first thread.




then i was surprised how much effort I needed to turn the spindle, so thought i would make a 'pre-cutting v shaped tool' to rough out the cut before finishing with the 1/16 wide cutter.
then the tool dug in and turned the work in the jaws putting it out of phase with the thread master.
the chuck fouled against the block I had screwed to the saddle so had to have the work protruding even more
next the master itself came loose, so had to strip down and drill for a grub screw (you can see it in one of the above photos)
then the tool broke, so I reset up with the finishing tool, but finally managed to get the first thread cut. It wasn't pretty - it was out of sync. with some of the other efforts- but cut nonetheless. 
to cut the second thread, i had come up with the idea of initialy using a piece of 1/8" scrap to pack the tool out to cut the first thread (hence the use of the toolmakers clamp in the previous photo) and then remove this to give the required offset. unfortunatly something went wrong and it got offset too much so when I cut the second thread you can see it's slightly out of phase.





it was then I realised I hadn't given much thought to cutting the internal thread, and moving the tool to cut the second thread. the conventional type of tool was out, if for no other reason than trying to grind it free hand, so i ended up coming up with the idea of filing a hook type tool- i only needed to thread for 1/2 depth- from gauge plate. the first one was too slender and bent when cutting, so made a second but modified the way i offset for the second cut . here they are




and here it is cutting a piece of scrap brass (I counter bored the back first for tool clearance)




the tool width is 0.070" and I drilled a 6.7mm clearance hole
did it it fit the screw? well of course it didn't! but it was trying to. it seemed to be just missing catching one of the threads, so I clamped the screw in the vice, putting some..er.. spanner flats on the thread, and using a light hammer and spanner, gave the nut a few taps while trying to turn it. both threads eventualy caught and I was able to run it on abou 1/2" before it went tight. well with the use of a needle file and some 400 grit grinding paste , within 1/2 hour I was able to run the nut the full length of the screw!








it's undoubtedly only catching on one helix and the threads wind themselves round the screw more drunkenly than i find my way home on a friday night, but work it does! it is good watching the nut race along the screw with a few turns, much better than with a die cut thread- one turn of 3/8 whit moves 1/16", here its 1/4. I will definately remake this. Might even see how much it would cost to get a proper follower and nut made by a local machine shop. And i would urge anybody to have a go, especialy with a screw cutting lathe. even if you only produce a single 8 TPI or 10 TPI square thread. they realy look the part. i think the stumbling block is cutting the internal thread, but the tool doesn't need to be HSS or long and can be easily file and hardened from gauge plate or drill rod. give it a go. It's well worth the grin factor at the end.


Oh, and PLEASE don't ask why I didn't use the compound slide to move the tool. I have one some where, but so seldom use it, it never entered my head.


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## peatoluser (Dec 21, 2011)

After messing with screw cutting it was good to get back to some simple swarf making.
turned and bored some phosy bronze to 1 5/8 OD by 7/8 bore





to make the steam passages, rather than drill at an angle, i decided to file a large flat (it was too difficult to hold in the 4 jaw) on to cylinder and solder a block on to this.
i milled a groove each end on the cylinder for the steam




I squared up some brass and then milled the steam passages on this as well as the port face slots








here are the two parts before soldering. you can see some centre punch marks to give the capillary gap. get the job hot enough and the solder will flow, so long as there's a gap for it. although I think this job would be ideal for some of bog's silver solder pallions (?)




i figured that this might be a better means of producing the steam passages than trying to drill them at an angle. well at least with my drill anyway!
to clean up , I turned a stub mandrel a tight fit for the bore, gently filed a small leading chamfer on it , and wrung the cylinder on ot it to face the ends




next up will be the chest and valve
thanks for looking

peter


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## danstir (Dec 22, 2011)

A very interesting build. Thanks for posting.


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## steamer (Dec 22, 2011)

Peat! I've done threading like that on a screw cutting lathe....but never with a follower!

Well done!  Just the kind of lateral thinking that can get you out of a bind!

I always love watching someone put the beany on and think a way through a problem! :bow:

Dave


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## peatoluser (Dec 24, 2011)

Thanks for the compliment Dave.
I think most of my problems with the scewcutting arose because I didn't quite believe I could pull it off, so wasn't really giving it the full attention I should have. 
still, not bad for my first attempt at screwcutting. Only ever used taps and dies before.
definitely going to make another screw though. 

peter


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## bronson (Jan 22, 2012)

Just read through this whole thread and found it very interesting. I really like the triple engine one of my favorites. The fact that you are building everything on a taig lathe is very impressive. The engine is looking great can't wait for the next update.


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## peatoluser (Mar 4, 2012)

Slow progress, but I'm then I dont want to start getting things badly wrong at this stage.
I didn't have any material thick enough to make the cylinder bases including the piston rod gland, but I did have some 1/4 brass plate so decided to use this for the bases and solder the gland bosses in seperately. heres the plate being skimmed and bored to take the gland. it's on a shop made faceplate. the screw holes will dissapear when i file it to shape.




the body of the HP cylinder is quite thick , so I wanted to skim it down but couldn't use the lathe because of the port face soldered on. then I remembered seeing somebody on here do a similar job but used a milling machine to take a series of tangental cuts and then cleaned up with a file. So , bolted the cylinder to cross slide, and using various thicknesses of packing, I managed to do the same.




 part of the reason I wanted to thin it down was to fit some lagging. I had quite liked the way Dr Jo had used wooden coffee stirers to lag her model , and wanted to do something similar.I also noted her idea of using a tile saw to cut the brass banding. I don't have one but it got me thinking, and I quickly cobbled together this table to use with my slitting saw arbour




the bands came out flat and parrellel and here is the suitably lagged cylinder




I know the drawings show all 3 cylinders as one block, but it wasn't that uncommon for the HP cylinder to be seperate and the IP & LP to be one block, and thats the set-up I intend to model. I guess it would be due to the casting ability of the foundry or the size of the machinery to machine the cylinders.


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## peatoluser (Mar 4, 2012)

When I came to make the valves , I realised i couldn't use the drawings , as i had had to make the port face block slightly narrower. on the plans the valve is moved by a valve buckle as in full size practice rather than a square nut set into the valve as in most models. I liked the idea of the adjustability of the valve buckle so devised my own method of an adjustable bobbin. here are the parts




It was when I came to make the chest that I ran into problems. my drill is a cheap far eastern one, and has quite a lot of play in the quill. it's fine for drilling shallow holes or through ones in thin sections, but anything over 3/8 and it's hit and miss where the drill will come out. so rather than clamp cover, chest and cylinder together and drill as one, I marked and drilled the cover tapping size 7BA and used this as a jig to drill the port face and tap 7BA. everything fine up to this point. I then used the cover as a jig to drill the chest. because of the thickness (9/16), the drill went every which way but straight. even when I opened the holes to 1/8 - and 7BA is only 3/32 dia. - some o them still didn't line up 
here's a mock up of the cylinder and valve. the photos poor, but some of those holes are very close to the edge




so, while I work out what to do, I decided to carry on with the IP cylinder. Some of you might have noticed on a seperate thread were I made some jaws for the 4 jaw to allow me hold larger diameters more comfortably
here's the cylinder being bored




i decided to use the same method of making the steam passages as on the HP cylinder. but the problem was I couldn't file a large enough flat on the cylinder to accomodate the port block. so I came up with the idea of having one broad flat face with two 45 degree angled faces either side. this would mean that the block would need two angled wings to suit. but how to file the wingss accurately?
first I decided to make 45 degree marking block. I bought a large countersink and milled down some 3/4 by 1/2 bar to give me the required slope




(I hope to use the countersink to make some v blocks and a cross hole drilling jig for the drill as well)
I bolted this to a piece of scrap to give me a guide as to how the filing was going. I could check it against a light or use a small smear of marking blue.
for the port face block, I milled the centre out of a block of brass, then used the 45 block to check progress as I filed the wings 45 degrees. 




one of the few times i use the vertical slide. I much prefer to clamp to the cross slide directly. far more rigid.
here are the parts and block . the black mark is showing the width of the 45 degree slope on the cylinder






the fit is quite good. certainly good enough for soldering. I dont think I could have filed it freehand and got the fit that good.
I now need to mill the ports. But for the LP cylinder I might have to come up with a different tactic. i dont think I have any brass big enough for the port block.

thanks for looking 

peter


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## Ramon (Mar 4, 2012)

Hi Pete, I've just had the pleasure of reading your thread for the frst time. 

Just like to say you are doing a cracking job given the limited kit you have. The way you have tackled what is, after all, a challenging project with the best of equipment should be awe inspiring to all of us with basic resources and just shows what can be done if you've a mind to it. Your approach throughout is resourcefulness at it's best for me but that in achieving the two start screw is just brilliant :bow:

Good luck with the rest of the build Thm: Thm:- I look forward to more inspirational ingenuity

Ramon


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## peatoluser (Mar 8, 2012)

Thanks for the vote of confidence , Ramon. I guess when machinists like yourself, steamer, deanofid et al make such positive comments, then I must be doing something right!
I've been trying to refine the way I make the thread follower, and came up with this method





I rolled (well, bashed really) from a piece of thin plate one helix of a 4 TPI T thread that was a tight fit over some 5/8 bar and then used it as a guide for a hacksaw, cutting a shallow groove three-quarters of the way round, repositioned the tube, cut a bit more etc. It took a few attempts to get the tube right, but looks far more accurate than filed follower. just need to sort out the tool offsetting , but I think I really should press on with the cylinders in the mean time.

yours
peter


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