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2 Cylinder Slidevalve Steam Engine -1- 2 Cylinder Slidevalve Steam Engine By Thor Hansen After making a slide valve engine that I managed to get running I decided to try and make a 2-cylinder version. Since the first one was a vertical steam engine, I made the 2-cylinder horizontal. The engine uses the same 16mm bore and 20mm stroke as the previous one, but with a different multi-throw crankshaft with the two crank pins at 90 deg. Many thanks to Graham Meek for his advice. Materials I had acquired a 32mm dia. piece of leaded gunmetal and used that to make the cylinders. I bought a few pieces of brass and some rods of free-cutting stainless steel; the rest was mild steel from my box of scrap. Crankshaft The Crankshaft was made from 8mm dia. bright mild steel rod and four pieces of 8mm thick black mild steel plate for the webs. I used a hacksaw to get the pieces roughly to dimension and glued two web pieces together to make a pair and drilled and reamed a 6mm and a 5mm hole 10mm apart. I made a fixture to hold the web pair in the lathe – see right photo. The pair of webs could then be turned to an outside diameter of 33mm. The work was then transferred to my milling machine and mounted in a 4-jaw chuck on the rotary table so I could mill the webs to final dimensions – left photo. Below is the result. The second pair of webs were made the same way.

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Page 1: 2 Cylinder Slidevalve Steam Engine - Webnode2 Cylinder Slidevalve Steam Engine -1-2 Cylinder Slidevalve Steam Engine By Thor Hansen After making a slide valve engine that I managed

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2 Cylinder Slidevalve Steam Engine By Thor Hansen After making a slide valve engine that I managed to get running I decided to try and make a2-cylinder version. Since the first one was a vertical steam engine, I made the 2-cylinderhorizontal. The engine uses the same 16mm bore and 20mm stroke as the previous one, butwith a different multi-throw crankshaft with the two crank pins at 90 deg. Many thanks toGraham Meek for his advice.Materials I had acquired a 32mm dia. piece of leaded gunmetal and used that to make the cylinders. Ibought a few pieces of brass and some rods of free-cutting stainless steel; the rest was mildsteel from my box of scrap.Crankshaft The Crankshaft was made from8mm dia. bright mild steel rod andfour pieces of 8mm thick blackmild steel plate for the webs. I useda hacksaw to get the pieces roughlyto dimension and glued two webpieces together to make a pair anddrilled and reamed a 6mm and a5mm hole 10mm apart. I made a fixture to hold the webpair in the lathe – see right photo.The pair of webs could then beturned to an outside diameter of33mm.

The work was then transferred to my millingmachine and mounted in a 4-jaw chuck on therotary table so I could mill the webs to finaldimensions – left photo. Below is the result. Thesecond pair of webs were made the same way.

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Before using heat to split the two parts I turned the side of the webs down slightly, about0.25mm except around theholes for the crankshaft andcrankpin. This is so most ofthe web will clear the bearingor big end of the conrod. Theholes in the web were openedup to 7.8mm and reamed to8mm. The webs were glued to thecrankpins and Crankshaftusing anaerobic glue. Istarted by gluing the crank-pins to the web. The Crank-shaft was put through theholes without any glue whilethe glue on the crankpinscured. The crankshaft restedon a couple of V-blockswhile the glue cured. Since the crankpins must beat 90 deg. to each other tomake the engine self-startingI made a spacer that wouldjust slide under the crank-shaft while it was resting onthe V-blocks. This spacerwill make sure that thecrankpin will be resting atthe same height as thecrankshaft – right photo. I also made a small square tomake sure that the othercrankpin will be at 90 deg.to the crankpin resting onthe spacer. After the glue had cured Idrilled 1.6mm holesthrough the webs and

Crankshaft and inserted some mild steel pins togetherwith a drop of anaerobic glue. The Crankpins were"pinned" in the same way. When the glue had cured Iused my Dremel clone to grind the pins flush – seephoto above. After the glue had cured and the pins ground flush, Imounted the Crankshaft in the ER collet chuck in thelathe and supported the other end with a revolvingcentre and trued up the webs. I used a boring tool tobe able to turn the side of the webs.

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Bedplate The Bedplate (or base) was made from amild steel profile I found in a skip. After abit of hacksawing I had three pieces Icould weld together. Since my weldingskills could do with some improvement Ihad to use an angle grinder and then a fileand some elbow grease to get to this: The Bedplate was left like this until I hadmade the Bearing Blocks.Bearing Blocks The bearing in the middle of the Crankshaft has to be split, so I started with that. The othertwo bearings were made the same way I made bearings for the vertical steam engine. I started with a piece of 8mm thick steel that I milled square and milled each side so it endedup about 7.5mm thick. I used a hacksaw to cut the piece in two about 0.5mm above the centreline of the Crankshaft. The largest piecewas milled flat on the top just at theCrankshaft centre height. I then milled a11mm wide slot to a depth of 5.5mm.Then I used a 3mm slot drill to mill aslot at the bottom of the wider slot. Forthe bearing I used two pieces of brassleft over from another project. The brasswas milled so it could just be pressedinto the wide slot. On the bottom part ofthe brass I milled a small ridge thatwould fit into the 3mm wide slot in theBearing Block – right photo. The photoalso show the bottom part of the splitbearing. The brass part is a light press fit,I also used a drop of anaerobic gluebefore pressing the brass in place. The work was then transferred to thelathe. I used two M3 cheese head screwsto hold the two parts of the bearing blocktogether, and another two screws toclamp the bearing block to the jig – seeright photo. I drilled a pilot hole first but the drillwobbled a little so I used a slightly largerdiameter end mill to get the hole true.After boring to just under 8mm the holewas reamed to 8mm. The other two "outer" bearings doesn’thave to be split so they were made thesame way as those I made for the verticalsteam engine. I used 6mm thick steel andmachined the work to dimensions. Thetwo blocks were mounted to the same jigas the split bearing, to make sure all three holes for the Crankshaft ended up at the sameheight. The holes in the two blocks were bored to just under 10mm so the pieces of 10mm ODbrass tube was a press fit in the hole. The brass bushes were then reamed to 8mm. The brassbushes were made over length, and the blocks were mounted again on the faceplate jig and

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the bushes turned so just about 0.25mm protruded on each side. Since I did something similarwhen making the webs there should be about 0.5mm clearance between the webs and thebearing blocks. Next, the top of the Bedplatewas milled flat and thebearings were mounted onthe Crankshaft and theassembly placed on theBedplate and the positions ofthe bearings marked out. Inthe Bedplate there needs tobe two holes for the webs. Idrilled a few holes and used ahacksaw to cut out most ofthe material. Then theBedplate was mounted on themilling table and the twoholes milled to the markedout outline – right photo.

I also made a flywheel and asmall pulley. I used a M4setscrew to secure the pulley.For this engine the largeflywheel is probably notnecessary, and I will probablyonly use the pulley. But Iguess the flywheel can be usedon another engine. I drilledthrough the Bedplate using anoversize drill and mounted thebearing blocks using M3cheese-head screws. The over-size holes in the Bedplatemade it possible to make smalladjustments to the bearingblocks so the Crankshaftrotated freely – right photo.Trunk Guide I fabricated the Trunk Guide for the Cross-head fromsome 3x30mm brass flat and 18mm OD, 16mm IDbrass tube. I cut two square pieces from the brass flatand two pieces just over 37mm long from the brasstube. The square brass pieces were mounted in the 4-jaw and a hole drilled through the centre, the hole wasopened up so the brass tube could just pass through. The flat and the tube were silver (hard) soldered andpickled in citric acid. The corners of the brass flat weresawed off and the work mounted in an ER collet in thelathe and the octagonal piece turned to a diameter ofabout 29mm and then faced – right photo.

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The next operation was to mill awaythe sides to make the apertures oneach side of the Trunk Guide, I usedan 8mm end mill.

Bottom Cylinder Cover The Bottom Cylinder Cover wasfabricated from pieces of brassflats and a short piece of10mm diameter brass rod. Ialso used a thin brass nail totry to prevent the pieces frommoving during silversoldering. It worked well onone, not quite so well on theother – right photo. I alsomade a steel ring with 29mmouter diameter and a 16mmreamed hole that was used to

test the fit of the spigot that will enter the bottom ofthe Cylinder. I also plan to drill 6 holes spaced 60deg. apart on a 24mm PCD so I can use the ring as adrill jig. I decided to mount the work in a 4-jaw independentchuck on my rotary table and mill the spigot, thatworked fairly well. I didn’t have any suitable parallels so I simply used acouple of 10mm end mills, when I measured theywere 9.99mm wherever I measured the diameter – seeleft photo that also shows the ring used to test thediameters. While the cover was still on the rotary table I usedthe steel ring and drilled six 3mm holes spaced 60deg. apart on a 24mm PCD. The rest of the work on the Bottom Covers will haveto wait until I have made the Cylinders.

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Cylinders The cylinders were made from apiece of leaded gunmetal just over32mm diameter, 34 or 36mm wouldhave been better. To be able to hold the cylinderswhile machining the outside I made aflanged mandrel 16mm diameter andthreaded on the other end and made asuitable nut – see right photo, it alsoshow the ring used as a drill jig forthe screws holding the covers. Theflange has six 3mm holes spaced 60deg. apart on a 24mm PCD, just likethe ring. This way the cylinder can beclamped on the mandrel whilemachining the outside. I used a hacksaw to cut the gunmetalto get two pieces just over finishedlength and then faced the cut ends.The ends were marked out, the centreof the bore is just over 2mm from thecentre of the gunmetal rod so I couldget a port face – right photo. I willprobably have to solder a portblockonto the cylinder.

The cylinder blank was mounted inthe 4-jaw and adjusted so the markedout centre of the bore was runningtrue. I used a centre drill to get a true startand drilled a pilot hole through thework. I had stoned the edge of a fewtwist drills to prevent them fromsnatching in brass and used them toopen up the hole in steps to 13mm –right photo. The drills worked well. I then used a boring bar to bore thedrilled hole out to 15.8mm, I thenmounted my ER-32 chuck in the lathetailstock and used it to clamp the16mm reamer. This worked verywell, better than the drill chuck I hadused before. The front was faced and the diameterturned down to just under 29mm for alength of just over 2mm, this wasdone so the machined end of theBottom Cylinder Cover would fit.

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The Bottom Cylinder Coverwas then fitted and orientedin the correct way withrespect to the cylinder portface and I used my Dremelclone rotary tool to drill a2.5mm hole in the cylinderend – right photo. I tappedthe 2.5mm hole M3 and useda cheese head screw to holdthe cover in place whendrilling (and then tapping)the next hole. With threeholes drilled and tapped Icould secure the cover to thecylinder and face the spigotof the gland and drill andream the hole for the Piston Rod.

The outer end of this hole was centre drilled.The cheese head screw were removed andreplaced with short pieces of M3 threadedrod, so short that the only protruded half-wayinto the cylinder cover. These short threadedrods will make the cover rotate with thecylinder and a centre in the tailstock willpush the cover against the cylinder – rightphoto. This way I could turn the spigot forthe Trunk Guide and be sure that it wasconcentric with the cylinder bore.

The next job was to try andmill the outside of thecylinders to make them look abit like they were cast. I mounted one cylinder on themandrel I had made earlier andused some M3 cheese headscrews to clamp the cylinder tothe mandrel flange. A ring anda nut at the other end was alsoused to clamp the cylinder.The mandrel was mounted inmy home made dividing headand the other end supported bya tailtock. I used a 5mm endmill to mill the outside whilerotating the work with the dividing head. The milling worked but for the first cylinder I just

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counted revolutions of thehandle and my old brainmanaged to loose count.The port face part was thelast part to be milled usinga 30mm carbide tipped facemill – right photo. For the second cylinder Imilled the port face firstand then used a 5mm endmill to machine the rest ofthe outside, this procedureworked out better and waseasier. A friend of mine sand blasted the outside (except the cylinder ends and port faces), this madethe cylinders look a bit more like castings. Later I soft soldered a portblock to the portface.Top Cylinder Covers The top covers were made from a piece of 3 x 30mm brass flat. I cut off two pieces 30mmlong and marked out the centre with a small centre mark. I could then use a compass andmark out the cylinder boreand the outside diameter. Ithen used the ring I madeearlier for marking out thebolt holes on the bottomcover and marked out threeholes on the top covers. Idrilled the holes 2.5mm andtapped them M3. Using thering I could now clamp thework to the ring, cut off thefour corners with a smallhacksaw and mount thewhole in the 3-jaw and turnthe 1mm spigot that will fitinto the cylinder – rightphoto.Piston & Piston Rod The pistons and piston rodswere made from stainlesssteel. I used 316 for thepistons since I had a suitablepiece and 303 free-cuttingstainless steel for the rods.The 316 rod was a sliding fitin the cylinders so I justmounted it in the 4-jaw andused a dial indicator to centreit. Then the rod was facedand a centre drill used to startthe hole for the piston rod. Iused a 2.5mm drill anddrilled to a depth just overthe length of the piston. Then a 3mm drill to a depth of 5mm. The 2.5mm part of the hole was

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tapped M3. A parting off tool was used to turn the groove for the packing, and the piston wasthen parted off. I also drilled two shallow 2mm holes at the top of the piston, I can the use asmall pin spanner when tightening the piston onto its rod.Crosshead The crossheads were madefrom a piece of mild steel rodjust over 16mm in diameter. Iturned down one end to asliding fit in the Trunk Guideand drilled an axial 2.5mmhole. Then I moved the workto the milling machine andmounted the steel rod in thechuck on my indexer. I used a 10mm slot drill tomill each side – right photo –until there were 6.5mmmaterial left in the middle. A3mm hole were then drilledabout 4mm from the end, andat 90 deg. to the previoushole. The work was then returnedto the lathe and the firstcrosshead parted off. Theaxial 2.5mm hole was tappedM3 and the other endrounded off a bit with a file.The process was thenrepeated for the secondcrosshead – right photo.

Conrod I decided to fabricate theconrods from steel parts anduse brass for the split bigend bearing. I used a pieceof 15mm diameter mild steelrod for the small end (withthe fork), and a piece of8mm x 18mm mild steel forthe steel part of the big end,the rest if the big end weremade from brass as I didn’thave any suitable gunmetal. I started with the small endpart of the conrod. The workwas mounted in the indexer– right photo – and one sidemilled flat. The work wasturned 180 deg. and asimilar flat milled to the same depth – to give a width of 8mm. The work was turned 90 deg. and a new flat milled but less deep than the previous. The work

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was again turned 180 deg. and a flat milled to a similar depth so that the spigot was just over12mm wide in that direction. I then had an 8 x 12mm spigot about 20mm long. I then milled a 6mm slot to a length of about 11 mm and then used an end mill to widen theslot to just over 6.5mm so it would fit over the narrow part of the crosshead. The work wasturned 90 deg. in the indexer and a 2.5mm hole drilled about 4mm from the end. The hole wasdrilled through both the top andbottom part of the fork. The hole inthe top part was tapped M3, theother was opened to 3mm. I made asmall steel pin that was threadedM3 for a short length and fitthrough the holes. The work was then transferred tothe lathe and a 3.3mm hole drilledaxially at the end of the forked partand tapped M4. The part with theM4 thread was turned down a bitand the work parted off. Then a filewas used to round the end. Here’s aphoto of the small ends mounted onthe crossheads. The piece of M4 threaded rod will be replaced by a 4mm diameter rodthreaded M4 at each end. The next job was to make the bigend, I used a piece of 12mm squarebrass for the split bearing and apiece of 8mm thick mild steel forthe part that will thread into the4mm mild steel rod. The 8mm thick steel was mountedin my 4.jaw about 8mm protrudingfrom the jaws – see photo. Thework was faced and a short spigotturned. A 3.3mm hole was drilledto a depth of about 7mm. I used ahacksaw to cut of a length just over5mm, the work was then transferredto the milling machine and hesawed surface milled flat.

Next I used a small hacksaw to saw the12mm square brass in two and mill thesawn surfaces flat – left photo.

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The two brass pieces and the mildsteel piece were glued together withanaerobic glue and the positions ofthe two 3mm holes were marked outand I used a 2.5mm drill to drillthrough all three parts. The 2.5mmholes in the mild steel part weretapped M3 – right photo. Heating weakens the glue so afterremoving the mild steel part the2.5mm holes in the brass parts wereopened up to 3mm.

The two parts were held togetherwith some M3 screws and theposition of the 8mm hole was markedout and a pilot hole drilled. This holewas opened up to 7.8mm and thenreamed to 8mm – right photo.

I then clamped a piece of 12mm mildsteel rod in the lathe and turned a shortspigot to a diameter just over 8mm so Icould clamp the split bearing onto thatpart of the rod- photo above. This way I could face each side of thesplit bearing to get the correct width and turn a 0.25mm protrusion around the 8mm hole. The

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split bearing was test mounted onthe crankpin and it movedsmoothly. The 4mm diameter rod connectingthe small end and big end was cutto length and threaded M4 at eachend using a tailstock dieholder. Thethread closest to the small end wasthreaded over length so I could usea locknut. The cylinders were placed on theBedplate and their position markedout. I drilled 3mm holes in theBedplate, two for each BottomCylinder Cover. I could then usethe holes in the Bedplate to spot the2.5mm holes in the BottomCylinder Covers and tap the holesM3. The threads on the rod closest to the small end were adjusted so the cylinders movedfreely. The photo above shows the cylinders and covers mounted on the Bedplate.

Steam Chests I managed to source some 6 x12mm and 5 x 12mm brass flatsand decided to use these to fabricatethe Steam Chests. I used a Juniorhacksaw to cut the pieces of brassand milled the two end pieces sothey were the same width – rightphoto.

The end piece with the gland part was heavy so Idecided to pin it to the long side-piece – left photo.

Even then the parts moved a bit whilesilver soldering/brazing the parts so maybe small brass screws next time, the phototo the right shows one of the brazed SteamChests after pickling and a few strokeswith a flat file on the underside.

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The work was then transferred to the millingmachine and top and bottom milled flat – rightphoto. I will probably mill away a bit on theinside after drilling the holes for mounting theSteam Chest to the Cylinder.

The work was then transferred to thelathe and mounted (with packing) inthe 4-jaw, so the hole in the glandcould be drilled and tapped – leftphoto. To drill the smaller hole in the

other end I used a long series Centre Drill to make a mark and then a long 2.5mm drill.Port Block After I had made the Steam Chests Irealised that the Valve Rod would hitthe Bearing Block unless I bent therod. In the end I decided to softsolder 5mm thick brass Port Blocksto the Port Faces of the Cylinders –right photo. I tinned the matingsurfaces first.

After soft soldering the brass flats to thePort Faces of the Cylinders I marked outpositions in each corner and drilled a2.5mm hole through the brass flat andaround 4mm into the Cylinder. The holeswere then tapped for M3 studs (well, piecesof threaded rod) – left photo.

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After drilling and tapping the fourholes in each portblock the next jobwas to mark out and mill the SteamPorts. First I drilled a 1.5mm hole nearthe ends of the 1.6mm steam inports to a depth of just over 4mm,so the tiny slot drill would have aneasier job. I managed the four slotswithout breaking the tiny slot drill.

For the exhaust port I used a 3mmdrill first before milling

I could then just turn the work 90deg. in the dividing head to drill thepassage from the exhaust port to theoutside – right photo.

The photo to the left shows the steam chestsmounted, I still need to drill some holes for lettingsteam into the steam chests.

The Steam Chest Covers weremade from a piece of 1.5mm thickbrass sheet. I could use the four3mm holes in the Steam Chests asa drill jig so it was easy to get thecovers to fit – right photo.

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Slide Valves The Slide Valves were madefrom a piece of free-cutting (303)stainless steel rod. I clamped the rod in a small 4-jaw independent chuck in mylathe and used a DTI to centre thework, and then faced the end. A5mm slot drill was then used tomill a small cavity in the facedend. The cavity was nearly 2mmdeep.

The 4-jaw with the work couldthen be moved to my indexer onthe milling machine table, and theend milled to get a rectangularform 9mm wide and just over10mm high. Two 3mm holes weredrilled at 90 deg. and 4.5mm infrom the end – right photo. Thiswill give a rounded bottom in theslots that will be milled later. The 4-jaw with the work wasthen moved back to the lathe andthe valve parted off.

The parted off valve wasmounted in the milling vice anda 2mm slot drill used to mill thecavity to dimensions using thehandwheel dials – left photo.

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The last operation was to mill thetwo 3mm slots, one slot for theValve Rod, the other for the ValveNut – right photo.

The left photo shows one of the finishedvalves. The Valve Nuts were made frompieces of 3mm brass flat.

Valve Rods & links The Valve Rods and links were madethe same way as the single cylinder slidevalve engine I had made earlier. The rodwas clamped in the ER-32 chuck on mysmall lathe with just a short endprotruding, this was turned down to justunder 2.5mm. Then the rod was movedout a few mm and that part turned downto 2.5mm, this was repeated until alength of about 9mm was turned down to2.5mm. Then a M3 die in the tailstockdieholder was used to cut the M3 threadsfor a length of about 12mm. The workparted off at correct length and the otherend threaded M3, the final Valve Rod isshown (with temporary nut) to the right. The Valve Rod is connected to theEccentric Rod with a small link. Thelink is made up of a fork like part with apin and a rod that fits in between thefork. The fork like part was made from apiece of 12mm steel bar. The bar wasfirst mounted in the lathe chuck andturned down to 5.5mm for a length of5mm. A 2.5mm hole was drilled to adepth of 5mm and tapped M3. The workwas then transferred to the indexer onmy milling machine and milled square –right photo. One side is 5.5mm AF, theother almost 6mm.

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Two holes were drilled at 90 deg anda bit offset. One 2.5mm hole and one3mm – right photo. The 3mm hole is closest to the M3threaded hole and will give a nicerounded bottom for the milled slot.

The work was then transferred back to thelathe and the fork parted off and then a fileused on the corners. The left photo showsthe finished fork on the Valve Rod.

The Eccentric Rodswere made from alength of 3mm dia. mildsteel rod. I used the ER-32 chuckon my small lathe tohold the rod and faceand chamfer the endbefore using a M3 die inthe tailstock dieholder tocut the thread. The rod was movedfurther out in the chuckand parted off to thecorrect length. The parted off rod wasthen mounted in the ERchuck and chamfered and the M3 thread cut. Two rods were made. A piece of 6mm dia. mild steel rod was used to make the Eccentric Rod heads. The rod wasmounted in the ER chuck and the end faced and chamfered. A 2.5mm hole was drilled to adepth of between 4 and 5mm and threaded M3 with a tap. The work was then transferred tothe indexer on my milling machine and the non-threaded part milled to just under 3mm acrossflats. A suitable hole was drilled through the flats so a pin could be inserted – see abovephoto. The above photo also shows that one of the Steam Chests is connected to the compressorusing a small adapter I made for another single cylinder steam engine. Since I used the samedistance between the mounting screws on the steam chests of both the single cylinder and thetwo-cylinder, I could use it to test one cylinder at a time. After giving the flywheel a spin thetwo-cylinder started running even if only one cylinder received any air.

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Eccentrics I made the eccentric sheaves frompieces of cast iron I had left overfrom another project. Instead ofturning a groove in the sheave andusing a split eccentric strap I simplyturned a shoulder. To prevent thestrap from falling off a thin piece ofmild steel plate is attached with acouple of small screws. Below is aphoto of the sheaves after turning.

The straps were fabricated from twoshort pieces cut from a steel tubewith 18mm I.D, and 22mm O.D. I silver (hard) soldered twosmall pieces of mild steel to the tube pieces. I will drill a2.5mm hole in each and tap M3 for the Eccentric Rod –right photo, and a threaded hole for a grub screw.

Steam Connector To be able to supply both SteamChests with steam (or compressedair) I used a piece of coppertubing and some pieces of brass tofabricate a steam connector. Theright photo shows the parts readyfluxed in my makeshift hearth.

After pickling the steam and mounting holeswere drilled, the left photo shows the enginerunning on compressed air.

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