# Double-Acting Twin Beam Engine Build



## crueby (Feb 18, 2014)

Got a start on an engine that I've been wanting to build for a while - a twin-beam double-acting steam engine, in a larger size to allow for more ornate style. I had done a Stuart Half-Beam kit years ago, think that got me going on this style.

Below are some sketches that I drew up to work out the general arrangement and to see what cylinder size would fit my lathe/mill setup (sherline). After finding some nice bar stock at Yarde Metals drop zone (good prices, small selection since it is off-cuts), I settled on a 1" bore, 2" stroke, 12" beam arrangement. These sketches are just the starting point, details may well change as it goes, and will be making detail drawings to post as each part is done.

Build will start with the cylinder assembly....


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## crueby (Feb 18, 2014)

First up on the build, making the end caps for the cylinders. Started with a length of 1.25" brass (C360) in the 4-jaw chuck. Having learned the hard way about getting bolt holes to line up in parts, I am setting up the mill for drilling with the chuck on the rotary table to do the drilling for the perimeter bolts, and locking down the cross slide table until all the end caps, cylinders, and base plates are made, so that I can be sure that the holes will all line up (much easier than redoing the setup multiple times!).

The stock was centered up in the 4-jaw, and the end faced off for the bottom cap. Then moved the chuck and stock over to the mill to drill the 5 bolt holes (#43 drill), each one 72 degrees farther around than the last - rotary table makes this setup so easy - first centered the table, then offset the table 0.550" to put the center of the drill in the middle of the cylinder wall, and locked down the table for the rest of the operations. Then, drilled each hole and advanced the rotary table 72 degrees.

Moved the chuck back to the lathe to part the cap off, 0.150" thick. Repeated for second bottom cap (leaving stock in chuck for all this saved having to recenter each time too).

Next up were the two top caps, which have the packing gland recess in them. Faced off the end, and machined in the recess around the outer edge (leaving a 0.835 diameter, 0.150" tall protrusion). Took that to the mill for a set of 5 bolt holes just like the bottom caps. Came back to the lathe, and bored a 0.250 center hole for the piston rod, then with a small boring bar widened that out to 0.500, 0.200 deep for the packing gland. With that all done, parted off.

There is still some work to be done on the top caps to bore/tap holes for the packing gland, but that will be done later, since it requires moving the rotary table, and I dont want to do that till after the cylinders are made.

Wish I could put the commentary between the photos - anyone know a way to do that while still using the HMEM photo upload service?


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## crueby (Feb 18, 2014)

Next up is to make the cylinders - Started with a longer piece of 1.25" brass (finished length will be 2.5"), centered it up and faced off one end. Moved chuck to the rotary table on the mill, still set up in same place from making the end caps, and drilled #50 holes in the perimeter, 0.200 deep, 72 degrees apart, and tapped those holes with a 2-56 bottoming tap.

At this point, was ready to re-chuck it in the 4-jaw with the other end out. However, to make sure that there would be enough room to bore through the brass without crashing into the chuck (since the bore would be larger than the center hole in the chuck), I put in a set of 2-56 cap screws in the cylinder first. That left enough gap for the end of the boring bar to come out of the stock but not touch the chuck face.

After recentering, faced off the end and turned it back to the final 2.5" length. Then, back to the mill. At this point, it was important to get the bolt holes in the second end to line up with the first end, since a flat will be milled in the side of the cylinder to make a mounting place for the valve assembly, and the flat will span the gap between two of the bolt holes. So, using a square I transferred the location of one of the holes to the other end, and used that position as the starting point for drilling. Since it would have been a pain to get that mark to the zero position on the rotary table, I just rotated the table till the mark lined up under the drill, and read off that angle. Turned out to be 32 degrees, so did the rest of the drilling at 32+(72 * hole_nbr) increments.

Then, back to the lathe, bored a 3/8" starter hole, and was ready for the boring part - boring out the center. Since my larger boring bar would not fit in the starter hole, began boring with a small bar, then switched up to the larger one after a few passes. Lots of swarf later (had to vacuum out the bore every couple passes since the chips would build up in the long cavity), the final passes were done with a series of light cuts to leave a smooth finish that only needed a little polishing. All done - except this is a twin beam, so had to do all that again for second cylinder!

One last item to use the rotary table position for - drilled/countersunk a set of holes in a pair aluminum plates that will be used as base plates to mount the cylinders plus the valve cranks later on. For now, just drilled for the holes to mate up with the bottom end caps.

Next up - milling for the valve chest.....


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## crueby (Feb 18, 2014)

Okay, ready for the next step, milling in the flats and mounting the base for the steam chest. In a casting set, this would all have been done as one piece, but since this build is from bar stock, the base for the steam chest is being added on.

The cylinders were clamped in the mill table vise, checking to make sure the top was parallel to the travel of the cutter, and then a 5/8" wide flat was milled in with a fly cutter. I like the finish that the fly cutter leaves better than using an end mill, use it whenever I can.





Then, a piece of 3/4" x 3/8" flat bar stock, rough cut slightly longer than the cylinders, was clamped in place and soldered in place, making sure that the flux/solder flowed all the way through the joint since the steam passages will be passing through this area later and leaks would be a problem.




Then, back to the mill for a light pass to trim the end of the bar down flush with the top of the cylinder - important to get the piece properly aligned/vertical so the final face matches the top of the cylinder for a good seal with the end caps.




The cylinders look plain at this point - later on I will be milling in some ribs and recesses to dress them up. First though, I think the next step will be to make the packing glands and fit them to the top caps....


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## romartin (Feb 18, 2014)

Hi Crueby! I shall be following your build with relish. So far it looks great. 
I'm curious to know what solder you used for joining the steam chest base to the cylinder?


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## crueby (Feb 18, 2014)

Hi Romartin - For soldering these two parts, I used Tix silver solder, made for jewelry work - it has a low melting point, so it is no good for anything near flame, but it has very high strength and it flows deep through tightly fitting joints. The flux for it is corrosive if left on the metal, so you have to flush it with water afterwards. It is available from most jewelry tool suppliers, and some model catalogs. Bit pricey, but it does not take much at all to do a large joint. Again, not for use on any parts that will be near direct flame, like a boiler or IC engine, but since I mainly run on air that is not a problem for me. I started using it on ship model fittings, since it works so well on small parts, wicking itself into the joints and leaving little on the surface. Highly recommend using thier flux with it, been using same small bottle for years and years.


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## weez (Feb 18, 2014)

crueby said:


> Wish I could put the commentary between the photos - anyone know a way to do that while still using the HMEM photo upload service?



After uploading images you can click on the arrow next to the attachments icon (paperclip).  This will bring up a box with the uploaded images listed.  Clicking on one will place the image where the cursor is currently located -shown as .  It took me awhile to figure this out too.  I do think it makes for better posts when there is text by each picture instead of one big lump of text followed by a bunch of pictures.


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## crueby (Feb 19, 2014)

weez said:


> After uploading images you can click on the arrow next to the attachments icon (paperclip).  This will bring up a box with the uploaded images listed.  Clicking on one will place the image where the cursor is currently located -shown as .  It took me awhile to figure this out too.  I do think it makes for better posts when there is text by each picture instead of one big lump of text followed by a bunch of pictures.
> View attachment 67959



Excellent - Thanks much!! I'll do that from now on.

We have the technology, just dont know how to use it!


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## crueby (Feb 19, 2014)

crueby said:


> Excellent - Thanks much!! I'll do that from now on.
> 
> We have the technology, just dont know how to use it!



It let me go back and edit the 3rd post to try putting the pictures inline - great, thanks for the tip!!!


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## Herbiev (Feb 19, 2014)

Looking really great. Love the clear pics


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## crueby (Feb 19, 2014)

Got the packing glands made and fitted to the top caps. I changed my mind on the bolt holes for the glands, had originally drawn it as having 5 to match the cap-to-cylinder bolts, but decided to go with two instead, to make it easier to align. I am thinking it will float the alignment on the piston rod this way - that is how I did it on other engines and seemed to work fine there.
So, I updated the drawings for the caps/glands (and fixed/added a couple missing dimensions too), here is that new version:



For the glands, turned a short length of brass rod down to 0.835 and center drilled it 1/4" for the piston rod:



and then turned down the shoulder on both ends to 0.50 diameter, 0.225 deep to fit the top caps:



Then, moved the chuck over to the mill, set it for 0.325" from the center of the piece, and drilled a pair of #43 holes through, 180 degrees off from each other. 





Leaving the rotary table locked in that position, went back to the lathe and parted off the two glands, leaving the rims at 0.125" thick. Then, using the same position on the mill, drilled matching #50 holes in the top caps, 0.200 deep and tapped them for 2-56 screws.



The finished top caps/glands:



Next thing to be done is to drill the steam inlet/exhaust passages in the steam chest bases. After that will most likely mill some ribs into the outside of the cylinders to make them look more like cast pieces - they are a bit too plain as they are...


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## weez (Feb 19, 2014)

crueby said:


> Excellent - Thanks much!! I'll do that from now on.
> 
> We have the technology, just dont know how to use it!



You're welcome, glad I could help.  Great start to this engine.  I will be following along.


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## lennardhme (Feb 19, 2014)

Looks a good project - will follow also.
Nice pics, thanks.


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## crueby (Feb 21, 2014)

The outside of the cylinders were looking too bland, so went back and milled in some recesses to dress them up, looks more like castings with ribs now.

To start, set up the rotary table tipped up to horizontal, and chucked up the cylinder, using one of the top caps on a live center to steady it, with the packing gland side in since the larger hole on the outside was too big for the center. Marked off the locations for the ribs, and set the mill to take a 0.080" cut with the cross-slide back:



Then, ran the cross-slide forward till the mill was centered, and used the rotary table to turn the piece to make cuts in one direction, feeding the table side to side between cuts till one full window was milled out:



That process was repeated for the rest of the windows:



Same sequence for the other cylinder:



And then started sanding/polishing them to get rid of the end mill marks. There must be a way to mill like this without getting the tool marks showing each pass - anyone?



After that, ready for what is always a nerve-wracking sequence for me - drilling the steam passages through from the cylinder to the chest. Lots of double-checking angles and measurements to make sure that things will line up. This is one place where the tilting table comes in real handy, much easier to tweak the angle than trying to do it in the vice. 

Started with drilling in the exhaust/inlet ports while still horizontal, these holes just go halfway into the base plate:



After that, drilled from the side of the plate to make the exhaust passage - this hole meets the center one in the base plate:



Then  two holes to the side of that one, drilled/tapped 2-56 to give a place  to bolt on the exhaust flange. I like to have a seperate fitting to bolt  on the exhaust pipe, makes it easier to install/remove when needed than  if it was screwed directly into the base plate.



Then ran the table back up to around 5 degrees, and sighted in from there till the holes would line up. Then milled a small recess from the edge of the cylinder back to where the passage will start:



And center drilled for the start of the passage in that new flat:



And drilled down from there till it met the inlet port (lined up!)



That finished off the major work on the cylinders themselves, other than making mounting the steam chest and valve....


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## crueby (Feb 22, 2014)

Time to build the steam chests for this engine. First, refined the original drawing for the cylinder/chest:




Frist step was to drill/tap the mounting holes for the steam chest into the base plate on the side of the cylinder. These are 2-56 tapped holes, 0.200 deep, positioned to center the steam chest opening on the steam inlet/exhaust passages:




Then, squared up a 2" length of 3/8" x 3/4" brass bar stock, set it 0.125" from one edge, and started boring for the valve rod. This is a set of 3 concentric holes, starting with a 3/16" dia. shallow hole for the packing gland, then a 1/8" dia. hole for the valve rod, then a 5/64" hole at the end for the narrow end of the valve rod (which narrows down once for the valve nut threads, then again past the threads to fit into the guide hole at the far end of the valve chest. I've found it easiest to get the holes to line up to start with the largest diameter, and work down. So, started with the 3/16" hole, 0.150 deep:







Then, without moving the table, drilled a 1/8" hole down 1.5" deep, which is where the opening in the valve chest ends - the larger drill resists drifting more than the smaller one, so went as deep as possible with the 1/8" drill:




Then, finished up with the 5/64" drill - had to have as much as possible sticking out to reach that deep (actually had intended on using a smaller drill size originally, but that drill would not reach).




After that, moved the table to each side by 0.175 and drilled for the packing gland mount holes, #50, 0.200 deep. These are tapped 2-56. These holes fall just inside the mount holes for the valve chest, which are to be drilled next.







Turned the valve chest on its side, and laid out and drilled the 6 #43 holes for the mounting bolts. Also did matching holes in the valve chest cover while I was at it:




Here are those parts all test fitted. Took some 2-56 bolts and cut the heads off to make the mounting studs, which will be loctited in later on. Hex nuts will be used to close it up. Using studs rather than bolts makes it easier later on to pull off the valve chest cover to time the valves, without letting the chest fall out of position.







Last step on the chest is to mill out the opening in the center. After drawing it in place per the plan, used a drill to hog out the majority of the metal in the opening....



Then came back with a mill to open it up in a series of narrow passes:



The finished part:



And in place on the cylinder:



Only parts remaining on the chest are to drill the steam inlet and mill some recesses in the cover, and to make the packing gland itself. Not a bad day's play in the shop! (happily retired, lots more time to play!)


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## crueby (Feb 24, 2014)

On to more parts of the steam chest. To start, did the recesses in the cover plate, and drilled the steam inlet hole:




both plates done, ready for sanding/polishing later...



Made the valve packing glands from some short lengths of brass square. Drilled the 1/8" hole for the valve rod,




Then the #43 clearance holes for the 2-56 mount bolts either side of the valve rod, 0.175" from the valve rod center to match the holes in the valve chest:



Then chucked the piece up on the lathe to turn down to the outside of the valve rod hole, leaving a T-shaped piece:



After that, just a matter of some time with a file to taper the ends and round the corners:



Here is how the parts are looking so far:



Next up was to make the valve rods themselves, starting with a length of 1/8" steel rod. I left them a bit long for now, till I work out the linkage details. Started by turning down the narrow end, that will ride in the bottom hole of the valve chest:



Then threading the middle section where it will have an adjusting nut to hold the valve itself. Originally was going to make this a 5-40 thread, but realized I did not have a die for that (have 5-40 tap, wonder why I never got the die too? Oh well), so switched it to 5BA, which is very close, and have a tap/die set for that. Used a tailstock die holder I made recently - amazing how much easier that tool makes threading long lengths without wandering!



Here is how it looks in place:



While in threading mode, turned down shoulders on both ends of lengths of 1/4" steel rod for the piston rods, for mounting the pistons on one end and the clevis on the other. These shoulders were turned down to 0.1875" dia. and are 3/8" long.



The shoulders were threaded 3/16-40:



Same done for second rod for other cylinder. Funny perspective from the camera - these two rods are really the same length...


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## crueby (Feb 24, 2014)

Up to making the steam valve sliders. Started with a length of steel bar long enough to make both sliders - easier to hold two steady for most of the work then cut them apart later. Started out by spot drilling the depth for the end mill - the set I have is not center cutting:



Then started in with the end mill, making the slot on one of the valves:



Then thr other:



Turned the valve piece over, and started milling in the posts (guess its really milling away everthing BUT the posts?) that will hold the adjusting nut. Started by making the outside edge cuts in one direction,



Going deeper over a few passes....



Down to the final depth:



Then switched to a 1/8" end mill (same diameter as the valve rod) and started making the lengthwise cuts down the center:



Also taking several passes down to same final depth:



Then started making the final cuts to make the slot to hold the adjusting nut on one valve:



And on the other:



Final steps on the valves were to make a light pass with the fly cutter to narrow down the pieces to final width and then to cut them apart.



Here is how it looks so far:



Then, made the adjusting nut from a scrap of 1/8" thick brass...



And putting it all together:



Later on, when I decide the design of the valve linkage, the upper ends of the valve rods will be trimmed to length and fitted out as needed.


Almost done with the cylinder assemblies - just the pistons to go!


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## crueby (Feb 24, 2014)

Time to make the pistons. Started with chunks of 1" steel rod, centered up in the four-jaw very carefully, and faced down both sides to final thickness:



and then center drilled #20 and tapped 3/16-40 to match the piston rods



The piston rods were screwed on and held with high-strength loctite, then rechucked the piston rod in the lathe, and again got it all centered carefully. On some previous engines I just used the 3-jaw chuck at this stage, and wound up with pistons that were not quite concentric with the piston rods, causing all sorts of grief. Hope I learned that lesson permanantly!



Then the nervewracking part - turning down the outside of the piston, sneaking up on the final dimension to match the cylinder bore:



Once a snug fit was acheived, moved the piston out, applied some diamond lapping paste (had that on hand for final honing of chisels) along with a little bit of oil, and lapped the piston to the bore. Started out hand-turning the spindle to spread the paste and to make sure it would not grab, then ran the lathe at very slow speed, moving the cylinder back and forth till I felt same resistance all the way up and down....



Cleaned off all the paste/oil again, put on a little new oil, and did a quick compression check - with the bottom cap on the cylinder, dropping in the piston I could hear it pushing air out the port. If I covered the bottom port, the piston would just sit there, then slide down when I uncovered the port. Should be a good fit! Very happy with how this one is coming along...


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## Davewild (Feb 25, 2014)

Lovely work Crueby, I have the same machines, however you have some tooling I don't recognize, where did you get the boring bar? It looks much longer than the stock Sherline, I have been trying to find a longer boring bar to no avail!!!

Regards

Dave


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## crueby (Feb 25, 2014)

Davewild said:


> Lovely work Crueby, I have the same machines, however you have some tooling I don't recognize, where did you get the boring bar? It looks much longer than the stock Sherline, I have been trying to find a longer boring bar to no avail!!!
> 
> Regards
> 
> Dave



Hi Dave,

I got that boring bar and a couple other items from a friend in my archery league that was a retired machinist. It has C.M.C. USA on the side. It is a very nice bar, quite rigid, and takes only a small hole to start boring in. Not sure where to get one, have seen simaler ones in catalogs like McMaster-Carr, Enco, Graingers, usually for a steep price - tough to find a smaller diameter one.

The quick-change tool rest I bought from A2Z Corp - they make a bunch of aftermarket Sherline parts (also got the longer z-axis column for my sherline mill). Really like the quick change setup - have a number of the tool holders that I leave set up with left/right/center cutters, cutoff bar, and boring bar. Nice thing is that the height adjustment stays with the tool holder, so no need to reset the height every time. The one thing I did on there rest was re-mill the bottom surface - they sent it fairly rough, so it would not stay in place, kept rocking/turning under pressure. In their instructions it said to put a piece of paper underneath to prevent that - instead, I remilled the bottom flat, with a slight hollow in the middle, so it would grip properly around the edge when tightened down.
I also got a set of larger-shank tool holders that take replaceable inserts to use with them. Very handy.

Another real handy item are the welders parallel clamps - they are Kant-Twist clamps, in the two smaller sizes. Come in real handy for holding multiple parts together to place into the vice. Grip really well, dont twist parts out of alignment when tightening, and also have a groove on one side of the block that let you grip round stock.

Some of the other items, like the tailstock die holder, are home made - got info on that one from others in the forum, very handy. If you dont want to cut morse tapers, you can get blanks in alum. or steel from places like LatheCity.

Chris


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## bb218 (Feb 26, 2014)

The bar looks to be a Circle brand, solid carbide with steel head.  I have seen them on Ebay and also you can buy them direct from several Circle distributiers here in the US.  Great tools.


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## Davewild (Feb 26, 2014)

crueby said:


> Hi Dave,
> 
> I got that boring bar and a couple other items from a friend in my archery league that was a retired machinist. It has C.M.C. USA on the side. It is a very nice bar, quite rigid, and takes only a small hole to start boring in. Not sure where to get one, have seen simaler ones in catalogs like McMaster-Carr, Enco, Graingers, usually for a steep price - tough to find a smaller diameter one.
> 
> ...



Hi Chris

Thanks so much for your very detailed response, I went on Ebay after reading your post and there are many small boring bars on there, I also had a look at A2Z very nice equipment, I'm currently offshore working but will be placing an order once I get home, thanks again.

Dave


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## crueby (Feb 27, 2014)

Time to make the valve crank assemblies, to transfer the horizontal motion of the bar from the eccentric to a vertical motion to move the slide valve. Here are the parts to be made:




Starting with the crank bases, from 1/2" square bar stock:



First drilled 3/16 for the cross bar, then milled around that to leave a boss:



and milled out down to the base. Then flipped it over, and did same to other side:



And a couple passes on the sides to taper them



and milled out the centers for a little more style...



Drilled the bases for the mount holes (#43), then started on the horizontal crank arms. To make holding/aligning in the vice easier, made all 4 in one bar to be separated later. Started by drilling the 3/16" holes for the crossbar in one end and the 0.780 holes in the other for the clevis, and then started milling down between the larger holes:



Leaving the 4 arms to be sawn apart, and tapered on the sander and file:



Simaler steps with the 2 vertical crank arms, except these will have a slot in the arm so that an adjustable link can be used. This will allow for adjustments in the length of the throw to fine tune the valve movement distance. The adjustable link will be made later. For now, drilled the 3/16" crossbar holes, and rows of smaller holes for the slot.



These smaller holes were joined up with a jewelers saw and smoothed out with flat needle files:



Then, milled down the arms on both sides



sawn apart and the ends rounded with files:



That just left the linkage bars. Endcaps were made by crossboring some 1/8" holes halfway through some 3/16 rod, and rounding the top ends, and boring 1/8" holes in the bottom ends. 



The middle caps, to connect the valve rod to the linkage, were made in a simaler way, except the cross hole goes all the way through, and the tops were filed to an acorn shape. These middle caps will not be soldered to the cross bar, but will allow the bar to rotate.



The endcaps were then soldered onto lengths of 1/8" rod, with the middle cap slid into place, to make the final linkage bar assemblies, shown to the side of the cylinders below. Still need to make the clevises to attach them to the cranks, and solder the middle cap to the valve rods..



Starting to look like an engine finally! Been doing some sketching to decide on the decorations for the main beams and the inserts for the bars to link to the valve eccentrics (will be way too long to just use thin bar, so will be two bars with an insert between. More on that to come...


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## crueby (Mar 1, 2014)

Time for some fiddly-bits - the clevises for the valve cranks. There are 4 needed to connect the vertical rods to the cranks, and 2 more needed to connect the cranks to the arm going to the eccentrics on the crankshaft. They are very simaler, only different in that the 2 for the eccentric arm are threaded in both holes for fine adjustments.

Here are the dimensions for these parts:



To start, drilled pairs of holes that will be connected up later with saw/file to make the slot in the end of the clevis. Drilling them now but not making the slots, to allow places to grip during later steps. Did these in sets of 3, easier to get them levelled up in the vice that way.



Then cut them apart, and chucked each up in the 4-jaw on the lathe, with the end drilled for the slot in the chuck. This is why I did not saw out the slots yet, needed that metal for gripping in the chuck. First drilled the 1/8" hole in the base (note that on the last two, drilled different size for threading)



Then rounded down the outside of that area:



Leaving the parts looking like this:



Then connected the holes drilled in the first step with a fine saw:



And cross drilled for the clevis pins (on last two, drilled/threaded 2-56, since those pins will be removable to allow spinning the clevis on its shank thread for adjusting the length of the arm).



and finally rounded the ends with files and soldered the 4 clevises to the ends of the vertical valve rods.



Last parts to make for this assembly are the adjustable pivots for the vertical crank arms - these allow the pivot point to be moved up and down the arm, changing the amount of throw, to allow fine tuning the valve travel when timing the engine.
To start, milled a slot in the side of a piece of brass bar, making the slot the same width as the arm, and the depth of the slot is just under half the thickness of the arm. This way, when the screw is tightened down, the pivot will clamp itself to the arm.



Then drilled a #43 hole in the center of that slot for a clearance fit on the screw:



plus a hole out near the end of the piece, where the clevis will attach



and milled the end of the piece down to match the slot in the clevis:



Using same setup, made the other half of the fitting, which is same as first half but without the extension for the clevis attachment. It is essentially a nut with flanges to grip the arm so it cant spin.

A little filing to round the end of the piece, and a trial fit on the arm. Here you can see how it screws into the slot in the crank arm.



And here are all the pieces so far assembled on the bases:



That pretty well finishes off the fabrication of the cylinder side of things (still more sanding/polishing to do when the mood strikes). Now I think its time to move onto the crankshaft assembly, now that I can take some measurements of how close together the cylinders can be, and how close looks best - easier (and more fun) to slide things around on the table than to draw it all out ahead of time!


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## aonemarine (Mar 1, 2014)

wow, this engine is going to be pretty sharp. Nice work!!


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## crueby (Mar 3, 2014)

On to the crankshaft - given that it will be a 1" offset/2" throw, figured that I should spend a little time to get it balanced or it would be pretty rough running. I took a low-tech approach to it, and made up a card-stock pattern of the crank web, and trimmed on it till it balanced a little bit towards the wide end. That way, I can always grind off more metal there to get final balance later on once things are put together. As it turned out, it got me pretty close (learned this way of doing it when designing a boat, and that was the old way to determine center of lateral resistance for the underwater profile of the hull - figured a simaler approach would work here, and it did).

Here is the drawing I wound up with:



Making up a crank this size on my sherline by chunking away at a large piece of steel would have been very difficult, let alone a waste of an awful lot of metal, so I decided to go the built-up method. I started with 4 pieces of 1/4" x 1.5" x 2.5" steel, and traced out the pattern from the card stock. The holes will be measured in on the mill, but this gave me references for cutting it down to size.



When I went to clamp it in the vice, I found that the edges were too rounded and uneven to sit flat and straight, so started off by milling the sides square with at fly cutter. From this point forward, I kept 2 pairs of the blanks together with clamps at all times through the drilling/reaming steps to come, to make sure that everything would come out straight and square in the final assembly. Not that big a deal if one hole is a quarter smidgen out in a pair, but it is a big deal if you mix one of those with another out in a different direction.



Then, clamped each pair up in the mill vice, and drilled for the 1/4" crank rod and the 3/8" shaft rod. I drilled to the nearest size under 1/4" that I had (size 'D'). To be sure the drill did not chatter and go too large, first drilled a smaller hole and then went to the D drill.



and reamed that to final size with a 0.001 under reamer, to leave a tight press fit. 



And did the same for the shaft hole, drilling up to size 'U', winding up with a 3/8-under reamer:



Here is how things looked at that point:



Then, did a bunch of sawing and then shaping with a table-mounted disc sander, to bring them all to the finished shape. Kept the pairs together through all that...



and pressed them onto the rods, with 3/8" gaps in each pair, and the pairs 2.25" apart and rotated 90 degrees from each other, and soldered it all up. Given the press fit holes, everything came up square without any other machining steps needed.



With everything soldered up, I could then trim off the overhangs from the 1/4" rods, clamp it in the mill vice, and drill all the crossing points for 1/8" pins, again going one drill size small....



before reaming the holes to 1/8"-under



and pressing in the 1/8" pins



before trimming them down flush with the sander and soldering them in place for good measure...



At this point, all the joints are held with both the pins and the solder, all very rigid. All that is left is to trim out the 3/8" rod between the web pairs.

Next up will be the bearing blocks/etc for the crankshaft. Here is the sketches for how that will proceed:



One thing to note - since the distance from the crank to the cylinders is quite long, around a foot, I decided to go with a more fancy rod assembly, both for appearance and to stiffen up that rod. So, you will notice that the eccentric follower does not have a center hole on one side to take the shaft. Instead, there will be a pair of rods, each going through one of the flanges on the eccentric halves. Those rods will come form a triangle, coming together at a point just before the valve clevis. Betwen the two rods will be a fancy pierce-work sheet to tie them together and also give it a victorian look. A similar set of patterns will go into the main beams. More to come on that part later!


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## crueby (Mar 7, 2014)

On to the main crankshaft bearing blocks - time to get some parts spinning!

Clamped up pairs of 3/8 brass flat stock pieces and drilled through holes for the mounting bolts:



Ran some nuts/bolts through these holes to hold the pairs together, and chucked them up in the 4-jaw with the seam between the two pieces on the centerline for drilling...



and reaming out the holes for the main shaft (.001-over)...



and turned back the face to form the boss that will ride up to the edge of the crank web:



Then, over to the mill to take the top edge down to final height and form the shoulders for the bolt. For this had to take apart the halves - to make sure they went back together with the proper halves, I stamped numbers into each piece. A set of small number stamps are very handy - a stamped in number wont rub off like pen or layout fluid.



Also made the oil cup in the top with a small center drill - left a nice taper in the top of the hole:



Took a stack of square steel bars for the supports - ran screws  up from the bottom, positioned so that the screw ends will be hidden by  the bearings themselves. Then, drilled/tapped holes to match the bearing bolt holes in the steel support blocks:



Cut the heads off some 1" bolts and loctited the threaded rod into the support blocks, so the brass bearings could be held on with nuts, giving a set of bearings that look like this:



The top of the bearings is still squared off in that photo, went back afterwards and sanded/filed them off round - that shows in some of the later photos.
Next step was to mount all the blocks to a base plate. Assembled the crank into the blocks, centered it all up on a 3" x 5" piece of aluminum plate, and held it with clamps so I could mark the hole positions with a drill in a pin vice (first made red marks on the plate with a marking pen so the drill would leave a visible dot).



The plate was clamped to a block of wood so I could clamp it in the mill table vice (vice wont open far enough to hold it directly), and spot drilled



and drilled/tapped for the mount bolts.



giving a plate that looks like this:



Here are the dimensions for the plate:



You may have noticed that the cylinder assemblies as well as this crank assembly are on seperate base plates. I am doing this for ease of working with the assemblies on my small capacity mill/drill (sherline). These smaller plates will be positioned on a larger one later, and in the final engine the larger plate will be covered with wood planking, to make it look like the floorboards of the engine room.



Next, need to make the eccentrics and flywheel...


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## crueby (Mar 7, 2014)

The eccentrics started as a bar of 1" steel rod, trued up and then cut in the slot with the cutoff bar, 0.050 deep. This slot will hold the follower, which will have a protruding tongue on the inside edge.



Then, offset the rod by 3/32" to one side, using a dial indicator to measure the offset. This will give the 3/16" throw for the valves.



Drilled/reamed the hole for the main shaft (3/8") using a slow speed, due to the off-center wieght of the rod:



and turned down the boss before cutting off the eccentric:



For the flywheel, I started with an iron casting for a handwheel - had gotten several of these surplus a while back. The castings are pretty rough, with rough tapered edges on the shafts. Since I did not trust them to stay in place spinning fast on the lathe in that state, I started with the casting held on the rotary table and did some preliminary milling to get the outer circles:



and also milled off the boss the casting had for the handle, on the edge of one of the spokes, while milling down the inner hub:



With that done, there was enough of a good surface for the chuck to hold onto safely, so went back to the lathe and started cleaning up the rest of it...



and forming the hub down:



getting down to shape, and drilled/reamed the center hole for the shaft:



Here are those parts added on to the crank assembly:



That flywheel is nice and heavy, everything is turning smoothly.



At this point, the cylinder and crank assemblies are pretty much done - started laying it out on a larger base to measure out dimensions for the center column. At this point, I think I will go with one heavy center column supporting a horizontal shaft that will hold the two beams. I have some 1" square brass bar that would make a nice pillar - square at the ends, tapered column in the middle. Going to play around drawing up the profile....


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## crueby (Mar 9, 2014)

In my original sketches for this engine, I was thinking of using two main columns, either one per beam directly or maybe with a crossbar that held the beams. After getting the cylinders and crankshaft done, and seeing how the placement looked, I changed my mind and went with a single column with a T-shaped top to support a beam on either side, since the beams are only 2 1/4" on centers. Here is the sketch I came up with:




Starting with a length of 1" square bar, squared up the ends on the mill and drilled center holes in the ends for lathe centers on both ends. Put that in the lathe and turned down the center area round, leaving the ends square for the base and top:



Then, using a thin cutoff tool and files, made the fancy bits at the top



and the bottom (note that the turning at the top goes down to a smaller diameter - the middle section will be tapered)



Then, time to offset the headstock for the taper. My lathe dog is too small to hold the 1" bar, so ran a set of nuts/bolts through the faceplate slots to act as a lathe dog. Really only needed one, but that would have thrown the balance off and made it vibrate, so put in one in each slot to balance it. Used the dial indicator to measure the offset distance from center - had to be slightly more than the difference in the diameters of the top and bottom  parts, since the centers are farther apart than that.



Top view of the offset headstock - you can see that the top end, which will get the smaller diameter, is at the headstock. For a lathe with a tailstock that can be offset, it would be other way around. So - ready to turn in the taper.



Here it is with the taper turned in:



Then, clamped it in the mill to drill the hole for the crossbar. The chuck only goes to 3/8", so started there....



and brought the hole up to 1/2" with the boring head:



and also cut the slot for the support knees, from the crossbar hole down to the top ring:



The top was looking too plain, so did some more cutting to fancy that up a bit - recess down each side, then an angle up to the top:



Now for an interesting setup - to flute the sides of the column, set it up in the mill, held with the rotary table at one end and a center rest at the other. I had made an adjustable holder for the center rest for a past project, so I set that to match the offset that was used on the lathe and angled the rotary table a few degrees to bring the top edge of the column level. Since I dont have a small ball end mill cutter, I used a normal square end cutter with the headstock turned at an angle, so the side of the cutter would do the work leaving a round bottom cut:



For each flute, lowered the headstock down into the column, then moved the column the length of the cut. Between cuts, rotated the table 45 degrees. Instant old-style column (Greek? Roman? Whatever....)


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## crueby (Mar 9, 2014)

Last part of the main column is the crossbar and its supporting knees. The crossbar is a length of 1/2" steel bar, with the outside 1/2" turned down to a 3/8" diameter. Those shoulders will go in the center holes of the beams. Some decorative grooves were cut in next to the shoulder. The end was also drilled/tapped for 8-32 threads.



The bolts to hold the beam in place were also made from 1/2" bar, with the end turned down and threaded 8-32



The bolts were then chucked up on the rotary table and the hex flats milled in, leaving a full 1/2" shoulder to ride against the beam, before cutting off to length:



Here is the completed crossbar:



Some knees were cut out of some sheet stock scraps with a jewelers saw, fitted with a file, and it all loctited together. Here is the head of the column:



and the whole thing:



At this point, I laid out the major pieces on the base plate, and drilled/tapped the holes for the column and the crankshaft. I am going to wait to finally place the cylinders until the beam and connecting rods are made, to make sure that it all lines up properly.


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## ShopShoe (Mar 10, 2014)

Crueby,

Thank you for showing that setup for milling the columns. Another technique I would never have thought of.

--ShopShoe


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## crueby (Mar 14, 2014)

ShopShoe said:


> Crueby,
> 
> Thank you for showing that setup for milling the columns. Another technique I would never have thought of.
> 
> --ShopShoe



Part of the fun is coming up with something that would look good - then figuring out 'how the heck would I make that??!'


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## crueby (Mar 14, 2014)

Been giving the main beam design a lot of thought during the build up to this point - wanted them to have a fancier look than just a plain slab. The direction I wound up settling on was a I-Beam shape, tapered to the ends, with a pierced-through pattern between the bearings.

Did a number of sketches, lot of erasing, and wound up with this pattern:



The Beam itself is 12" long and 1/4" thick brass bar. The four bearing points (center, ends, and parallel linkage) will have steel rod run through them, which will be drilled for the linkage pins. 

To start, drilled



and reamed



the holes for the end and parallel-linkage bearings. These are all 3/8" diameter, with the parallel-linkage bearing 3.5" from the center of the beam. The center hole was drilled/bored to 1/2" diameter, giving the two blanks for the beams:



Then, with the outlines of the beam drawn on as guides, the beams were clamped to the mill table with the line for one finished edge at a time parallel to the side of the table, so running the table back and forth would go along that line. Then, the mill was lowered in 0.075" and the interior of the beam was milled out. The areas next to the bearings were left a little large, they will be rounded off in the next stage. With one edge milled in, the blank was rotated to put the other edge parallel to the table for finishing off the interior. Same process for the other side of the blank, leaving a 1/8" web down the center, like an I-beam. Lots of cranking back and forth. And more cranking. And a little more....



Next the beams were clamped down to the rotary table to better round off the areas next to the bearings. Maybe someone better at etcha-sketch when they were a kid would have done this rounding in the previous setup, not me! I used a rod, the size of the bearing holes at one end and the size of the hole in the center of the rotary table at the other, to position the beams for clamping. 



Then the rod was removed, the mill lowered down to meet the surface, and milled the areas next to the bearing hole round. In this photo you can see that the larger center hole is still rough, that one was done last.



With all the interior milling done,



the beams were clamped together, the tapered sides levelled up in the mill vise, and the sides taken down with the fly cutter:



That completed the primary shaping on the beams. Next up was to do the pierced pattern in the center. I printed out the pattern on heavy paper and cut out the pattern with a xacto knife:



that pattern was traced onto one side of each beam, and a series of holes drilled in each opening, to start the saw blade in:



The pattern was then cut out by hand using a jewelers saw (like a lightwieght hacksaw frame with very thin/narrow blades). Here is one beam cut out and filed/sanded. Same steps to do on the second beam (tomorrow maybe, let the fingers rest!)



Once the second beam is cut out, the bearings will be made and installed. After that, a simaler pair of tapered beams will be made for the linkages between the eccentrics and the valve cranks. More on that to come...


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## romartin (Mar 17, 2014)

Crueby, I'm really enjoying this build! A master craftsman at work not only with lathe and mill but also with saw and file is a pleasure and an inspiration. Thank you for providing such a thorough log.


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## crueby (Mar 17, 2014)

romartin said:


> Crueby, I'm really enjoying this build! A master craftsman at work not only with lathe and mill but also with saw and file is a pleasure and an inspiration. Thank you for providing such a thorough log.



Thanks for the kind words - figured I owed it to the group to give back, having learned so much from here. Still am learning a lot, amazing to look back over my previous efforts and see how far I've come (then look at some of others work and see how much there still is to learn!).


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## crueby (Mar 20, 2014)

Finally got the second beam piercings cut out and cleaned up - time to make the bearings and clevises (clevisi? cleviseses? whatever the plural is!)

For the bearings, they are simply a length of steel rod with the center drilled and tapped for the bolts to hold the beams. Each beam has three bearings 3/8" diameter, 3/8" long, tapped 8-32,



and one center bearing 1/2" diameter and 1/2" long with a 3/8" untapped hole. I put a couple of decorative cuts near the ends of these:



Once all were made, they were silver soldered into the holes in the main beam. A set of shouldered bolts were made for the smaller bearings, just like they ones for the ends of the crossbar in the main column, shown in an earlier post.



Next up was to make a handfull of clevises for the connecting rods. For these, I started with a bar of 12L14 steel (very nice stuff to machine - wish I could find it in more shapes/sizes). I did not have a square bar of it large enough, so took a length of round bar and squared it up with the fly cutter, and then cut in the shoulders on one side:



Then drilled a series of #7 holes through along one edge for the posts:



Then cut them apart and dressed them to thickness with the side of an end mill:



Laid out the shape of the openings in the cleves, and rough cut them out with a hacksaw (cross-cut the ends with a jewelers saw). Note that two of them have a shorter opening - these are for the lower end of the piston connecting rods. The rest are the upper ends of the piston and crank rods, and have to be longer to reach around the beam to the bearings:



The inside edges were cleaned up and taking to final dimensions with a mill - the center openings of most are 3/8" wide, to fit around the bearings on the beam. The two for the lower ends have a 5/16" wide opening for the fitting on top of the piston rod.



Next up was to relief cut a boss into the outside edge of the clevis. This was done with the clevis held in the 4-jaw chuck on the rotary table. A 0.020 deep cut was made, rotating the piece on the table to leave the boss, and the ends were rounded over too:



Here is what it looks like so far - getting close, but still a little to chunky looking:



Took a little off the sides below the boss to improve the looks of them:



Finally - drilled and tapped the hole in the base (3/16-40). If I was making them again, I would have done this step before cutting out the centers - with the centers cut out I could not put much pressure on the sides, so they are mostly held by the two  jaws in the middle.



Here is how things look so far - ready for the rods and can start assembling the linkages:


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## crueby (Mar 20, 2014)

Time to get the pistons connected up - first made the fitting at the top of the piston rod to fit into the clevis at the end of the connecting rod. Turned a 3/8" round on the end of a piece of square steel, and drilled-tapped it 3/16-40:



Then cross-drilled and tapped the other end 8-32, and rounded the end over:



Test fit for the piece with the clevis:



Next up was to make a short connecting rod, with a 3/16-40 thread at each end. The end of the thread at the shoulder was relief cut with a cutoff tool to let it thread all the way on:



Made a longer set of rods for the crank end of things (that set is left long till the bearing is made to connect it to the crank), and did a test assembly. Really starting to take shape now!



Next up is probably to make the bearings at the crank end, then will come back and make the parallel linkage at the piston end of the beam. After that, valve linkages, steam/exhaust pipes, and throttle valve...


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## sssfox (Mar 20, 2014)

Crueby,

This is a beautiful engine, but I have a question.

On other engines of this type, the designers seem to go to great lengths to develop mechanisms that keep the piston rods exactly lined up with the pistons and cylinders.  Yours doesn't appear to do this.

On yours, are the rods indeed lined up with the pistons and cylinders throughout their travel or does it appear to matter?

Thanks,
Steve Fox


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## crueby (Mar 21, 2014)

sssfox said:


> Crueby,
> 
> This is a beautiful engine, but I have a question.
> 
> ...



Hi Steve,

This engine definitely will have the parallel motion linkage (watts type), I just have not gotten that far yet. One end of the linkage will attach at the bearing that is part way up the main beam, another part will attach at the clevis on the piston rod/connecting-rod joint - that one will get a longer bolt to hold the extra links. Without the parallel linkage, it is possible to hand-move the engine through a cycle, but it does bind a bit at the ends of the throw.

Here is the diagram of watts linkage that I am going by (borrowed from wikipedia):


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## crueby (Mar 22, 2014)

Time to make the bearings to connect the crank rods to the cranks - once that is done the engine can at least be turned round by hand (and stared at for a bit!).

The bearing assemblies are in two parts - an inner brass bushing and an outer steel case (got to be a proper technical term for these parts - will google that later!).

Here is the sketch of the parts I worked out:



I made the parts from the inside out, started with the brass core figuring it would be easier to fit the steel to that (it was). Started with a 1/2" square of brass, 3/8" long, and cut it in half. Mounted the halves together in the 4-jaw chuck, and drilled the center 1/4" and reamed it to .251. Then turned a boss on the end where it will ride against the crank web:



Turned it around (carefully lining up the halves) and turned a matching boss on the other side. Here is how it looks so far:



Then needed to cut in the slots all around the perimeter where it will slide into the steel surround - these slots are 0.050 deep, and 1/4" wide to match the steel:



Here is one with the slots around the edge, one to go. The black marks are felt-tip pen, so I could keep the two sets together and right-way-round easier:



Got out the steel bar I used to make the crank webs, and hacksawed out the rough shape for the bearing holders:



Milled the edges square and down to size, and turned the top round. Drilled/tapped the top 3/16-40 to take the connecting rod end:



Clamped the two halves together and drilled for the 4-40 bolts that will hold it all together. The top half was clearance drilled, the bottom half tapped:



Here it is so far, with the center holes sketched in. As you can see, the joint between the two halves is above the level of the joint in the brass bushing - I wanted to have the slot in the bottom half hold the two brass pieces in the proper place by itself, and not let the play in the bolts allow it to shift:



Milling out the suqare hole in the center of the steel pieces. I did the bottom pieces first, then marked the locations of the edges on the top halves to make sure they lined up when assembled:



Here are the parts so far - the bushings are a snug slide fit into the steel holders:



Last step on these parts was to radius the bottom edge so it would clear the baseplate at the bottom of the stroke. Did that with the part clamped to the rotary table with a spacer to hold it above the table:



Then, assembled the parts in the crank, so I could mark the lower ends of the connecting rods to the right length.



Cut off the excess on the rods, and turned them down/threaded 3/16-40 for the bottom 1/4". Got lucky on the first one - the shoulders bottomed out just right to line up the bearings and the clevis at the top. On the second one had to take off another couple thou. to get them lined up:



And here it all is so far - at this point can turn it over by hand. I like this stage, everything new going on actually does something. Next stage will be to make the links for the parallel motion mechanism above the pistons. Till that is done, I have not drilled the mounting holes for the cylinder baseplates - I have not done a parallel motion set before, and dont want to lock myself in on the positions until I can verify things line up properly.

Not sure if I will turn down the links from wider bar, or piece them up - have to do a little scrounging in the metal piles and a little experimenting....


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## crueby (Mar 24, 2014)

Got started on the linkages for the parallel motion part of the mechanism, which guides the piston rod in a straight line from the end of the main beam.

Here is a diagram of how the linkage works (thanks to wikipedia). The parts I am making now are labeled D-E, E-F, and E-K on this diagram. The bushing is what holds it all together at point 'E'.






The parts for this are pretty straightforward, just a lot of them. To start out I'll make the link bars and the bushing that connects them:



The bars will be pieced up from 3/8" dia. ends and 3/16" dia. rod. Since there are 12 link bars altogether it is definitely a case for mass production. Started with 3 lengths of 3/8" round steel, each long enough to make 8 ends. Drilled a 0.191 hole down the length of the rod, and then cross-drilled and tapped a series of 3/16-40 holes along the side (center drilled first, or main drill would skate off the curve):



The ends were then cut off, 0.200 thick. Made the rods from 3/16" bar:



and threaded/soldered the ends onto the rods:



Once all those were made (lot of the little buggers!), made the center bushings from 3/8" rod. The ends were turned down and shoulders threaded at the ends to hold an 8-32 nut:



Here is the first set together, showing the order the rods fit on the bushing and where the piston clevis will go in:



and both:



Next up is to make the shoulder bolts/nuts for the assembly, and get the parts hung on the beam. After that, need to make another support column set to hold up the forward link (at point 'K' on the diagram above).


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## crueby (Mar 28, 2014)

Okay - got the rest of the parallel motion linkage done (ran out of 3/8" rod, had to get some more - amazing how much stock this engine has taken so far). Made up the shouldered bolts from 3/8 stock - first turned down the portion going through the links, then threaded the end 0.150, and cut them off. Several sizes were needed, for the different number of links they had to go through - all done the same way, just with a different length shank.



On the rotary table, milled in the hex on the end. In this shot, first two flats are done.



Final step - cut in a little shoulder on the end to dress it up a little:



All that just for a bolt....



Last parts needed for the linkage were a pair of columns to hold up the final links. These were made of 1/2" brass rod, tapered and fluted to go with the pattern on the central column. Here are the dimensions for the support columns:



First, turned in some steps at the base:



and rounded that over into a bead with a file:



simaler thing at the top end, but cut in deeper:



Then, just like was done on the main column, offset the headstock to turn the taper on centers:



A cross hole was drilled halfway through the top section to hold the crossbar, and the bottom was drilled and tapped 8-32 for the screw to hold the columns to the base:



Finally got to bolt everything up and see how it looked. All went together okay, but it was looking a little chunky (good in a chocolate chip cookie, bad in an engine). So, went back and thinned down the clevises and the bolt heads. Also had to thin the spacers to match. After that, it was looking more in proportion.

So, here is the parallel linkages assembled:





Here are a  couple shots of the progress so far (made up the wood base too - needed that to get it to lay flat, given the bolt heads underneath. There are shallow holes drilled in the wood so the plate will lie flat):



Later on, the aluminum base plate will be covered with a thin wood layer to make it look like a factory floor. The black-painted plates will show through the floor boards.



Looking pretty good so far, I think. Next up is to make the eccentric followers and the linkage bars for the valves. The bars will have a pattern like the main beam....


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## crueby (Apr 1, 2014)

On to the valve eccentric followers. Here is a sketch of the dimensions for them:



They are pretty standard, with the exception that rather than having a connection point in the top for the connecting rod, I will be running one rod from each side, running them down to meet at a point near the cylinder, with a pierce web between them to match the main beam (photos in next post showing that assembly).

To start, took some 1/4" thick brass flat stock, and milled in a step on either end:



then drilled 1/8" holes for the rods:



ran some bolts through the holes to clamp the pieces together and marked for the center:



and drilled a starter hole for boring out the middle:



With it mounted in the 4-jaw, it is too large to fit on the lathe (sherline), so rather than reset everything with the riser blocks, I figured it was just as easy to bore it out on the mill with the rotary table. Started boring out the center:



and all the way out to the 0.900 diameter that will form the ridge sticking out in the center, which holds it in place in the slot on the eccentric:



then set the cutter to be 0.100 down from the edge of the hole, and 0.050 out, milled one side out to the 1.000 final dimension:



That did one side of the ridge - now turned the piece over in the chuck, and recentered it again (could have used a keyway cutter on the original setup, if I had one...)



with it all centered up again, milled the matching step on the second side:



Here is a closeup of the ridge after milling (have not deburred it yet in this shot)



One down, same to do on the second follower:



With the insides done on both, rechucked them with one pair of jaws on the inside step, and milled down the outside, first on one side:



then the other:



Here are both follower sets, ready for the rods:



Thats all that the site will let me upload in one post - next will continue with the rods....


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## crueby (Apr 1, 2014)

On to the connecting rods between the valve eccentrics and the valves. Since the distance is so great, it was either use a large diameter rod (too plain looking), or use a pair of rods, from either side of the follower, tapering in to meet near the valves. I saw the paired rod way done on some other engines, and liked the look, so I went with that style. The area between the rods will be filled with a pierced brass web, in a pattern to match the main beams. So, drew that pattern out on some sheet brass (left over from some clock gears), and started milling out the holes. I dont have any cnc setup, so it was back to etcha-sketch time on the mill table:. The sheet brass is clamped down to a scrap of wood to keep it off the mill table itself:



First set of holes done:



continuing on to the rest of the holes:



here are the finished web inserts next to the followers:



Threaded some 1/8" steel rod at the ends, for nuts to hold the followers together, bent them just below the threads to match the angle of the inserts, and wired them to the inserts to solder it up. Oh, and the top of the follower has a small notch filed in to hold the insert in place.



Here are the pieces so far all together. Still need to make a fitting at the narrow end, to connect it up to the valve lever:



Here are the rods in place on the engine (high-tech eraser to hold up he forward end for its portrait!)


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## crueby (Apr 2, 2014)

Okay - got the ends of the valve rods made up. Started with a chunk of 3/16" steel long enough to make two ends (easier to hold), and drilled 1/8" holes in the ends, slightly angled to match the rod ends (drilled slightly oversize so they would go onto the rods - should have made them before soldering up the webs. Oh well, still worked).



Hacksawed out the center section and went to the mill to clean up the curves:



center cleaned up



and the two ends cut apart:



Then, drilled a 1/2" deep hole in the tip, and tapped it 5-BA:



Soldered the ends onto the ends of the valve webs, and made a couple short sections of 1/8" rod to hold the clevis at the end (clevis was made weeks ago when valve cranks were made). The rod was threaded both ends, and the clevis loctited on. the end of the rod where it goes into the end of the conn rod is threaded longer, and serves as the length adjustment.



Here it is all installed on the engine. The point labelled '1' adjusts where the connecting rod attaches to the valve crank, moving it up and down changes the ratio of the travel on the cranks, allowing for adjustment of the length of travel on the valve. The point labelled '2' is where the adjustment is made for centering the valve travel - threading that rod in and out changes the center point. Between the two I have all the adjustments needed without having to change anything in the steam chest itself, which is a pain to get at with all the other stuff around it.



And a couple more shots of the progress so far. Getting near the end of the build - still need to make the inlet and outlet manifold piping, and a needle valve for the inlet. It all cranks over by hand cleanly, and I can hear the air blowing in and out, so it SHOULD run well. Hopefully!


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## danstir (Apr 3, 2014)

Simply beautiful.


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## RonGinger (Apr 3, 2014)

Great work, and it looks like on a Sherline?

Can you tell us a bit about the proportions of the parallel bar links?  I know the 4 links must make a  parallelogram but what is the relationship between the bar that 'grounds' them to the frame and the beam lengths? It seems to me this must all be very closely related.


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## crueby (Apr 3, 2014)

Hi Ron,

Yup - I have a sherline mill and lathe.

The parallel linkage does have some important distances. Going from this diagram,




the distance from A->D needs to be same as from E->K, and are best set to 1.5 times the stroke distance on the piston. Also, the D->E and C->F distances must match each other to form the parallelogram, and are best set to 2/3 the stroke distance. There is a good writeup on this at http://en.wikipedia.org/wiki/Parallel_motion 
Its an interesting linkage - first time I've made one. Without it, I think I would have needed a longer connecting rod and a fixed guide - this way is much more fun to watch.


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## crueby (Apr 4, 2014)

Down the home stretch - need to make the intake piping (just some tubing and blocks), and a needle valve to control speed on the engine. Here is the sketch for the valve:



The body is brass - started with a block and bored in the end holes for the valve stem



and the counterbore to fit the tubing



the hole for the inlet - threaded to take an adapter to the compressor hose:



and a couple holes for screw mounting it to the base



Here is the body so far, with the compressor hose adapter screwed in



For the valve stem, offset the headstock on the lathe a few degrees to turn a taper on the end



then threaded the stem above the taper



and cut it off just beyond the thread. The shoulder there will act as a stop for the handwheel



Parts so far



Made up a quick handwheel - threaded same as valve stem



and loctited the handwheel onto the valve stem



Looked a bit blocky, so put in some steps, mirroring the shape of the internal passages



completed valve:



and it in place with the intake piping



Still need to make a block to hold up/support the valve body....


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## crueby (Apr 4, 2014)

[SIZE=-1]Got the twin beam engine up and running - still have a spot where one piston is sticking a little at the top of the stroke so it is a little uneven still, but it runs quite slow on just a few pounds of pressure. Not bad for first run! Still need to make a support block for the needle valve and get it running smoother (fix that sticking point, tweak the valve timing a little more, it sounds like the right one is a little out still), but just could not wait to get it turning...! 

[ame]http://www.youtube.com/watch?v=xgopmZu3pts[/ame]

[/SIZE]


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## Looper7 (Apr 4, 2014)

That looks awesome with all those moving parts and the contrast of the brass and stainless


Jeff


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## Davewild (Apr 4, 2014)

crueby said:


> [SIZE=-1]Got the twin beam engine up and running - still have a spot where one piston is sticking a little at the top of the stroke so it is a little uneven still, but it runs quite slow on just a few pounds of pressure. Not bad for first run! Still need to make a support block for the needle valve and get it running smoother (fix that sticking point, tweak the valve timing a little more, it sounds like the right one is a little out still), but just could not wait to get it turning...!
> 
> http://www.youtube.com/watch?v=xgopmZu3pts
> 
> [/SIZE]


Beautiful job, I'm really impressed.

Dave


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## crueby (Apr 4, 2014)

Did some more running on the engine, and tweaked the valve timing some more, it is starting to smooth out. There is still a slight hitch in the travel at the top of the stroke on the right piston, but that is wearing in - think it mainly needs some more running in. Sigh, just have to run it more! 

Got some shots of it next to the last engine I made, a miniature double acting beam engine. Looks really small next to its big brother!







And the engine by itself:






Here is a new video of it running, bit smoother than the first one, still needs a little more run-in on the right side. I think that side was the first one I lapped, and did not do enough on it (was concerned about bell-mouthing the ends, and apparently was too conservative on the one end). It runs well at higher speeds, and will go down so slow that the flywheel is not really doing anything, and you can see it speed up/slow down as it switches back and forth from running on 1 piston/2 pistons/1 piston again at the top/bottom of the strokes.
[ame]http://www.youtube.com/watch?v=pYgt7npWCMM[/ame]


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## romartin (Apr 11, 2014)

Well done Crueby! Your engine is very beautiful and watching running is really facinating. You can be very proud.


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