Author Topic: Stuart Beam Restoration  (Read 16874 times)

Offline smfr

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Stuart Beam Restoration
« on: July 21, 2012, 07:49:20 PM »
[Copied from *cough* another site. Apologies if you've seen this before.]

Hi folks

I've been working on restoring a Stuart Beam, and thought that I should put up some photos. I bought this engine along with a 501 boiler on eBay in 2010, before I even had a lathe, and fixing it up was a good excuse to get one ;D

The engine had its share of problems, a really ugly paint job, and some odd modifications. It had obviously seen quite a bit of use, with some notable wear on the conrod big end, a fairly loud knocking when running, and a lot of looseness in the parallel linkage.

My goal is to get it back to a nice quality, smooth-running engine. This is my first real steam project with the lathe.

Here's the engine in its original state:

Stuart Beam by smfr123, on Flickr

Offline smfr

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Re: Stuart Beam Restoration
« Reply #1 on: July 21, 2012, 07:49:40 PM »
Some more pre-restoration pics:

No fish-bellying on the linkage:


The previous owner loved brass! So much so that they put thin brass strips over the entablature arms:


They did something awful to the steam chest: drilled a hole in the side for the displacement lubricator, which forced them to set the valve mechanism at a weird angle:


Oil cups soldered onto the main bearings:


Another bit of brass covering the flywheel, and aluminum disc press-fitted onto the pulley:

Offline smfr

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Re: Stuart Beam Restoration
« Reply #2 on: July 21, 2012, 07:49:56 PM »
Step 1: paint stripping.

I don't have any pics of the stripping process. Basically I smeared the painted parts in Citristrip http://www.citristrip.com/, put them in a ziplock bag overnight, then cleaned everything off the next day.

After stripping, I put it back together. Looks better already!



Only then did I noticed how loose it was, so it got pushed to the back of the workbench, pending lathe availability.

Offline smfr

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Re: Stuart Beam Restoration
« Reply #3 on: July 21, 2012, 07:50:12 PM »
Steps 2-N

Lots of work represented in this picture:



I decided to machine new parts for the parallel linkage, since the existing ones were rather sloppy, and not very pretty.

There are eight parallel links, machined from CRS bar. I first drilled and reamed the holes, then turned between centers, using the crosslide to get the fish belly taper. Then the ends were rounded off using a rounding fixture. They still need final filing and trimming to thickness, and I think I'll remake a couple of them; you can see a few boo-boos if you look carefully.

On the right are the various linkage spindles, make from 3/16 drill rod, and the linkage spacers. In the lower right is the new crankpin. This needs a slot cut in the head to allow it to be tightened up.

On the left is the original connecting rod, but I added bronze bushings to both ends to tighten things up. The hole in the big end was actually oval from wear. I've also made bushings for the beam, but have not yet drilled and reamed out the holes in the beam to fit them yet in the photo.

Offline smfr

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Re: Stuart Beam Restoration
« Reply #4 on: July 21, 2012, 07:50:28 PM »
Now for some work on the column. I noticed that the arms weren't parallel with the base, so had to correct that in two ways. First, I enlarged the bolt holes in the bottom of the column to allow for some adjustment. Second, I re-machined the top of the column. I also skimmed the top and bottom of the column between centers (via the original punch marks!) to correct the fact that it was too tall.

Here I'm tidying up the base of the column (it wasn't machined square by the original builder).



Now it's time to clean up where the arms attach. Note the 1-2-3 block used as an angle plate.



This leaves the arms about 10 thou closer together than they should be, but I can take that up in the linkage spacers.

Offline smfr

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Re: Stuart Beam Restoration
« Reply #5 on: July 21, 2012, 07:50:43 PM »
Now for some new radius link bearings. The hole was off on the originals. I cut up some bronze bar stock using a slitting saw, and discovered that bronze sure does like to squirm around in the vise when being cut! See the messy cuts on the upper right piece. Some paper between the bronze and the jaws fixed that though.



The originals are the two on the left; my new ones on the right. They started out oddly shaped because I got two out of one slice by placing them diagonally. The lower right one shows another boo-boo; I was a bit eager with the rough milling. Oh well, time to use the extra piece of bronze!

Getting closer now, just need some filing:



I turned some filing buttons, and used them to shape the radius:



My first use of filing buttons!

Offline smfr

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Re: Stuart Beam Restoration
« Reply #6 on: July 21, 2012, 07:50:59 PM »
The next adventure was to make a new crankshaft. I had some 7/16 drill rod, reduced one end to fit the crank (actually this took two tries :) ), and then wondered how to fit the pin (which was used on the old crank). I knew there was no way I could drill the pin hold with the crank in place; the drill would just wander toward the crank. So I turned a sacrificial collar, lower left.



With the collar in place, fitting tightly, I started to drill:



Darn, broken bit >:( The collar rotated while being drilled, catching the drill. Let's try again:



Much better! Another option would have been to Loctite the collar on, I guess.

Now with the crank in place, I drilled a slightly larger hole to clean up the mess from the broken drill:



Turned a pin to fit the hole, and knocked it in:



After some cleanup, not too bad!


Offline smfr

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Re: Stuart Beam Restoration
« Reply #7 on: July 21, 2012, 07:51:20 PM »
I got the radial link bearings done today (other than the final polishing). Here I'm taking them down to the final 3/8" thickness:



For drilling the attachment holes, I taped them to the arms:



The tape both kept them in the right place, and took up any difference between the bearing and arm thicknesses so that they'd both be secure in the vise.

Some careful hole drilling:



and after a bit of clearance drilling, and tapping the arms, we're done. I did make one minor error, which was to choose too large a drill for the clearance holes in one bearing. I was reading the drill size table upside-down :D



I'm not sure if those are the right screws, but it's what was in place before.

Offline smfr

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Re: Stuart Beam Restoration
« Reply #8 on: July 21, 2012, 07:51:44 PM »
Now it's time for the piston rod. I debated whether to make a new one, but the old crosshead had an ugly hole in the top:



and there was no way I was going to be able to unscrew that crosshead from the piston rod without damaging it. The old rod is also slightly undersize, and is not stainless steel. Here's what the whole rod, piston and cylinder cover look like:



So, I started with some 3/16" drill rod, and made a collet out of aluminum so that I could hold it in the chuck without marking the rod.. I turned the piston end, and threaded. Here's my handy home-made tailstock die holder:



The top end gets a 2BA thread, to fit into the crosshead:



I decided to attach the crosshead to the piston rod before drilling the other hole and bringing it to size so that I could ensure that things were square to the piston rod. The chunk of CRS for the crosshead was drilled and tapped, with a bit of messing around with the depths, since it felt loose even when screwed in. However, once I screwed it on tight it was fine, and Loctite helped ;D

I made a little fixture to keep the piston rod horizontal in the vice while I machined the sides of the crosshead:



then drilled and reamed for the linkage hole:



You can see that I'm too lazy to remove the layout dye from my vise clamps :)

Here's my ghetto DRI when I need to move the carriage accurately:



It's a micrometer that I knocked on to the floor, and bent the tips. It's still good for this purpose though 8)

OK, now we're here:



Time to chuck it up again (in the collet, centered in the 4-jaw) to turn the shoulder, and bring to length:



And this is when disaster struck. I had done the shoulder with a nice bevel, and then thought that it would be smart to use the parting tool to cut off the top. Big mistake! As the tool broke through, it bent the top of the piston rod; not a huge amount, but enough to write off the part
 :'(



Oh well, now I have an excuse to re-make it using precision-ground SS rod, which is what I should have used for the piston rod in the first place :)

Offline smfr

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Re: Stuart Beam Restoration
« Reply #9 on: July 21, 2012, 07:52:00 PM »
I had a couple of hours this evening, and after yesterday's piston rod disaster, decided to do a dry run fitting the new parts together. Here's the parallel linkage, with newly machined parts:





It's a real jigsaw puzzle to put together. But once assembled, I was very pleased to find very little play in the mechanism: it's a bit stiff, but I think that's good. It should run in nicely. There's a bit of play in the piston rod, but I'm pretty sure that's play from the piston rings moving in their groove (I plan to make a new piston).

There are more serious problems at the crank end. As the crank rotates around it's forcing the crankshaft to wiggle, and I can't insert the spindle through the little end of the connection rod and the beam because of misalignment. I'm guessing that something is out of whack with the crank or the connecting rod. I can make a new conrod, and maybe drill out the crank pin hole in the crank, fit a bushing, and drill it straight.

Offline smfr

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Re: Stuart Beam Restoration
« Reply #10 on: July 21, 2012, 07:52:34 PM »
I managed a bit more work on the crank/conrod to try and relieve some of the stiffness there. After messing around with squares and such:



I decided that the big end was not drilled square originally, so I made a new bronze bushing (with a dimple for centering) and pushed it in:



so that I could then drill and ream it in-place.

That required making a fixture that would hold the conrod in the correct alignment: what's important is that the holes in each end are aligned. A couple of bits of Al were pressed into service. I milled a slot in one:



then superglued them together, and drilled and reamed a 3/16 hole for a pin that would go through the little end of the conrod, thus ensuring that the rod is aligned.



I placed some packing under the big end to make sure the rod was horizontal. Then I drilled and reamed the bushing on the mill (I don't have any pictures of that, because I'm embarrassed about my crappy clamping job ;D). I also found that bronze loves to grab drill bits if you do step drilling, but with some careful drilling, and a 1/4" "over" reamer, managed to get a nice hole.

After all this, things are much better aligned when I hook up the conrod, so progress has been made!

Offline smfr

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Re: Stuart Beam Restoration
« Reply #11 on: July 21, 2012, 07:52:55 PM »
I made quite a bit of progress today. I started with a new cylinder base. I chose to make a new one because I want to adjust the position of the cylinder relative to the column, and because the holes for the countersunk screws that go into the cylinder are not aligned correctly, causing those screws to stand proud, which in turn means that the cylinder base doesn't sit well on the main casting. I also wanted something that looked a bit prettier :)



Guess which is which! I used some 1/4" steel plate (not sure what kind; I got it at the Aluminum Rem Center in Santa Clara, CA), milled to a fairly accurate 2" x 2". I then started to fix this in the 4-jaw, thus marring the nice clean sides :( before realizing that I needed to turn in from the edge.

I moved it back to the mill, centered it up, and used a 5/16" end mill to cut the central depression (that allows room for the nut on the end of the piston rod at bottom dead center). That provides a footing for a stub mandrel; I turned the end of of a bit of scrap drill rod to 5/16", center-drilled into the other end, and used it in the tailstock to push the plate against the chuck (using a handy chuck spider that I made a while back):



Since the mandrel is a snug fit, I used it to indicate for accurate centering.

Because it's just pushed against the chuck, you have to take light cuts (ask me how I know). Maybe some paper behind it would have helped. It's also a pain to turn down to size to fit the cylinder, since you have to remove it for test fitting, and then re-center it every time, so I went by the calipers most of the time.

I left the problem of locating all the holes to another day...

Offline smfr

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Re: Stuart Beam Restoration
« Reply #12 on: July 21, 2012, 07:53:09 PM »
]I also smartened up the cylinder head today; the sides and top were not machined at all before. Here's the result:



It's an improvement in that it gives the bolts a flat surface to bear down on, but feels perhaps slightly too blingy for this model. We'll see once everything is together.

Offline smfr

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Re: Stuart Beam Restoration
« Reply #13 on: July 21, 2012, 07:53:24 PM »
OK, it was time for a second try making the piston (see earlier messages for the fate of the first one ;D).

I bought a 6ft length of precision-ground 3/16" stainless steel from McMaster-Carr for this, but the entire rod came with a gentle curve >:( so I went back using drill rod. Machining this part was uneventful, though I was careful to not make the 1/4" threaded portion on the top end too long.

I attempted to re-use the top piece I made before:



but when screwed onto the new rod, it was obviously misaligned. This vindicates my technique of machining this piece after attaching it to the rod. So I started with a new chunk of CRS (on the right in the picture).

It was faced, center-drilled, then drilled and tapped 2BA. I was careful to not drill and tap too deep, because the piston rod has to tighten up to the right length. I then screwed in the rod with Loctite:



I'm wondering now if I messed up here. I recall reading that this needs to remain adjustable to tweak the piston travel :'(

Anyhoo, here I am turning down the neck of the piston rod:



where I went a wee bit over, but this isn't a critical dimension. And here we are after two sides of the head have been milled down:



After milling the head to size, it's time to locate, drill and ream the 3/16" hole. I used my trusty vernier height gauge, with the piston standing upright on a spacer on the surface plate, and measure from the top of the piston to where the hole should be. I'm gradually learning what the height gauge is good for (and how to read the vernier scale!). Now into the vise again (with a fixture to keep the rod horizontal), for drilling and reaming:



This time I took the head down to size by holding it in the 4-jaw (with some Coke can packing to avoid marring). No parting off this time!

Now we can have some fun making the piston! I started with a length of bronze (that's the old piston in front):



and here we are after some machining:



The central depression was made with a 5/16" end mill in a chuck the tailstock, and I've drilled and reamed the center 1/8". Unlike the old piston, the groove for the piston rings is a snug 1/8". I'm leaving it oversize for now, to do the final tweaking when it's fixed to the rod.

That leaves me with the new piston parts:



(old above, new below).

Here the rod is protected with tape while I cleaned up the head with a file.. I'm also test-fitting a 3/16" spindle with a spacer. I was pondering rounding off the top to match the radius, but left it square for now.



So, almost done with the piston (new above, old below):



I just hope that the length is right 8)

Offline smfr

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Re: Stuart Beam Restoration
« Reply #14 on: July 21, 2012, 07:53:39 PM »
One final picture for today. This shows the old valve chest and parts at the top:



There are a couple of interesting (i.e. bad!) things to note. First, the valve rod is really worn and corroded, so I'll be replacing that. Second, some fool drilled a hole in the side of the valve chest to fit a displacement lubricator, which is crazy because it interferes with the valve linkage. I temporarily plugged it with a brass bolt, but wanted a better long term fix. So I ordered a new valve chest and cover from Stuart Models (lower in the picture), and will be machining those later.

Offline smfr

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Re: Stuart Beam Restoration
« Reply #15 on: July 21, 2012, 07:54:07 PM »
After being away for a few days, I got some time in the garage yesterday, and decided to clean up the cylinder bore a little. It's pretty corroded at one end:



probably from sitting with moisture after being used with steam. To take off the pitting, I think I'd have to bore it out another few thou or so (after setting it up absolutely straight), and that sounded tricky. So I decided just to lap it to smooth out the rest of the bore. I think most of the pitting it outside the piston travel anyway.

So I made a lap from some Al rod (another estate sale find!). I cut off a length of rod on the chop saw:



and turned to just under 1", drilled and tapped for M8 1.25, then used the slitting saw on it:



(if you look carefully you can see I'm not quite on the centerline, despite measuring and using dials to get there :( )

Now I can adjust the lap by screwing in an M8 bolt. Here's the cylinder in place:



You can see the three grades of lapping paste. The lathe was run at low speed, and the cylinder is held by hand (carefully!) and moved up and down the lap, reversing it every so often.

I was trying to figure out how to make the lap so that it expands in the center, rather than at the end; I wasn't able to drill deep enough to have the end of the screw thread further in. Having the lap expand in the middle means that the cylinder is less likely to be misaligned as you move it back and forth (which would result in a bell-mouthed bore).

Anyway, I lapped off about a thou or so, which smoothed out some of the roughness. No after pics, alas.

I then mounted the piston on the piston rod, and carefully turned it down to size. Not carefully enough, apparently, as it ended up a sloppy fit  :(

So I made another piston from bronze, and brought that one down to size with emery paper. Apparently I was too aggressive there as well, because that one ended up a bit sloppy too, but close enough for now. With the piston rings fitted, it feels quite snug. I seem to recall reading that you needed some room for piston expansion if it's going to be run on steam anyway.

Offline smfr

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Re: Stuart Beam Restoration
« Reply #16 on: July 21, 2012, 07:54:38 PM »
I've been trying to find the source of some tightness at the crank end, and spent much of today chasing a couple of theories.

My first theory was that the holes in the crank were misaligned, causing binding as the crankshaft rotates. To test this, I made a new crank, starting with a chunk cut from an old toolholder, milled to size and marked out:



I located the first hole, drilled and reamed, and then used the dials to move over exactly an inch for the second hole:



I've learned that it's best to take care of the precision aspects of a part early on, while it's easy to hold; the shaping can come later.

After some rough milling, it looked like this:



and here we are in the 4-jaw after turning the larger boss.



It was tricky to get between the bosses; if I had a rotary table, I think I'd use it for this. I just wanted to get far enough to do a test fit, so turned down some spare 7/16" drill rod to act as a crankshaft and did a press-fit. Here are test and original cranks next to each other:



You can see my attempts at turning out the space between the bosses. It's hard to get tools in there, without dinging the bosses (which I managed to do).

Anyway, after putting everything back together, this new crank didn't seem to make things any better, so I guess the problem isn't in the crank!

Offline smfr

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Re: Stuart Beam Restoration
« Reply #17 on: July 21, 2012, 07:54:52 PM »
So, next theory. The holes in the beam are misaligned. Certainly the spindle hole at the crank end seems a bit off:



so I spent a bit of time on the surface plate, trying to figure out if there really was a problem:



and decided that there was. I suspect what happened is that the beam is slightly twisted, and doesn't lie flat. The beam was clamped down for drilling, but when released, it sprung back, resulting in non-parallel holes.

So I pushed out the bronze bushings that I'd made earlier, and turned new, solid bushings, which I plan to drill in situ. Since I was doing one, I decided to do the other two spindle bushings too, and re-locate the holes as well as straightening them. With the bushes fixed in place with Loctite, I then tried to figure out how to mark things up:



The important thing is that the spindle holes are aligned with the center of the main spindle, so here the beam rests on V-blocks while I try to find a centerline through the center of the main spindle, to mark on the bushings. I'll use this to align the part on the mill.

Likewise, I want to ensure that the spindle holes are drilled parallel to the main spindle, so I think I'll use a setup something like this:



where the main spindle is held in a V-block on its side. That's not my final setup; way too much overhang on the ends ;D

It's interesting how far off the centerline is from the original holes:



so the original builder didn't seem to be very accurate with the beam. I just hope none of my holes hit the edge of the bushing!

So tomorrow I'll have a go and fixing this down (without twisting!) and drilling. Hey, at least I can push out the bushings and make new ones if I mess up!

Offline smfr

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Re: Stuart Beam Restoration
« Reply #18 on: July 21, 2012, 07:55:09 PM »
Got a little bit more done today. I turned a mandrel to hold the beam during machining, since I wanted a longer length to hold in the V-block, and the original spindle is a sloppy fit (which is OK while running, because it's held in with a lock screw).



With that secure in a V-block, which was held in turn in a 2" vise, I aligned the beam so that the centerline was parallel to the plate (and thus the base of the vise):



and marked out a line on the bronze bushings. I had to take care to not knock this out of alignment for the rest of the operation. Now onto the milling table on my Emco Maximat. I had to go front-to-back because the table is deeper than wide, which required moving the part for each end. Here I'm indicating on the base of the vise to ensure that's it's parallel with the direction of travel:



and found that just aligning the vise to the edge of the table was good. Then I centered on the mandrel:



I'm using a ball-end wiggler; with the mill running, I move the quill wiggler lightly into the center drill hole, and can see when the wiggler gets pushed aside when misaligned. I took care to pack under the beam with shims to avoid torsion when clamping.

Now I can use the dials (double-checked with calipers) to move over the required 3.5" to drill and ream:



Then I flipped the whole fixture around and repeated the operation for the other two holes. A quick fitting suggests that this solved most of the binding at the crank end, but I had to dash off to a social obligation, so the real test will have to wait! ;D

Offline smfr

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Re: Stuart Beam Restoration
« Reply #19 on: July 21, 2012, 07:55:30 PM »
Time to fix the cylinder to the new cylinder base that I machined earlier! This meant spotting the holes through somehow (since I had to match the existing holes in the cylinder).

I initially started with annoying little bits of paper:



but then had a better idea. I fixed the cylinder up in the vise with a kind of jig that would let me place the base on top repeatably. Then I could just line up on a hole using a drill that was smaller than threaded hole



by carefully lowering the drill and looking/listening for interference. Then I just put the cylinder base in place, bottom side up, and, without moving the table, spot-drilled with a center drill:



Then I could transfer just the base to the vise, and drill and countersink each hole. Presto, nice fit:



Next will be spotting the holes through from the main casting to the cylinder base, which might be a bit trickier.

Offline smfr

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Re: Stuart Beam Restoration
« Reply #20 on: July 21, 2012, 07:55:48 PM »
OK, now that I have a turning table (http://www.homemodelenginemachinist.com/index.php?topic=16765), I can show you how I went about making the linkage links. We start with some bar stock:



Actually the top two pieces there are the old entablature arms, which I thought it would be neat to re-use. However, after cutting them to size, I realized that they have screw holes :o

I'm making two links here. The bar stock is cut to length accurately for repeatability, and center drilled at the ends, for turning between centers. The length was calculated so that the center drill holes don't hit the metal we want to keep. That's one of the old links on the right.



Now the two holes are center drilled, drilled in steps, and reamed 3/16":



As usual, since the distance between these holes has to be accurate, I do them early in the steps.

I've also learned not to worry about under/over reamers; I just use the exact size. This seems to give a nice snug fit with the drill rod that I'm using for the spindles, but maybe that's because the reamer is pretty new, and is cutting oversize?

Now to turn the fishbellies. We set up between centers, driving via the faceplate. I'm using a bit of thick copper wire as a dog, through one of the holes. Works great!



Now I did a bit of math to work out the correct angle to set the compound rest at; it's around 1.2 degrees (from what I recall), but we'll end up adjusting this a bit. I also made myself a little cardboard template to show me where the middle is, and where I should stop turning:



Once I had a cut that covered half of the turned section, I measured the larger and smaller diameter to see if the difference between them matches what the plans calls for; getting it right required adjusting the angle of the compound rest several times, by small amounts. I'm moving the tool right to left via the compound rest to get the taper, then adjusting the cross-slide to control the final diameter.

Once one half is done, I flipped the part around and do the other half (this is where it's useful to have the bar stock length be accurate). Then came some filing to smooth out the middle, and several grades of emery paper to remove the tool marks (easier to do this now while turning between centers than later!).

Here's one link turned, though it could still use some smoothing:



Now I made use of the rounding table to round the ends:



and we end up with:



The ends still need reducing in thickness, and there's quite a bit of filing to do. I'll clean up all 8 links at the same time (at least until I get bored of filing ;D). 8 links, 16 ends, 32 faces ... that's quite a bit of work :-\

Offline smfr

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Re: Stuart Beam Restoration
« Reply #21 on: July 21, 2012, 07:56:04 PM »
Lots of rather tedious stuff today. Got all 8 links rounded down on the rounding table (some a bit undersize until I realized that I could use a carriage stop to make sure I didn't go too far!), and the 2 new links milled to the right thickness.



(Yeah, I can't count. That's 9. I'm making one extra ;D)

I made myself a fixture to help with filing, and some filing buttons:



The bit of drink can is to prevent the round file from digging into the end of the turned portion, and tape protected the rest. I'm using needle files to do rough cleanup, then various grits of emery paper (220 to 2000) to finish, with a final polish with the Dremel.

2 down, 7 to go, ugh!


Offline lazylathe

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Re: Stuart Beam Restoration
« Reply #22 on: July 21, 2012, 07:56:17 PM »
I really love following along with rebuilds!
Taking an old engine and breathing new life into it.
An amazing talent!

Great work Simon!

Andrew
A new place to hide my swarf!

Offline smfr

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Re: Stuart Beam Restoration
« Reply #23 on: July 21, 2012, 07:57:12 PM »
Thanks Andrew! A few more posts to copy...

I spent a couple of evening filing the links, and got bored so decided to start on the new valve chest. I bought a new casting from Stuart because the existing one has a hole drilled in the side :-\

The casting was cleaned up with a file, and faced in the 4-jaw chuck on both sides. I started on the valve cover as well, which still needs taking down a little:



I think the corners of the valve cover look different because I don't have enough support behind them in the chuck, and they are flexing under the tool. There also look to be some hard spots in that casting, or maybe the unevenness of the turning is because of something I'm doing?

The valve chest after some lapping on the plate glass:



That's the easy part! I have to transfer the holes from the cylinder itself on this one, and drill for the valve rod etc.

Offline smfr

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Re: Stuart Beam Restoration
« Reply #24 on: July 21, 2012, 07:57:34 PM »
I've been thinking that I need to clean up the valve surface on the cylinder, since it's pretty messy:



It has some bad pitting. I also noticed that the valve surface wasn't perpendicular to the cylinder base:



so decided to take a pass over it in the lathe. That sounds like a good job for the faceplate! I don't have an angle plate, but figured that a couple of 1-2-3 blocks would hold it quite nicely:



I used a square with the blocks on the edge of the surface plate to true up the valve surface:



and took off maybe 0.01" on the lathe. After some cleanup, it looks like this. I took the Dremel with a wire wheel to the rusty bits, and that cleaned out a ton of rust, leaving a bit of a crater :o



I was a bit worried about taking more off. I hope that massive rusty hole isn't going to be an issue, since the valve just about clears it:



That's the valve face of the cylinder taken care of!

Offline smfr

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Re: Stuart Beam Restoration
« Reply #25 on: July 21, 2012, 07:57:50 PM »
Now back to the valve chest. After lapping the faces, I trued it up in the vise, and drilled for the valve rod:



Ideally it would have been rotated 90deg in the vise for better clamping, but I need to see when the drill hit the bottom. The top hole gets drilled and reamed for 1/8", and the valve rod requires a 3/32" locating hole in the bottom. I used the larger drill to make a small face in the bottom surface so that the thinner drill didn't wander. Luckily I had a 3/32" jobber drill lying around, since my stubbies wouldn't reach that far!

Here's the bottom of the valve chest after making the counterbore for stuffing and the gland, with two 7BA holes drilled and tapped for the gland cover. New on the left, old on the right.



I have to clean up those messy file marks. I'm not sure whether to smooth off the entire valve chest surface, or leave it looking like a casting.

Now I have to transfer the holes from the cylinder. I did this like before; set up the cylinder in the vise, here truing it up with the trusty 1-2-3 blocks:



then adding various bits of packing so that I can repeatably position the valve chest:



I then locate a hole in the cylinder valve face using a drill slightly smaller than the hole size (without the valve chest in place), switch to a small center drill, put the valve chest in place then spot-drill the valve chest. After spotting all 6 holes, I remove the cylinder from the vise, put the valve chest in, and drill those holes through.

Here we are, with studs in place, showing that the hole transfer was a success! I even used a slightly smaller clearance drill than the original builder ;D



Now I can transfer the holes to the valve cover in the conventional way.

Offline smfr

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Re: Stuart Beam Restoration
« Reply #26 on: July 21, 2012, 07:58:05 PM »
Got most of the valve rod done today. I used 303 stainless, so hopefully it won't rot like the old one ;D



Not sure what the original builder was thinking; his rod is about 1/8" too short!

I made the little valve thingy out of SS too; just need to make it slightly looser in the valve so that the valve floats nicely.

Offline smfr

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Re: Stuart Beam Restoration
« Reply #27 on: July 21, 2012, 07:58:26 PM »
I've made a start on new parts for the valve linkage. They are pretty simple, but there are two more fish-bellied links, longer and skinnier than the parallel motion ones (old at the top, new and in-progress at the bottom):



Those go to 3/32" at the ends. The top one is a little non-concentric, but since these parts don't rotate I don't think anyone will notice ;D Obviously I have to finish the ends.

Offline smfr

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Re: Stuart Beam Restoration
« Reply #28 on: July 21, 2012, 07:58:51 PM »
More progress has been made!

Of course I managed to mess up one of the valve links on the rounding table:



Note to self: add end stops to rounding table! Second note to self: when using larger end mill, don't rotate table as far! I'm too keen to get things running, so I'll come back to making another one.

It was bugging me that the sides of the valve chest, the cylinder casting and the valve cover didn't line up, so set up things in the vise to give them a once-over with an end mill. Here's my setup to get things parallel to the cylinder bore:



I trimmed the top and bottom of the valve face on the cylinder casting with a small spherical burr (that came with a dremel; I don't have a ball-end mill of the right size):



I then also put the valve chest in the 4-jaw, and cleaned up the valve guide for some bling:



Finally I polished the valve itself, and the valve face with three grades of diamond lapping paste, and found a great way to leave frosted sections on my glass plate ;D



Here's what she looks like back together now:


Excuse the blueing on the cylinder cover and elsewhere. I still have to attack that hard spot once the carbide drills arrive (hence the only 5 bolts).

The cylinder head bolts also need work. I'm thinking about going for a slightly more authentic look with studs on these and the main bearing bolts, but that could be a lot of fiddly work.

Offline smfr

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Re: Stuart Beam Restoration
« Reply #29 on: July 21, 2012, 07:59:17 PM »
It runs!

« Last Edit: January 18, 2016, 02:55:58 AM by smfr »

Offline smfr

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Re: Stuart Beam Restoration
« Reply #30 on: July 21, 2012, 07:59:50 PM »
OK, now I know that this thing is going to run, it's time for some cosmetic cleanup!

I was very glad to get to cleaning up the bearing oil cups. It had ugly soldered-on cups, so first thing I did was to unsolder them:



Then I touched an end mill to the top of the bearing to make a nice seat for the cup, and drilled and tapped 1BA, being careful not to go through to the bore. A smaller thread would not have worked due to the existing hole.



Now to make some oil cups to fit! I started with some 3/8" brass bar, and sketched out some rough dimensions for oil cups in my notebook. First, I took about 1/2" of the bar down to 0.312", which is the largest diameter of the cup, which is the base. Then I reduced 0.2" at the end to 0.21", and threaded 1BA (fitting to the bearings as I went, since the threads were pretty short). I drilled a small hole (#58 from memory) about 1/2" in. Then I turned the rough profile of the rest of the cup, basically marking the diameter changes with a small grooving tool, and parted off.

I made an aluminum fixture with a 1BA threaded hole, and screwed the cup into it for turning and filing the other end. After some careful turning and filing, I ended up with something like this (not quite finished yet):



This was my first attempt, when I was planning to go with a hex base for tightening, but later decided that this made it look too tall, and that I could just hand-tighten. Anyway, here's my prototype cup in place:



This cup later broke because I drilled the inside too deep ;D

I roughed out 4 more cups, seen here in their respective bearings, with the prototype to the top right, and the fixture in the lower right:



A bit of filing and sanding tomorrow should leave me with 4 nice oil cups. That should add a bit of bling!

Offline smfr

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Re: Stuart Beam Restoration
« Reply #31 on: July 21, 2012, 08:00:07 PM »
Four oils cups done:



and in situ on the cleaned up bearings:



I'm really not sure how to finish the bearings. I don't like the high gloss look, so I might go at them with a green scotch pad. They're pretty dinged up and non-square, and the holes are all over the place; stuff that I can't really fix without making new ones. I just think of it as adding character to the engine :D

While fiddling with brass work I decided to fix up the cylinder drain cocks; I needed some aluminum washers of the right thickness for the cocks to tighten to the right position, so turned and drilled a piece of scrap, and parted off a few washers of different thicknesses:



I found that I could just peel off the burr left from parting and clean up the washers with a countersink.

What occupied the rest of the day was reaming the bearing blocks. It took me a while to figure out a good setup for the crankshaft bearings. I ended up with a couple of 1-2-3 blocks square to the table, with the castings clamped, and some support under the ends:



The way I got the table positioned right was to put some 7/16" bar in the mill, and approach it with the part, wiggling the carriage hand wheel and advancing the cross slide gradually until the bearings just seated on the bar:



I did this with the bearings loose on the casting, then tightened up the bolts to start off everything straight. Then I could bolt the bearing caps on, put the reamer in a collet, and ream. I kept the cross-slide in the same position (gibs tightened down) for the main bearing on the body, and the bearing on the crankshaft support, so that they match vertically.

I did the bearings on the top of the column as well, and found that one was about 10 thou shorter, so made a brass shim to go that one. The beam spindle is also a tad undersize, so I put bits of paper between the bearings for reaming with the hope that they'll be nice a snug that way.

I haven't reassembled yet, so it will be interesting to see if that affects the running. But I'm glad I got the reaming done, even if it didn't take much off!

Offline smfr

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Re: Stuart Beam Restoration
« Reply #32 on: July 21, 2012, 08:00:41 PM »
I did various bits of cleanup today. First thing was to tighten up the eccentric strap by filing down where the two parts meet. There are some odd markings on one side of the strap:



which look like filing guides, perhaps? I like them, so I'll just leave the finish as it is.

Next up, I decided to polish the external surfaces of the beam. This required taking a file to the casting, since the two sides were not very well aligned, followed by a finer file and many levels of grit.



A bit hairy, but I think I ended up with an OK profile. It took a while to polish out the tool marks on the sides, and I didn't totally remove them, but it's better.

Then it was time for the flywheel! At first I had the flywheel on a mandrel (supported by the tailstock), held only by the grub screw. That was OK for the outer rim, but when trying to clean up the sides, there was enough flex in the wheel to cause chatter, leaving some ugly marks (visible in the image below). So I moved it to the faceplate, still on a 7/16" mandrel in a collet to keep it centered.



That worked much better, and allowed me to polish the rim and one side:



before flipping it over for the other side. Shiny!

Offline NickG

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Re: Stuart Beam Restoration
« Reply #33 on: August 03, 2012, 07:02:45 PM »
Brilliant work Simon, I once restored a Stuart beam when I was much younger ... to nowhere near this standard but still made a healthy profit on it!  :ThumbsUp: