Just thought that as I'm sort of taking the day off, I'd go back in time six weeks or so and continue the saga of problems found on this "Bargain" half horse Sipp.
After finding that the crankshaft was not causing the bind, it was time to disassemble the piston rod, crosshead and open up the cylinder to find where the bind actually was coming from. As noted before, the crank rod ends seem not the issue either, and to further examine that linkage train, I will now note that the crosshead slide seems to have just about the right amount of "slop" or tolerance, to slide smoothly without binding, though the slide shoes are shimmed with gasket material to attain a closer tolerances for that clearance.
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Having disconnected that from the piston rod, next move was to open up the cylinder end cap, free the piston rod packing gland nut and back the piston out of the cylinder. While this was easily done, as it appears there was only a sleeve in the packing gland and no actual packing, it was noticed that there was more than a little drag on the movement of the piston as it was pushed back in the cylinder. So it seems that at least a goodly part of the rotational drag noted on the flywheel/crank assembly likely has the piston/cylinder as its source, so much further investigation was needed here next!
Upon opening up the cylinder and removing the piston, a couple of other telltale features were immediately noted. First, the cylinder cover bolt hole drilled and tapped just above three o'clock violates the steam passage port from the steam chest, while the next one down at about five o'clock into the rim of the cylinder, had initially been miss-located, but was caught and corrected before it had been drilled too far, or more likely the pre-assigned spot was missed to match with a misalignment in the drill holes of the cylinder end cap. Whichever is the case, something wasn't done quite right, as seen here:
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Also note in this photo, at the front end of the cylinder (rather out of focus) the drill gouge and threading marks from the large hole that was drilled and plugged into the front bottom of the cylinder for no known reason.
But an interesting aspect of this is that while that hole and plug are down at about seven o'clock in the photo, the gouge and thread marks are up at around ten o'clock, so that brass front face of the cylinder is an insert that is pressed of screwed into the cast iron cylinder casting, in order to provide for the piston rod packing gland set-up as seen here:
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Now, even at this point I'm unsure as to whether this brass packing gland assembly "insert" is just pressed in or actually threaded, but I suspect it is only an interference press fit, and will test this assumption the next time I tear the engine down. Based on the rotation of the plate on the inside of the cylinder, as evidenced by the changed location of the drill gouge, it could be either, but a press fit perhaps makes more sense, we shall see.
In any event, now knowing at least much of the drag is coming from the piston/cylinder combo, I felt it time to make do a little measuring, testing and hopefully improving any situations that were remedial in this area. Thus I measured the cylinder bore for cylindrical conformity in a couple of different ways:
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Having so measured the bore all around and in and out, I found it to be quite consistent within a couple of thousands, and believe that runout only to be caused by the roughness of the bore, due to a scale or corrosion build up mostly along the bottom 1/4 where you'd expect condensate to collect after a run. It seems likely the cylinder was originally factory bored to be this good compared to how much of the rest of the machining seems to be done. To be sure the worst of the roughness was along that bottom portion of the cylinder, but in fact all walls of the cylinder seemed to be unnaturally dark with some form of deposit or buildup, and thus I felt the next step to take of benefit, would be a bit of honing of the bore. So a lashed the engine in an end up position to the trailer hitch ball on my trucks bumper, so as to align the cylinder vertically for ease of working, and thus reducing any tendency of gravity to cause uneven honing around the bore, as seen here:
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In the last photo you can better see (now in focus) the gouge in the front plate of the cylinder left over from drilling the plug hole that can barely be seen at about seven o'clock, and how it is now rotated up to about ten o'clock. This few minutes of honing evened the bore noticeably and smoothed it to the touch as well. Perhaps I'll go another round of honing next time I have it apart, but the upshot is that clearly doing this did help materially in smoothing the engines motion.
Moving on to the piston now, there is lots to see and do here. First thing I noticed here was that the piston had to be made in at least two parts (possibly as many as four) that were screwed together in order to capture the large cast iron piston ring. Next thing I noticed was how incredibly rough the outside edges of the piston face plates appeared, as seen here:
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Sadly, I was unable to get any kind of a purchase on the rims of the piston's face plates without causing damage, in order to try unscrewing them. Will likely make a clamping fixture to grip one side while I chuck the other side and may be able to unscrew it that way, the next time I have this engine apart, as there is plenty else that needs be done here, as there is much else wrong.
I did feel that since I was going to reassemble the engine right away to try and run it a little at the GPU, that I should "clean up" the rough edges around the rims of the piston's face plates and proceeded to do so chucked up in the lathe with a collet on the piston rod. However, as soon as I saw the amount of runout both in circumference, as well as laterally, I knew that something was definitely not right here, so proceeded to indicate off of the offending surfaces and found over .007" difference in the two face plate's circumferences and concentricities, but even more staggering was that there was some .040" of lateral runout. Which is to say that the faces of the plates were wobbling wildly, the meaning of which is simply explained by the fact that the hole, which was drilled and tapped through the piston assembly to mount it on the piston rod, was neither centered nor square with the surfaces of the piston's face plates! That much lateral runout means that the piston sits in the bore of the cylinder at an angle about 1 1/2 degrees off of a true 90 degrees. NOT GOOD!
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As it appeared that the piston ring was still wearing quite evenly, and no significant amount of running was expected soon, other than a short run for the GPU, I decided to defer any serious work on the piston problem until the next disassembly, when I can make a tool to take the piston itself apart, to perhaps rebore and retap and make an adapter insert, or possibly just to build a new piston. But that's for later.
Well you've certainly got a tiger by the tail with this engine Daniel.
One consolation is that currently as a static model...at least it looks good!
Now to jump from the piston/cylinder end back down to the flywheel/crankshaft to hopefully wrap this tale of woe up until actual restorations get underway.
Upon opening up the crankshaft bearing caps, I was immediately presented with a host of odd shaped and multi-layered oily gasket and brass shims on both sides and top.
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While it all seems to work okay, I think it may be wise to try to make a new set of shims that allow for only one in each position, and possibly even mill the bearing blocks themselves slightly to reduce the total thickness of shims required. But at this point all I did was to punch stamp each of the bearing halves, so as to assure that they would remain in proper pairs and properly oriented.
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Next to be considered was the attachments of the crank arm and flywheel, where a very ugly situation was discovered, in that there is no keyway milled into the crankshaft for the attachment of either of these features, which appear to be gripped by more of an undersized key caming action, than by anything else.
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So clearly when I do manage to get the flywheel and crank arm off of the crankshaft, I will be wanting to mill a keyway into the shaft of a size to properly accept a whole key to secure these critical features.
And finally .... now onto the truly "Fatal Flaw", that makes this engine essentially irredeemable ...
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To wit, three of the adjacent spokes exhibit hairline cracks showing through the paint, which likely suggests that these spokes are in fact cracked all the way through from some former drop, or sideways blow to the flywheel. This is likely the source of the flywheel wobble noted in my earlier posting, and I can think of no practical way of making such a repair, so if any of you out there know the whereabouts of any spare half horse Sipp flywheels, I'd sure like to hear about it!!!
All i can say is it looks like an interesting project .
I would build a new piston .
I would do some serious investigation of the flywheel does it wobble from the cracks or is the bore wonky
Quite a few flaws of significant importance there.
I agree with Dennis, forget about that piston, and make it a new one.
In fact i think i just would have made it a fast one, running a teflonring or similar, just to see how the engine behaves with something properly sized in there.
When the bore is properly honed, there might not even be a reason for anything more in your case, as it would last decades if merely intended to be a demonstrator, rather than an all day workhorse under load.
Would be a good thing to get those bearing machined to fit a single shim, and the flywheel will tell whether it really is bent, or the bore crooked, as soon as you get it off there to attend the keyway on the shaft anyway.
If it isnīt too badly bent, those 3 cracked spokes could be brazed, and it would be back to a relatively high structural health.
This is really a fascinating account of the many things that can be wrong with an old engine, and possible solutions, very educational, Thanks!
I admire your sticktoitness re:this beast Daniel , you were Leary of it from the Start & rightly so , this one appears it will never be completely sound with anything less than a complete remake but sometimes we can get it to as good as possible with what we have to work with . carry on good Sir . & thanks for the updates.
Thanks for the detailed diagnosis of the issues with this engine Daniel.
Way beyond my skills.
The flywheel cracks are the most concerning.
As Jim said, you have caught a tiger by the tail and she will thrash you about until you get her dialed in.
That said, All the evidence you show above clearly points to a raw casting kit example. I have seen and worked on many Sipps over the years and I have never seen a factory built example with this many serious flaws.
I agree that new piston is the way to go.
Thank you for sharing these updates.
Gil