Author Topic: Muncaster's Joys Valve Engine  (Read 159486 times)

Offline smfr

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Re: Muncaster's Joys Valve Engine
« Reply #240 on: February 25, 2014, 06:51:58 AM »
I turned and tapped the expanding mandrels last night, and cut the slots today:



This is the first time I've used the square collet block, but it's ideal for this purpose!

1/4" and 1/2" mandrels:



If you look carefully you can see that the 1/2" one has expanded out at the end; maybe 303 stainless wasn't the best material for these. It had to be persuaded back to size in the vise. It was usable, but now a bit undersize in the middle.

Next problem: tightening up the screw caused the bearings to pop open, breaking one side of the solder join  :hammerbash:



so a machinists clamp was pressed into service. To prevent it from being flung across the shop, I threaded a zip-tie through it, and ran at low speed, but that was good enough to skim the surface:



Before and after:



The smaller bearings also popped a seam, but were tight enough to skim without resorting to a clamp:



The bearings will never look this good again :D (especially after I silver-solder on a bit to fix my earlier over-eager milling).



You'll notice the uneven flange widths on the big bearing, which cover a boo-boo I made on the conrod by making the slot too deep, but once these are fitted to the crankshaft I don't think it will really look too bad.

I still need to put a radius on the inside edge of the bearings. Not quite sure how do do that yet (the radius is smaller than my smallest corner-rounding end mill, so I can't use the "end mill as radius tool" trick).

Simon

Online Kim

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Re: Muncaster's Joys Valve Engine
« Reply #241 on: February 25, 2014, 03:06:30 PM »
Those look great Simon!  You do meticulous work there!
Keep up the good work. I always enjoy reading your updates!
Kim

Offline kvom

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Re: Muncaster's Joys Valve Engine
« Reply #242 on: February 26, 2014, 06:27:41 PM »
I received the full-size drawing set today.  The side lever at the cylinder end isn't show on the plans, so it is almost certainly to operate cylinder drains that might be needed to operate on steam.

Offline smfr

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Re: Muncaster's Joys Valve Engine
« Reply #243 on: February 26, 2014, 06:36:43 PM »
I received the full-size drawing set today.  The side lever at the cylinder end isn't show on the plans, so it is almost certainly to operate cylinder drains that might be needed to operate on steam.

Right. The original drawing show no cylinder drain cocks; I haven't decided how to fit them yet, but am tempted to put them either in the cylinder covers, or coming out of the side of the cylinder block.

The original drawings also don't show oilers on the conrods, crossheads or crosshead slides, just on the main bearings, so I'll have to think about those too.

Simon

Offline Tennessee Whiskey

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Re: Muncaster's Joys Valve Engine
« Reply #244 on: February 26, 2014, 07:03:30 PM »
Simon, those bearings look great. I think your little offset error actually made them look better. It all looks harmonious. I've had one soft soldered joint fail in the past. On the crank bearing pillars on my present build, I used Locktite SuperGlue. It worked well, Withstood side milling and drilling, as a matter of fact, had to get the torch out to separate the halves.

Whiskey

Offline kvom

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Re: Muncaster's Joys Valve Engine
« Reply #245 on: February 26, 2014, 10:31:46 PM »
There is a note on my drawings saying that cylinder cocks, if desired, would be bottom-center of the cylinder bore on each end.

Offline Don1966

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Re: Muncaster's Joys Valve Engine
« Reply #246 on: February 27, 2014, 02:53:54 AM »
 :slap:Simon you sure do some pretty work and like Eric your Boo Boo is unnoticeable and I still have trouble seeing it. Just awesome bud and I like.......... :praise2:


Don

Offline zeeprogrammer

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Re: Muncaster's Joys Valve Engine
« Reply #247 on: February 27, 2014, 01:20:32 PM »
Looks real good to me.
I appreciate all the build details too (both the good and the boo-boo).
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Offline smfr

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Re: Muncaster's Joys Valve Engine
« Reply #248 on: March 03, 2014, 07:49:35 AM »
A few more bits and bobs doing this weekend.

To make the radii on the inside edge of the bearings, I decided to make a form tool with a small (3/32") radius. Actually two, so I could pick the better one :) These started life as bits of gauge plate. I drilled holes a known distance from the end and one side, then added lots of clearance with countersinks:



then the corner was milled away, moving the cutter by distances calculated based on the hole location, to end up with the radius in the corner:



Excess material was ground away, and some filing done to blend the milled surfaces and the drilled hole, and to add clearance. Not much of the countersunk area remains!



They were harded by heating to cherry red, holding there for a minute or so, then plunging into water.

Now the bearings need to be set up in the 4-jaw, accurately. I do this with the help of some 1/2" bar held in a collet in the spindle bore, and slide the bearing onto it, then snug up the jaws one by one with approprate packing:



One of the bearings had split by now, so a tap with a ring on the bar ensure the two sides are aligned:



The parts are adjusted with the help of an indicator:



and then we can make the cut, sneaking up to the diameter and depth with care (some Sharpie marks help show how much is being cut away)



4 sides done:



Now the bearing gap can be milled; I put a bit of rod in the bearing and used a height gauge to determine how much to mill on each half, since the joint wasn't quite on centerline. I aimed for a 1/64" gap between the halves (a bit small, perhaps?)



I don't have any photos, but I made up for the earlier mistake of taking too much off the tapered surface by soft-soldering in a bit more bronze and milling it back to size, so now the wedge travel is reasonable on both conrods:



So that's the conrod bearings done.

I was keen to make progress on the main (crankshaft) bearings too, so that I can fit my temporary crankshaft, and check the motion of the crossheads. My plan is to drill out the two bearings in the vise, undersized, then to line-bore them in situ.

So they were marked up in situ, then set up for drilling:



up to 7/16". To line bore them, I need a few bits of tooling and fixtures! First, I whipped up a couple of temporary bearing caps, then made a boring bar out of some 7/16" rod:



The hole for the bit was drilled at a 45deg angle, with a grub screw for bit adjustment, and another from the top to lock the bit in place. There's very little room to play here (only 1/32" sticking out of the rod!) so I had to futz around with grinding down the grub screws!

The other thing I need is some packing pieces under the base to get it to the correct height on the table. I started on those, which you can just see sitting under the base here:



I'll mill them down to height in-situ for accuracy, then clamp the base on top.

Simon
« Last Edit: March 03, 2014, 07:52:45 AM by smfr »

Online fumopuc

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Re: Muncaster's Joys Valve Engine
« Reply #249 on: March 03, 2014, 09:52:10 AM »
Hi Simon, I am still watching with much interest. Great Job.
Kind Regards
Achim

Offline smfr

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Re: Muncaster's Joys Valve Engine
« Reply #250 on: March 10, 2014, 05:17:53 AM »
Workshop time is getting a bit more scarce now that work is getting busy, and the weeds are growing in the garden, but I made some progress over the past couple of weekends.

When we left off last time, I had milled down a couple of bits of Al on the cross-slide table to set the base at the correct height. Just to make sure, I check will a drill bit that fits the bearing hole:



and it goes in nicely, so we're good  :ThumbsUp: Note how little clearance I have at the back of the lathe with the base mounted this way; about 1/4"!

I have to bore each bearing out individually before I have enough clearance for the boring bar, and I wanted to do this with the bearings in situ, so the 1" boring head goes into the lathe spindle, and I bore to about 15/32":



then flip the base around, indicate it in using a parallel in the bearing slots, then open up the other bearing:



Now we're ready for line boring.



This didn't go as smoothly as I hoped  :facepalm2: I was getting a lot of chatter on the left bearing but not the right one (which I don't understand; the behavior of the boring bar shouldn't really be affected by the position of the carriage), so I opened up the right one to about 0.494" (leaving enough for reaming), then flipped the boring bar around to try it the other way. Chatter was still terrible:



but then I wised up and reduced the RPMs, and things settled down. I wish at this point that I'd been brave enough to just take the bearings to final size by line boring; accurate adjustments of the boring bit were pretty easy with an indicator in place:



but no, I chickened out and got out the reamer:



which reamed slightly oversize, and left a poor finish  >:(  but neither problem is a showstopper, given that these bearings are adjustable, and will bed in during use. At least a bit of test bar fits nicely:



Now I could finish the bearing faces in the 4-jaw, leaving a nice boss in the middle:





but at this point (it was getting late) I made another mistake, and proceeded to put a radius on the outside face of one of the bearings (I guess I was all eager to use the form tool just like the conrod bearings). That face shouldn't have a big radius  :hammerbash: Luckily it's the one behind the flywheel, so will be mostly hidden. Don't tell anyone.

So now that I had bearings, I pulled out my test crankshaft hoping to get some parts running. The journal needed cleaning up, so I made some fixtures to hold the crankshaft to rotate around the journal axis:



The bandsaw is a quick way to cut the slot, provided you're careful to set the part at the right angle, and stop it when it breaks though to the appropriate hole:



So we have these, which are mirror images of each other:



I took care to align the journal. That indicator and Starrett base were $5 at an estate sale this weekend; I just had to clean off the sawdust  :ShakeHead:  ;D



Well, after setting this up between centers on the lathe and putting and indicator on the journal, things were all over the place; I was getting runout of about 0.006", which changed when I tightened up the live center, or even put a bit of pressure on the part  :ShakeHead: so I tried some spacers between the fixtures and the throws, and that helped a bit:



but I wasn't able to get the runout below a few thou. One idea I had to improve these fixtures was to actually drill and ream holes through where the dead center and live center sit, say 3/8", and make two bits of bar center-drilled in one end, and long enough to reach the throws; that would ensure that the tailstock pressure bears on the journal, to avoid distortion of the part. However, it would make turning the outsides of the throws impossible.

I did manage to clean up the insides of the throws with a tool ground for the purpose, and clean up the journal of solder bits reasonably well:



at least well enough to do a test fit with a conrod:



But it was bad news here as well; when rotating the crankshaft, the other end of the conrod wobbles around by about 0.03", so the journal is obviously misaligned. Good thing this is just a test crankshaft  :D

After all these trials with a silver-soldered crankshaft, I'm considering the Loctite and pins method. But I I'll try doing the second journal on this shaft with silver solder for practice, and to see if I can improve on the alignment.

Simon

Online fumopuc

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Re: Muncaster's Joys Valve Engine
« Reply #251 on: March 10, 2014, 06:40:24 AM »
Hi Simon,
even if things sometimes are not going the way they should, we all have the same problem there, your progress is amazing. At the end this engine will be a beauty. Nobody will take care, or also see, if the crankshaft is soldered or Loctite fixed. This is only a special thing in the builders head.

Kind Regards
Achim

Offline zeeprogrammer

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Re: Muncaster's Joys Valve Engine
« Reply #252 on: March 10, 2014, 10:42:58 AM »
Sorry to hear about the struggles. But your skills and attention to detail will no doubt get you what you want.

Looking forward to the next installment.
Carl (aka Zee) Will sometimes respond to 'hey' but never 'hey you'.
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Offline smfr

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Re: Muncaster's Joys Valve Engine
« Reply #253 on: March 10, 2014, 04:15:41 PM »
Thanks Achim and Zee! I don't really care about the crankshaft since it was always an experiment, but I'm still kicking myself over the bearing!

Simon

Offline Roger B

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Re: Muncaster's Joys Valve Engine
« Reply #254 on: March 10, 2014, 08:33:27 PM »
These things are sent for us to learn from  ;) It's looking good  :ThumbsUp: :ThumbsUp:

I have always (three times!) made my crankshafts from solid. You make more swarf, but I feel that you are more under control. Nothing can move except for a bit of stress relief.
Best regards

Roger

 

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