Member postings for John Purdy

Dave
     My #5A was also acquired part built but by an unknown person and I have been working on it off and on, but whoever had started it has butchered the bed plate casting and bearing caps. It really needs new castings but the current price is putting me off. I'm trying to find a way to salvage them.

     Back to your problem; my plans are dated the same as yours and I have added up the relative dimensions and this is what I have come up with:
Cyl.centre line to valve rod centre line: 1 15/16"+5/8"= 2 9/16"
Bed plate centre line to Bearing outer face: 1 1/8"+3/4"+3/16"= 2 1/16"
Therefore valve rod centre line to bearing face = 1/2"
Eccentric face to valve rod centre line (in eccentric rod ): 1/64"+1/8"+7/64"+9/64" = 25/64" (for the reverse gear )
This then gives a gap of 7/64" (.109 ) between the eccentric sheave and the bearing face to clear the 1/16" extended dia. on the crank.
    Or am I missing something?
John

Edited By John Purdy on 19/02/2022 19:27:47

Just out of curiosity I got out the plans for the #5A and its reverse gear, and added up the dimensions to see if the reverse gear expansion link and valve rod line up on it. No problem with this one, everything lines up.

John

Just add a 1/4" or so to the 1/2"dia. x1 3/4" long steel supplied for the reverse lever anchor screw and nut.

John

Agreed. But that would mean a re-draw of the plans. We'll see how they respond!

I've just checked the reverse lever casting in my 5A reverse gear set ( they both use the same one, also the same expansion link casting )  and I don't think the boss is long enough as cast to make it 1/4" and keep the turned handle at the end centred on the shaft.

John

Edited By John Purdy on 18/02/2022 18:51:30

Noel

I sent a msg. back to Stuart Models thanking them for their reply and included the following statement:

"If the drawing was amended to show the boss on the reverse lever to be 1/4" wide (vice 3/32" ) and not the width across the whole reverse lever this would solve the problem. Either that or a note with the drawings specifying a 5/32" wide spacer between the reverse shaft and the support bracket boss."

We'll see how they respond.

John

Edited By John Purdy on 18/02/2022 18:26:23

There is an problem with the drawings for the reverse gear for the Stuart Turner (Models ) #1 engine. If made according to the drawings the valve rod and the expansion link are out of line by 5/32". To correct the problem, either the boss on the reverse lever has to be made 1/4" wide, vice the 3/32" as drawn, or a 5/32" spacer be inserted between the reverse lever and the boss on the support bracket attached to the valve chest. Either change will require a longer 1/4" pivot pin than is shown on the drawings.

John

Got a reply from Stuart Models this morning. Seems they are still using the same plans and are not aware of the problem. Here's a quote from their msg.

"We are still working from the same drawings as you seem to have,

I haven’t had anyone notify me of this issue before, but this maybe that they have worked around the issue.

Will moving the reverse shaft bracket solve the valve rod alignment, also on our engine, there is a spacer between the reverse shaft bracket and the reversing lever, so this may be the get around."

Looks like their fix is the same as I have come up with!

I've added a post to the "Drawing Errors " section about this error in the drawings.

John

Edited By John Purdy on 18/02/2022 17:12:51

Noel

Before I read your post I had sent off an e-mail with some pictures to Stuart Models explaining the problem and listing the discrepancy in the drawing dimensions as laid out by Jason above and confirmed by me . We'll see what their reply is, and when I get it I will pass it on here. The info on my drawings is as follows: DRG #70090 dated 18.10.56, ALT. #32 20.01.67 and issued 18 SEP 1975, so fairly old, Stuart Turner pre Stuart Models (they appear to be the same ones Jason has). Thanks for the comment on the engine ( more pics in my album ).

John

Edited By John Purdy on 17/02/2022 23:04:58

Noel

That's my plan. Make a new longer 1/4" pin and a 5/32" spacer between the reverse lever boss and the bracket on the steam chest. Everything would then line up. I was just wondering if I had screwed up of was missing something. It now appears that it is the drawings that are in error.

John

Thank you Jason, I'm not crazy after all. I had also added up the dimensions as you have done and came to the same conclusion, but was wondering if I was missing something. I'm sure many examples of this reversing gear have been made to these drawings, how many others have had the same problem and how have they got around it? Are Stuart Turner aware of the errors, are the current drawings the same as ours or have they been amended?

John

Noel and Jason

No that's not the problem. The outer boss on the support fastened to the valve chest which supports the vertical link is .375" wide as per the drawing ( the other side is actually about 5/16 not 1/4 as the drawing but it is in the wind so to speak).

John

Jason
I had previously measured the valve chest cover at .250" and the valve chest at .750" as per the drawings. The valve rod is in the centre of the valve chest, ie. .375" in from either edge. Cylinder bore is 2.000". I've just taken off the cyl. top cover and the measurement from the outside of the valve cover to the edge of the cylinder is 1.752". Therefore cyl. centre line to valve rod centre line is 2.127", close enough to the drawing dimension of 2.125"

Yes that's the problem, if I move the whole reverse gear assembly over to line up with the valve rod then the reverse lever doesn't line up with the rest of the reverse assembly as shown in the second picture above.
John

Edited By John Purdy on 17/02/2022 19:10:39

Here are a couple of more pictures with different views. The first, Jason, is from the back and shows that with all the reverse linkages lined up the eccentrics are spaced out on the crank shaft and the valve rod and the expansion link don't line up.. The second shows the eccentrics moved in on the crank to line up the valve rod and the expansion link, but now the reverse lever is spaced out from the rest of the reverse linkage. The position of the reverse lever is fixed by its fastening to the slotted link which is bolted to the valve chest cover. The obvious fix is to make a longer 1/4" pivot pin and a spacer between the reverse lever and the rest of the linkage. But my question is have other people had this problem or am I missing something, or are the drawings of the reverse gear in error?

John

Edited By John Purdy on 17/02/2022 18:32:01

Colin

The UNC/UNF series of machine screws run from 0 to 14. #0 is defined as .060" major dia. and each number up increases in major dia. by .013", so #1 is .073", #2 is .086" etc., hence #5 is .125" as said above. Preferred sizes are 0. thru 6, 8, 10, and 12. There is also a series that runs down in size following the same .013" rule to #0000. Can't help with where to get them over there as I live on the other side of the pond. I make my own hex headed ones.

John

Edited By John Purdy on 17/02/2022 17:36:53

I've finished all the parts for the reversing gear for the ST#1 except for the valve rod head and the die block. On doing a trial assembly there is a problem. The valve rod doesn't line up with the expansion link. As can be seen in the picture below the link is a good 5/32" further out. I have an idea how I can fix it by making 2 new parts but I was wondering if others that have made the #1 reverse gear have had the same problem and how they got around it. The valve chest and cover and all the parts of the reverse gear are dimensioned according to the plans.

John

Thanks Bo'sun, but DiogenesII had a spare and has very kindly agreed to send it to me. Once it arrives I will try and ascertain what the thread actually is so if someone else is in the same situation they will be able to make a replacement.  One of my imperial thread gauges goes from 4 to 80 TPI including 48,50,56,60,64, and 72 so one of them should fit. I can't see it being metric as it was bought in the early '70s, but then my Myford S7 from '76 has a mix of imperial and metric fasteners!

I should come clean as to how it went missing! When I was making my radial steam aero engine I was trying to measure a 2" dia. spigot close to a shoulder and because the locking sleeve extends out beyond the body of the mike I couldn't get the mike square to the shoulder to measure it. So I removed the locking sleeve, which enabled me to make the measurement, and I put it somewhere safe so I wouldn't lose it. Obviously I put it in a very safe place as I can't find it now!!!

John

Edited By John Purdy on 16/02/2022 18:27:39

I guess the title is a bit ambiguous, Never thought of it that way when I wrote it. Sorry about that.

Maybe the moderator could change it to Micrometer Lock?

John

Edited By John Purdy on 11/02/2022 17:49:27

I seem to have lost the locking sleeve on my Moore & Wright # 966/2 1-2" mike. It goes where the arrow is in the picture. If someone with one could measure up theirs so I could make a replacement I would be most appreciative. I need the OD and pitch of the threaded part and the dimensions of the bore. I suspect the bore might be tapered to compress the split sleeve around the spindle thus locking it. Below is a pic of the mike and a cross sectional drawing of what I think the locking sleeve looks like. I suspect the thread will be 55 deg.

Thanks.

If everything goes as normal, as soon as I make a new one the original will show up in plain sight!

John

Edited By John Purdy on 10/02/2022 23:32:28

Roger

I've sent you a PM.

John

Jason

Thanks for the reply. What I have been doing is as you suggest, using the main engine drawings for the sheaves and straps and scaling from the drawing elsewhere as necessary. I was just wondering if there was another drawing sheet I was missing? At the moment all I have left to do are the eccentric straps and rods.

John