Member postings for John Purdy

Rod

It looks like your castings are the same as mine were except that your base appears to be CI were as mine is Ali.

If your castings are the same vintage as mine one thing you might want to check is the top cyl. cover. I found that the distance between the piston rod and valve rod gland bosses was about 3/16" too short. So I cut it in half just shy of the valve rod boss and silver soldered a piece of steel ~3/16" wide between the two pieces to give the required 1" dimension between the piston rod and valve rod. See pics.

John

Edited By John Purdy on 25/03/2016 20:22:44

Edited By John Purdy on 25/03/2016 20:24:26

Mike

Mike

I forgot the a few dimensions of the steam chest and cover in my last. The bosses are drilled 4 mm dia and threaded internally 1/4 - 40, 10 mm deep for the valve rods. The cover is 72 x 55 mm outside by 3 mm brass. It has 17 mounting hole around the periphery drilled 3.4 mm, spaced 3 mm in from each edge at the corners and spaced out 11 mm along the long edge and 16.5 mm along the short edge. As well there are two bosses threaded 5/16 - 32 with a 5 mm bore for the steam pipes. They are placed 12 mm from each edge in the corners of one of the long edges. The bosses extend 8 mm above the surface of the cover. There is also a 9.6 mm hole centred on the long dimension and 25 mm from the edge where the steam pipes are situated. This is for the exhaust pipe connection to the blast nozzle. The drawing also shows two through holes tapped 5 BA centred in the short edges of the steam chest. I'm not sure what these are for as there is no mention of them in the text and they aren't shown on the cover, jacking screws maybe?? A dimension I didn't see in my last is it shows the wall thickness of the short side of the steam chest as 6 mm which would make the one I assumed was 59 mm actually 60mm.

John Purdy

Mike

I'm not quite sure which dimensions you need, but the bosses are 10 mm dia. centred on the long edge ( back face) of the steam chest at 28 mm centres. The outside dia. of the boss is flush with one edge and the centre of the boss is 7.5 mm from the other edge. The bosses are 12 mm long. The overall outside dimensions of the steam chest are 72 x 55 mm, and 12.5 mm thick. Inside dimensions are 42 x 59 mm ( the 59 dimension is a guess as it is not shown on the drawing but is assuming that the walls are all of the same width). I hope this is clear!  If you need any other dimensions I have all the mags here by me.

John Purdy

Edited By John Purdy on 20/03/2016 20:07:36

Edited By John Purdy on 20/03/2016 20:08:32

Mike

The drawings for the steam chest and cover are in issue #4373, 12 March 2010.

John Purdy

Simon

Thanks for your info. That will at least get me in the ball park. Alex Farmer recommends tip sizes of 11, 13, and 18 for the various operations. I have a Liquid Air #312 torch and they list their tip orifice sizes by # drill size, 00 being #76 and 13 being #12. As an aside when doing the loco boilers I found I could not keep the propane torch flame lit when trying to solder the stays inside the firebox (3" x 3 1/8" x 3 1/2 deep) . As soon as I got it close to the end of the firebox it would blow out. That's a problem with naturally aspirated propane torches, they don't like being directed into closed spaces. I eventually bought a multi-flame heating tip for my oxy-acetylene torch and used it with propane and oxygen. Did the greatjob but sure used up the oxygen.

John Purdy

Fizzy

No! I've built built 3 boilers, two for 3 1/2" gauge locomotives and one a 3" dia. test boiler, all with propane. The two loco boilers were done with a 1 1/2" dia. burner. My next boiler is for a 3 1/2" gauge narrow gauge D&RGW K28 2-8-2 loco. The boiler is 6" dia. by 23 inches long and 5 1/2 across the back head. I got Farmer's book as guide to building it using Propane for pre-heat an then the oxy-acetylene for the final heat up to soldering temperature. His book describe how to build a large boiler using oxy-acetylene as the final heating medium. But he only lists the recommended tip sizes by BOC #, Not much use to us that don't have BOC equipment. Hence my initial question.

John Purdy

oxy-acetylene

John Purdy

In Alex Farmer's book on boiler making he lists the various welding tip sizes he uses only as B.O.C. numbers, without giving the actual tip diameter. Does anyone out there have a list of the B.O.C. tip numbers and their respective drill sizes? I have a Liquid Air torch and their numbering system is totally different. In fact I have a chart that compares Linde,Liquid Air, Purox, and Harris tip sizes and non of them are the same! Obviously there's no industry standard.

John Purdy

Edited By John Purdy on 29/01/2016 18:04:27

Mark

I removed one from my lathe (Super 7B) and it is 2 BA with a slotted cheese head .375 dia and .150 thick. They are .925 long overall and threaded for about 2/3 of the length under the head.

John Purdy

John

You were right, the sleeve will side horizontally, although with considerable effort. I managed to slide it back the 10+ thou. to get it aligned. It took a while as it was quite sticky and would jump either side of where I wanted it. In this case it had to be slide out. Thanks for the suggestion.

John Purdy

I'll try and download a couple of pics soonest. Can't do it right now as my daughter has the camera!

John Purdy

A while back I treated myself to two internal mikes, a. 2" to 1.2" and a 1-2" one from one of two tool suppliers I usually use (China manufacture). Both are very accurate as far as I can tell but the .2-1.2' inch is confusing and error prone when reading. As you turn the thimble to set it to say .5", as the edge of the thimble approaches and splits the .5 line on the sleeve the thimble reads 15 not 0 as it should. If the thimble is then continued to be turned to set the 0 opposite the horiz. ref. line on the sleeve the .5 graduation line is completely covered and the edge of the thimble is very close to the .525 graduation on the sleeve. This I find makes it very prone to reading errors. Does any one know how (or if it is possible) to adjust the position of the thimble relative to the sleeve? On the end, where the anvil would be on an outside mike, there is a screwed cover and inside there are two lock nuts on the end of the rotating shaft that is attached to the thimble. Are these possibly for adjustment? The only tool that came with the mikes was a two ended hook pin spanner but no adjusting instructions. One end is to adj. the friction on the ratchet and the other is for fine adjustment of the scale on the sleeve to line up the '0' on the thimble to the horiz. reference line on the sleeve when setting to the standard (which was included with each mike). This adjustment works well but leaves the edge of the thimble .010 further down the sleeve than it should be.

I hope my description isn't too confusing!!!

Any help would be appreciated as I have to be very careful reading it so as to avoid a .025 reading error. The 1-2" one lines up perfectly.

John Purdy

Matt

Like John I've always bought mine from the local welding supply company, normally Liquid Air, in Summerside and Charlottown PEI, Winnipeg MB, now in Cambell River on Van.Is., normally off the shelf. I've found that they will order if you want something they don't normally stock. When they did it for me I had to order a minimum quantity. (In my case it was 250 grams of .75mm Easy-Flo 45, as I wanted some fine wire for soldering up boiler fittings). It was expensive but I offered to sell it to the club members in Winnipeg in 1 oz coils at cost and got enough guys interested to make it feasible.

John Purdy

I have a ash pan on my 5" gauge 0-4-0 Gemma that is closed in the front and sides, but is open at the back with a door hinged so I can open or fully close the rear opening. I have it fully open when lighting and getting up steam but once on the track find I can close it completely as enough air comes in around the edges. The ash pan is made of stainless (about .025 thou thick, with the front silver sol. in) and is about 3/4" deep. It has survived well for the 25 years it's been in position (a little warped now though). About every 30 min. or so when stopped at the station I use the poker to rake out the accumulated ash (the track through the station area is over concrete,so no fires). By doing this I have never had it clog up. The original SS built up grate is still in excellent condition with only a bit of discolouration.

When I was in the Winnipeg club, we had, during the summer 20L pails of water strategically placed around the track as there were a couple of engines there with open bottomed ash pans (and one with no ash pan!) as invariably some one would drop a hot coal and start a grass fire, and someone would have to run across the field, grab the nearest pail and put it out!

John Purdy

Reference to my earlier post (01 Jan) the total valve travel should have been .28125 (9/32), not .21825 as stated (a little dyslexia?).

John Purdy

I'm in the process of trying to complete a Stuart beam that I bought as a part complete unit in 1996. All the parts, plans and materials were there but no fasteners. I bought Andrew Smiths book and started on it about 2-3 years ago. My plans are dated 1972 and show the eccentric offset as 11/64. The book (1987 printing) is as you say 11/64 in the text and 9/64 on the drawing. After doing a little math to see what was the appropriate dimension to give the correct valve movement I decided that 9/64 was correct and that is what I made mine. Total valve movement required is .21825 to fully open the ports at each end, thus an eccentric offset of 9/64 will give this movement to the end of the eccentric rod and hence to the valve rods (#32 on the drawing).

If you do contact Stuart Turner let us know what their reply is please.

John Purdy

The first appears to have the same configuration as a Brown & Sharpe # 21 collet but from memory looks to be smaller. Sorry I don't have one any more to measure to confirm that.

John Purdy

HansR

Details of Jim Ewin's lubricator can be found here:

Engineering in Miniature Jul '82 pg 48

ME 1999 Vol. 181 #4077 pg 401 & 4081 pg 636

2002 Vol. 188 #4164 pg 79

2005 Vol. 195 #4252 pg 87

2007 Vol. 199 #4314 pg 685

2008 Vol. 200 #4216 pg 29

John Purdy

I've just completed E.T Westbury's Wyvern engine and I found the following errors/ problems on the drawings. I checked back to the originals in the '63 ME series and they are there also.

1. The drawing for the mixer shows the recces in the upper body for the throttle as 7/16" deep but for the outlet hole in the throttle and the body to line up it should be 1/2" deep.

2. The front mounting bolts on the main bedplate interfere with lower flange of the water jacket if spaced at 2 1/4" as shown. By machining off the bosses and spacing the holes out to 2 1/2" ( the same as the rear) the problem is alleviated

3. The lubricators are all shown at 3/4" dia. For the two on the main bearings this gives zero clearance on the crank webs. Reduce the dia. of these two to provide clearance.( I made mine .680 dia. but if doing it again I would make them all about 1/2 to 2/3 the size as I think they look out of scale for the engine.)

4. The timing diagram is backwards. Either the crankshaft rotation arrow should be reversed to give CCW rotation or the valve events should be flipped 180 degrees.

5. The cam shaft cannot be assembled with the rear camshaft bearing made as drawn. The drawing shows the distance from the centre line of the camshaft to the flange on the bearing as 1/4", but the camshaft gear is 5/8" in dia. (ie. 5/16" from the gear centre line to the outside) as well one of the bearing mounting bolts is in the way. I moved the right hand mounting bolt down to the bottom spaced out as the left hand one. To make clearance for the gear I mounted the bearing in the mill vice with spindle centred on the bore and plunge cut with a 11/16" end mill to scallop out the mounting flange to give clearance for the gear. (see the picture in the albums section under Wyvern)

6. The left hand 1/2" dia of the crankshaft is shown at 3/4" long. If made at this length the centre lines of the camshaft gears do not line up, in fact they barely engage. The 3/4" length should be lengthened by ,095" to line up the centre lines of the gears. (As well the outer 1 1/2" length could be made longer to accommodate a lock nut on the flywheel retaining nut as without it the nut keeps undoing as the engine is running!)

7. The inner 7/8" dia. hub on the left flywheel had to be chamfered back at 45 deg. for a face width of about 1/8" as I found it hit the camshaft gear.

Neil

I'll post the errors/problems in the errors thread as suggested.

John