Member postings for John Purdy

Neil

As Rod says Cupric Chloride might be worth a try. I switched to using it for etching circuit boards many years ago as it has many advantages over Ferric Chloride (lasts forever as it is easily regenerated after use,amongst others) , and I can testify that it does etch aluminum as I have a heater mounted on an old ali electronic chassis that I use to heat the etchant and it has numerous well etched spots on it from spills.

It can be easily made by dissolving 200gms CuCl2 in100gms conc. HCl (37.5 %) and diluting to 1 litre. The Cupric Chloride is readily available from pottery suppliers as a glaze material, and I use Muriatic acid (readily available at a builders supply) adjusting the quantity as it is normally only supplied as 20 baume which has a density of 1.16 as apposed to the conc. which is 1.18. If maintained at a density of 1.17 g/mL and a acid concentration of 3.5 to 4.0 % or 1.1 to 1.3 Molar it lasts for ever and just keeps increasing in volume.

John

Why I wrote six holes instead of seven I have no idea, it's definitely 7 as Jason says, Sorry about the confusion.

John

Tony

Edgar T. Westbury's Double Tangye model has six studs on the cylinder covers. Detailed in ME Vol. 110 and pictured in Reeves catalog.

John

Martin

If you can't find you book let me know and I'll get you the info.  It's on page 1654 of my edition #20.

John

Edited By John Purdy on 24/01/2018 20:56:50

Martin

There is a table/graph in "Machinery's Handbook" that details the suggested pilot hole sizes for the various sizes and lengths of taper pins. Basically the initial hole should be the size of the small end of the pin, but if the pin is long the hole should be step drilled with two or more larger sizes especially if using a straight fluted reamer as opposed to a spiral flute one. If you don't have access to the book if you let me know the dia. of the pin at both ends and it's overall length I can tell you the appropriate drill size(s).

John

Edited By John Purdy on 24/01/2018 19:26:42

Geoff

Further to my last, to quote from part one of the EIM series " The project is divided into six parts #1, Engine, #2 Displacement Lubricator, #3, Hand Pump, #4, Boiler, #5, Boiler fittings, and #6, Gas Burner."

John

Geoff

The series in EIM is by the same author and started in Oct.'16 and is still going. It started with a similar preamble then detailed the making of the engine, which finished in Nov. '17. The latest serial (part 11 Dec. '17) details the displacement lubricator. He hasn't got to the boiler yet.

John Purdy

To echo Maurice, I too had some Clarkson castings that were severely chilled in areas. I put then in my kiln at 1400 deg F for about 2 hours and left them in the kiln overnight to cool. They then machined beautifully. If you can find a friend with a small pottery kiln that is the way to go

John

Thanks to all who have replied. That's the info I was looking for (I knew someone here would know the answer ! )

I have dug out the three articles and the MEW one and the ME Oct '96 articles are the ones I remember.    This was instigated by a request from a friend here who is trying to measure the alignment of his lathe's headstock and tailstock and asked if I knew of any accepted standards. Thanks again.

John Purdy

Edited By John Purdy on 30/11/2017 23:12:35

Jason

Thanks, that's the name I was trying to think of. German or Swiss? Now to see if I can find the article.

John

Edited By John Purdy on 30/11/2017 19:38:38

Could someone tell me the name of the standards for errors in the alignment of machine tools. I believe they are based on ones set out by a (German I think, name starting with an "S"?) person many years age. I recall an article in one of the mags dealing with them but can't find it. I've searched the various indexes without any success, but obviously I'm not using the right search criteria. Thanks.

John Purdy

I have a bit of a conundrum, hoping someone might be able to shed some light on it. I have a commercial 4" centre height dividing head which I use on the mill. The spindle nose has been modified the take my Myford chuck. Runout on the nose register is less than .0002 TIR. If I place a piece of stock in the chuck ("Griptru" on the lathe, roughly true it then skim it to clean it up so that it reads essentially "0" TIR and transfer the chuck to the dividing head on the mill, that same surface shows a runout of between 4 1/2 and 5 thou TIR as I rotate the head and chuck through 360 degrees. It doesn't matter how many times I remove the chuck and replace it back on the dividing head the runout remains the same (within tenths) with the high reading at the same relative position of the head and chuck. If I then zero it with the Griptru adjusting screws to as close to "0" TIR as I can get and transfer it back to the lathe it is then out the same 4 1/2 to 5 thou but with the high point 180 degrees relative to the chuck body as it was on the dividing head, I am totally flumuxed. Anyone have any ideas as what could be causing this??? ( Runout in the lathe spindle nose is essentially zero.)

John

Matt

The torch I use is a Rexo-Therm Pro-Torch which I bought from the Liquid Air welding dealer in Winnipeg in the mid 80"s. I believe it cost about $80 at the time. It is a modular unit consisting of different types of handle, different lengths of neck tubes and different burners. The one I got has a trigger handle which allows for a pilot flame, a 8" long neck tube and 3 burners, 1 1/4", 1 5/8" and 2" dia. It has easily handled making 3 copper boilers (a 3 1/2' and 5" loco and a small stationary one). The company appears to still be in business but a Google search doesn't show a web site but only multiple business site listings for it in Etobicoke referencing various heating products including the Pro-Torch. An inquiry to local welding supply outlet might produce something. I hope this may be of some help.

John

Nigel

Normally you would drill a hole slightly larger than the small end and use a taper pin reamer to open it out till the pin fits in the distance you want. A taper pin reamer is like a normal hand reamer except that rather than being parallel it is ground to the same taper as the taper pin of the same size. This allows the taper pin to fit the hole for it's entire length. If you have access to a copy of "Machinery's Handbook" there is a table in it of suggested drill sizes (for pins # 7/0 to 10) including step drilling for the larger sizes which makes reaming easier. ( page 1654 in my edition, #20). Suggested sizes are .0469 for a 7/0 up to .5781 for #10 ( which requires 4 drills at different depths with the largest being .7031). Step drilling is recommended for sizes 2/0 and up.

John

Phil

I found that the two bedplates were different lengths, the LP one about 40 thou shorter, so the con rod lengths will be adjusted to suit so that the cyls. are central on their mounting pads. Also there are a couple of potential problems on the drawings. The piston is shown as being 7/16" thick, and if you add up the dimensions of the cyl., piston and stroke, that gives zero clearance at the ends of the stroke. I reduced the thickness to 3/8" which gives 1/32" clearance at each end. The other dimension that is suspect is the length of the piston valve, shown as 13/16". With the eccentric throw of 3/16" as drawn the valve at the extremes will be 1/32" beyond the inside edge of the inlet ports. For it to line up with the inner edge the eccentric throw would have to be reduced or the valve made longer. As I had already made the eccentrics when I discovered this , I increased the length of the valve to 7/8". If this was deliberate to make it run better as a compound I don't know, but I can always shorten the valve if necessary after seeing how it runs.

As you say Jason it will be interesting to see how it runs on air, as that will probably be the only way I will be running it (not having a stationary boiler big enough to run it). I suspect it will require a higher pressure than if it was a single or double high pressure.

John

Here's some pics of the latest project I am trying to complete, a Clarkson's horizontal compound mill engine (3/4" and 1" bore by 1.5" stroke). Only the crank pins, con rods, and eccentric rods to do, and mount the cyls.. Then figure out what to make for the base and what colour to paint it. Anyone got any suggestions?

I acquired them in Apr. "98 in a job lot from a fellow down the road in Ladysmith BC who had bought them from someone else. It was the complete casting set plus drawings in the original shipping box. They had originally been bought by a fellow in Victoria BC from Caldwell's of Luling Texas on 17 June 1960 for $84.53 (51.86 current UK pounds).

Along with these there was a part built 3/4" scale 4-8-4 Northern loco, tender, and boiler (which is what I had gone down there to see in the first place), a Stuart Turner beam and 5A with reverser and pump, which were partially built (complete castings and materials, but missing some fasteners) and untouched complete sets with plans for ST #1with reverser, ST#9 and pump, ST boiler steam feed pump, #4 cyl casting set, and two #6 cyl. casting sets.

I was really only interested at the time in the loco but he would not sell the items separately and the price he was asking for the lot was less than the then current price for the #1 and #9 so I couldn't refuse.

I found for the most part they machined very nicely (the valve chests and covers were chilled but after a few hours at 1400 deg in the kiln and overnight cooling were OK). Some though required very careful setting up as there was minimal machining allowance, particularly the trunk guides as the wall ended up only .050" thick. Also a number of castings were smaller in the cast state than the finished drawing dimensions. Namely the valve chests and covers, main bearing top caps and main bearing pedestals ( as cast 7/8" tall whereas the finished dim. is to be 1 1/16" above cyl mounting pad.)

These problems were got around but required some extra thought and planning.

Edited By John Purdy on 19/08/2017 21:36:14

Edited By John Purdy on 19/08/2017 21:48:26

Edited By John Purdy on 19/08/2017 21:53:40

V8Eng

Thanks for the link. That fellow has quite the collection. Looking through the Bing section I did notice that there are a couple that look similar but I noted that there were numerous details on the horiz. engines that are very similar if not identical to mine. ( the steam dome with dead weight safety valve, the boiler drain cock, the corrugated black cyl. cladding, the fire hole door, the blue and red lined cast engine base, and others) So based on all the details that appear to be the same I think it is most probably a Bing. What era? 20's, 30's?

John

Although not exactly model engineering I was wondering if anyone can identify the manufacturer, and era, of the "toy" steam engine in the following pictures. It has no markings of any kind on it anywhere. I suspect it might be European as the pressure gauge is in bar not psi. The base is about 14" x 16" , the boiler is 3 1/4" dia by 9" long, the flywheel is 5" dia. with a 3/4" wide rim, and it is fired with a two burner vaporizing alcohol burner.

A fellow arrived at our club track site in Winnipeg one Sunday afternoon early summer of '89 wanting to sell a "Tich", a freelance horiz. mill engine ( about 1 1/2" bore and stroke and a 9" dia flywheel) and this steam engine. They had been owned by his grandfather who had built the Tich and mill engine. The consensus of those present was that he wanted too much for the Tich and mill engine but this one seemed reasonable so I bought it.

Edited By John Purdy on 31/07/2017 23:21:38

Edited By John Purdy on 31/07/2017 23:30:05

Tom

Here is a table that you might find of interest. I made it to convert BA to UN (I live on the west side of the pond), but in can just as easily go the other way. It also gives the closest imperial size hex for the one size smaller ME heads and nuts. I'm not sure if you are aware but if you look at the last column (major dia. of the UN sizes) you will see that a #0 machine screw is .060" dia. and each successive size up is .013" larger. (Odd numbers above 6 are no longer produced).

John

David

As Jason says a short pin is pressed into a 1/16" hole in the crankshaft to key that gear. I fixed the one on the camshaft on mine with a 1/16" roll pin. You might also read my post of 02/11/15 in the "Drawing Errors and Corrections" section of this forum (if you haven't already) as there are a number of problems with the drawings for the Wyvern.

John