Member postings for John Purdy

Sandy

I don't recall either being serialized in ME (that's back to '79 as far as mine go ). The feed pump is available from Stuart models.

Blackgates now have the Clarkson drawings and castings, check their catalogue. The cat I have says the drawings are currently available and to call about castings. The only castings they currently list in the cat are for the 1" vert. and 1" horiz. steam engine. Both of these engines use parts in common with the twin compound. Namely the cyl., cyl covers,bed plate, valve chest and cover, trunk guide, crank disk and flywheel. The flywheel is what is used on the compound for the ends of the rope drum (which you seem to be missing along with the casting for the drum itself ).

John

The red ones are definitely for the Clarkson's compound mill engine as Jason says. (I know as I am just finishing one). It's the complete casting set minus the 3 castings for the rope drum. Three of the bronze ones are for Stuart Turner's steam boiler feed pump. The main frame/ pump body, cyl., and one cyl. cover.

John Purdy

Adrian

George Thomas's proportions for aesthetically appealing ball handles ( listed in his Model Engineer's Workshop Manual, also ME 3 Feb 78 ) are as follows:

The large ball diameter (D), 2 to 2.4 x the thread diameter

The small ball from 0.75D to 0.80D

the length of the handle, between ball centres, from 2.5 to 3.5D

Diameter of the shank at either end, not more than .5 of the adjacent ball dia., preferably 1/32" less

Angle 10 to 20 deg.

Flat bottom on large ball turned back 0.25D, leaving dia. of the face 0.87D.

I seem to recall that Prof. Chaddock also listed proportions for ball handles in one of his articles ( can't put my hands on it at the moment). If I remember correctly they were similar but I think the shank was longer.

John Purdy

Has anyone built O.B.Bolton's triple expansion marine engine following J.P.Bertinat's series in ME 18 Aug 85 et al.

Any comments/suggestions for someone contemplating building it? Castings quality, problems, etc.

Thanks

John Purdy

Robert

To echo JA's post I also built the floating reamer holder offered by Hemingway Kits and found it easy to make and it works well. One mod I made was to replace the 1" dia. MT2 holder with a 1" arbour with the end screwed and bored for ER20 collets ( actually I just use the one from my Quorn). The reason I did this was that all my machine reamers have parallel shanks. One thing I found when using it is that you can't just advance the reamer into the rotating work with the tail stock as it will chatter and run around it circles before ti gets started in the hole. This is because as it is floating in the holder it will sag under it's own weight and the end will be considerably below the lathe centre line. The way I use it is , with the lathe stopped, to advance the reamer with the tail stock while holding the end up with my finger till the taper on the end of the reamer just engages with the hole in the workpiece, I then start the work rotating and at the same time slowly advance the reamer into the work.

John Purdy

Neil:

Thanks for the complement, but I can't take credit for that shot as my daughter took it ! ( the rest are mine though).

Michael:

The height gauge is to George Thomas's design from his " The Model Engineer's Workshop Manual" book.

The whole unit swivels around in the mounting tube screwed to the back of the bench so as to get it out of the way if necessary.

Having got frustrated looking for that elusive Allen key, wrench or other lathe accessory in the swarf under the lathe. I decided something had to be done about it. This was the result. Now all the normally used items are readily accessible and not covered in oil or swarf.

I claim no credit for its' originality as, if I remember correctly , I based it on a picture that I saw in ME in the early 80's. I've looked but can't find the original picture.

I thought others might be interested to seen how I solved this, what I considered was a frustrating and often time consuming situation.

Mike

K. N. Harris also wrote " Model Stationary and Marine Steam Engines". I'm afraid he passed away in 1972. There was a tribute to him by Martin Evans (editor of ME) in Smoke Rings, in the 3445 issue of Model Engineer page 683 and another in issue 3447 page 787.

John Purdy

Norman

Try 5 Sep 86 (3784) page 272 , and 20 Nov 87 (3813) page 610, for alternate ways of making the rotating base.

John Purdy

Edited By John Purdy on 14/07/2016 19:19:39

Edited By John Purdy on 14/07/2016 19:22:23

Stew

The Everlasting blowdown valve was made by an American company ( as Clive says) and was fitted to most North American locomotives ( also lumber donkey engines). A model one was detailed by LBSC in his book "Shop Shed and Road". His is 7/8" dia and threaded 1/4- 40 for screwing into the boiler. It opens fully with about a 45 deg movement of the operating lever. I have one fitted to my 5" gauge 0-4-0 and it works great. Occasionally dribbles when cold but takes up once hot. Mine is fitted just above the foundation ring at one corner of the backhead. In LBSC's description he shows it fitted to the front just above the foundation ring.

John Purdy

Rod

The attached photo shows the boiler I use to steam my Stuart 10V. It was described by Tubal Cain in the Feb '77 issue of ME. It's a 3" dia. water tube boiler (see attached plan). At 10 psi the stop valve is barely open to steam the 10V at a reasonable speed ( opened up the engine races way too fast). In the introduction to the article he states that this boiler should produce 8500 cu. in' /hr of steam at 60 psi, (enough for an engine of 5/8 to 3/4" bore) and 2-3 times that amount at 10 psi.

John Purdy

Are you using any cutting fluid? What is the material you are milling? This looks like the material is welding itself to the corners of the mill, hence making it slightly longer, causing the grooves. It then breaks off allowing the mill to cut normally till some more builds up. Hence the erratic pattern. I've seen this before when milling (or turning) very ductile materials, like soft aluminum or mild steel. The application of lots of cutting fluid will prevent the buildup on the cutting edge thus preventing the rings.

John Purdy

John

I've tried the Ballcut programme on Marv's site as it looked like it would give me what I want but I can't open the output file. Windows says " can't open file as I don't know which program made it" or words to that effect. I've tried opening it with the Ballcut programme but all it does is restart the programme.

John

John

There is an article on making a hand rivet squeezer in the 15 May '87 issue of ME, page 574 that might fill your need.

John Purdy

I need to turn a large radius curve on a length of mild steel round. There have been a number of articles on generating spherical surfaces using coordinates in the model engineering press, but I have not been able to find them no matter what key words I use in the various indexes. Can any one help me.

John Purdy

Does anyone know a source of 16 BA brass round, or cheese head screws. The smallest I have been able to find is 12 BA. They are for replacement of missing ones on a model I'm overhauling, so I don't want to go larger unless absolutely necessary. Thanks

John Purdy

Rod

Yes that's part of it. What I would like to know is does the 1/8" pin on the valve cross rod that the eccentric rod valve end and latching lever fit on to have a groove in it for the latching lever to fit into. It appears from your drawing that it must as the latching lever has a 3/32" round ended slot in it, whereas my drawing shows it flat.

John

Geoff

What I do to get all the wheels the same is to machine them as Ian says, then mount them on their axles, quartering if required. I then mount them in the lathe between centres and starting with the smallest one at the tail stock end I set the top slide to the cone angle and using the top slide take a light skim to just clean up the tread, lock the cross slide and saddle. Then reverse the set and do the same with the other of the pair. Then do each set in turn. This way all your wheels will end up the same size an concentric with the axle.

John Purdy

Rod or anyone else with these drawings

On the Blackgates drawings for the Sanderson does the pin, on the arm on the end of the valve shaft, that engages with the locking lever on the end of the eccentric rod disconnect unit have a groove turned in it for a slot in the locking lever to slide into to connect the eccentric rod to the valve shaft? My drawings show a flat on the pin and a flat on the lever to mate with it. I can see this only working if the pin is free to rotate in the arm which I think would be hard to accomplish with no slop in this size.

John Purdy

Gunmetal is generally considered to be 85-5-5-5 bronze. That is an alloy of 85% Cu 5% Zn 5% Sn 5% Pb. ( Also known in some circles as Red Brass). As has been already mentioned it will turn greyish black not only when heated (as for silver soldering) but also it will come out of the mould greyish black when first cast. Normally cast gunmetal parts would then be pickled to get rid of this surface oxidation. Perhaps the ones you've seen have not been pickled?

John Purdy