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Member postings for Tony Martyr

Here is a list of all the postings Tony Martyr has made in our forums. Click on a thread name to jump to the thread.

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Thread: Slitting saw
16/02/2010 09:35:55
Chris
Meyrick is absolutely right - the sound of the saw is very useful when you are feeding by hand and if you over cook it then it jams. The real danger is poor alignment and clamping; then you can seriously damage things.
I used the same slitting saw during my loco build on stainless steel and brass tube - there is a photo on my album on this site of it being used on the smoke-box tube.
On stainless steel I used Roco; RTD compound as a lubricant but the speed and feed were set by 'feel' rather than from any table and I always cut through the full depth of the material in such a way as to give a long cutting surface and to clear the swarf.
Tony
Thread: D-Bits and taper plug valve seatings
12/02/2010 13:20:24
In spite of faithfully following 'the books' I have never made a 100% success of using a home-made D-bit to form a flat bottomed hole that would form a text-book valve seating. In my present case I am making a steam regulator body of a simple Martin Evans design. My D-bit all hardened and correctly tempered did not seem to cult the (gun-metal) drilled hole bottom but rather scuff it.
In all other cases where a flat bottom hole is required I have managed to find a milling cutter or slot drill of the desired diameter but not in this case.
Since the taper of the regulator spindle is sharper than the bottom of the drilled hole I can't see why my nasty semi flat hole gives a better seal than the cleanly drilled one - but I bet you can!
Tony
Thread: Boiler Design: Girder or Plate Stay Design
08/02/2010 17:11:33
Hello Weary
The two books to which I refer on all boiler matters are:
Model Locomotive Boilers, Martin Evans ISBN 0 85344 022 0
How Steam Locomotives really work, Semmens & Goldfinch ISBN-13: 978 0 19 860782 3
the former is probably out of current print
Tony
Thread: Bending steel tube
08/02/2010 16:42:05
 
I spent a happy year of my apprenticeship bending steel
and nickel-copper-iron tube into complex shapes and fitting
them to Admiralty turbines. For steel tubes we always used
fine dry sand thus - wooden plug in the tube and pour in
sand, tapped the tube over its full length, pour in more sand
and repeat until the level drops no more then drive in top
wooden plug - heat the tube in the area of the bend and pull
into shape when bright red. Now the fun bit; cut off the 'spare
end' complete with plug and pour sand into dry container then
heat the other end just before the pug until red hot then turn off
oxygen and blow acetylene up the tube until it explodes and
blows the plug out as a smoking projectile far down the
pipe-shop - highly satisfying!
I feel obliged to say = 'Don't try this at home'
For exotic (seawater resistant) and thin walled pipes we always
used lead which was much hotter work and far less fun.
Tony
 

 

Edited By David Clark 1 on 22/02/2010 15:10:12

Thread: Brass nuts on boiler stays?
05/02/2010 17:13:00
Hi John
I looked at using long 1/8" copper rivets but decided to go down the traditional route described in various books. I also found drawn bronze stays are not only stronger but machine beautifully.
The only mistake I have (nearly) made is to forget that the external stay heads have to be thin for the bottom two rows otherwise there is insufficient clearance between the frames.
I think will use brass nuts on the inside of the firebox and make sure the stay end is well silver soldered - not a task I am looking forward to but with a cyclone burner and a heat shield across the tube face I hope all will be possible.
Meanwhile 5 stays at a session ensures I don't get tired and do something silly - like breaking a tap.
Tony
Thread: can i build william without a small milling machine
05/02/2010 09:47:45
Julie what colour did you paint your model William?
There is intense disagreement in my family about this subject!
Tony
Thread: Brass nuts on boiler stays?
05/02/2010 09:33:21
I am beginning to make boiler stays from 3/16 drawn bronze bar; the nearest job to a batch production task on the whole engine project. I don't relish the job of having to make the equivalent number of bronze nuts. even if I had the bronze hex bar, particularly as I have lots of 4BA brass nuts in stock.
The question is - since these nuts and the stay ends will be silver soldered does it matter that they are made of brass and not bronze?
Tony
 
Thread: can i build william without a small milling machine
04/02/2010 20:01:23
Hello Trevor
I feel responsible for your choice of loco!
The Book (Rob Roy / William ISBN 0 85242 929 0) by Martin Evans is based on using a lathe exclusively although for jobs like the coupling rods and expansion link I found the milling machine a great advantage.
Certainly a good drilling machine and table is needed.
Having both machines means that I don't spend so much time breaking down and setting up different machining configurations.
Feel free to contact me direct if my recent experience can be of any use.
Tony M 
Thread: piston packing
28/01/2010 18:13:16
As soon as I posted the response I realised that because I had just been fitting rings on an IC engine I was going off in the wrong direction!!
I still think that gland packing is best when using graphite - it beds in while O rings wipe the lubrication off and then wear.
Tony M
28/01/2010 18:10:20
You really need to define the engine type and the materials used in the bore and piston.
For bronze / gun metal type cylinders and pistons in steam engines, where the pressure load works on both sides of the ring, graphite is quite forgiving towards surface finish and, to a degree, self lubricating over the working temperature range. Some leakage past the ring in a double acting model steam engine doesn't seem to me to be too critical as to need an O ring, which I reserve for installations such as boiler feed pumps where the delta t is quite small and leakage is to be avoided.
In small IC engines with cast iron bores and steel pistons I have only used split cast iron rings working in a honed bore because of the high max surface speed.
In stirling engines, where the internal friction has to be very low I have never used rings of any sort but used PTFE or graphite pistons.
Horses for courses?     
Tony M
Thread: cutting 6BA thread on bronze bar
25/01/2010 13:49:19
Hello Les
I am using a Sievert 3525 burner which I believe is rated at 10.3kW.
It is probably over-kill for a 3 1/2" loco boiler but I thought that it was better to be able to back off a big burner than struggle to get enough heat into the work as I had when I started the project. In fact the burner has a smaller OD than conventional burners.
Of course working with the flame inside the firebox, where a cyclone burner is essential, and with insulation all around the box, the heat builds up very quickly and although wrapping thin solder wire around every tube was fiddly the result when it all flashed was very gratifying.
Tony
25/01/2010 12:28:13
To end the story.
I never did get a good result with the tailstock die holder and resorted to using the same die in a handheld die-holder. I think the clamping/adjusting screws in the holder skewed the die an amount which is critical in such a small thread.
On a more positive note and following advice from this forum I used my brand new cyclone burner in the boiler firebox and silver soldered the tubes in place without drama.
Tony
21/01/2010 11:59:46
I am failing to cut the thread on 6BA bronze bar used to make screws to retain the regulator flange on my boiler backhead.
I am mounting the die in a tailstock die-holder and I have adjusted the die using a commercial screw thread so I know it is not too tight or slack.
I can only think that the die is tilted in the holder since the bar gets reduced to near root diameter at the end and then tapers to the head end where there is some semblance of a thread (they are 1/4 long U/H).
Is this my problem? I have made sure the die is seated correctly but it may tilt via the clamping/adjustment screws, or is bronze particularly difficult to thread?
Perhaps commercial hard Cap-head screws are a better choice in this location with a smear of copperslip?
Tony M
Thread: why cant you silver solder in the workshop?
02/01/2010 11:54:36
I have never suffered from rusting in my unheated garage/workshop until I started making my boiler and dunked hot metal into a sulphuric acid pickle - then I had a thin rust form selectively on my lathe chuck and milling table where there was no oil film.
Undoubtedly the cause was the acid fumes condensing on cold, unprotected metal.
I had been using the propane torch previously to anneal the copper without any rusting.
I now silver solder with the large door open and the pickle bucket has been removed to the garden in the hope it will reduce the pH of the soil and not rust my workshop equipment.
Tony
Thread: Band saws
28/12/2009 11:36:51
Allen
 I developed a hate for hacksawing early in my working life so when I was equipping my workshop I bought a Clarke 4 1/2" bandsaw and never regretted it.
It has dealt with jobs including 4" stainless steel boiler flues and, as it has wheels, it can be moved out of the way easily when not needed. It has a vertical table that I have not yet used in anger but will do so when I have my loco running boards etc to work on.
Tony
Thread: Water gauges for small boilers
23/12/2009 11:27:19
Having faithfully followed the Martin Evans design for my boiler I find that the commercially available water gauge assemblies are all threaded 1/4x40tpi while his design has water gauge bushes threaded 1/4 x 32tpi.
Do members know if and where I can buy the 32tpi versions?
I know that I could make the units myself but I have decided that the two safety critical boiler fitting: safety valves and water gauge, were the items I would buy.
I would also like to know the operational advantages, if any, between the 3 cock gauges and the plain blow down type.
My escape from Christmas is blocked because the garage/workshop has been taken over by boxes of food and alcohol sufficient to feed and stupefy most of the parish - Happy New Year
Tony
Thread: Just bought myfirst lathe now what?
21/12/2009 13:58:49
Steve
My first project after buying a lathe and a break of years in model making was a low delta t Stirling engine.
It has a number of turning jobs which test you and the machine, it doesn't take years to complete and if you follow a similar design to mine it will run off the heat from a cup of hot water so you don't have to deal with ancillary equipment. Best of all (according to my wife) it doesn't make a noise.
good luck
Tony
Thread: Yet another boiler making question
20/12/2009 13:49:29
Thank you Meyrick
No risk of teaching granny to me on this subject; I truly belong in the 'marginal heat' of the beginner's forum - if we ever get onto dynamometers I will claim some expertise but not yet!
Now I know the special purpose of a cyclone burner I will get one - a late post-Christmas present and I was concerned that the flame would be quenched in a confined space. Can I assume, for my small firebox that a 3524 would be OK?
The large radius of the end plate means that the solder goes quite deep into the 'trench' but it can be seen as a thin line inside the box - I intend to sort out the doubtful rivets when I am ready to fix the tubes.
Tony
19/12/2009 09:12:08
I noticed in one of the books a photograph of a boiler being soldered with two or more people and two torches involved. Perhaps I will have to recruit my son two wield the big torch while I deal with a smaller one plus the solder.
As it is I find handling thin solder and a powerful flame while wearing heatproof(ish) gloves is quite tricky and the garage window ledge already bears witness to how tricky!
I have posted a photo of the firebox in its rough, post soldering, state and there are 2 rivets that do not show solder rings around the heads, one on the side plate which is probably OK and one holding the crown stay which may not be OK because the surface contact is lost on the radius of the stay.
I am going to give the box a proper dressing over and consider what to do after the Christmas clean-up of the workshop.
Thanks for the help 
Tony
18/12/2009 20:26:51
What is the best way of getting a small part of a larger copper section up to silver soldering temperature?
I have found no problem in using a 710 deg C solder running on the backplate bushes when the plate is lying on a thermal blanket and I use a large nozzle.
Soldering the tube plate of the firebox with easyflow was OK
But reheating a missed rivet head on the top of the firebox and soldering with Easyflow has been a nightmare.
I have tried stuffing thermal blanket inside the box and all around the critical area but the heat seems to flow out of the mass of copper. Is it better to use a small nozzle concentrated on the spot? I assumed that the hottest part of the flame is just at the end of the blue inner flame - is that correct?
I dread the idea of silver soldering the boiler stays if I can't get these small areas up to temperature without blasting the whole surface with my biggest nozzle.
I know that the remelt temperature of these solders is higher than the first melt but does that mean that solder wire that has bent because of unsuccessful attempts to apply it to material that is not quite hot enough, is more difficult to melt?
(Must get a refilled propane cylinder before Christmas!)
Tony
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