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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: Specifications for 3 1/2" Gauge
08/11/2011 20:59:48
"There seems to be a lot of variation"
Indeed there is, when I was building my 3 1/2" William a went around and measured the rail to rail distance on a few tracks and decided that a bit of tolerance was required on all dimensions except those concerned with diameter and quartering of wheels and effective lengths of coupling rods.
My buffers are at 4 1/4" centres and 3" above the table when the loco is sitting on its flanges. The rise and fall has to be sufficient to cope with the track you are running on and must allow for skew across and axle (one rail going up relative to the other) so I prefer phosphor-bronze axle bushes not CI and not ball-bearings. How much running are you going to do is the question.
I will be interested to hear from experts
Tony
Thread: Crankshaft construction
08/11/2011 12:07:50
Not having access to a CNC machine centre and having to rely on my trusty Myford I am going to first try a 'pin and locite' fabrication followed by finished machining. I will normalise the steel parts after cutting and see how it goes - at least there will be less swarf
Tony
Thread: water leak repair without major surgery
08/11/2011 12:02:15
I have ordered a kit of 'SureSeal' from Tank Care Products and will advise on the results
06/11/2011 16:55:16
Thanks Gordon - I found a possible source of a two-pot coating liquid for saving old petrol tanks by search M/C restoration sites. I have emailed for advice on my application and will advise on the success or otherwise.
Tony
06/11/2011 09:57:23
I have discovered a small water leak from 'somewhere' in the bunker tank of my loco. This is after final painting and assembly so I really really don't want to strip the whole assembly apart and have to a re-solder (even if I could locate the exact source) and re-paint.
The problem is that this tank is totally enclosed and the only penetrations are the two stub pipes leading to the side-tanks and the breather tube running up through the coal bunker.
It occurs to me that a concentrated dose of Halfords Radiator repair fluid might be the answer but I'm not sure if that needs to be heated to work - I could circulate hot water I suppose.
Any bright ideas - I can't be the only one in the 'first loco' build community to make this error?
Tony
Thread: Crankshaft construction
02/11/2011 18:07:46
Years ago I built a Mastif 4 cylinder IC engine and machined the crankshaft out of a piece of normalised steel plate, not too difficult because the cranks are all in the same plane.
I now want to produce a three cylinder TE steam engine with cranks set at 120 degrees to each other.
Building the crank up out of bits of bar and webs that are either loctited or silver soldered together and then machined true, feels to be a receipt for a wobbly old shaft.
I think it would be better to machine it out of a 2" solid bar where I can insert sections at the machined out cranks to hold the bar rigid while hogging out the next crank.
Seems a out of metal removal but a better result - what do those with more experience say?
Tony M
Thread: Flat bottom holes
23/10/2011 16:15:18
I have never been able to get a decent flat bottom to a hole in a bronze valve casting using a home-made D-bit, chatter or an undulation has resulted. The next job I have to do is not a blind hole (more difficult) but a 9/322 flat bottom hole with a 5/32 through drilling into which the 45 deg valve spindle head screws. Having given up on D bits I think I will buy a 9/32 slot milling cutter to do the job in an expensive bronze casting.
Is this sensible?
Tony
Thread: Post-build review reveals one major defect (incompetence)
17/10/2011 17:54:47
Thanks to all contributors - I have my Christmas present list sorted.
A question to those who recommend co-ordinate drilling using DRO units:
Are there published tables or web based calculators for producing the co-ordinates or does one have to choose a datum hole and then work out the location of the others by basic trigonometry?
Tony
Thread: Steam plant for Bolton/Bertinat TE engine
16/10/2011 20:00:24
I have committed myself to build the Bolton triple expansion engine; looking far ahead I would like to know if there is a standard design of boiler that has a suitable pressure and flow rating to power the beast.
My only experience of (model) boiler is confined to 3 1/2" loco types.
Thread: Post-build review reveals one major defect (incompetence)
09/10/2011 10:05:05
Thanks for the comments so far - I have concluded that I will purchase a non-magnetic OCP and that starting each hole with a small centre-drill bit is vital. The small the drills shorter should be the exposed shank length, if possible, to prevent wander.
Jeff's idea of using coordinates on my mill table may be worth thinking about - but when I was an apprentice in the 1960s the only machines that we were not allowed near were the jog-borers in their air-conditioned cells so I never learnt the practical skills required. I have not found my 6 months training on Maag gear grinders of much help in my model making.
I have tried to clamp matching covers and blocks together and drill through both with an undersize drill but still found with the smallest items that the cover does not fit in all radial positions. I know the answer is to apply the upmost care and NEVER do the job in bad light or when I am tired.
A note to NJH re. William - I think the superheater ( an object of great beauty to me only) is a mistake, test indications are that it is a chronic grit trap and I doubt that its theoretical (heat energy) advantage is greater than its draught blocking disadvantage.
Tony
08/10/2011 17:23:35
I have just about finished my 3 1/2" William - final assembly of painted parts to go, but nothing major.
Lots of lessons have been learnt about techniques and problems that I had not met during my previous 'career', when building model ic and stirling engines. Such as the fact that I needed much more heat than I first thought when silver-soldering the foundation ring of a loco boiler and once you close up the firebox it is VERY difficult to fix an internal boiler-stay leak.
But my major defect as a model engineer is the drilling, with sufficient precision, of matched holes in such items as cylinder blocks and their covers. I even made a steel jig-plate for the cylinder holes using a rotary table but still managed to get less than perfect alignment, perhaps the drill wandered(?)
I certainly need a better type of centre-punch (blame the tool!) as I frequently find the 'dot' is not exactly on the marking out cross.
Since I have always wanted to built a marine TE engine this defect in my work is rather critical as there are many instances where precise alignment of tapped and clearance holes on a precise PCD are vital.
Any suggestions other than better glasses?
Tony
Thread: Consort, Double Crank Triple Expansion Engine
04/10/2011 21:31:38
Russ
Looks like you're leaping!
I am considering a more conventional TE engine as I am just finishing my first (and only) 31/2" loco (William). I built a Mastiff 4 cylinder CI engine some years ago and learnt the importance in knowing the critical dimensions from those that were not critical to the alignment of the various entablature parts, something the drawing didn't make clear.
Good luck in your endevours
Tony
Thread: Miniature gas torches
06/07/2011 14:12:53
I am struggling to solder brass beading strips to the edges of 1.2mm brass sheet work.
I think I need a much finer flame that would allow me to 'tack' one end in place while working on the difficult curved sections with highly localised heat. My present burner just puts too much heat into the whole area and a have had not luck with a soldering iron because the brass sheet simply bleeds the heat away.I notice that B&Q have 'GoSystem Micro-Tech Pro Torch Kits' but I have no idea if they would do the job.Can someone advise me of the best tool/method for this sort of soldering task?Tony
Thread: What size of beading to use
01/07/2011 17:15:30
I need to put half-round brass beading around the cab door frame and the edges of the coal bunker of my 3 1/2" William.
The brass work is made from 1.2mm plate.
Do I use 1/16 or the larger 3/32 half-round material?
I have no idea which will look best.
Tony
Thread: Fixing side-tanks and cab to running boards
22/04/2011 15:15:03
I was intending to investigate this question at the Harrogate Show but the closure of the camping area at the show-ground (Why?!) and the cost of fuel has led me to cancel the trip.
What is the generally accepted way of joining the cab and integral side-tanks to the runner-boards on a 31/2" loco? I have fitted brass angle along the base of the cab area and at the leading end of the side tanks and it is clear that attaching it along their length will pull the running boards nice and straight.
Is it usual to screw the parts together with nuts under the boards or rivet the four parts (2 x boards + 2 x sides) together permanently ?
of course if I rivet I will have to paint or at least prime the parts before fixing.
I can't really wait until the Midlands Show in October to look at other engines to find the best alternative!
Tony
Thread: Boiler cladding material
08/04/2011 09:12:02
To clad my boiler using one sheet of 26swg brass sheet it would need to have dimensions of 13"x13" and I can't find a supplier who sells any of that size. - Reeves 2000 sell a 12" square but that is shorter than the circumference so I can't use it in two sections.
So what do you guys with bigger boilers than my 3 1/2" loco use and where is it obtained?
Presently I am finding that soldering up side tanks so that they are water-tight is not as easy as it might appear!
Thread: Cutting disks of 1/16 hard brass
03/04/2011 11:53:37
I have to make the hinged lids for the water filler points in the side tanks of my 3 1/2" loco. I need to make three neat edged disks from hard brass plate 18-20 gauge thick. At work, long ago, I used to cut out much lager disks for windage baffles by fixing the brass plate to a wooden board mounted in a 4 jaw chuck and then slicing them out with a sort of parting-off blade (trepanning?)
Is this the standard method or is there an easier method that does not require a hole in the centre of the disk?
Thread: silver solder with butane
26/02/2011 18:41:57
My chemistry books pre-date metrication so in those ghastly old Btu:
Butane C4H10 = 3225 Btu/ft3
Propane C3H8 = 2572 Btu/ft3
a bit counter intuitive unless you take mhj's points into account
 
Thread: 3 1/2" William by Martin Evans
15/02/2011 20:39:52
The running boards are dimensioned as having 1 7/8" total width.
This width would no allow the stiffening strip to sit in the cut-out on the motion plates nor would it cover the steam chest fully.
I believe the correct dimension should be 2 1/32.
Best check before cutting metal
Thread: Soft soldering of loco running boards
14/02/2011 20:32:00
It works!
The old cored solder seems to make a remarkably strong joint and I remember the trick of painting Tipex down the edge of the area to be soldered to prevent it running into critical areas. The only error that I have made tonight has been to pre-tin critically fitting areas so the gap is too wide before the solder melts but I think I'm up the learning curve a bit more than I was before your help.
I still have to explain to my wife why her little caramelising gas torch is now 'gasless'
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