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Member postings for David Haynes

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

Thread: Stroke
12/02/2012 21:02:59
I have just looked at Nick Feast's Q1. He has the crank axle offset from c/c as 19mm and yet the wheel cranks are strangely 20mm from c/c.
11/02/2012 16:02:01
Thanks for the comments.
The sectional plan shows that when the right hand (inside) connecting rod is a back dead centre, the right hand coupling rod is at front dead centre. At this position, the left hand connecting rod is at top dead centre but the left coupling rod is not shown; by deduction it will be at bottom dead centre. On the subject of balancing, the driving wheel balance weight is ahead of the crank pin slightly, on the left hand side it is about 35 degrees ahead of the crank pin. Are the left hand balance weights a mirror of the right hand? In this case, would the right hand balance be 35 degrees behind the crank pin?
Thanks again
Thread: Imperial/Metric?
11/02/2012 11:08:19
I have an imperial lathe and my current and future projects are imperial. When I recently ordered a new milling machine, I could have the model I wanted in metric immediately and it was suggested I could just put the 3 DROs on so imperial use would not be a problem. I am not in an urgent need for the machine but did not want to have to spend more on DRO and also have to fit it; the micrometer dials on this machine have a good reputation and as I am used to those on a 50 year old lathe, backlash and all, the new none DRO machine did not seem an issue. Unless already fitted, DRO is an 'add on later' as needs dictate.
Thread: Stroke
11/02/2012 10:41:59
Thanks Neil. Yes this is in 3/4" scale, but I would have thought the issue would apply to all scales. To clarify, I am comparing the stroke of the inside piston with the 'stroke' of the coupling rods, i.e. the offset from the crank pin to the wheel centre. The prototype drawing states 'Cylinders 1' 7 1/2" Dia. 2' 2" Stroke'. This statement clearly refers to the cylinder stroke, but at no other point on the drawing, a well detailed G.A., is the driving wheel crank offset from the axle referred to. Scaling off the drawing, the offset from the c/c of the driving axle to the c/c of the big end journal is 13". So far so good, as this would give a stroke of 2'2" as indicated. However, using the same scaling, the c/c of coupling rod journal to the c/c of the associated axle, the distance comes out as 11 1/8". clearly not the same as the piston stroke. Of the few 3/4" scale drawings of inside motion I have access to, all have the same dimension for stroke and wheel crank offset. I wonder why this is?
10/02/2012 18:41:38
Simple question, when does the stroke of an inside motion differ from the stroke off the wheels? I suppose there is the matter of mechanical advantage that is applied for different loco uses, but I just wondered if there was any more thinking behind it.

Edited By David Haynes on 10/02/2012 19:08:55

Thread: Myford Lathe service
04/02/2012 15:30:13
Let's say 35 pence per mile, say 300 mile round trip that's £105 travel costs. Add 2 x 4 man-hours at £15 per hour, that's £120. Add say £30 for miscellaneous pieces from the list of NEW BELTS, WIPER, WICK, BARREL , and my grand ball park estimate is £255. Of course, in no way would I want to under price these artisan workers and so apologies if I have underpriced!

Edited By David Haynes on 04/02/2012 15:30:34

Thread: Small Milling problem
04/02/2012 12:19:27
With the clevis that Tel has shown, I find it takes ages to set up so that the saw is correctly located to cut the slot. I am still trying to make it a quick and accurate process but usually take too long or the slot is wrong and the job scrap.
Thread: Pipe union nuts, olives & ends.
04/02/2012 10:07:28
Are similar details also to be found in one of the reference books, such as by Tubal Cain or Harold Hall? If not, I can get the M.E. from my society if necessary.

Edited By David Haynes on 04/02/2012 11:58:57

Thread: Small Milling problem
02/02/2012 17:13:38
I find rounding of corners gets difficult with such as an anchor link 3/4" long x 7/32" wide. It can be done but the fingers are get scraped a bit. Any favourite way of dealing with small components?
Thread: Milling - difficult to gauge exact cut
29/01/2012 07:05:14
When milling a flute in a coupling rod, for example of narrow arms on the sides of the slot, the flute is usually milled first in a piece of metal wider than the finished rod. Then the sides can be accurately offset, one at a time. That may be easier that milling the slot in a rod of the finished width and having to get both arms correctly located in one attempt.
Thread: Vernier vs Micrometer
27/01/2012 08:39:49
The Moore and Wright 0" - 1" micrometer that I use belonged to my grandfather. I find the mike to be easy to use and accurate, even though it probably dates from pre war. I tend to use the mike for diameters but I also have a 6" Mitutoyo dial caliper which is used the rest of the time. None are battery operated as I find that less fuss.  My grandad served his apprenticeship on the Furness Railway/LMS but later became an engineering inspector in the high precision, temperature and humidity controlled 'Blue Room' at the Vickers Shipbuilding and Engineering works. He had a love of both traction engines and locomotives and it is a shame he isn't around to see this and many of his other tools being used for the current good purpose.

Edited By David Haynes on 27/01/2012 08:41:47

Thread: setting up new Axminister ZX30
25/01/2012 10:08:46
Also, the X3 guide suggests taking the spindle out of the bearings using a press, to ease them and regrease; I know in some cases this is not necessary so I suppose it's a case of seeing how well it rotates beforehand. I know of one who has not needed to do this but I don't know what other X3 owners have found.
Thread: Milling a curved end
20/01/2012 08:37:55
It is an ongoing discussion that has even permeated the ME competition arena; how do you compare fine ME models that have been built by differing methods? How do you compare a model built from a kit with one built by CNC and one built entirely by hand. The last 'entirely by hand' is a misnomer, because we all depend to some degree on external inputs which may have been anything but 'by hand'. I think a basic acceptance is developing that some folk use different routes to get to a model. The majority may have a manually operated lathe as their main machine tool but some may have the latest full spec CNC system. I am sure that subconsciously we all recognise that different skills are in use in all these variations, some more hands on and 'artisan' than others. We cannot get away from the fact though, that these basic first principal skills remain important, even if only as a step towards more digitally based ones. Otherwise we will simply move straight to computer simulators with an authentic smoke aroma generator at the back!
By the way, filing buttons are great, but so is the gadget for machining the curve.
Thread: Snifting valve
18/01/2012 18:06:24
Hi Nigel, when the cylinders are cool, there may be condensation, especially if the steam is not superheated as it is going to condense a lot easier. Water ahead of the advancing piston could do damage as the piston approaches the cylinder cover and the waste water doesn't exhaust properly (that small gap is good with a steam cushion but not with a lump of water). With piston valves this water is allowed to escape through cylinder drain valves which are closed when the loco is moving and the cylinders warmed. With slide valves, as the valve can lift by a wee bit, the water can escape up through the valve. Traction engines nearly always (always?) have slide valves so this trapped water should be less of an issue.

The snifting valve, also known as as pressure release valve, is only there to break the vacuum, but it does seem to have this useful side effect of helping to prevent the superheater burning out when steam is not flowing through it,
Hope that answers both 1 and 2 in a round about way!

Edited By David Haynes on 18/01/2012 18:15:24

Edited By David Haynes on 18/01/2012 18:16:11

Edited By David Haynes on 18/01/2012 18:37:09

18/01/2012 13:11:16
Hi Nigel, yes you are correct, the coasting cylinders will act as a pump and the subsequent vacuum will try to pull from any opening to a lower pressure and also provide a resistance to the coasting pistons. The generally accepted pressure (vacuum) release valve, also known as snifting valve is installed at the wet header end of the steam circuit. That way, cool air will be drawn though the superheater and to the cylinders. If it is installed on the hot or dry end of the superheater, the air will take the short journey to the cylinders, this will allow the superheaters to get hotter and run the risk of burning out. This is especially true if the superheater is radiant, poking right into the firebox.
18/01/2012 12:56:42
Hello Nick and thank you very much for responding. The timescale of your response is not that important as this is not for a Charlie I am building but for a locomotive I am drawing and that is still 'in the drawing office'. I am also building a small locomotive. With Charlie, I have found the whole series informative and I have no concern for the small 'health and safety' issues that some people have been picking up as I believe common sense should be the overriding caveat for all published articles. With your series, I have borrowed some of your ideas to put on my drawing but acknowledgement will of course be given, not so much from a commercial (I can't see it being published) as an ethical point of view. The locomotive shares some things with your Q1, but also with several others including LBSC's Mona, Don Young's 4F, Martin Evans' 5" Metro &etc.
My question about snifting valves on your slide valve Q1 related to the actual connection point around the wet header, but as you say, in your case you found that they kept leaking steam,. I suppose if I found the same problem, then removing the valves and coasting with the regulator cracked open may be a solution, but I wonder if a spring in these valves would prevent this problem?
Thanks also to John for his comments.
Thread: Milling Course
17/01/2012 19:19:11
Thanks Harold, I didn't want my comment to come across as a complaint and I understand the situation. I will buy the earlier book!
Thread: collet holders???
17/01/2012 18:54:03
Hi Bill, if you get a chance to go for the ER32 it will give you a bit more flexibility. I have some and I use a threaded mandrel adapter (from RDG) for my ML7 and it works a treat..
I had originally tried MT but had problems (MT2 collet slipping) that were solved by switching to the screwed adapter.

Edited By David Haynes on 17/01/2012 19:11:45

Thread: Milling Course
16/01/2012 15:17:43
Wolfie, it's good to see your milling machine progress, going through Harold's Milling machine course book (WPS 35). Although I chose the later book in the series, the Milling Machine (WPS 49) fom last year, I was most disappointed to find that although all these accessories are discussed and photographed, there are no working drawings. It seems a shame that the latest book in the series misses these useful items out.
Also, does your lathe do screw cutting? I have had a lot of success making compression springs with my ML7. Okay, so it's only piano wire, but okay for most purposes.
Thread: Metal thefts
15/01/2012 21:50:23

This is a very low but, sadly, common action. My commiserations to a firm who I have always found very helpful. I suppose if castings are disappearing, there is more of a likelihood they will appear intact on the market, making recovery and appropriate prosecutions possible. Sadly though, some of the thieves are so thick (?) they do not simply put them on EBay as 'valuable castings'.


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