peteh
Statesman
Still making mistakes!
Posts: 760
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Post by peteh on Jan 31, 2020 10:30:56 GMT
Boston models (e j winters) stock tufnol
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Neale
Part of the e-furniture
5" Black 5 just started
Posts: 283 
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Post by Neale on Feb 2, 2020 16:45:54 GMT
I'm also working on Black 5 tender springs. I'm building the DY design for the chassis - in effect, everything below the tank - but also have the "Galatea" drawings by Allcock which are said to be a more detailed version. Which is great if you can read the very cluttered drawings! However, the Galatea spring design is well-drawn with individual leaf lengths given. Happy to pass on a PDF extract of the relevant bits (PM me). Problem is that the design is for 1.2mm tufnol leaves which might have been available once but now it seems to be a choice of 1mm or 2mm. I have bought a 600x600 sheet as the engine uses something similar as well. I'm planning to make a sample spring to drawing (ignoring difference in material thickness for now) and just see how it goes. I also have some annealed spring steel (thinner than the tufnol) and my plan is to stiffen the spring with some of that, suitably machined then tempered, as I suspect that the tufnol alone is going to be too weak. The idea is that I can CNC cut a set of spring leaves to drawing from the tufnol sheet.
I'm also working on trying to figure out how to assemble the body/tank assembly from a laser-cut kit. That's not entirely intuitive either! However, I'm swapping between the two tasks depending on which I find least frustrating at any given moment...
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Post by Deleted on Feb 2, 2020 17:09:01 GMT
I'm also working on Black 5 tender springs. I'm building the DY design for the chassis - in effect, everything below the tank - but also have the "Galatea" drawings by Allcock which are said to be a more detailed version. Which is great if you can read the very cluttered drawings! However, the Galatea spring design is well-drawn with individual leaf lengths given. Happy to pass on a PDF extract of the relevant bits (PM me). Problem is that the design is for 1.2mm tufnol leaves which might have been available once but now it seems to be a choice of 1mm or 2mm. I have bought a 600x600 sheet as the engine uses something similar as well. I'm planning to make a sample spring to drawing (ignoring difference in material thickness for now) and just see how it goes. I also have some annealed spring steel (thinner than the tufnol) and my plan is to stiffen the spring with some of that, suitably machined then tempered, as I suspect that the tufnol alone is going to be too weak. The idea is that I can CNC cut a set of spring leaves to drawing from the tufnol sheet. I'm also working on trying to figure out how to assemble the body/tank assembly from a laser-cut kit. That's not entirely intuitive either! However, I'm swapping between the two tasks depending on which I find least frustrating at any given moment... Hi Neale If you have a sheet of tufnol it might be worth you enquiring about getting the "springs" laser cut. Paul |
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Neale
Part of the e-furniture
5" Black 5 just started
Posts: 283
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Post by Neale on Feb 2, 2020 18:01:15 GMT
Thanks for the comment, Paul, but I have a CNC router that should be able to handle it OK. Yes, laser-cutting might manage squarer internal corners, but with a small milling cutter I think I can do all right for this job. The great thing about keeping it in house is that, for example, I can cut just one set, check how it looks/works, then have another go before I commit to a full set of 6. The router has done quite a good job to date in cutting various little components in brass and steel so I reckon it's fit for Tufnol! I bought the laser-cut set of brass for the tender body as much as anything because it didn't actually cost an enormous amount more than buying the brass myself and trying to machine it but apart from things like that, I try to do it myself. We each make rods for our own backs!
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Post by Deleted on Feb 2, 2020 19:40:31 GMT
Just a few points on this which might be useful from what I have experienced so far..You need at least spring steel for the top and bottom springs. Tufnol alone won't work, it has no energy to support the weight of models like ours. Finding the correct mix of steel and tufnol is a trial and error scenario and you won't really find the correct mix until the model is completed. IIRC my various sets of springs on 4472 have two steel on the top, one steel at the bottom and then a mix in between, this mix has changed (certainly for the trailing axle) during construction. All steel will be far top strong, some machine the centre's out to reduce the stiffness when using all steel so you can do this but I followed Don's advice. Having built a few springs now I don't think that it would have worked removing the centres if all steel leaves, I think it would still have been too stiff.
I have detailed how I made my own in my build of Doncaster, the tender springs are covered in the most detail which may be of help.
Pete
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Post by runner42 on Feb 3, 2020 6:47:52 GMT
Having reviewed Pete's construction methods for leaf springs, I have decided to adopt the alternative design that was suggested in the dialogue happening at the time of his postings, ie the use of dummy leaf springs with the actual cushioning obtained by the use of coil springs. Since the coil springs cannot be housed in the dummy leaf spring as per LBSC's tender spring design I have opted for utilising the dummy shock absorbers to house the coil springs. Something like this.  spring arrangement by Brian Leach, on Flickr Brian |
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Post by Deleted on Feb 3, 2020 14:39:17 GMT
In an earlier post I suggested laser cutting tufnol springs, apparently you cannot laser cut tufnol but water cutting is an option.
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Post by delaplume on Feb 3, 2020 16:04:04 GMT
In an earlier post I suggested laser cutting tufnol springs, apparently you cannot laser cut tufnol but water cutting is an option. In fact it might prove better in some cases.........With Steel Laser tends to leave a thin, hardened edge whereas the water cuts the material physically rather than burning and so no hard edge....They still use the Computer control etc so it's just as accurate... For my "Bear" frames I used Maidstone Engineering's water cutting service and very good they turned out too................  |
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Post by delaplume on Feb 3, 2020 16:24:53 GMT
Hi Brian,
Could you not move the outer casings upwards such that they are in contact with the upper brackets ??.........That way those coil springs will be out of sight.....Just a thought for visual improvement...
On full size those units are actually dampers rather than shock absorbers in the normal sense ( eg telescopic ), and usually consist of oval-shaped rubber pads alternately fitted with oval-shaped steel pads....the whole assembly being contained within a thin steel outer body....
Thanks
Alan
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Post by runner42 on Apr 18, 2020 6:37:50 GMT
Nearly completed the tender chassis, except for the tender wheels which have been on order before Christmas, but due to the Christmas shutdown and the subsequent COVID-19 causing working only on half shifts at the foundry the supplier has had difficulty in getting them cast. I was awaiting the delivery and machining of these before posting another installment, but having had to think of ways to make the tender brake blocks I decided to add my approach. The first operation was to machine the brake block face which is a 2 1/4" radius, this I achieved by loctiting the 6 blanks to a back plate at the required distance from the lathe centre axis and using a boring bar produced the 2 1/4" radius. The second operation was to machine the rebate on one side whilst it was in position on the back plate. Loctite proved to be a good adhesive and the bond was only broken by heat. The blanks were then profiled to the required shape and the fixing hole drilled. Because the rebate reduced the possible use of loctite again, due to the contact area between the brake block and back plate was small to achieved an adequate bond to withstand the machining operation, I decided to machine a metal plate of some thickness and 4 1/2" diameter and soft soldered the brake blocks to this and bolted it to the back plate. Brian  Tender brake blocks by Brian Leach, on Flickr |
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Post by runner42 on Apr 19, 2020 3:55:10 GMT
Well what a cock-up. Don Young has confused me once again, it was until I thought about which side the brake shoe fits to the brake hanger that I realised that I have made the brake shoes incorrectly. What I thought was rebates either side of the profile was in fact not correct and that what I was looking at was a slot so the brake hanger fits in this slot, positioning the shoe centrally. I have included the drawing of the brake shoe to show what should be produced, but also indicate that the front elevation does give a slightly misleading view and to make it obvious it requires a side elevation drawing. Brian  brake shoe by Brian Leach, on Flickr |
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Post by Roger on Apr 19, 2020 7:44:16 GMT
Well what a cock-up. Don Young has confused me once again, it was until I thought about which side the brake shoe fits to the brake hanger that I realised that I have made the brake shoes incorrectly. What I thought was rebates either side of the profile was in fact not correct and that what I was looking at was a slot so the brake hanger fits in this slot, positioning the shoe centrally. I have included the drawing of the brake shoe to show what should be produced, but also indicate that the front elevation does give a slightly misleading view and to make it obvious it requires a side elevation drawing. Brian brake shoe by Brian Leach, on Flickr How annoying, but these mistakes happen when interpreting flat drawings. I'm currently making a connecting rod for the Burrell Traction Engine from a set of old drawings. I sent the 3D model to the club so they could see whether it looked ok, only to be told that the rod was round! I'd drawn the tapered connecting part as having flat sides because nowhere on the drawing did is say Diameter or have the symbol for it. Easy mistakes to make when the person drawing the part assumes you know what it ought to look like. I'm a big fan of those 3D CAD generated 2D drawings where the designer thoughtfully adds a small isometric view on the sheet to aid visualising what's drawn. I also like to have the 3D model from a customer so I can cross check any dimensions. Maybe one day ME will be this way, but probably not in my lifetime! |
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Post by keith1500 on Apr 19, 2020 7:45:35 GMT
I think if I had drawn that I would have shown broken lines to indicate the hole not just shown the holes centre line. That would make it more clear.
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uuu
Elder Statesman
your message here...
Posts: 2,864
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Post by uuu on Apr 19, 2020 10:33:28 GMT
Jessie drawings have the word "slot" on the relevant dimension.
Wilf
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Post by runner42 on Apr 19, 2020 22:55:41 GMT
Jessie drawings have the word "slot" on the relevant dimension. Wilf My thoughts exactly. Brian |
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dscott
Elder Statesman
Posts: 2,440
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Post by dscott on Apr 20, 2020 0:23:43 GMT
After working from Ken Swans Drawings everyday I shudder to return to basics.
He includes two assembly drawings. Well two sheets with two drawings each on them.
Notes all over describing various holes. 42 3/32 rivets needed each side.
52 6 BA small head bolts for footplate fixing down 2 countersunk.
Then all the pipes are drawn in position and numbered referenced to another sheet
that gives the lengths, diameters, what is needed at the ends etc.
BLIS.
I do have a mass of Black Five photos if any builders would like me to send the parts being
worked on at the moment and in the future. Hundreds actually.
Best Regards
David and Lily.
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Post by d304 on Apr 20, 2020 9:28:37 GMT
Hi Brian
Just had a look at Don’ Locomotives Large and Small issue 52. The drawing for the break shoe is different again.
When I make a part I look at the bigger picture of how he part fits in with the rest of the machine. Know your enemy and develop the finished item in your minds eye before you cut, machine, and ultimately unfortunately remake. I am like you and don’t CNC parts but I have the 3D image in my head. The benefit is usually the remake is far better than than the first attempt, just the inconvenience!
Happy to email the other drawing.
Regards
David (CBR)
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Post by delaplume on Apr 20, 2020 10:26:25 GMT
Hello chaps, re}--- Brake shoes.....confusing, isn't it ??......On full size there were quite a few varying designs during private ownership times...Then there are the locomotive types, the coach types and the freight types... Yes, I agree about ME so-called drawings etc. but it's all part of life's rich pageantry---- apparently !!.....In the plan view the dotted lines for the pin holes are missing whilst those two horizontal extension lines from the 3/16" width of gap might be confusing and could have been left out... Don't forget to match the wheel tread angle on the shoe as well so that you get full face contact rather than a line contact........This normally comes as-cast with new shoes.. Remember also that all bearing surfaces within the brake rod system need to have a few thou clearance in order to operate correctly.....Whatever you do don't make the pins a size-for size fit or they will drag or lock up......I usually make the pins to size and then drill the matching hole.... When I was a Fitter on BR at Reading depot we had 1.2 Hrs to change a set of DMU power car shoes.......So that's slacken off the adjusters, knock the taper retaining pins out and remove the old shoe--- leaving it on the rail head from within the inspection pit.......Do that 16 times then collect the shoes in a sack truck and take them to the old shoe dump ( As a younger member of Staff I usually got the Power car furthest away from the dump ..) Next, collect 16 new shoes and deposit one on either side of the 8 wheels.....return sack truck to the stores ----- then go down into the inspection pit and re-fit new shoes and finally adjust.... A dirty, messy job that usually lost you time on the Time & Motion assesment sheet !! Happy days...........not !  |
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barlowworks
Statesman
Now finished my other projects, Britannia here I come
Posts: 878
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Post by barlowworks on Apr 20, 2020 10:35:58 GMT
One thing I have noticed while building my Britannia is that the drawings often do not look anything like the real thing, to a greater or lesser degree. I now always have a good brainstorming session looking at as many prototype photos as I can before embarking on the next part to be made, often making modifications to the drawings as I go to reflect this. I'm also lucky that a full set of works drawings came with the loco (a part build) but they are so big I have to commandeer the front room floor to look at them.  Don't be disheartened, you are still making remarkable progress. Mike |
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don9f
Statesman
Les Warnett 9F, Martin Evans “Jinty”, a part built “Austin 7” and now a part built Springbok B1.
Posts: 961
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Post by don9f on Apr 20, 2020 17:13:50 GMT
A bit of a”bummer” indeed ! Another thing that may be relevant for you is the reference on the drawing to “radius to suit wheel flange”....I think this means the sharp corner should be removed (ie radiussed) on one side, so the shoe (brake block to me) fits snugly into the root radius of the flange if it needs to. This will depend on how the hangers present the shoes to the wheels, slack in the system generally and lateral movement of the wheel sets etc.
Hope that makes sense....
Cheers Don
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