jasonb
Elder Statesman
Posts: 1,209
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Post by jasonb on Mar 8, 2020 20:07:52 GMT
The question of scale will depend a lot on what you make. In Roger's case works drawings are available and he is able to work from those. The engines that Jo mostly makes are not scaled from anything but were built to units of the day that suited working with a steel rule and built for performance not to look like any full size prototype. I may make completly freelance designs or work from a patent engraving or just a photo maybe with a single known dimension if i'm lucky so I have to proportion things by eye so seldom need to design to 2 or 3 decimals. Also the designs I make available for beginners who may not have DROs, height gauges or much in the way of accurate measuring equipment I try to stick with whole mm where possible as it keeps thing manageable for marking out and allowing for backlash on machine handwheels plus it makes a drawing look a lot less daunting and tempts them to have a go.
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Post by David on Mar 8, 2020 21:49:02 GMT
Roger and Jason, what do you guys use for replacements of ME and BS? threads?
What would you replace 1/2x26, 3/8x32, 1/4x40, and 3/16x40 with? My initial guess would be M12, M10, M6, and M5. But standard or fine?
Do you think the thread pitch is terribly important regarding strength for boiler fittings?
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Post by delaplume on Mar 8, 2020 22:03:35 GMT
Hello all, Like the majority on here I also try to keep up with the latest ideas and practices and at the same time keep mentally and physically active via this Hobby.......For example the DRO on my Vert Miller is a real boon in several ways whilst learning about the ongoing efforts to squeeze even more BHP from traction batteries for our cars is fascinating... To go back to John's original point}--- I agree entirely with that.......We can learn from the past but we don't have to live in it....despite some calling it "Retro" or "Shabby Chic" or whatever... I have a life-long passion for music----especially live performances....Alas, Joyce and I have had to abandon the idea of seeing Andre'Rieu at Liverpool's excellent concert hall venue---Plus recently I had to give up my Alto saxophone due to a problem within my lungs}--- a double whammy, but I reserve this little offering of "Living in the Past" as it also contains my favourite track}-----"Locomotive Breath" and, more applicable perhaps is the aptly named "Too old to Rock and Roll"............sigh !!
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Post by Roger on Mar 8, 2020 22:38:13 GMT
Roger and Jason, what do you guys use for replacements of ME and BS? threads? What would you replace 1/2x26, 3/8x32, 1/4x40, and 3/16x40 with? My initial guess would be M12, M10, M6, and M5. But standard or fine? Do you think the thread pitch is terribly important regarding strength for boiler fittings? The strength of any thread is determined by factors such as the length and depth of thread as well as the materials both parts are made from. The decision of what thread to use is often determined by the amount of space you have. I choose threads that allow a root diameter that will accommodate an 'O' ring of at least 1mm cross section on boiler fittings. I doubt if strength is the governing factor in deciding what to use. The forces from the boiler pressure aren't that great. The issue is more likely to be through over tightening in an attempt to seal a leaking joint. If you use 'O' rings, you won't need to do that, finger tight is enough to get a seal. Anyway, here's my conversion chart that shows alternatives to any BA and ME sizes. The Metric threads are a combination of Coarse and Fine ones. Some are intermediate but still preferred sizes such as M3.5 or M7 which are less common but still out there. M3.5 is the thread used on the fascias of light switches or sockets in the UK, and M7 is used by VW on their cars. Most Model Engineers probably won't be aware of the intermediate Coarse Thread sizes, let alone Metric Fine threads. I think this fuels the impression that alternatives don't exist when in fact they do. Metric thread selector by The train Man, on Flickr Take a look at this pair of charts for Metric Coarse and Metric Fine threads. You can get any of these from reputable Industrial tool suppliers. You'll notice that there are two or more different pitches available for all diameters. I've also got M6 x 0.5 which doesn't appear on the Fine Thread chart. You'll also notice that the same pitches keep getting used on the different diameters, allowing them to be screwcut using a small set of inserts. This is where I get most of my taps and dies from.
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dscott
Elder Statesman
Posts: 2,438
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Post by dscott on Mar 9, 2020 2:09:21 GMT
I reserve this little offering of "Living in the Past" as it also contains my favourite track}-----"Locomotive Breath" and, more applicable perhaps is the aptly named "Too old to Rock and Roll"............sigh !! From Delaplume.
Yes, we were at their 2006 concert in Oxford complete with a Chinese Violin player in bare feet... My other passion exposed!!!
I got to the last bits of a pair of Union Links for Jessie and went back to the past to slim the last bit. Not much to hold onto. Sort of Girl Joke we could tell in the past.
Lots of bits done today and a strange repair to build up the rear buffer beam. Almost as if it had been caught in some rollers. Super Steel to the rescue. Some accurate marking and drilling. And slot cutting.
Best regards David and Lily.
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Post by andyhigham on Mar 9, 2020 6:55:55 GMT
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jasonb
Elder Statesman
Posts: 1,209
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Post by jasonb on Mar 9, 2020 7:21:52 GMT
Roger's chart covers what I tend to use as well either the preferred metric fine threads or the constant pitch series like M? x 1.0, 0.75 or 0.5 in place of ME and sometimes even BSP if i'm not using commercial bends etc to mate with.
You don't need to splash out on the traditional 3 taps of each size if going over to metric, most can be done with a single Spiral flute tap, they may be sold a s"machine taps" but work just fine buy hand particularly if some form of tapping guide is used just don't wind them back to break the swarf as it will clear better if wound straight in. Even available form ME suppliers like ARC these days in coarse and fine
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Post by andyhigham on Mar 9, 2020 7:56:26 GMT
Spiral flute taps are great for blind holes as the swarf is ejected back up the hole Spiral point taps are good for through holes as the swarf is pushed out ahead of the tap
Another useful thing to remember about metric threads, Subtract the pitch from the diameter to give the tapping drill size eg. M6 x 1 (6-1) = 5mm, M4 x 0.7 (4-0.7) = 3.3mm
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Tony K
Elder Statesman
Posts: 1,573
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Post by Tony K on Mar 9, 2020 8:12:21 GMT
Nobody mentioned drills so far. I realised some time ago, but I had already bought number drills and all the other nonsense sizes, that all I actually need is metric drills in 0.1mm steps and I can, given the tolerances, do all I need. Many small nuts and bolts I use could actually be metric - and metric are easily available in all forms and materials and mostly cheaper. As for modern materials - who would countenance using epoxy for a boiler repair? Yet, choosing the right one, and not just picking up plastic metal, yields at least equal properties and mostly superior, to a silver-soldered copper repair and does not require the heat and the risk of buggering up the rest of the boiler. Time to move on a bit methinks. I think we will only get real metrication when we start to think what we are doing and using metric components, rather than comparing to the old system all the time. When we can say "Oh Yes, I need an M6 bolt there," instead of "I need an 0BA bolt there" or "That'll be 0BA but I haven't got one but I can use M6 instead" - we will have made it. In other words, think metric. IMHO and all that. Enjoy today folks - this is a hobby - why so serious?
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terryc
Active Member
Posts: 10
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Post by terryc on Mar 9, 2020 10:08:27 GMT
One of the biggest problems in this hobby, apart from the red tape around boiler tests is the mind set of many of the people in the hobby. It like them are firmly suck in the past. If you compare a model engineering magazine from the USA to one from the UK, the difference is there to see. The America mag, will have drawings with 3D images, some great new ways of using cnc, I remember reading the story of how one chap designed and made a big boy live steam locomotive using an old oxygen cylinder for the boiler. Here in the UK, time stands still. Who’s to blame, well I don’t think that the federations have helped out any, new methods of boiler making have left them far behind. Let’s be honest the hobby is in decline, if it is to survive it truly needs a new mind set on so many issues.
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jem
Elder Statesman
Posts: 1,067
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Post by jem on Mar 9, 2020 17:31:55 GMT
The hobby can use metric no problem, but if we are also doing all the house hold repairs etc, then we also need pipe threads, whitworth BSF unf and all the other taps and dies as well, so it is really impossible to manage only with Metric.Don't misunderstand me, I love metric, but the outboard is unc, the pipework in the house is Bsp, in Spain we have lots of Whitworth and so on.
It is time the world standardized, but try telling that to the USA Japan etc!!!
Jem
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Post by jon38r80 on Mar 9, 2020 18:21:52 GMT
Another usefull thread chart I use for metric threads is here mdmetric.com/tech/M-thead%20600.htm, It even has Rogers M6x0.5 I use it when I cant find the thread I want on the old circular Shetack Engineers Thread Chart I bought in the 60s. I use/make metric threads all the time but I have BA/unc/unf/Bsw fine and course etc which all get used from time to time. Usualy to fix some ancient piece of equipment or tool rather than let it die. Along with Tracy tools I have found these people very usefull too www.avontapdie.co.ukTap and Die in London have a marvelous selection but the prices make my wallet wince. The last Whitworth taps I bought came by slow boat from China and were very nice quality, shame about the wait though.
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Post by silverfox on Mar 9, 2020 18:27:07 GMT
Tony mentioned epoxy for a boiler repair
Would hydraulic Loctite come into this category and has anybody used it to repair, or make an additional screwed bush into a completed boiler?
And if so any comments form them or the subsequent boiler inspector!
Ron
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Post by goldstar31 on Mar 9, 2020 19:40:24 GMT
The hobby can use metric no problem, but if we are also doing all the house hold repairs etc, then we also need pipe threads, whitworth BSF unf and all the other taps and dies as well, so it is really impossible to manage only with Metric.Don't misunderstand me, I love metric, but the outboard is unc, the pipework in the house is Bsp, in Spain we have lots of Whitworth and so on. It is time the world standardized, but try telling that to the USA Japan etc!!! Jem It was the same with mine in Menorca! People should broaden their horizons. My wife planted the date palm in the septic tank. Need I say more Norm
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Post by andyhigham on Mar 9, 2020 20:34:32 GMT
The only internationally used metric pipe thread is M5 Most of the world has adopted the BSPP and BSPT threads (sometimes referred to as G and R) The USA uses NPT and NPP Some German fittings use DIN pipe pipe thread with a 1.5mm thread
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Post by David on Mar 9, 2020 21:20:40 GMT
I ask about thread replacements because I think some designers could start using metric threads, but I also think the threads used should be the commonly known and available ones - M1.x M3, M4, M5, M6, M8, M10, M12. My reasoning is keeping to the really common ones makes it a lot easier and cheaper for builders to get the taps and dies.
I think a lot of people are still 'living in the past' when it comes to threads is just because they already have the taps and dies and know which ones are suitable for what purposes. Why would you change when you have all that in your toolbox and in your head?
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Post by Roger on Mar 9, 2020 21:56:49 GMT
I ask about thread replacements because I think some designers could start using metric threads, but I also think the threads used should be the commonly known and available ones - M1.x M3, M4, M5, M6, M8, M10, M12. My reasoning is keeping to the really common ones makes it a lot easier and cheaper for builders to get the taps and dies. I think a lot of people are still 'living in the past' when it comes to threads is just because they already have the taps and dies and know which ones are suitable for what purposes. Why would you change when you have all that in your toolbox and in your head? You can't really use Metric Coarse threads like you suggest for most things in ME because they are too coarse. If you go to some of the German suppliers, you'll see that they have adopted their own standard sizes for all of the usual steam bits and pieces. We don't need to invent any new standards when we can adopt theirs. You're quite right about most people not wanting to changing when they have a set of taps and dies in your workshop. As it happens, I did already have quite a few ME taps and dies which I bought when I was a teenager and started building a Rob Roy. However, over the years I've learned that there's no reason why modern standards can't be used, so I made the conscious decision to use Metric standards throughout, even though I didn't have all of the sizes I needed. To my mind, it makes little sense for newcomers without any tools to buy obsolete sizes that are only available through niche suppliers when Metric ones are readily available and will remain so for the forseeable future. Part of the problem is that a lot of MEs don't have the confidence to change anything in a published design.
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dscott
Elder Statesman
Posts: 2,438
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Post by dscott on Mar 10, 2020 1:27:54 GMT
Our latest bung together electric creation uses 3 metric sizes which everyone laughs at... Until she goes full power up the incline from a standing start. A disabled buggy motor direct drive to single axle with the weight of battery pushing down. 2 units the same resting on a 4 wheel bogie between. Wires all over the place and control unit at the top in the middle. You can just about lift each unit without the battery! On or off the track in about 5 minutes. Scalded cat describes performance.
OH YES M6 M8 and M10, mostly Nylocks of course.
David and Lily.
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Post by David on Mar 10, 2020 6:37:00 GMT
Most newcomers won't have the confidence to substitute metric threads for those on the design, and most newcomers will be building an older published design. You've just shown that if I'd done it I would have done it wrong. Plus if they're buying fittings they have to use the threads on the fittings.
Some of us could start using the German standards now, but it will be a long time before UK or AUS ME suppliers will be putting those threads on their products. But not as long as if we don't start the move!
Perhaps metric material and measurements are a safer place to start than threads, or we could at least use metric threads for non-boiler related work. It's going to have to be a pretty fine thread to get many turns in a 1.5mm frame stretcher.
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jasonb
Elder Statesman
Posts: 1,209
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Post by jasonb on Mar 10, 2020 7:29:39 GMT
Most newcomers won't have the confidence to substitute metric threads for those on the design, and most newcomers will be Perhaps metric material and measurements are a safer place to start than threads, or we could at least use metric threads for non-boiler related work. It's going to have to be a pretty fine thread to get many turns in a 1.5mm frame stretcher. Well as soon as you start using metric round materials why start turning them down to take an imperial thread. As per my earlier who wants to turn down say a 5mm stainless piston rod so it can be threaded 2BA or 3/16" x 40 As for boiler fittings 0.75 pitch @ 33.9tpi is not going to be far of 32tpi ME , 1.0mm pitch is only just off 26tpi and if you want finer there are the 0.5mm pitch threads. The chances of new people coming into the hobby having imperial taps and dies is becoming less and less, probably get a lot more beginners over on ME forum than here and they don't have them, don't understand imperial as never taught it in schools and if under 50 probably never even did metal work at school. Those coming into the hobby from RC models will possibly have metric tools from that as I did many yesrs ago. For those that can't make a decision themselves on the builds that I have written up and provided drawings for I show say M5 x 0.5 but also say that 3/6 x 40 could be used so if you have it and don't want to buy metric you have the choice. There are now enough barstock based stationary engines and IC engines about to get a beginner started but until the likes of Stuart start to do the 10 series in a metric option the beginner is forced to follow the imperial route as the usual first engine is generally suggested as a 10V or 10H. Subject came up a while ago and I'm almost tempted to do one and write it up for ME just using the castings and getting rid of all supplied materials and fixings at least I can make the metric drawings fit the castings which seem to be undersize for the imperial drawings. Same applies to Locos without any of the popular designs being republished in metric the beginner has little option as they don't have the experience to know what can be substituted and what can't. Chances of that happening are very slim, when was the last time you saw Myhobbystore or now Sarik make any new design (imperial or metric) available? I doubt we will ever see a new plan set and it will just have to be back issues and hope any new designs are in metric. At least a few of the popular traction engine designs can be had in both metric and imperial. J
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