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Post by doubletop on Jul 4, 2015 7:27:34 GMT
Hi Pete, I was involved with the Hvmes While I was at university in Wellington approx 1999 - 2002ish Nelson and Palmy prior to that. Currently my step-father is the president of the PN club. It was definitely March 2013, as I currently live in the UK, and that was the last time I was in NZ. Sounds like your Northumbrian runs well, even if its a bit light footed. Being aware of the lack of weight problem I'm planning on building some extra weight into the engine, heavier horns, filling the bottom of the smokebox with lead etc. If nothing else, building Rainhill is allowing me to learn how to use a lathe and mill properly. :-) Just about have a set of engine and tender beams and pump stay machined up now... Robin Ah! small world. Doug C from PN is doing the boiler for my Dart at the moment. I did the Northumbrian because I wanted to try to make a 'proper' boiler and had the 3"tube to hand. I did the frames first, then the boiler, once I was happy with the boiler I forked out for the castings. I took a while to pluck up courage to start machining the cylinders. I think doing the boiler early is a good way to go and once that's done there's incentive to do the rest. Doing the motion first and the boiler second can mean a chassis running on air and no boiler. I'm sure there must be thousands of locos in that unfinished state. Pete at GLR told me they sold in the order of 75 sets of Nortumbrian astings. Where are the locos? BTW I wasn't at Locomotion in 2013 I first went in 2014 and again this year. Maybe there is another Northumbrian out there? A few build pictures would help illustrate progress. Pete
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robinw
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Post by robinw on Jul 9, 2015 10:36:37 GMT
Hi Pete,
Yes it is a small world! Not sure I'm scared of the boiler, just trying to treat the whole project as a learning curve, and definitely need to invest in a higher heat source before I can get onto the boiler.
I was hoping to have some pics to post by now, not through lack of trying though. I just don't seem to be getting past machining up the last beam. I think I understand why most people get frustrated and give up on a build. I'm about to start attempt no. 4 of the front beam. So far a murdered end mill, 6 BA taper tap and a no. 42 drill… Oh the joys of learning curves!
Robin.
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robinw
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Post by robinw on Jul 10, 2015 20:05:42 GMT
At last some progress! Not much to show, but at least I have my version of the engine and tender beams complete, as well as the pump stay, which I've drilled out smaller because I intend on fitting a smaller axle pump of 1/4 x 1/4 instead of LBSC's 5/16 x 3/8 which is rather over sized for this engine. Rainhill beams
Next on the mill will be the horns… I was unimpressed with the hornblock castings as supplied, so I will get further acquainted with the mill and will end up machining them out of the solid. I want to keep them on the heavy side, not for strength.. but for weight!
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robinw
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Post by robinw on Jul 18, 2015 8:27:07 GMT
This week I'm planning on machining the horns out of BMS flat bar. Should a be normalising the metal before proceeding with machining?
Have I understood the process of normalising correctly - that I should heat the metal up to a dull red and keep it there for a few minutes before letting it cool down slowly?
Thanks in advance for any advice given.
Cheers,
Robin
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Post by Roger on Jul 18, 2015 21:34:03 GMT
I'm not sure that BMS is a suitable material for horns, perhaps someone else can comment on this. Usually the castings are made from Cast Iron or some kind of Bronze which is has better bearing properties. You also have to consider what the axleboxes are going to be made of so that they compliment the material chosen for the horn blocks.
In answer to the specific question, I'd say that you definitely need to anneal any BMS when you're removing large amounts of it, leaving quite a slender 'U' shape. I think it would bend like a banana if you didn't. Your method of annealing sounds fine so long as you can cover the blocks with insulating tiles to keep the heat in else it will cool too quickly.
When machining something like that, I'd rough it all out first, leaving say 0.3mm all over before finishing. This gives it a chance to distort if it's going to. It's unlikely to distort when taking the finishing cuts.
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robinw
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Post by robinw on Jul 19, 2015 5:57:49 GMT
Cool, thank you very much for the advise Roger.
The plan is to use the cast bronze bar for the axle boxes. Being such a small engine. GLR supplied bronze castings for the horns. Which were a bit lacking in material.
I was planning on machining the horns in pairs, so that I end up with an open rectangle before separating, completing the final milling of the slots and feet in situ on the frames. LBSC just described bending up some 1/8" sheet for the horns, riveting them on. Not sure I like that, plus I want to add a bit of weight by making mine deeper etc.
If I can't cover the metal enough when annealing/normalising, should I continue to play a dull flame over the bits as they start to cool perhaps?
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Post by springcrocus on Jul 19, 2015 6:22:45 GMT
Buy a cheap charcoal-fired barbecue, fire it up and get it nice and hot. Get your materials up to temperature with a blowtorch, toss into the barby and cover with glowing coals. Close the lid and forget about it till tomorrow. Great for de-chilling cast iron as well.
Steve
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Post by Roger on Jul 19, 2015 7:31:23 GMT
I don't think it's practical to lower the temperature slowly using a blow torch, Steve's idea is an option although I've never used it myself. The surface will absorb carbon though, although I can't see that matters unless you subsequently heated and quenched one of those surfaces. Finishing the horns after riveting makes good sense, I would never assume that the shape would remain the same after riveting although it is done. It's another source of error that can be avoided so I'd do it the way you describe. Julian suggests buying Thermalite blocks from a builders merchants for making a hearth because they can be easily shaped, they're cheap and have the right thermal resistance. Again, I've not done this myself but I intend to. A little impromptu furnace made from tiles or blocks is invaluable for things like this, and you can make it so that you have pieces to nicely fit around what you're Normalising. edit... googling Thermalite also seems to show Celcon as an equivalent which you can get here
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Post by ejparrott on Jul 19, 2015 8:24:36 GMT
Rough out the shape before stress relieving
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Post by Roger on Jul 19, 2015 9:02:29 GMT
Rough out the shape before stress relieving Make sure you leave plenty of material on if you do it this way, you may be surprised by how much it distorts when you machine it, and it may bend again when you normalise it.
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robinw
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Post by robinw on Jul 21, 2015 5:51:23 GMT
Thank you all for the advise. Will let you know how i get on once i get back home again. I think I'll make up a channel out of firebricks that I can heat the horn blanks in and can cover over with another brick afterwards. I guess If all else fails I can try the barbie method.
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robinw
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Post by robinw on Jul 24, 2015 7:53:04 GMT
Success. The first pair of horn blocks machined up without warping. Thank you Roger, Steve, and EJParrott for the advise. Only another 3 pairs to prepare. :-) First pair of hornblocks - Every time I try to attach a pic the forum spits it's dummy!
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Post by Roger on Jul 24, 2015 11:20:09 GMT
Well done, that's good news. There's a sticky on the subject of images and the Forum so I won't repeat all that here. Many of us use Flickr or Photobucket to host the files which then appear to be embedded here.
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robinw
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Post by robinw on May 14, 2016 8:04:00 GMT
At long last some progress... which leads to the next questions. I'd like to tackle the axle boxes next. How much clearance should I allow for the axleboxes in the horns? Less that 0.001" seems a bit tight, if I've understood Tubal Cain's Hand book correctly. Surely 0.002-0.003" would be more appropriate? Engine and Tender Frames: www.flickr.com/gp/140958588@N03/r9pu31
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Post by Roger on May 14, 2016 9:18:38 GMT
At long last some progress... which leads to the next questions. I'd like to tackle the axle boxes next. How much clearance should I allow for the axleboxes in the horns? Less that 0.001" seems a bit tight, if I've understood Tubal Cain's Hand book correctly. Surely 0.002-0.003" would be more appropriate? Engine and Tender Frames: www.flickr.com/gp/140958588@N03/r9pu31Excellent! It's good to see progress. Personally, I'd aim for near zero clearance to begin with, you don't want the axleboxes hammering back and forth in the horns when it's running. It's easy to add clearance as needed, but as long as it moves with little effort then why add more? Be aware that the drawings never show the clearance required to allow the axle to be higher on one side compared to the other so that it can accommodate the undulations in the track. The inside flange is pretty much irrelevant since it doesn't touch, some people leave that off altogether. I've shown the axlebox clearance in my Wiki 'Building LBSC's SPEEDY'
I've clicked on your image in Flickr to get the picture up on the screen and then clicked the share arrow. I then selected BBCode and then copied and pasted it into this message. image by Robin Ward, on Flickr
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robinw
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Post by robinw on May 16, 2016 5:03:40 GMT
Hi Roger,
Thanks for the message, and advice. Have bookmarked your wiki for further reading. The Rainhill design calls for a single flange, and was expecting to have to radius the flange a little, Just wasn't too sure about the fit in the slots. Just attempting to avoid doing the same job twice if I can :-) ... Have lots to catch up on your speedy thread too.
R.
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Post by Roger on May 16, 2016 6:06:09 GMT
Hi Robin, I'm afraid that the SPEEDY wiki isn't particularly large because I abandonded making SPEEDY and decided to do my own thing. Hopefully others who are building SPEEDY will find it a good place to put their own helpful comments but there's a limit to what I can sensibly add there myself now.
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