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Post by mr swarf on Jun 14, 2018 15:25:41 GMT
A recent thread bemoaned the lack of contributors so here goes with my humble efforts with Doris. Some time ago I bought a Doris chassis on ebay. When it arrived it was somewhat of a disappointment. It barely turned over & had all sorts of problems. It didn't cost too much & the castings which came with it, including cylinders, more than covered the price so I put it under the bench whilst I though about what to do with it. After getting fed up with moving or knocking it I decided it was time to fix it or bin it so here goes. Some of the early stages are before I joined here so I didn't think to take pictures. I started with the bogie. The axle's seemed to be very bright material. I couldn't work out what it was but it didn't seem right for axles and they were larger than 3/8". They would get replaced to start with along with the stays which were also way oversize. As I would be scapping the axles & stays I just sawed them in half and knocked the wheels off. I still could not work out what the material was, it seemed to shiny for stainless so I left them out in the rain to see what would happen. P6141925 by Mr Swarf, on Flickr As you can see, only the turned surfaces rusted. My best guess is chrome plated steel. Certainly not the best choice & glad I chose to replace them, especially with the poorly machined bearing surfaces. I also made new axle boxes as the existing ones seemed to be 2 bits of different section brass sweated together! At this point I realised after looking again at the chassis, that it seems to have been made with whatever scrap he had to hand! So here is the refurbed bogie with new axles axelbox's & stays. Thankfully the wheels were nicely turned, maybe someone else did them. A lick of paint to finish it off & look like I have achieved something. P6141926 by Mr Swarf, on Flickr P6141927 by Mr Swarf, on Flickr More rescues next time, Paul
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Post by Deleted on Jun 14, 2018 15:34:35 GMT
That's looking very nice Paul...one of our club members has one, it runs very nicely....I'm looking forward to further updates.....
Pete
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Post by simplyloco on Jun 14, 2018 16:33:18 GMT
Excellent! I look forward to your updates: we'll beat the contributor bogie yet! John
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Post by springcrocus on Jun 14, 2018 22:06:26 GMT
Back in the day when I was involved in the manufacture of hydraulic cylinders, it was not unusual to have the rams chrome-plated. They were turned to a very fine tolerance (and a few tenths undersize) prior to sending out for plating where they were first copper-plated, followed by polishing and finally chrome plating. It is possible that your axles were made from some salvaged material of this nature and would probably, therefore, be EN24T or something similar. Tough as hell!!
Regards, Steve
Edit: It is unlikely you axles were decorative plating on mild steel as this would have flaked and be instantly recognisable.
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Post by mr swarf on Jun 14, 2018 22:47:38 GMT
Back in the day when I was involved in the manufacture of hydraulic cylinders, it was not unusual to have the rams chrome-plated. They were turned to a very fine tolerance (and a few tenths undersize) prior to sending out for plating where they were first copper-plated, followed by polishing and finally chrome plating. It is possible that your axles were made from some salvaged material of this nature and would probably, therefore, be EN24T or something similar. Tough as hell!! Regards, Steve Edit: It is unlikely you axles were decorative plating on mild steel as this would have flaked and be instantly recognisable. My first thought was that it had come from some shop fittings but there are clearly other industrial uses of it. Incidentally, how does the chrome plating perform as a bearing surface on plain bronze/gunmetal castings for example?
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Post by gwr14xx on Jun 15, 2018 6:35:07 GMT
Paul, You say it looked as if the loco was built from whatever scrap was available - could the axles have been turned from piston rods from hydraulic/ pneumatic cylinders? They are often some obscure diameter and chrome plated, so would probably need the ends machined. The plating would also make them more rigid, and protect them from corrosion - a novel way of overcoming the cost of electroplating!
Regards, Eddie.
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Post by steamer5 on Jun 15, 2018 10:19:18 GMT
Hi guys, Some time back I got ahold of some old shock absorbers, no good for cars but the shafts are great, Getting thru the chrome can be a bit dodgy but the steel turns very nicely.
The dodgyest bit is cutting the shock apart........some are ok but the ones still under pressure are a bit surprising!
Cheers Kerrin
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Post by mr swarf on Jun 17, 2018 16:56:55 GMT
So on to the chassis itself. It came with poorly made coupling rods so they were removed to start with but we'll see them later. The first thing I noticed was 3 different sizes of axle. I had 1/2”, 13mm & 14mm. I got the sense that they didn't look quite square across the frames. With the wheel sets removed, a square across the horngaps confirmed this. I could mill them out & fit new axleboxes to suit or fit new hornblocks. It so happened I had a set of unused hornblock castings so I would do this as the axleboxes seemed nicely machined & I could bush them back to 1/2" bore if I wanted to have the same diameter on each axle. With the rivet heads milled off the existing hornblocks & the rivets removed they should have just tapped out. Numerous taps with a small hammer showed no sign of movement. A bigger hammer eventually produced a bit a movement. They had been soft soldered to the frames as well as riveted. I have not heard of this before has any else? The new hornblocks were riveted in and with frames bolted together milled out to suit the existing axle boxes. P6171930 by Mr Swarf, on Flickr Such was my enthusiasm for doing this I forget to fully tighten the chuck and, you guessed it, the cutter gradually started to unscrew. By the time I realised it this had happened. I'm supposed to be fixing problems not making more ! P6171931 by Mr Swarf, on Flickr What to do? I could soft solder a bit of brass/bronze in. What do you suggest? Paul
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Post by Deleted on Jun 17, 2018 17:53:47 GMT
Hi Paul
I think soft solder would be my choice, other option being loctite...use something like a micro torch though so you keep the heat localised, it shouldn't take much heat. You could just leave it if not concerned with aesthetics...the sides are what's important...you still have metal there to stop the horn at it's max height...I doubt that it would ever get that high once sprung anyway...
Pete
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uuu
Elder Statesman
your message here...
Posts: 2,800
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Post by uuu on Jun 17, 2018 17:57:26 GMT
I thought those Autolock chucks were supposed to be self-tightening. In any event you could just leave it. It will be hard to spot when things are assembled.
Wilf
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Post by mr swarf on Jun 20, 2018 9:12:43 GMT
That little accident on the horns was niggling me so I had a go at soft soldering a piece in. A bit of brass was made to fit in the gap but slightly thicker & longer. It was soldered in & smoothed back. P6201933 by Mr Swarf, on Flickr Putting the frames back together I noticed the front buffer beam seemed to be squeezing the frames up so I checked the slot width. It was a little short, should be 2.875. P6201935 by Mr Swarf, on Flickr I wasn't happy with the front profile of it any way as it didn't look like the full size so a new one was made using some 25mm x 3mm angle. This time with a profile more in line with the full size. P6201936 by Mr Swarf, on Flickr At this stage I also decided to make a new pump stay. The original was a welded up affair, had poorly formed threads and really needed to be thicker for 26 tpi. A new one was made 3/16" thick. The thread was screwcut, holding the stay in the 4 jaw, as I don't have a 9/16 x 26 tap. P6201937 by Mr Swarf, on Flickr
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Post by Deleted on Jun 20, 2018 9:23:56 GMT
looking good Paul, the soft solder repair is excellent sir..
Pete
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Lisa
Statesman
Posts: 806
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Post by Lisa on Jun 20, 2018 10:01:56 GMT
^ What Pete said, I couldn't tell that that was the repaired casting when I first looked.
Also, as a matter of interest, did you use bright or black angle for the replacement buffer beam? I've heard arguments for and against both.
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Post by mr swarf on Jun 20, 2018 12:24:43 GMT
Hi Lisa, I used bright angle as I had some in which has square corners. The black angle I've seen had rounded corners. The bright may suffer from stress release after cutting the slots but it didn't in this case.
Paul
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Post by mr swarf on Jul 16, 2018 14:36:57 GMT
The chassis did not come with a axle pump so whilst the lathe was still set up from screw cutting the stay I made the pump. Axle pump by Mr Swarf, on Flickr The previous builder had not done anything on the brakes so whilst the frames were apart it seemed the right time to make the brake cylinder stay & drill the frames. Brake Stay by Mr Swarf, on Flickr Some of the bolts used on the frame are 1/8" x 40. Whilst the thread is not a problem the heads were very oversize. I had a die so I have made some replacements using some 3/16" steel hex. 1/8 x 40 bolt by Mr Swarf, on Flickr Now I can put it all back together and see if I have made any improvements. Paul
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Post by mr swarf on Jul 22, 2018 17:39:13 GMT
Whilst putting together the wheel sets I noticed the crankpins looked a bit rough. It looked like they had been subjected to files, pliers and even a sawcut in one of them! New ones were made from silver steel. Crankpin by Mr Swarf, on Flickr You may remember from an earlier post that I had 3 different sizes of axle. I bored out the axle box's, fitted a bronze bush & then bored & reamed them all out to 1/2" diameter for new axles. I also made new eccentrics as they were a bit on the rough side as well. axlebox by Mr Swarf, on Flickr All ready for quartering now. Paul
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Post by doubletop on Jul 22, 2018 21:15:19 GMT
Paul
Déjà vu - been there done that. Keep it up and you'll end up with something you are far happier with. I started my Dart refurbish expecting to make a few bits of the motion. In the end absolutely everything inside of the frames was replaced, including the boiler. The only bits that remained were some of the stretchers. ... and there were the cockups on my part.
Good luck
Pete
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Post by springcrocus on Jul 22, 2018 21:19:51 GMT
Paul Déjà vu - been there done that. Keep it up and you'll end up with something you are far happier with. I started my Dart refurbish expecting to make a few bits of the motion. In the end absolutely everything inside of the frames was replaced, including the boiler. The only bits that remained were some of the stretchers. ... and there were the cockups on my part. Good luck Pete Three new heads and four new handles but I still have Grandad's original broom. Familiar story, Pete. Kind regards, Steve
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Post by mr swarf on Aug 8, 2018 19:43:12 GMT
Quartering was done in the lathe between centers using high strength retainer. A center was turned on some stock the same diameter as the crankpin, 1/4" in this case. A piece of bar was then set in the toolpost with its top exactly 3.375" high. A square was then clamped to the bed up against the 1/4 bar. The wheels are then placed between centers with one crankpin against the square & the other resting on the bar in the toolpost, not forgetting to add axelbox & eccentrics . Quartering by Mr Swarf, on Flickr
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Post by mr swarf on Aug 10, 2018 10:56:39 GMT
So that was quartering done, or so I thought. After removing the square & withdrawing the tool post I just casually flicked over the wheels. Oh dear, the wheels were wobbling all over the place! I was sure they had gone on square to the axles so what was wrong? After a few minutes thought I got the dti & micrometer out to see what was happening. It turned out that the rim varied in thickness by about 12 thou & the bore was not done square to the face & tread. No wonder the previous builder couldn't get it to turn over with the rods on, the crankpins must have been doing their own merry dance as it went round. Thoroughly disheartened it all went back under the bench for a few weeks while I thought about just scrapping it. I kept thinking about it & just couldn't bring myself to scrap it so I had a go to see what could be done. Looking at the wheels again, I couldn't take anything off the rear face as that would leave the flange to thin so the rear face would be the starting point. The wheel was mounted on the faceplate and after a few minutes gentle tapping I got the tread running true to under a thou. Clocking Wheel by Mr Swarf, on Flickr I then bored out to 1/2" to fit a sleeve to bring it back to 7/16". This also got rid of the remains of the poorly done 5BA hole used for pinning. Boring Wheel by Mr Swarf, on Flickr I then faced the front removing just enough to true it up. This was repeated for the other wheels. With the sleeve fitted I now had 6 true wheels although about 10 - 12 thou light on the thickness. I don't think it will fall through the track. Quartering was repeated, this time producing 3 wobble free wheel sets. Coupling Rods next. Paul
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