Author Topic: Burrell Single Crank Compound Traction Engines - 4" Scale  (Read 35675 times)

Offline jadge

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Burrell Single Crank Compound Traction Engines - 4" Scale
« on: May 31, 2015, 10:51:52 AM »
As promised in my introductory thread here are some sample pictures of progress on my traction engines. Here are the two engines, and assorted parts in progress. I am building the engines according to what interests me at the time, rather than in a logical order. I started with the gears, because I like gears:



And from the other side, showing the differential. The bevel gears are true bevel gears, rather than the normal approximations, made on my CNC mill:



I've made the pistons and piston rods, but instead of the normal aluminium pistons in this scale I chose to design and make hollow cast iron pistons; the two halves screw together. The stiffening ribs were designed using a FEA software package. The pistons are oversize and will be ground to final size once the liners are made and fitted:



I have recently finished the brake shafts and nuts. This was an interesting exercise as I have never cut a square thread before. It worked out better than I thought it might:



Here are the serial taps I made to cut the square thread in the bronze brake shaft nuts:



I've also been busy making the studs and nuts for the engines, mostly " and 5/16" BSF, I still have some 2BA studs to go, and assorted bolts:



I am currently making the gear change mechanism. This has been redesigned as the drawings are a fantasy. Having 3D printed the parts to make sure it worked as intended I am now converting the parts to metal. Once finished I'll have a go at the water pump. This has been completely redesigned, as I think the original one, as drawn, has a ram that is way larger than needed. I have also taken the opportunity to redesign the internals to incorporate proper winged valves, as per full size. Here's a section of the 3D CAD model:



My morning tug pilot duty has been cancelled due to wind and rain, so I've got the rest of the day in the workshop!

Andrew
« Last Edit: August 11, 2017, 09:49:34 PM by jadge »

Offline Dave Otto

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #1 on: May 31, 2015, 04:38:09 PM »
Very nice work!

It appears that you keep your toys in the kitchen? you must be single :lolb:

Dave

Offline b.lindsey

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #2 on: May 31, 2015, 04:53:07 PM »
Wow, that is some heavy iron Andrew. But well done from the looks of them too!!

Bill

Offline peatoluser

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #3 on: May 31, 2015, 04:59:13 PM »
very impressive work indeed!
very professional looking shop made taps as well. what size are they and how did you go about making them?
thanks for taking the time to post the pictures

peter

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #4 on: May 31, 2015, 10:24:32 PM »
Dave: Any resemblance to a kitchen is purely accidental. It is actually the assembly hall, casting storage area, and potential workshop - spot the coil winder, dead weight pressure tester and Pultra lathe on the table. I just happen to cook in the same area. And yes, I am single, the last girlfriend left in a huff muttering about lifestyle issues.

Bill: Indeed they are big, the engines will weight over a 1000 lbs each when finished. But they are an antidote to the electronics I do in the day job where the components are getting so small I can't see them. One sneeze and that's the entire packet of resistors gone for good.

Peter: The brake shaft square thread is " OD and 8 tpi. I'll dig out some pictures and post an outline of how I made them tomorrow. I see that you are in Liverpool; I was there in the late 70s doing my first degree at the university.

Andrew

Online steamer

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #5 on: June 01, 2015, 03:05:18 AM »
That's beautiful work Andrew!   I l really like that pump! :ThumbsUp:

Dave
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Damned ijjit!

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #6 on: June 01, 2015, 11:45:05 AM »
Dave: Thanks for the compliment. I had quite a lot of help over on TractionTalk from somebody who designed pumps commercially. He mentioned a whole load of parameters I hadn't thought of and challenged me to show that the pump wouldn't cavitate on the suction stroke. It took a while but I managed enough theory to convince myself that it wouldn't cavitate. He also suggested glass filled PTFE for the wing valves rather than the bronze I was intending to use. I will be interested to see how the glass filled PTFE behaves when being machined, as pure PTFE is a bit of a pig when trying to hold exact sizes.

Peter: As promised here is an outline of making the taps. The taps are made from silver steel (aka drill rod). Cutting the basic threads, turning the shank and forming the drive square are all straightforward. The taps are serial, ie, taps 1 and 2 do not cut to the full depth. I took values of 41%, 81% and 100% of full depth for each tap from Machinery's Handbook.

For cutting the flutes I used 1/8" radius cutter  on the horizontal mill, the depth of cut being determined from a CAD sketch, adjusted until it looked about right. Note the home made extension to the dividing head tailstock to avoid cutting into same:



The taps were hardened in the electric furnace, quenched in brine and then tempered at 215C. I ground a relief on the tapered portion of the taps as it gave me an opportunity to try out the drill and tap grinding accessory I bought last year, although it would have been just as easy to use a needle file before hardening:



I made the two nuts as one to start with, to ease holding. In this picture the threads have been counterbored with a " slot drill to shroud the sharp edges where the thread starts:



I made a couple of boo-boos when making the taps. First, I failed to notice that the size of the small end of the taps should vary as well as the depth of thread. If I'd done that the taps might have required less effort when cutting the thread. Second, I failed to harden the first tap properly, so it twisted slightly when being used.

Nevertheless it was an interesting exercise, and it's another tick in the been there tried that boxes.

Andrew
« Last Edit: August 12, 2017, 11:34:19 AM by jadge »

Offline Jo

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #7 on: June 01, 2015, 12:09:40 PM »
Dave: Any resemblance to a kitchen is purely accidental. It is actually the assembly hall, casting storage area, and potential workshop - spot the coil winder, dead weight pressure tester and Pultra lathe on the table. I just happen to cook in the same area.

:lolb: Sounds like my dining room table.. I just happen to eat off it.

Jo
Usus est optimum magister

Offline pgp001

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #8 on: June 01, 2015, 01:08:18 PM »
I bet your kitchen assembly hall floorboards are groaning a bit  ;D

Phil

Offline peatoluser

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #9 on: June 01, 2015, 04:11:19 PM »
Andrew,
thanks for the photos/explanation of tap making. specially the depth ratios. filed away for future use

peter

(apologies, for some reason I called you Dave! - (i blame the beer!)
post properly amended
« Last Edit: June 02, 2015, 08:50:02 AM by peatoluser »

Offline fumopuc

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #10 on: June 01, 2015, 06:59:08 PM »
Hi Andrew, you are showing us some impressive work.
Kind Regards
Achim

Offline Don1966

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #11 on: June 02, 2015, 12:56:18 AM »
Nice setup you have Andrew and very impressive work on those traction engines.

Don

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #12 on: June 02, 2015, 10:24:26 PM »
Thanks for the compliments. I'm always amazed at the speed with which other people knock out great looking work. It seems to take me ages to achieve anything; although I do keep having diversions into the engineering behind the design.  :D

Phil: The assembly hall is nothing compared to the weight of the machines in the workshop! Unusually the floors in my bungalow are concrete, so there shouldn't be a problem. The downside is that the central heating pipes are buried in the floor, so if I have a leak............. :(

Andrew

Offline pgp001

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #13 on: June 02, 2015, 11:19:26 PM »
Andrew

I am following your build with interest as I have a set of drawings and castings waiting under the bench for a the 1" version of the same engine.

Burrell's are in my blood so to speak, we used to own a full size engine called "Dalesman" a 6HP DCC 1912 road loco a few years ago.
At the same time we also had a 10HP Fowler road loco "Titan", but the Burrell was always my favourite on the road.

A friend of mine has 99% finished the restoration of a 6HP SCC Burrell which should be out this season.

Phil

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #14 on: June 03, 2015, 10:15:54 PM »
Phil: You're way ahead of me as you have owned and operated full size. I can always dream, although I have a covenant on my property banning the operation of traction engines.  >:(

A lottery win, that's what I need, not only a traction engine but a P51D Mustang too. A Spitfire would be good, but even a lottery win may not be enough for one!

I wasn't intending to do a build diary as such, but if people are interested I am happy to detail the design and machining of some of the more interesting parts.

Andrew