Author Topic: Burrell Single Crank Compound Traction Engines - 4" Scale  (Read 39403 times)

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #165 on: March 29, 2019, 07:32:28 PM »
I have been somewhat distracted recently dealing with builders, double glazers and kitchen companies in order to get a new kitchen fitted. I've also had to do a lot of painting and sorting out the issues left undone by the workmen. Over two months without a kitchen is tough - there are only so many cans of soup you can eat in a row. However, I did get the locking mechanism fitted to the smokebox door, and the smokeboxes fitted to the boilers before Christmas. Here are the component parts:



Although loosely based on the drawings I have changed quite a lot of the internals to give a proper, symmetric, locking mechanism and I have tried to scale the external parts from pictures of a full size engine. The square hole in one of the locking handles was filed by hand, just for the hell of using old school techniques. The parts fit together nicely and the locking is positive and firm:



Having shown this picture on another forum an error was pointed out. The outer, locking, handle should lock before 6 o'clock, not after, so vibration doesn't loosen it. A bit of quick work with a file sorted that out. I dithered about how to fit the smokebox to the boiler; make a fudge up and that's 1500 quids worth of boiler up the spout. Measurements were made, double and then triple checked. I didn't fancy driling holes through 3/8" steel with a portable drill - too easy to go skew whiff. I needed little incentive to splash out on a mag drill and tube mounting accessory:



The smokebox was aligned by setting an electronic angle meter to zero across the top of the hornplates and then getting the reading to zero again by moving the smokebox assembly with the meter sitting across the top of the chimney base. In order to get to the underside of the smokebox I had to remove a lot of parts at the back and sit the  boiler and smokebox vertical. Quite a lift on ones tod, glad they weren't any heavier. With the boilers vertical it wasn't easy to get the mag drill clamped in the right place while supporting its weight and getting the drill bit lined up with the existing hole. It took sweat, some tears and a lot of swear words. This shows the boilers with smokeboxes fully fitted, plus the front wheel axles:



Just for reference this is a picture taken in the same place, but with the new kitchen installed:



Notice a difference? No engines! The boilers are in the hall, the machined parts and work in progress in the sitting room and the castings in the study.

Andrew

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #166 on: March 29, 2019, 08:59:09 PM »
Prior to fitting the spokes to the remaining two rear wheels I need to fit the strakes around the rim. The strakes were machined, drilled and countersunk months ago from flat bar. The issue is how to bend them to fit the rim. They need to be curved along the short side, as well as following a helix on the long side. The "normal" ways of using bending rolls or twisting in a vice didn't work for me. In retrospect I could have rolled some flat sheet of the appropriate width and cut the strakes from that on the skew. Although I have been advised that it's a serious amount of work to cut and clean up all the strakes. Given that I l already had flat strakes how to form them? I've seen a Dutch website where they hot pressed the strakes. That seemed like a reasonable way to go, and better yet it's not something I've done before. I started making the press tools by cleaning up some hot rolled steel. That gave me the chance to use one of the slab mills I bought years ago via Fleabay. The slab mill is 4" x 4" running at 88rpm, DOC of 2.5mm, WOC of 32mm and feedrate of 160mm/minute, a bit under 0.1mm chip load, lots of swarf and steam:



It's a UK built mill (Adcock & Shipley) but a US made vice.  :ThumbsUp:

I've still got a lot to learn about driving the horizontal mill hard, and even more about clamping the work. I tried doubling the DOC but the cutter pulled the work out of the vice, and then carried on as if nowt had happened but with a much bigger DOC! The curves on the press tooling were done on the CNC mill using a 10mm ballnose cutter. Initial scallop depth was 0.05mm. Here are the press tools fitted on the flypress:



As expected trying a strake cold simply resulting in the strake springing back with no forming. So I tried one red hot (800░C). That worked well but there were two issues. I'd made the press tool radius a couple of inches smaller than the wheel rim in the hope that the outer edges of the strake would touch first and then the middle of the strake would be pulled down by the rivets. It turned out I needed to decrease the radius by a bit more. Second the scalloping on the press tool marked the work, despite some judicious filing after machining. So I tweaked the CAD model, redid the CAM and also set the scallop depth to 0.01mm. These parameters resulted in a nicely formed strake:



Although not obvious the strake is curved along the short edge, by about 10 thou, as well as having the pronounced helix. The strake is a fair fit on the wheel rim:



And also along the short edge:



The fit is pretty good considering that the wheel rim is less than perfect due to weld distortion.

I'm probably going to run with this, and acknowledge that each strake may require a bit of hand tweaking. I've done some searches, but haven't found anything to indicate how full size strakes were formed. Possibly something similar but with a blacksmith and anvil?

Andrew

Offline Dave Otto

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #167 on: March 30, 2019, 12:01:44 AM »
Nice work Andrew and the new kitchen looks great!

Dave

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #168 on: March 30, 2019, 10:51:43 AM »
Thanks Dave, I try to do nice work, even if I don't always suceed.

I'm pleased with the new kitchen. Even I would admit that the old one was getting very grubby and starting to fall apart. The worst aspect was tiled worktops which, along with the slightly porous finish on the cupboards, was impossible to keep clean. I told the kitchen people that the number one, two and three priorities were easy clean!

Andrew

Offline Kim

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #169 on: March 30, 2019, 04:57:44 PM »
Wow! Those took up most of your kitchen!  Are you going to move them back into the kitchen now that it's finished?
Kim

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #170 on: March 30, 2019, 08:31:02 PM »
Are you going to move them back into the kitchen now that it's finished?

I'm afraid not, I've been banned from putting them in the kitchen. And if you'd met my mum you'd know it's not worth arguing if you want a quiet life.

Andrew

Offline Admiral_dk

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #171 on: March 30, 2019, 08:37:00 PM »
Nice work all the way round Andrew  :cheers:

Online Jo

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #172 on: March 31, 2019, 09:03:36 AM »
Are you going to move them back into the kitchen now that it's finished?

I'm afraid not, I've been banned from putting them in the kitchen. And if you'd met my mum you'd know it's not worth arguing if you want a quiet life.

Andrew

:lolb:

You are not the worst I know of: ilvaporista's brother Dave had his Bridgeport milling machine in his kitchen  :naughty: and the chips would get everywhere  :LittleDevil: In the end his sister-in-law refused to visit and finally his Mum made him move it out :-\

Jo
Usus est optimum magister

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #173 on: March 31, 2019, 10:33:36 AM »
Nice work all the way round Andrew  :cheers:

Thank you.

In the round is my next issue. When I fit the strakes I need to predrill one hole per strake. I see two options; one, step round the circumference with dividers, making adjustments until I get back to where I started, as I did when fitting the spokes. Or two, mount the rim on the rotary table and drill each hole using the rotary table to index. I'm leaning towards the latter, as there are 36 strakes and the rim isn't perfectly round, so I suspect using dividers will end with me chasing my own tail.

Andrew

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #174 on: March 31, 2019, 10:38:53 AM »
had his Bridgeport milling machine in his kitchen

How on earth did he get it in there without a lot of dismantling/

It wouldn't suit me though. For a start I'd need to run a 3-phase extension lead from the garage. And a lot of the tooling is shared with my my other two mills, so I'd be traipsing back and forth like a yo-yo. Not only that I can just lift the dividing head from the shelf to the machine table. No way I'd be carrying it all the way from the garage to the kitchen; or if I did it would be followed by a trip to A&E.

Andrew

Online Jo

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #175 on: March 31, 2019, 11:22:07 AM »
How on earth did he get it in there without a lot of dismantling/

You only need to rotate the head down and slide off the table  :-X

Quote

It wouldn't suit me though. For a start I'd need to run a 3-phase extension lead from the garage. And a lot of the tooling is shared with my my other two mills, so I'd be traipsing back and forth like a yo-yo. Not only that I can just lift the dividing head from the shelf to the machine table. No way I'd be carrying it all the way from the garage to the kitchen; or if I did it would be followed by a trip to A&E.

Sounds like you have thought about this before  :lolb: I would recommend one of my rollerskates for moving around and lifting tooling on and off the machine beds  :ThumbsUp:

Jo
Usus est optimum magister