Author Topic: Burrell Single Crank Compound Traction Engines - 4" Scale  (Read 46335 times)

Offline Jo

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #195 on: July 28, 2019, 09:25:02 PM »
. even if I did nearly do myself a mischief lifting the dividing head onto the milling machine table to mill the hexagon and cut the slots:

A nice little hydraulic roller skate will prevent these little aches and pains  ::)

Jo
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Offline deltatango

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #196 on: July 29, 2019, 12:44:34 PM »
It's good to see the progress. Those wheels are impressive!
I can't imagine the local Council being very impressed with the effect of the ice spikes on their bitumen...

Will you be showing any of the bits at Forncett this year?

David

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #197 on: August 04, 2019, 08:07:13 AM »
Will you be showing any of the bits at Forncett this year?

Yes, that's the plan. I've sent my application form off, although I haven't had confirmation. That seems normal these days, so I intend to just turn up on the day. I hope to exhibit a completed wheel with strakes, plus the anchors, frost spikes and ancillaries. Also the crossheads and slidebars and possibly a few old favourites.

Andrew

PS: Given the poor state of the roads around here I doubt the council would notice any effect from the frost spikes!

Offline tangler

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #198 on: August 04, 2019, 04:41:28 PM »
Will you be showing any of the bits at Forncett this year?

Yes, that's the plan.

Good, I shall look forward to that.

Rod

Offline deltatango

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #199 on: August 04, 2019, 11:00:33 PM »
I'm looking forward to seeing them!
DT

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #200 on: August 05, 2019, 11:30:37 AM »
Oeeeer, better get my finger out and ensure I've got something new to show!

Andrew

Offline deltatango

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #201 on: August 05, 2019, 12:23:15 PM »
No pressure of course... :)
DT

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #202 on: August 09, 2019, 09:55:49 PM »
I've been assembling a wheel today; it's not going to plan and is painfully slow. My excuse is that I haven't been well recently. At least I remembered to drill the driving pin holes in these wheel hubs before assembly. It's going to blow a hoolie tomorrow so I hope to get one wheel completely spoked up. Just under two months to go!

Andrew

Offline cnr6400

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #203 on: August 09, 2019, 10:47:03 PM »
Blow a hoolie? no idea what that is.  :shrug:

 Good luck with the wheel.

Offline Jo

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #204 on: August 10, 2019, 06:27:54 AM »
Blow a hoolie? no idea what that is.  :shrug:

Tis named after the hooley which is a wild and noisy Irish dance... So blowing a hooley (or hoolie) is a wild and noisy wind.



Making traction engine wheels is riveting stuff  :lolb:

Jo
Enjoyment is more important than achievement.

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #205 on: September 08, 2019, 11:00:08 AM »
I'm pleased to say that I now have enough new parts to exhibit at Forncett. With a bit of luck I'll get a few more bells and whistles done in the next few weeks. Assuming of course that the country hasn't descended into all out civil war by then.

Andrew

Offline deltatango

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #206 on: September 08, 2019, 11:23:39 PM »
Great! I'm looking forward to seeing them. As to the civil war I think I maybe biting my tongue a lot while in England.
David

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #207 on: November 05, 2019, 11:59:20 AM »
I haven't posted for a while, but haven't been totally idle in the meantime. This is the first of a few short catch up posts showing progress on the engines. I apologise if anything is repeated; it's difficult to remember what has been posted and what hasn't. I've finished one of the rear wheels with strakes:



Before building the wheel I drilled a hole in the hub for the drive pin. The holes were carefully aligned relative to the axle bore on the inside of the hub, but I left it to lady luck as to where they came out on the outside. Fortunately they're not a million miles out:



These are the drive pins:



The pins are made in two parts screwed together, 3/8" BSF if I recall correctly. The external threads were screwcut to ensure they were true to the lathe axis. The pins are simply a bar with a tapped hole; due to a material fumble I made them from EN16T. Which is probably a bit OTT. The fancy ends were made using the hydraulic copy unit on the lathe, and are based on pictures of fullsize engines rather than on the drawings. I had a wobbly using the copy unit when the toolpost clamp broke and jammed said toolpost. It entailed dismantling most of the copy unit. That in itself required several tea breaks in preference to losing my cool and hitting something with a bigger hammer. At least it gave me the chance to clean up and oil inside the unit. The clamp is a daft design with the join between the clamp proper and the clamping screw in bending. Not surprising it broke. It's on the roundtoit list to make a new one, may be from higher strength steel, probably EN24T.

Andrew

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #208 on: November 05, 2019, 02:08:35 PM »
The crossheads are mostly careful milling and drilling. I've added a couple of features found on the fullsize engines. The hole for the little end bolt has a slot on one side. This is to fit a pin in the little end bolt, thus preventing the bolt from rotating under the influence of the connecting rod. I've also added some rectangular blind recesses. On the fullsize engines these were presumably cast in, and would have been to reduce the amount of metal needed. And consequently reducing the reciprocating mass. The slots were drilled and milled on the CNC mill, finishing with a 3mm cutter re-machining the corners. That's a lot of endmill sticky outy, about 20mm:



The bendy straw is an important accessory, used to blow the cast iron swarf out of the blind slot. Sadly bendy straws no longer seem to be available. The corners of the slots were finished square with a 1/4" toolbit in the slotting head on the Bridgeport:



While these slots are non-functional they are a prominent feature on the fullsize engines, so I included them. Here are the almost finished crossheads and little end bolts:



The slidebars and oilers have also been finished:



The oilers are intended to be proper wick feed, and the design and locations are copied from fullsize. All external (32tpi) threads were screwcut on the lathe to ensure perpendicularity. I had a few failures screwcutting the 5/32" 32tpi threads on the end of the copper tubing. Copper tube don't half bend easy! Note the cut away bottom left on the slidebar. This is to help clear the piston rod gland. Here are the pistons, crosshead, slidebars and connecting rod, plus shop made studs, bolts and nuts:



The diagonal measurement across the piston rods is seven tenths of a thou small compared to the CAD model, but the piston rod material is half a thou undersize, so not too bad. The height of the pistons from the far end of the crosshead is 5 thou over compared to the CAD. That's not a bad starting place and can be easily compensated for during fitting of the motion work to the boiler. Having made the oilers for the slidebars I threw away the oilers I made ages ago for the big end bearings and copied the fullsize oiler. The small bolt and nut is apparently a crude form of regulator for the oil.

The drawings call for tapered pins for fitting the piston rods to the crosshead. However, I will be copying fullsize practice and using tapered cotters.

Andrew

Offline Jasonb

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #209 on: November 05, 2019, 02:42:56 PM »
Have you been locked out of the workshop today ;)

Good to see some updates and at least a couple of assemblies that I have not seen before, hopefully see them in the flesh in a few weeks?

J