Author Topic: Burrell Single Crank Compound Traction Engines - 4" Scale  (Read 43272 times)

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #180 on: May 10, 2019, 11:52:58 AM »
That's IS big!

Of course I've been aware that it's definitely not a mantlepiece model. But having assembled it my jaw hit the floor; it brings it home that it really is BIG! Gawd knows where I'm going to put the second engine.

Andrew

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #181 on: May 10, 2019, 11:55:51 AM »
you may want to consider flushing up the rivit heads before you roll the other engine onto your laminate floor

Not too worried about that. The floor is el cheapo B&Q plastic wood. It already has quite a few gouges and lumps knocked out of it as a consequence of heavy engineering and assorted builders traipsing through the hall.

Andrew

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #182 on: June 29, 2019, 12:19:54 PM »
Now that I've chucked in my job and joined the band of the great unwashed, aka the unemployed, I'm hoping to have more time for flying, gardening and workshop.  ;D

The strakes have now all been riveted, by hand in small batches in deference to the neighbours, and the hammer marks, :embarassed:, cleaned up with an angle grinder and power drill with a coarse flapwheel:



The zig-zag pattern of larger holes are for anchors (aka spuds) and frost spikes. The anchors are made from metric angle, 30x30x5. As expected a cold bending test resulted in the metal cracking. So the ends were bent hot using a home made fixture to form the design radius and an oxy-acetylene cutting nozzle to supply heat:



Just remember not to activate the cutting oxygen handle! The anchors are deliberately left a bit rough in view of the fact that in full size they would have been forged by the blacksmith:



Here's an anchor in place; I still need to drill the fixing holes:



The distance from the wheel edge to the fixing holes varies around the wheel rim. In full size this was accomodated by drilling an oversize hole in the anchor. I'm going to copy that.  :ThumbsUp:  I've also churned out the anchor bolts and frost spikes. All done on the repetition lathe except for the tapered end of the frost spikes done on the centre lathe using the top slide and one pass. The rounded tip was formed with a file:



As well as drilling the holes in the anchors I also need to make rectangular slots in the bolts and spikes for the retaining keys. I'm proposing to drill/mill the slots on the CNC mill and use a keyway broach to square up the ends.

Andrew

Online Jo

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #183 on: June 29, 2019, 12:25:24 PM »
That photo makes the wheels look a lot smaller than they really are  :thinking:

Now that I've chucked in my job and joined the band of the great unwashed, aka the unemployed, I'm hoping to have more time for flying, gardening and workshop.  ;D

So are you officially now retired  Andrew or still considering looking for paid work  ::) ?

Jo
Usus est optimum magister

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #184 on: June 29, 2019, 10:06:49 PM »
So are you officially now retired.........

Sadly not, but as one of the other engineers said the company was a bit broken at senior level. Actually that's not true, it's a lot broken! So it was time to leave. I wasn't the first to go and I haven't been the last.

Immediately after I resigned the company asked if I'd be willing to go back as a subbie in the future. Fine by me, go in, do the work, get paid and no need to get involved in company politics. I've got a couple of weeks self-employment to do now. There's a good chance we can sell another couple of small jobs over the next few months as well. And a few other projects and ideas are simmering in the background. We'll see what happens over the next few months. If the worst comes to the worst I can always look for another job. In  the meantime it's gliding, gardening and workshop, but not necessarily in that order.

Andrew

Offline scc

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #185 on: June 30, 2019, 07:27:57 PM »
Enjoy your "Freedom"" while you can Andrew :cheers:              Engine is coming along nicely.        Terry

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #186 on: July 01, 2019, 11:45:19 AM »
I intend to, but already one week in and I'm overbooked; too many things I want/need to do and not enough time.  :'(

Andrew

Offline scc

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #187 on: July 01, 2019, 09:55:28 PM »
I intend to, but already one week in and I'm overbooked; too many things I want/need to do and not enough time.  :'(

Andrew

Sounds just like retirement  :Lol:           Terry

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #188 on: July 13, 2019, 07:27:54 PM »
The holes in the anchors have now been drilled to allow them to fit to the wheels. I used calipers to measure the distance, in millimetres, from the wheel rim to one side of the holes drilled in the strakes. I then took the average of the smallest and largest distance. To that I added the radius of the hole in the strakes and one millimetre for good measure, and to account for the fact that internal radii in the ends of the anchors are finite. A key part was noticing that on the Burrell wheel drawing in the book by Gilbert the shank of the anchor bolt is given as 1-1/8" whereas the hole in the anchor is 1-1/4". Scaling down that gives 3/8" for the hole in the strake and 27/64" for the hole in the anchor. The anchors are quite a nice fit. This picture shows an anchor in position:



The anchors can pivot, but given that the reaction to the wheel torque is into the picture, and the anchor pivot point is not symmetric the result will be to force the anchor into the fully back position.

The anchor bolts and frost spikes are also finished with rectangular slots cut for keys that will hold them in place:



There are 18 anchor bolts and 36 frost spikes, so clearly a job for the CNC mill. It's tempting to say I used a square drill. But they're unobtainium, and the normal method of drilling a square hole isn't really suited to a slot that is only 1/8" wide. So instead I drilled three 3mm holes with a carbide drill (time 10 seconds) and used a 3mm carbide end mill to open out the slot (time 2 minutes) albeit with round ends:



To form the square ends I used a 1/8" keyway broach. The broach was thinned on the surface grinder, half a thou at a time, until it was a nice fit in the pre-existing slot. An arbor press was used to push the broach using a 1/8" drill as a spacer and shims as required to get a nice square end. I had some problems keeping the broach vertical as, at best, only two teeth are in contact at a time. The work is resting on two lengths of nominally 1/8" keyway steel held in place with double sided tape:



It's quite possible that the original items were made in the blacksmith shop, so my parts are a least a bit better than that!

Nest job is to design and make the curved keys that will keep the bolts and spikes in place.

Andrew

Offline crueby

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #189 on: July 13, 2019, 07:41:18 PM »
Are the anchors like a paddle on the rim of the wheel, for traction in mud?

Offline jadge

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Re: Burrell Single Crank Compound Traction Engines - 4" Scale
« Reply #190 on: July 13, 2019, 08:38:32 PM »
Are the anchors like a paddle on the rim of the wheel, for traction in mud?

Correct, also known as spuds. Some manufacturers used T-section but for some reason, probably cost, Burrell used angle.

Andrew