Brassmasters Rebuilt Royal Scot, 46109

Dave Holt
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Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Sat Jul 18, 2020 9:37 am

Mmmm. Wonder what this might be in aid of?
Crank_001.JPG
Crank_001.JPG (154.9 KiB) Viewed 5330 times

Just loosely assembled at the moment.
Dave.
Last edited by Dave Holt on Fri Sep 11, 2020 11:04 am, edited 2 times in total.

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steve howe
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Re: Future Project?

Postby steve howe » Sat Jul 18, 2020 9:53 am

A single cylinder 0-1-0? :)

triumph3
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Re: Future Project?

Postby triumph3 » Sat Jul 18, 2020 12:28 pm

Dave, I know you have fitted an inside crank to your West Country many years ago, but the only loco I can think of on your “to finish” list is the L&Y 0-6-0 goods.

Are you going to silver solder this crank?

David

John Palmer
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Re: Future Project?

Postby John Palmer » Sat Jul 18, 2020 12:33 pm

Crank axle for a Gresley 3-cylinder engine?

Interference fits of shafts in the crank webs? And how are you planning to set up the big end bearing?

Dave Holt
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Re: Future Project?

Postby Dave Holt » Sat Jul 18, 2020 1:24 pm

All good suggestions, but actually it's for a Brassmasters Rebuilt Royal Scot.
Still at the early planning stages, but it's already apparent I'm going to have to make some significant modifications to the kit to accommodate inside valve gear. A major issue is that the kit design for the outside valve gear support frame has a stretcher going right across the frames at the front which does not exist on the prototype and which passes right through where the inside expansion link is located. I've had some thoughts about how to get round this but I'll have to see how practical it all is.
I'm intending that the crank parts are silver soldered together and possibly pinned as well. The con rod big end bearings will be split, with the rear half held in place by a strap (as per full size) which will be attached to the rod by a 14 BA screw inserted from the bottom. The eccentric and some parts of the inside valve gear will be made using the Brassmasters Fowler 4F valve gear etch together with suitable bits I can create from spare etches left over from various previous locos.
Probably all a mad idea anyway.
Dave.

John Palmer
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Re: Future Project?

Postby John Palmer » Sat Jul 18, 2020 1:53 pm

For some reason I'd got it into my head that the inside cylinder on a Scot was offset from the centre line but the GA reproduced in Nock's monograph shows that I was wrong.

An interesting exercise - look forward to hearing how you get on!

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Horsetan
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Re: Future Project?

Postby Horsetan » Sat Jul 18, 2020 8:51 pm

Dave Holt wrote:....all a mad idea anyway..


I like mad.
That would be an ecumenical matter.

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45609
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Re: Future Project?

Postby 45609 » Sat Jul 18, 2020 9:31 pm

Interesting Dave. How have you made the two cranks and what are they made from?

Morgan

Dave Holt
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Re: Future Project?

Postby Dave Holt » Sun Jul 19, 2020 11:07 pm

Morgan,
The webs were made by a colleague from the P&O group who has some small machine tools. The material is 1/16" thick ground mild steel. The axle and pin holes were drilled and reamed in a vertical mill, which he had intended to mill the web profile. However, it turned out his machine wasn't able to do the job and so he hand cut and filed the shape.
Dave.

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45609
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Re: Future Project?

Postby 45609 » Mon Jul 20, 2020 8:30 am

Thanks for the reply Dave. I thought it looked like steel. It will certainly be very robust.

cheers...Morgan

Dave Holt
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Re: Future Project?

Postby Dave Holt » Mon Aug 03, 2020 1:12 pm

Still at the plotting and scheming stage. As part of this process, I've marked out some key reference points for the inside valve gear on the main frames. A friend turned some centre locating buttons, which a a good push fit into the etched axle bush holes in the frames, to enable the axle centres to be accurately located. The inside of the RH frame has been marked with the inside cylinder centre line (at 1 in 50 slope), front and back faces of the cylinder and the centres of the expansion link pivot and the inside reverser shaft. The two latter have been drilled with a 0.5 mm pilot hole.
Marked out frame
Scot_001.JPG

and a rather cruel close-up
Scot_002.JPG

The double lines for the expansion link are due to a better dimension from the axle centre was derived after the initial position had been scribed. This had be based on scaling from published drawings - not the ideal process, but often necessary. The centre for the reverser shaft unfortunately coincided with edge of a half etched recess on the opposite side of the frame, which caused the centre of the hole to drift off slightly. I can live with this as the mechanism isn't functional and the error small.
Dave.

Dave Holt
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Re: Future Project?

Postby Dave Holt » Mon Aug 10, 2020 1:16 pm

The first component for the inside valve gear has been produced. But what is it?
Scot_003.JPG

Well, it's the support bracket which carries the inside gear reverser wey-shaft and the lifting arms. Here it is roughly (very) placed against the main frames. It will be attached to a narrow frame space which locates in the short vertical slot.
Scot_004.JPG

The inside motion plate has been modified to drop it lower, such that the opening for the slide bar ends and con-rod coincides with the centre line of the piston rod. The main opening still needs to be modified to support the rear end of the inside slide bars.
Scot_005.JPG

Dave.

Paul Hutfield
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Re: Future Project?

Postby Paul Hutfield » Tue Aug 11, 2020 6:41 pm

Absolutely nuts Dave, great stuff!! :D

Dave Holt
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Re: Future Project?

Postby Dave Holt » Fri Aug 14, 2020 11:56 pm

The inside crosshead, complete with the drop link has now been made.
It is based on a Brassmasters brass casting from the Fowler 4F kit, modified to provide the drop link necessary of the Scot inside motion. The resultant item is not strictly a scale replica of the actual part, but is an approximation which will fit the etched slide bars (from the same kit) and provides an attachment for the anchor link that is in the correct relationship with the gudgeon pin hole in the crosshead. The drop link is a loose item, attached to the modified crosshead by a 14 BA screw and a locating dowel, the idea being that the drop link can be attached to the anchor link, off the job, and than attached to the crosshead on final assembly within the frames.
Here are the component parts, with the cast crosshead modified by soldering a 1.5 mm thick spacer to the lower face and the cast piston rod replaced by an over-length piece of 1 mm N/S rod, the drop link made from 0.5 mm thick brass sheet and the 14 BA fixing screw.
Scot_006.JPG

and here is the complete assembly.
Scot_007.JPG

Scot_008.JPG
Scot_008.JPG (176.67 KiB) Viewed 4029 times

Dave.

essdee
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Re: Future Project?

Postby essdee » Sat Aug 15, 2020 10:29 am

Sheer Class, Dave...

Exquisite!

Cheers,

Steve

Dave Holt
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Re: Future Project?

Postby Dave Holt » Mon Aug 17, 2020 8:13 pm

Some progress over the past few days since the drop in temperature has made the modelling room more habitable.
The support bracket for the expansion link has been made and is seen here loosely placed in position on the motion bracket. It's dimensionally right but only representative in detail.
Scot_009.JPG

The inside cylinder has also been fabricated, complete with the unusually long rear valve chest. Where possible, I'm using commercially available bit and spare parts, so the valve spindle guides and cylinder covers are from the Comet standard LMS/BR etch. Not strictly prototypical and some spare, unwanted holes, but it saves scratch building. The front and back cylinder relief valves are just the mounting tube at present and there's the drain cocks to do.
Here is the cylinder assembly.
Scot_010.JPG

Scot_011.JPG

And here, loosely placed in position on the RH mainframe.
Scot_012.JPG

Slide bars and then valve gear rods next, I suppose.
Dave.

Dave Holt
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Re: Future Project?

Postby Dave Holt » Wed Aug 26, 2020 10:36 am

A start has been made on the inside valve gear with the production of some of the rods and assembly of the front portion of the gear. The anchor link is from a spare Brassmasters Black 5 etch and the combination lever and radius rod are from the same source, but modified by cutting the laminations to produce shorter items.
Here, the front part of the gear is temporarily assembled to the cylinder and cross head.
Scot_013.JPG

Scot_014.JPG

Scot_015.JPG

Scot_016.JPG

Some of the other components - shortened radius rod, slide bars from 1 mm sq brass rod, front and rear slide bar mounting plates (modified from a Brassmasters Fowler 4F etch) and the motion plate, now modified to allow the cross head/con rod assembly to pass through and with a bottom flange added. On assembly, the rear slide bar mounting will be soldered to the front face of the motion plate to locate the back end of the slide bars.
Scot_017.JPG

Dave.

Dave Holt
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Re: Future Project?

Postby Dave Holt » Thu Aug 27, 2020 11:04 pm

Some progress and a bit of a set-back, today.
The eccentric rod has been made by modifying the rods from the Brassmasters Fowler 4F valve gear etch. The length has been reduced and a pivoted arrangement provided so the rod can fit over the eccentric sheaves allowing the crank axle to be fitted and removed with the valve gear in place.
Hinged open:
Scot_018.JPG

Closed, using a brass wire staple:
Scot_019.JPG

The set back is losing one of the slide bar mounting plates - the rectangular one seen in the bottom right in the last photo in the previous post. Extensive searches of the work bench and floor have failed to locate the errant part. It's not something I think I could scratch make, with the four small (1.0 x 0.8 mm) rectangular holes. Fortunately, Brassmasters are able to supply a replacement part etch; so a big thank you to them.
Con rod next?
Dave.

Dave Holt
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Re: Future Project?

Postby Dave Holt » Fri Aug 28, 2020 1:26 pm

The eccentric rod, expansion link and radius rod have now been assembled. Nothing accidentally soldered solid for a change!
Scot_020.JPG

Con rod next, perhaps?
Dave.

Dave Holt
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Re: Future Project?

Postby Dave Holt » Mon Aug 31, 2020 8:56 pm

Bullet bitten and con rod created.
It went from this:
Scot_021.JPG

Two layers of the Brassmasters Fowler 4F rods (their model uses large eccentrics rather than a crank axle to provide some cross head motion), to this:
Scot_022.JPG

Component parts laid out on the jig used to assemble the rod with the correct centres of crank pin and gudgeon pin.
Rod with big end assembled and later, after some cosmetic improvements, fixed to the cross head, front part of valve gear attached and all placed in the cylinder.
Scot_023.JPG

Scot_024.JPG

Scot_025.JPG

Dave.

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Horsetan
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Re: Future Project?

Postby Horsetan » Mon Aug 31, 2020 10:15 pm

That looks excellent. Inside big-end method there for other classes, like the Bradwell J27
That would be an ecumenical matter.

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Fri Sep 11, 2020 11:22 am

Although this is still not my intended next job, some further progress has been made by assembling the frames. You'll notice I've also changed the title of this thread to reflect its new status.
A few modifications, especially to the keeper plate/springs unit, to accommodate the inside crank and eccentric and the MJT gearbox for the motor, have been required. The reversing shaft and expansion link brackets have been fixed in place. The motion plate is just temporarily sprung into place. It can't be fixed in the frames till after the outside motion bracket has been made up and modified to clear the expansion links.
Scot_026.JPG

Scot_027.JPG

Scot_028.JPG

Scot_029.JPG

Next job is to get the inside cylinder to fit nicely between the frames. I made it to an estimated width, based on measuring loose frame spacers. However, the assembled frames are slightly closer together, so about 0.2 mm per side has to come off the cylinder.
Dave.

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Sat Sep 12, 2020 4:38 pm

The inside cylinder has been trimmed to fit between the frames, the slide bars fixed to the cylinder and the whole lot trial fitted in the frames. Nothing soldered, yet. A simple jig has been made to help align the cylinder/slide bar assembly with the centre line of the front axle and is seen in situ.
Scot_030.JPG

Scot_031.JPG

Dave.

JFS
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby JFS » Sat Sep 12, 2020 7:19 pm

Very much enjoying this one Dave and looking forward to each installment!

Good luck and keep up the great work!

Best Wishes,
Howard

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Mon Sep 14, 2020 10:06 pm

Thanks Howard. Glad you're enjoying the ride.
Well, I've committed now; the inside cylinder has been fixed into the frames. The motion plate is still loose, but the layer that located the rear ends of the slide bars has been attached to the plate and the central hole opened up to allow the cross head to pass through.
Prior to fixing, a representation of the cylinder drain cocks and valve chest drain was added to the cylinder. The details of the arrangement are a bit of conjecture on my part although the position and stand-out of the cocks and shape of the discharge pipes are shown on the pipe and rod diagram. It's certainly not the standard arrangement, as used for the outside cylinders.
Three general shots of the frames:
Scot_032.JPG

Scot_034.JPG

Scot_035.JPG

And a couple, side on, of the drain cock arrangements:
Scot_033.JPG

Scot_036.JPG

Since the photos were taken, I also fitted the small cover plates near the front and the firebox/ash pan plates behind the large openings between the centre and rear drivers.
Lower ash pan sides next.
Dave.


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