Brassmasters Rebuilt Royal Scot, 46109

Julian Roberts
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Julian Roberts » Wed Nov 18, 2020 4:26 pm

Dave Holt wrote:I'm shortly going to have to decide whether to try and move the centre splashers outwards slightly to allow for some side play in that axle.
Dave.


Dave I expect you saw this from DaveB on the Frame Spacing thread? Perhaps you can get away without any sideplay on the middle wheel? I must say I was surprised to read it! - but I'm sure it makes sense considering the running clearance in P4. Just posting this in case it saves work that might be avoided?


davebradwell wrote: Have been using 16.2 over for years with axlebox flanges outside this. Most wheels need washers and everything goes round 1 metre curves - you need very little sideplay even at this radius because there is already clearance in the track, more so when the gauge is widened.

DaveB


Inspirational stuff, as always :thumb

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Will L
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Will L » Wed Nov 18, 2020 6:29 pm

I agree Dave is making a really nice job of this, I am a fan of all those extra bits of plumbing as some up and coming posts of my own will show.

In terms of how much lateral clearance you need over the centre axle Dave, I think I can help a bit. If you read through the first page of my Track Gauge Widening, All You’ll Ever Need to Know thread, you will find that, as a by-product of the original discussion, I generated a spread sheet that will tell you all you need to know to get a locos with a variety of different wheelbases round any given curve. This separates out the effects of any gauge widening, the extra clearance you get courtesy of the P4 standards (as opposed to the S4 exact scale ones) and the impact of a bit of side play on the middle axle. Near the bottom of the page, the Spread sheet is available to download if you fancy having a play with it.

Dave Holt wrote:....The instructions warn to be careful not to distort local to the cab spectacle windows when folding the sides. This seems virtually impossible due to the lack of material to hold. So, despite using a hold-and-fold tool, the front plate did distort and had to be pressed back to shape afterwards...


Never had a hold-and-fold as I learned how to fold etched brass before they existed, and I remain happier with my own methods which involve flat surfaces a steel ruler and a craft knife. You do have to be careful to do it right to avoid the sort of distortion you describe. This means that the bit with the hole close to the bend is held firmly against the flat surface with the ruler and the bit away from the hole is bent up. I presume something similar is possible with the hold and fold. However, it is made much easier if you deepen the fold line with a triangular needle file, until a witness line shows through. You get a sharper corner as well, but only one go at making the bend as it will snap if you try to bend it again. This tip I learned from Danny Pinnock for doing the long folds on his D&S coach kits. I do wonder what it does to DaveBs bend allowances though.

Bill Newstead
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Joined: Mon May 30, 2016 10:30 pm

Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Bill Newstead » Thu Nov 19, 2020 11:17 am

For small parts which don't warrant getting the bending bars out a steel rule can be clamped in the hold and fold. This ensures the rule will not move and keeps both hands free for the bending. I'm another who picked up the use of a triangular file from Dan Pinnock's instructions. This works very well but I did worry about what it was doing to the accuracy of the bend line and these days use the back of a no. 10 scalpel blade.

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Thu Nov 19, 2020 9:28 pm

Thanks for the helpful suggestions and comments.
Regarding the required side play in the axles and splasher clearances, I have been following the discussions about frame spacing and had read Dave Bradwell's thoughts, but thanks Julian.
Will, thanks for the reference to your gauge widening spread sheet. I tried it with 0.5 mm side play on the centre axle and it appeared to require minimal gauge widening for a 1200 mm radius - about the minimum I would hope the loco will cope with. I've probably complicated the issue by also allowing some side play at the rear axle.
Anyway, I decided to check for short circuits between wheels and splashers with the wheels pushed over as far as the side play allows and was pleasantly surprised to find none, even on the centre axle. So, I've decided not to move the centre splashers out but will apply a thin smear of superglue to the inside faces to act as insulation just in case of a momentary kiss if the axle twists in the cross plane due to track irregularities.
On occasions, I have resorted to filing out bend lines and even used an Olfa cutter to widen/deepen fold lines, but only on scratch made items or where I thought the width of the etched line relative to the material thickness was inadequate. I've never done etching art work, but I assume the the material is considered to bend on the neutral axis of the remaining metal below the half etched bend line? If so, altering the bend line will affect the dimensions of the finished piece.
Dave.

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Thu Nov 19, 2020 11:21 pm

Looking a bit more like a re-built Royal Scot.
Scot_085.JPG

Dave.

davebradwell
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby davebradwell » Fri Nov 20, 2020 10:14 am

I started this earlier but it seems to answer your comment Dave. Assuming that here we are referring to the usual model fold along an etched line but if you change the geometry of a bend in any way, as in making it sharper, then it will not come out as the designer intended - or rather thought he intended. He may, of course, have made an allowance for the slightly different result that comes from running a file or whatever down the bend and given instructions to do so. By the time you're building the model the main aim is to get a tidy result and you're reliant on the designer to have worked it all out correctly. If it's any consolation the difference here isn't great - each bend probably moves by up to 0.1mm in each direction depending how much vigour you apply.

DaveB

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Mon Nov 23, 2020 2:22 pm

The main structure of the cab is now complete, ready to fit to the footplate once the splasher tops are fitted.
The outer wrapper, various rain strips, roof ventilator and side beading have been added to the inner frame and the temporary stiffening plate removed from inside.
Scot_086.JPG

Scot_087.JPG

Dave.

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barrowroad
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby barrowroad » Mon Nov 23, 2020 8:16 pm

Coming along nicely Dave - the Scot looks great.

Robin

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Mon Nov 23, 2020 9:14 pm

Thanks, Robin.
How's progress with Barrow Road?
Dave.

Dave Holt
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Re: Brassmasters Rebuilt Royal Scot, 46109

Postby Dave Holt » Tue Nov 24, 2020 11:24 am

Whilst pondering the need to move the centre splashers outwards to avoid the risk of shorting, I indicated that I would try the chassis out on the tightest curves on my layout. I've finally got round to doing this before fitting the splasher tops, thus enabling a visual check from above that the centre wheels do not touch inside the splashers.
Even on the tightest curve - leading to the mill coal siding, it was clear that no contact was being made. Phew!
Here the chassis is seen on the cross-over into the loop/yard and also on the very sharply curved (about 900 mm radius, I think) mill siding approach, which a Scot would never be required to negotiate in practice.
Scot_088.JPG

Scot_089.JPG

Scot_090.JPG

The layout boards have been stored indoors for some time, but I was surprised how badly rusted some lengths of the steel rail had become whilst other sections had remained clean and shiny looking. Odd that it hadn't all reacted the same.
Dave.


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