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No 88 - the Horse Box


kitpw

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HB88web.jpg.89663a435613275b7566bae90fa0d15d.jpgL1030394web.jpg.6b3bd64420ebb477047aa3b33ce0e5f0.jpg

 

The famous GWR horsebox No 88 - no layout complete without one.  This is the drawing I made to work from and to program the Silhouette to cut out the panelling and openings.  I illustrated the cut out and assembled sides some while ago (2 years+) but stoppages on other aspects of Swan Hill and an awareness that a few things are getting a long way behind has seen an effort to try and tie up loose ends.  No 88 is one of them. 

 

This post deals with the body - the underframe will follow but the post ends with a question about how the clasp brakes with outside tie work - they're shown in the drawing (on the right) with my current best guess. More of that later.

 

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The basic material is Bristol board treated with shellac before the Silhouette cuts out the mouldings on one layer and the apertures on another layer.  There is an intermediate layer so that the rule of uneven numbers of laminations is respected (balancing layers/veneers) and to allow the glazing to fit into pockets.  The louvres are made with a steel comb filed up from an old cabinet scraper (last used for the scratchbuilt Siphon G pictured a few weeks ago):  the hinges are shellac'd paper with embossed bolts and bits of regular telecom single strand cable (orange and blue as it came to hand).  The wire is staightened by rolling on a flat surface.  The body ends were made in the same way - three layers with details added to the grooms' compartment end: steps are there but handrais and lamp irons will follow.

 

web081808.jpg.d2611d662584ed85bf806b1ded4f9e34.jpgThe roof is cold moulded on a former, in this case, made up of three 6mm mdf layers.  The roof profile (underside) is transferred to both ends and with a small plane, gradually brought to the required shape:  once the ends are pretty close to profile, the middle is completed using a  straightedge end to end.  The roof material is two layers of (approx) 0.4mm ply (aero-modeller's stuff) with a core of paper (overall, 3 layers for stability - balancing veneers).  The overall finished thickness is a touch under 1mm. I cut out the top sheet to the finished size required and mark it with longitudinal centre line (CL).  The paper core is a few mm larger all round, again with centre line.  The inner lamination is a few mm bigger again with centre line.  Working fairly quickly (hot weather requires greater speed) I coat the underside of the top sheet with pva, brushed to get the surface properly wetted.  That's plonked down on the paper layer and aligned to the CL.  The upper surface of the inner sheet is then coated with pva and the first two layers added - then rather quickly, the assembled sheets are stretched onto the former, using the centre line to get the shape right and the top former can be fitted and clamped on. 

 

web092608.jpg.728b57d1cd9e25a57d1f834c183c9bc5.jpgThere's a press on top which is designed to hold the middle down to the very flat arc centre section in the correct alignment.  The outriggers are shaped to hold the outer edges of the roof onto the tighter arc each side.

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web092721.jpg.1fe02a3e1fb63c0e3d1b306de2d89f9c.jpgWhen dry (allow 24hrs), the roof can be released from the mould and, curiously, I haven't found that there is any spring or recoil in the shape. 

I've pictured (left) a test piece of a shell roof which I made at least 20 years ago by the same method - it hasn't moved at all in that time and it's a much more complex shape.

 

More or less complete body + roof, now with its first couple of coats of paint.  The cold moulded roof sits down nicely on the end profile.

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The sketch below is the question I put in the first paragraph - how does the clasp brake with outside tie work?  There are some illustrations in GWR coaches vol1.  What I've drawn here is my take on it showing two brake blocks for one wheel (wheel not shown) called up as Left & Right.  L has a conventional hanger and a lever arm A to C to operate the brake.  R has a conventional hanger and a lever arm B to D.  The lever arm B to D pivots on the base of the column at point D.  The column is attached to the wagon underframe and stabilised by the raking strut. Also attached to the column is a cross tie to which is fitted a safety loop.  When the actuating rod C to E is pulled (by hand lever or vacuum) brake block L is pulled onto the wheel and, simultaneously because L and R are tied by the rod A to B, brake block R is pulled onto the wheel. The lever arm A to C also works the brake on the other side of the vehicle. From the photos I've studied, this sketch includes what can be seen of the braking arrangement and my experiments with the nutcracker illustrated below (which works on the same principal and has reliably cracked nuts these last 100 years or so) suggest that that's how the GWR arranged things  - but did they? 

 

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Edited by kitpw

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Impressive looking wagon. . 

 

The roof forming method is very clever, these subtle roof shapes are so difficult to get right but that looks spot on.  

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5 hours ago, Dave John said:

these subtle roof shapes are so difficult to get right

Thanks Dave for your kind comments - much appreciated.  Yes, the GWR (like other companies) seem to have employed subtle roof shapes and in some variety, so one former will do horseboxes in the early diagrams but later diagrams will need another - thankfully, the formers don't actually take very long to make as the arcs are in a single plane.  Much more difficult would be, for instance, the American style MET coaching stock with the ends rounded in both longitudinal and transverse directions.  The overall roof thickness at just under 1mm would, I think, make the system viable for 4mm scale.

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2 hours ago, MikeOxon said:

I wrote about the Dean clasp brake

Many thanks Mike for your comments and for taking time to find and post your reference to earlier research which I've looked hard at and I think I've understood!  It looks as if I'm on the right track in the above diagram but there are a couple of things which I'm not so clear about. The first is the connection between the pull rod worked by the vacuum/hand lever and the outer lever arm on which the brake block sits (A to C in my diagram).  If I've understood your illustration correctly, you have the pull rod connected to a crank on the lever arm.  There is a drawing of a diagram 25 6 wheel fish wagon on page 38 of Russell's Great Western Coaches part one: unusually, the drawing actually shows the brake rigging.  It looks from that drawing as if the pull rod is attached directly to the lever arm without a crank.  I've scanned that bit of the drawing (and I hope not offended copyright - if I have, I'll delete it).  The other end shows the same thing but with the pull rod rising to the same position relative to the wheel. It's this piece of reference which determined the point of connection between pull rod and lever arm in my diagram. The other thing I wasn't sure about is whether there is a single pull rod reaching to each brake set or whether there are two - one left and one right: again from Russell, it looks as if there might be a pair so each wheel is braked by its own pull rod.  I'd be interested in your thoughts if you've a moment to comment!  Many thanks...

 

HB7-brakes01.jpg.fd1ffa83db80ca41c40728e93a037338.jpg

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2 hours ago, kitpw said:

If I've understood your illustration correctly, you have the pull rod connected to a crank on the lever arm.

I think that was a mistake and I've altered my drawing   I hope the new version is clearer,

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Ah yes, No. 88, carrier of many a race-winner across multiple scales 🙂

 

An ingenious build.

 

Quote

 The louvres are made with a steel comb filed up from an old cabinet scraper

 

Thanks for that tip, so you simply scrape the comb mutliple times along the same lines?

 

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1 hour ago, Mikkel said:

you simply scrape the comb mutliple times along the same lines?

Thanks Mikkel.  This video explains what old fashioned carpenters/joiners call a "scratch stock".  Usually made in house, they were used for cutting simple mouldings in wood. 

https://www.finewoodworking.com/2008/07/31/how-to-make-a-scratch-stock  There are one or two things to note about the cabinet scraper version I made. 1)  there are two sets of teeth on the one illustrated, only one set is necessary (I should have pointed that out in the original post). 2) the teeth are angled so that as they cut into the wood, they also move sideways slightly to form the characteristic angled louvre rather than just slats - if you see what I mean.... and 3) I start with a small toolmaker's clamp on the scraper so that it's held against the edge of the wood, hopefully to a straight line - a similar "fence" is built into the scratch stocks illustrated in the video.  Once the scraper has cut into the wood a bit, I take off the clamp and the scraper follows the lines it's already cut.:  it's one of those things that you really have to try for yourself, you'll quickly discover the ins and outs of it.  The wood I use is jellutong (I think it's also known as bass wood, particularly in US).  It's favoured by pattern makers, has a close, straight grain and is very workable.

 

Left: the scraper (used for No 88's louvres) with a toolmaker's clamp attached.  Middle: the scraper beginning to form the louvres (in a bit of mdf to illustrate how it works - not suitable for finished work!) and Right: another corner of the same scraper with a more traditional moulding shape in it -used for building cornice in 7mm scale.

 

512087338_20220803_2110181.jpg.f65ba4dfd235404f94b70e140f4e943d.jpg                                        429899231_web2112131.jpg.0e91a485e7022c182bf70245578c6a99.jpg1561681085_web_2108171.jpg.cba95e3eb61633bb91405804f8ff10eb.jpg

 

 

 

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2 hours ago, MikeOxon said:

I hope the new version is clearer,

...it is! And thanks for clarifying - I think I understand what's going on now and I can begin to work out the dimensions of the various parts, just as you did for the very nice broad gauge mail coach.  I meant to say earlier that I thoroughly agree about card stock in the Silhouette - I did manage to get it to cut plastikard quite well but, as you say, only thin stuff.  I seem to be using card (Bristol board) more and more, liberally coated with shellac.  Again, many thanks for your comment and research on the brake question, all very helpful.

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Good day Kit,

 

You wrote "I illustrated the cut out and assembled sides some while ago (2 years+)", well I have gone through the blog end to end and I have not found the words and music about creating the sides.  Please offer a link to the relevant text/photos.

 

regards, Graham

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37 minutes ago, Western Star said:

creating the sides

Hi Graham ...oh dear!  When the images were lost on RMweb a few months ago, I eventually attempted to reload the missing pictures from my files here....but clearly not that: my apologies.  I don't think I wrote much about it but I did have photos of the unpainted sides (only) which I posted again above.  There isn't a lot to say about them.  The artwork for the Silhouette cutter was created as DXF files in layers - the outer layer (1) being the panelling: the next layer (2) the main side which was scored on the Silhouette to represent the planking and with complete cuts for the openings for the side and drop lights of the grooms' compartment together with the louvres to the horses' compartment.  The next layer (3) had oversized cut outs to accomodate the glazing and louvres and the last layer (4) is the "interior" such as it is. I discount the panelling layer as a full layer since it contributes little to overall stability of the assembly. The material is all Bristol board coated both sides with shellac prior to cutting on the machine (I didnt take pictures step by step).  The layers were laminated using regular pva "white" glue, brushed on, and the layers set up on the turn-under former (pictured below) which is no more than a board in the shape of a carriage side with a straightedge at the base so it's pretty similar to the method for forming the roof except that simple weights (my grandfather's "gravity clamps") do the job.  The left hand picture is the whole former - long enough for a 60' coach in 7mm (some hope!) and the right hand picture is the end elevation of the former showing its shape.  Once again, apologies for the wild goose chase - I've been on a few myself, only to find those annoying "placeholders" and no picture.  Best regards - Kit

 

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On 03/08/2022 at 22:28, kitpw said:

Thanks Mikkel.  This video explains what old fashioned carpenters/joiners call a "scratch stock".  Usually made in house, they were used for cutting simple mouldings in wood. 

https://www.finewoodworking.com/2008/07/31/how-to-make-a-scratch-stock  There are one or two things to note about the cabinet scraper version I made. 1)  there are two sets of teeth on the one illustrated, only one set is necessary (I should have pointed that out in the original post). 2) the teeth are angled so that as they cut into the wood, they also move sideways slightly to form the characteristic angled louvre rather than just slats - if you see what I mean.... and 3) I start with a small toolmaker's clamp on the scraper so that it's held against the edge of the wood, hopefully to a straight line - a similar "fence" is built into the scratch stocks illustrated in the video.  Once the scraper has cut into the wood a bit, I take off the clamp and the scraper follows the lines it's already cut.:  it's one of those things that you really have to try for yourself, you'll quickly discover the ins and outs of it.  The wood I use is jellutong (I think it's also known as bass wood, particularly in US).  It's favoured by pattern makers, has a close, straight grain and is very workable.

 

Left: the scraper (used for No 88's louvres) with a toolmaker's clamp attached.  Middle: the scraper beginning to form the louvres (in a bit of mdf to illustrate how it works - not suitable for finished work!) and Right: another corner of the same scraper with a more traditional moulding shape in it -used for building cornice in 7mm scale.

 

512087338_20220803_2110181.jpg.f65ba4dfd235404f94b70e140f4e943d.jpg                                        429899231_web2112131.jpg.0e91a485e7022c182bf70245578c6a99.jpg1561681085_web_2108171.jpg.cba95e3eb61633bb91405804f8ff10eb.jpg

 

 

 

 

Many thanks for that thorough reply, I understand it better now. I have made louvres in the past on the Silhouette cutter but they are fragile and tricky, this looks more sturdy but still very neat. 

 

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