Jump to content
 

Construction of model trusses


Recommended Posts

Hi all:

 

I'm currently working on mocking up the major buildings for my model of Banff (Scotland, not Canada), and am wondering about construction of trusses for the station building and goods shed.

 

In the case of the station building, there will be 9 identical trusses about 155mm wide for OO scale.  I'm imagining some sort of jig, but was wondering whether anyone might have a few tips or tricks for a beginner.

 

1962789525_BanffStationBuilding-trusses.png.d4e8d58a3cfb61a7fc2f8179c1b6a467.png

 

Thanks in advance for any who reply.

Link to post
Share on other sites

  • RMweb Gold
2 hours ago, aardvark said:

Hi all:

 

I'm currently working on mocking up the major buildings for my model of Banff (Scotland, not Canada), and am wondering about construction of trusses for the station building and goods shed.

 

In the case of the station building, there will be 9 identical trusses about 155mm wide for OO scale.  I'm imagining some sort of jig, but was wondering whether anyone might have a few tips or tricks for a beginner.

 

1962789525_BanffStationBuilding-trusses.png.d4e8d58a3cfb61a7fc2f8179c1b6a467.png

 

Thanks in advance for any who reply.

 

Just curious - why are the trusses flattened at the top chord whilst the gable walls rise to an apex?  It there a large flat roof atop these trusses.   Apologies but I’m an engineer and your 3D sketch has intrigued me.

 

Are the trusses to be visible in the completed station building model?   If not, they could simply be made of solid thick card (or whatever material you are using for the model) shaped to the required roof profile.

 

Regards

 

Darius

 

 

  • Like 1
  • Agree 1
  • Thanks 1
Link to post
Share on other sites

I have no experience of model roof trusses, but I have worked with full size versions.

I have built the odd timber viaduct and the piers use a very similar construction to a roof truss.

I used a piece of soft insulation board that would take pins and then marked out the size of the truss and added some pins to keep the cut sections in place during assembly.

You will also need to cut to length and mitre the sections and you can make an arrangement with pins and strip wood to allow the cut to come at the edge of the piece of insulation board.

Sounds complicated but all you need is a fixed length and angle jig for each section and another jig to hold them all together.

I prefer to use wood in cases where wood was used on the original but there is no reason you cannot use plastic or metal section.

Bernard

  • Informative/Useful 1
Link to post
Share on other sites

Draw and score the shape on plasticard with a silhouette cutter. The cutter won't cut thick plasticard but will score it to create a cutting guide. It would be possible to cut thinner plasticard and laminate it together to form the truss.

 The advantage of the cutter is a perfect replica of the first truss every time.

  • Thanks 1
Link to post
Share on other sites

Many thanks to all. I was hoping for one response, but got 5!

 

To answer Darius first, the station building has a skylight stretching much of it's ridge, and hence the trusses will be somewhat visible from the standard helicopter viewpoint.

 

637227710_BanffStationBuilding-roof.png.db369c60d61c89758b58110426fb8b65.png

 

My truss design is a simplified version of  the original construction.

 

Banffstation-1.jpg.316c8d22f01438df7f7e46b09c93f15c.jpg

 

 

I had not previously known of Ron Hegg, but if that man can put together those masterpieces from a few bits of plastistrip he had laying around (ok, not so few), then I should be able pull off the much much simpler Banff station roof trusses.  It gives me confidence.  Given my CAD, then it should be an easy matter to print out to-scale templates (hadn't thought of that), and a few jigs would improve the accuracy and repeatability of my cutting.

 

Given this, I see no need to go to laser cutting.   However, a silhouette cutter could well be plan B, as I am already considering one for windows and the skylight.

  • Like 1
  • Thanks 1
  • Friendly/supportive 2
Link to post
Share on other sites

On 22/12/2019 at 18:03, Enterprisingwestern said:

 

Please show us how you proceed.

 

Mike.

 

Thanks for your support Mike. I reallky appreciate it.  I will keep you posted, but I wouldn't recommend holding your breathe.

 

It's taken 4 years to build baseboards and get to mocking-up the major buildings.  The mock-ups will let me review the track plan, then lay the track, wire points and get some trains running.  After that, I'll look at building construction.

 

Although, I could just buy some plastistrip and build the trusses ahead of time.  A bit out of character, but you never know.

 

Christmas miracle, perhaps?

  • Friendly/supportive 1
Link to post
Share on other sites

  • 1 month later...

Time has passed, and not much has moved beyond a few gray cells.  Much thinking and reading of Ron Heggs' thread leaves me with a couple of options, and an equivalent amount of confusion. I'm hoping that the process of writing this post might help the decision process.

 

The preceding discussion left me with the idea of making a jig to assemble 6 pieces of 1x3 and 2x3mm plastistrip into one of nine trusses.  I'd need to be careful with the construction of the jig and the application of solvent to avoid inadvertently sticking the truss to the jig.  Do-able, but not trivial, especially as the 8 joints would be relatively weak butt joints.

 

Option 2 would be to follow Ron Heggs' approach of lap joints between multiple layers of 0.25 or 0.50mm plastistrip.  Again, a jig would be required, but the larger surface area of a lap joint should make it easier to tack together without danger of excess solvent gluing the assemble to the jig.  The disadvantage is a lot more bits of plasticard to cut.

 

Option 3 is the Silhouette cutter route, whereby a number of profiles are cut out of 0.25 or 0.50mm styrene sheet and laminated without tricky joints or alignment.  Not sure that a jig would even be required.

  • Friendly/supportive 1
Link to post
Share on other sites

  • RMweb Premium

I had to produce something like this for Brunswick shed roof.

t.jpg.e6470a75add0f468c312e46569bdca3b.jpg

I went back to almost forgotten model aircraft building technique and used various sizes of strip wood to construct the trusses. If anyone else remembers this model aircraft kits included a drawing which you pinned the various components on to while gluing them together, no jig needed just an accurate drawing. Once all the trusses are made they are pinned vertically on to another drawing and the longitudinal members added. At least your roof is straight - Brunswick was the only curved loco shed in the country (although the Severn Valley Railway have now built another one).

  • Like 2
  • Agree 2
  • Informative/Useful 2
  • Craftsmanship/clever 2
Link to post
Share on other sites

51 minutes ago, Michael Edge said:

Once all the trusses are made ...

 

Thanks Michael - I've never built a wooden model airplane, but I begin to get the picture.

 

I imagine that the trusses are built flat against "an accurate drawing", and may well get stuck to the paper.  I suppose you just sand the paper off after the glue has cured.

Link to post
Share on other sites

  • 1 year later...

A bit late to the table I'm afraid, but I had some success building “wooden” trusses in square brass bar using a jig cut from 1mm cardboard. The truss was drawn on, its shape carefully cut out to the widths of the material being used, and then the card was stuck to a mounting board.  This last part of the operation required using small sections the truss material to ensure accuracy, and two jigs were made to suit end and intermediate trusses. Individual truss sections were then cut from the material (square brass bar) and soldered up. Despite the heat the jigs survived and remained accurate for the whole build.  Best of luck.

DSCF2305.JPG

DSCF2311.JPG

DSCF2332.JPG

shed 4.JPG

Edited by D River
Grammar
  • Like 2
  • Craftsmanship/clever 6
Link to post
Share on other sites

  • RMweb Gold

Many years ago (21 in fact) I built 13 trusses for Headingley depot. these were from 2 and 1mm brass angle. 

 

the drawing was drawn with CAD, printed out and stuck to some soft board with double sided tape and the angles pinned in place and soldered. I think I only had to change the drawing for a fresh one twice. 

 

Incredibly strong when all put together. 

 

I have some large ones for the new layout and I have made a wooden jig, but the etches for the joining plates have only just turned up so i have not tried it yet. 

 

Andy RP2110021a.jpg.7b89c56f7f7462cc71b7111abb23bbe9.jpg

Edited by Trams and Locos
  • Like 3
  • Craftsmanship/clever 3
Link to post
Share on other sites

16 hours ago, D River said:

I had some success building brass trusses in square brass bar using a jig cut from 1mm cardboard a few years ago.

 

16 hours ago, Trams and Locos said:

Many years ago (21 in fact) I built 13 trusses for Headingley depot. these were from 2 and 1mm brass angle.

 

Not too late as I have yet to do anything.  One day ... but both posts are encouraging, instructive, and very impressive.  I hadn't thought about brass.

  • Like 1
Link to post
Share on other sites

  • 2 years later...

Since I started this thread a couple of years ago, I thought I should give it a conclusion.

 

After buying 1- and 2-mm plastistrip for the trusses.  I talked myself out of this approach, reasoned that it would be hard to cut the plaststrip accurately to the required lengths and angles without the use of a chopper, and perhaps even then, and that it would be hard to effect good butt joints between the pieces, so I put the price of the chopper towards a Silhouette Cameo 4 cutter instead.  So far, I've used it to make various OO-scale doors and windows, plus a grounded 8T goods van, and now trusses for the station building.

 

P1170716.JPG.48fd33faab771ad57094afd8d307e043.JPG

 

Each truss is made from three 20-thou plasticard trapeziums - I initially intended to use two, but needed the third to give the assembly some stiffness.  The smaller strips are added to the diagonals to mimic the construction of the prototype.

 

Edited by aardvark
  • Like 4
Link to post
Share on other sites

8 hours ago, aardvark said:

After buying 1- and 2-mm plastistrip for the trusses.  I talked myself out of this approach, reasoned that it would be hard to cut the plaststrip accurately to the required lengths and angles with the use of a chopper, and perhaps even then, and that it would be hard to effect good butt joints between the pieces, so I put the price of the chopper towards a Silhouette Cameo 4 cutter instead.

I found myself in exactly the same position a few years back, and I bought a Cricut cutter.

 

However, instead of cutting styrene (which my Cricut did struggle with) I decided to use cereal packet cardboard instead. It's much cheaper! Then, I cut out the trusses (etc) in completed 'assembled' pieces to save gluing the individual elements together, and ensure cleaner joints.

 

To get the required thickness(es) I simply glued several layers together using cheap clear PVA glue. These were then painted in the appropriate colours.

 

Here are the cereal packet 'bit's I cut out for my station forecourt canopy (some are already painted). Note the zig-zag joint I used to join 2-pieces of single-layer card together to get a good alignment and bond. This was necessary to get the required length that, otherwise, my Cricut could not cut.

IMG_20230309_102542_resize.jpg.f0baa95d6ba34ee8a55d2bb33ef9dc40.jpg

 

I couldn't cut the full length of the support truss either, so the layers were arranged such that the butt-joints didn't coincide:

IMG_20230309_102806_resize.jpg.fcf6e19f6863abd20b936162e9348417.jpg

 

Once the 'bit's were assembled, I had the following components:

IMG_20230311_210358_resize.jpg.e218cfab16ccadf7efb3e7d971378b24.jpg

 

That were glued together, again with clear PVA, to get the main canopy parts:

IMG_20230314_214152_resize.jpg.8d87a6464ad97cec25a2dd03c0d2d497.jpg

 

Once installed on the layout it looks like this:

IMG_20230523_203850_resize.jpg.1d884f5ebed9bbd0fbf065f9d4cc1f1a.jpg

 

I hope the above helps to show that a 'cutter' and cardboard can be effectively used to create 'passible' models of buildings (yes, the main station building is all cereal packet cardboard, painted and/or with inkjet printed textures applied).

 

Ian

 

  • Like 4
  • Craftsmanship/clever 4
Link to post
Share on other sites

Hi all,

This might be a little out there, But have you considered seeing if you can have them 3D printed. That way you will get 9 almost identical sets of trusses.

Edited by cypherman
  • Like 1
  • Agree 1
Link to post
Share on other sites

35 minutes ago, ISW said:

I found myself in exactly the same position a few years back, and I bought a Cricut cutter.

 

However, instead of cutting styrene (which my Cricut did struggle with) I decided to use cereal packet cardboard instead. It's much cheaper! [...]

 

 

Horses for courses, and you've clearly managed to get the Cricut to work for you.  I went with a high-force Cameo 4 and a 3mm Kraft blade, which cuts 20-thou plasticard easily, and manages to make a reasonable but incomplete job on 40-thou.

 

As for "cheaper", my 20-thou plasticard cost £0.46 a sheet, and I can cut 5 complete trusses from a single sheet.  Cereal packet is undoubted cheaper, but plasticard doesn't exactly break the bank.

 

I suspect you'd agree that using a cutter won't be for everyone.  There is a fair learning curve while you figure out what it can and can't do - and spending hours in front of a computer isn't everyone's cup of tea.

 

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...