# Howe Truss Deck Bridge -- Progress and Updates



## xo18thfa (Jan 2, 2008)

Couple of weeks ago I did a series on cutting scale lumber on a band saw

Cutting Scale Lumber on the Band Saw 

To prove the band saw techniques, I built a pair of “Howe” truss deck bridges. The bridges are an average of examples in “Model Railroad Bridges and Trusses”, Kalmbach Publishing Co, 1992, ISBN 0-89024-128-7 and sources on the internet.




























There are two purposes for the project. First is to build a nice, complex looking bridge using only a band saw, drill press, a hand drill, commonly available materials and simple construction techniques. No tricky steps, special tools or materials needed. Secondly, these will end up on a portable live steam layout I’ve been planning to do for years. Or something out in the garden. Another “roundtoit” project.

The bridges generally follow real practice. The truss rods are functional and under considerable tension. Very little glue is used. Lots if nails and 2 x 56 nut, bolt, washers. To start on the project, draw a full-scale truss panel section. Draw it out carefully so you can take measurements from it during construction.

Truss Panel Plan 

The panel drawing is in 1:1 dimensions. This bridge project is scaled 1:20.3. That will make a very stout narrow gauge bridge 69 feet in length. It will look just right for a light bridge in 1:13.7 scale, spanning 47 feet.

It is helpful to have a table of standardized scale lumber dimensions. This table rounds dimensional lumber to 1:20.3 scale to the nearest 1/32”. Well within the accuracy of the band saw.










The project proceeds in 4 phases. First is the deck section. Second the truss assemblies. Third the end bents. Lastly, final assembly.

Start first with the deck stringers. The stringers are 2 sets of 3 timbers 8 x 18 ganged together. Between the stringer timbers, insert 2” lengths of 1/16” thick plywood or leftover strip wood as spacers. Use 5 spacers over the stringer length.










Glue the stringers and spacers.










Add some detail to the stringer sets using 18 gauge nails to simulate bolts for mending or splicing plates. Use a 2” length of angle as a template to drill pilot holes for the nails.










Hold the jig in place by hand and drill pilot holes for the nails. 18 gauge nails are 0.047” diameter, so use a #57 or #57 drill.










Drive in the nails. Makes a nice looking detail. 










That’s it for today, next time we will finish the bridge deck.


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## Dwight Ennis (Jan 2, 2008)

Great stuff as always Bob! I'm always inspired by your craftsmanship!


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## jimtyp (Jan 2, 2008)

Thanks Bob! Looking forward to the angled blocks.


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## Stan Cedarleaf (Jan 2, 2008)

Very nicely done project, Bob. As Dwight shared, wondeful craftsmanship.....


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## NTCGRR (Jan 2, 2008)

So how many will it take to cross the pool?


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## general1861 (Jan 22, 2010)

I like to use the brad nails also for "bolt heads"


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## jimtyp (Jan 2, 2008)

Question, what type of wood is it you are using? Will you treat the wood? Will it be outside?


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## xo18thfa (Jan 2, 2008)

Thanks guys. I really enjoy making bridges in this scale. Maybe some more coming soon, never know.

- The material is something they call "whitewood" It's 2 x 4 from Lowe's. It has an very tight grain, very dry, small solid knots, stays straight after cutting. Really nice stuff to work with. It works like poplar but much softer. It almost never rains here so nothing rots outside. They are for a portable, but if they end up outside, the area is shaded from the sun. After the series is done, they will get a spray of Thompson's and that should do. 


- The brads make a nice detail and so easy to do with the drilling jig. 


- It's a lap pool, these two will span it with a pile in the middle. Debating that. 



Wife =







Band saw make powder, it all over house. She do







Bob =


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## Gary Armitstead (Jan 2, 2008)

Posted By xo18thfa on 15 Dec 2011 10:14 AM 


Wife =







Band saw make powder, it all over house. She do







Bob =










Bob,

This is beautiful! ^^^^^^^^^^^ Best one yet.


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## Dave Crocker (Jan 2, 2008)

I am also looking forward to the angled blocks


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## Dave Crocker (Jan 2, 2008)

I built one of these from the Kalmbach book a couple of years ago.
The finished bridge makes a very nice display stand. I couldn't put it outside after I finished it.
Making those angled blocks was hard, I can't wait to see the simple way without a table saw.

Dave


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## Dwight Ennis (Jan 2, 2008)

Posted By xo18thfa on 15 Dec 2011 10:14 AM 
Wife =







Band saw make powder, it all over house. She do







Bob =









I see you also have a way with words.


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## xo18thfa (Jan 2, 2008)

Install the 12 x 18 floor beams to the bottom of the stringer sets. This is done using short lengths of 3/16” diameter wooden dowel pin and glue. The stringers and floor beams go together with a drop of glue, “tinker toy” style.










Drilling for the dowel pins requires a little precision. Mark out the hole locations on the stringers and floor beam. Clamp a length of straight edge on the drill press table so the drill center is on the center of the stringer. Align the drill by eye with your mark. Set the drill press stop for consistent depth










Drill the holes along the length of the stringer. Flip it end for end to drill the other side f the stringer. Re-adjust the straight end to drill the center stringer member. This is a very quick and consistent method to drill holes along the edge of a board.

Use the same technique to drill the floor beams. The floor beans need additional holes to receive the truss hanger rods during final assembly. Drill them now while the pieces are easy to handle.










Cut lengths of the wooden dowel and slightly chamfer the ends. Glue them into the floor beams first. And then assemble with the stringers. A light tap with a soft mallet and they go right in.










Now install the 8 x 8 ties using 18 gauge nails, 1 inch long. Make a “L” shaped drilling jig from some scrap material.










Mark one tie with the hole locations, use it as a master to set the drilling jig. Clamp the jig to the drill press table aligned with the marking on the tie. Set a tie in the jig and drill. 










As before turn the ties end for end and drill. Since the ties are centered on the stringers, one jig setting will drill two holes. This is a very fast drill method. I drilled 6 holes in 100 ties in less then an hour. 

Nail down the ties starting from the center of the stringers and moving towards the ends. Apply a little glue to the tie. Center on the stringer with a ruler; square it with a square; space it with another tie. Holding by hand, use a hand drill to drill pilot holes into the stringers. Use a #57 or #58 drill so the nails go in just a bit tight. Drive in the nails. Repeat a bunch of times.










The process of nailing ties looks tedious, but it’s not. After 2 or 3 you get the hang of it and it goes quickly.

Next is the guard rail or guard cap. It is a 6 x 8 cap nailed on the end of the ties. Drill #60 pilot holes thru the guard cap using the straight edge fence on the drill press table. Use glue and tiny 20 gauge nails to spike it down. No pilot holes are need in the ties.










Go ahead and spike down some rail to the ties. It is easier to do it now rather after final assembly. This is code 250 aluminum rail, but use whatever you have.










With that, the deck assembly phase is done. Next time we will work on the truss assemblies.


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## Amber (Jul 29, 2011)

You certainly make it look easy enough to do! Great project!


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## xo18thfa (Jan 2, 2008)

Dave: That's a gorgeous bridge. You did a great job. 

Dwight, Gary: She was fuming. But I cleaned up the shop. Seems to have smoothed things over.

Amber: None if it is hard to do. Just very repetitive.


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## xo18thfa (Jan 2, 2008)

To start on the trusses, here’s an assembled truss with some nomenclature for the parts.










The braces are assembled to the angle blocks by a 1/8” diameter wooden dowel pin. Here is how that works.










Now that we know the answer, let’s work thru the steps. First making the angle blocks. A strip of angle block material is cut from the edge of a 3/4" board. Tip the band saw table to 45 degrees and clamp on a fence in the same manner as a regular rip cut.










Run the board thru the saw taking a diagonal cut. One cut is all.










Use the sliding table and cross cut stop to cut off individual blank angle blocks.

Next step is to drill the angle blocks for the 1/8” pins in the braces. Tip the drill press table to 45 degrees and clamp on the drilling jig you used to drill the ties.










The angle blocks have different hole arrangements. Some have three holes on one side and one on the other. Some are two and two; some are two and one. Carefully inventory the plan so you drill them correctly. You don’t want an unused hole or come up short.

Next glue the angle block to the chords.










Now it’s time to drill the braces. Turn the drill press table to 90 degrees. Clamp on some straight edges for guides and stops. Drill both ends of the brace.










Get ready to assemble the trusses. Cut short lengths of 1/8” dowel and glue them in the braces. The brace ends that go in the angle blocks are dry. DO NOT try to glue the braces into the angle blocks. Insert braces into the angle block on the bottom chord. Insert braces into the top chord starting at one end and working to the other. This is real fiddle work, need about 59 hands for this. Eventually they go together. Tap down with your hand to seat all the braces.










Add some cleats on the top side of the bottom chord and shoes to the bottom.










Cleats and shoes go on with nails and glue.










The cleats are very important. The outboard angle block on the bottom chord has no support other then some glue. It will snap off when the truss rods are tightened. Makes sure the cleats are tight against the angle block, well glued and nailed.

Let’s have a look at the progress.










Looking nice. Next time we’ll work on the end bents.


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## Dave Crocker (Jan 2, 2008)

Very nice Bob, 
Using 45º makes cutting the angle blocks much easier. 
I don't remember what the angle was in the Kalmbach book (around 39º if I remember) but that made it hard to cut on the table saw. 
First cut was easy but getting that second cut was tough. 

I will copy your dowel technique in the future if you don't mind, some of my pin nail/glue joints have come loose over the years. 
I don't see that happening with the dowels. 
Thank you for the great tutorials, I hope they will be turned into PDF's when they are finished. 
Dave


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## xo18thfa (Jan 2, 2008)

Thanks Dave: I don't remember exactly what the angle was either, but it seemed too steep to do comfortably on a table saw. That's why this one ended up 45 degrees.

By all means, use whatever technique tou wish.

They only thing I would do different next time is make the angle blocks from maple. Maple drill so clean and is much more durable.

Thanks, Bob


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## xo18thfa (Jan 2, 2008)

Let’s get on the end bents, final assembly and wrap this project up. The end bent assemblies are straightforward. They are made up using the glue and dowel pin technique as on the deck assembly. The first thing to do is attach the top beam to the stringers.










Next get the bent posts and bottom beam cut and drilled for 3/16” dowels. Measure the lengths of the bents from the actual project, not the plan. By now errors have crept in and the plan is only guidance.










That’s about it for fabrication of the bents. The rest of the bents go together during final assembly.

Now it’s time to start final assembly. First cut the 12 x 12 bottom stunts that go under the trusses. Drill them for truss rods to match the floor beams above. The bottom struts need a short length of 1/8” dowel to secure them to the trusses.










Those 1/8” dowels holding the bottom struts in place are important. They assist in getting the bridge together. They also prevent the bottom struts from getting knocked out of place if the bridge gets bumped by accident.

Now for truss rods. There are 3 options. First is to use solid rod and run a threading die over the end. The second is to use “all thread” rod. The third is to use bicycle spokes. 

The most realistic option is solid rod. However it requires a die to cut the threads, which is a specialized tool. Solid rod is somewhat difficult to die unless you have a way to align the die to the rod. Eye balling it is kind of difficult. For this project I wanted to avoid special tools and methods.

Bicycle spokes come in various lengths and are threaded on one end. I have not tried them, but I am sure they work fine.

I went with #2 x 56 “all thread” rod for this project. All thread in this size is available in 6-foot lengths from McMaster Carr. #2 x 56 is a bit larger then M2. Use M2 or M2.5 if that’s available.

To assemble, set the trusses on the bottom struts and place the deck on top. Have an extra set of hands available. Cut lengths of all thread. Put a nut and washer on one end. Drop it down thru the holes and put another nut and washer at the bottom. 










Tighten each rod a little at the time until all the braces pull down tight on the angle blocks.

Use two washers against each nut. One washer is a regular, the other an extra wide fender washer. Fender washers distribute pressure better and won’t dent the wood. Regular sized #2 x 56 nuts will work fine, but don’t look right. Use “small pattern” nuts or model hex nuts. McMaster Carr has small pattern nuts.

Next, install the end bents. Turn the bridge up side down and drop in the bents.










Position the bents plumb and square. Place a clamp across the truss to hold the bents in place.










Drill a 3/16” whole thru the truss shoes into the bottom bent beam. Glue in a length of 3/16” dowel.










Install 6 x 12 cross bracing on the truss ends.










Install #2 x 56 stretcher rods between the bottom chords. Use nuts and washers on both sides of the bottom chords.










And finally, install 6 x 12 cross bracing on the end bents










I forgot to mention drilling all the holes for cross bracing and stretcher rods ahead of time. Carefully come up with a drilling plan so you all that before everything is assembled.

Well, that’s it. Ready to install on the pike. While they look complicated, they are not difficult to do. Every dimension cut was taken on the band saw. A drill press and a hand drill were the only other power tools. There were no tricky or hidden steps. All hardware and materials easily available.










Thanks to everyone for their kind word and stopping by for a look.

Take care, Bob


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## Phippsburg Eric (Jan 10, 2008)

Wow that is a precision bridge!!! Well done.


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## jimtyp (Jan 2, 2008)

Absolutely gorgeous Bob! Thanks so much for the instructions and many pics. I'm ready to tackle one myself now.


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## Dave Crocker (Jan 2, 2008)

They are fine looking bridges when they are finished. 
Are you going to put any stain or preservative on them?


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