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Old Jun 03, 2012, 01:53 AM
oldtribefan
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United States, GA, Kennesaw
Joined May 2007
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Build Log
1/8 Scale Banjo Steering Wheel

How to scratch build a banjo steering wheel for a runabout.

A good friend of mine is building a Dumas Racing Runabout and is less than satified with the steering wheel included in the kit. Since I have some experience with upgrading Dumas wheels, I agreed to help him out by making a replacement wheel. This is a photo of where the project currently stands. It is an 18" diameter banjo wheel in 1/8 scale (2.25" od). The rim is made from brass rod, the spokes from SS pins. You can see that I still need to do some work on one section of the finger crenellations, the fittings that attach the spokes to the rim need to be soldered onto the rim and the center hub (yet to be made) is currently represented by a SS finish washer. I will post construction photos and commentary on the process I used to get to this point, and what I do to finish the wheel.

Oldtribefan
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Last edited by oldtribefan; Jun 03, 2012 at 03:58 PM. Reason: Add information
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Old Jun 03, 2012, 01:58 AM
Taking care of the pond.
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United States, CA, Sanger
Joined Apr 2004
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I'm watching this build.
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Old Jun 03, 2012, 02:01 AM
Grumpa Tom
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Old Jun 03, 2012, 11:56 AM
oldtribefan
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United States, GA, Kennesaw
Joined May 2007
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“Where to begin a project like this?” was the first question I asked myself. I needed to know what a real steering wheel looked like so did a bit of internet searching and found these banjo wheels. With these photos I could closely determine the wheel diameter, rim thickness, number and position of finger crenellations and spoke spacing of a real steering wheel. I like the look of the wheel where the spokes splay outward a bit at the hub, so that is what I decided to model.

Next, building the rim.
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Old Jun 03, 2012, 12:53 PM
BabyBootLegger
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United States, CA, Alameda
Joined Nov 2010
657 Posts
Great build!
Do you visit Spreckels Lake?
I would like to see this when completed.
I do lost wax silicon bronze casting and could cast the steering wheel rim a dozen at a time . Would this make sense to you?
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Old Jun 03, 2012, 01:23 PM
WooHoo!
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Lake Balboa, CA
Joined Jun 2007
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Very cool Kip.
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Old Jun 03, 2012, 01:36 PM
oldtribefan
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United States, GA, Kennesaw
Joined May 2007
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Thanks Sunworkco. I have been to Spreckles Lake in the past and displayed my two boats at Wooden Boats on Parade. SMYC sure has a nice set up there! Bronze casting the wheel rim would be a time saver for someone going into production on this type wheel. As for seeing the finished wheel, unfortunately you will need to travel to Australia and visit my friend as this is where the wheel is headed when it is done.

Since he wants to replace the Dumas wheel from the kit, I asked him to send me the measurements of the Dumas supplied wheel. He measured the Dumas wheel outer diameter at 60mm and the hub at 15mm (Australians and their metric measurements!). Since I don’t do metric well (and my equipment is all set up in inches), I resorted to the handy online metric/inch converter to find out that the rim is 2.36” diameter, or a scale 18.88”. That is a bit too large as my research showed that many of these wheels were in the 17 – 18” diameter range with none larger than 18”. So I decided to model a 17.5” wheel, or 2.1875” in 1/8 scale. Using a clear photo of an actual banjo wheel, I determined that, on a full-scale 17.5” banjo wheel the wheel rim is .75” thick, or 3/32” (.0937”) in 1/8 scale. However, the cross section of a rim is actually a bit egg shaped with a greater thickness from top to bottom due to the finger crenellations. To allow for the proper rim diameter in scale, I determined that 1/8” brass rod would work, allowing me to make the 3/32” cross section of the rim and have 1/32” extra brass in the top/bottom direction of the rim to machine the finger crenellations.

Next: how to make that straight brass rod into a round steering wheel rim.
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Old Jun 03, 2012, 01:46 PM
"Take the Cannollis"
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Wow ! Just Wow !
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Old Jun 03, 2012, 02:35 PM
oldtribefan
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United States, GA, Kennesaw
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I needed a way to accurately bend the 1/8” brass rod into a 2” id circle, the size I needed to model a 17.5” wheel in 1/8 scale. After looking around in the garage for something that was 2” diameter to use as a bending jig and finding nothing, I decided to make one out of hardwood. I happened to have some 2 Ό” wide x ½” thick teak that would work well. After laying out a center and a 2” circle on the teak, I cut two 2 Ό x 2 Ό pieces to laminate into a 2 Ό square x 1”thick blank. This would give me enough thickness to hold the square blank in a 4-jaw chuck and turn a 2” diameter plug on my Sherline lathe around which I could bend the brass rod to form the wheel rim. It seems that wood is tricky to lathe cut; you cannot use the same tools you use for metal/plastic, but must use hand-held cutting tools. Because of this I could only get the diameter to 2.0005", 5/10,000 of an inch too big! I guess that is close enough for this type work.

After cutting the blank, I drilled a 1/8” hole into the wood plug. This is to hold the end of the brass rod while bending it around to create the rim of the wheel.

After using a MAPP gas torch to anneal the brass, making it more pliable, I bent a 90 degree angle ½” from one end of the rod. This will be inserted into the 1/8” hole drilled earlier in the teak bending jig. The annealed brass easily bent around the jig.

Next: cutting the rim blank and silver soldering.
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Old Jun 03, 2012, 09:52 PM
oldtribefan
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The next task was to cut the brass ring so it can be precisely soldered into a 2” id ring. The challenges here are: (1) all metal has a certain amount of spring-back when bent. The brass would have to be tight against the form when it is cut to make the 2” ring; and (2) how to cut the brass so both cut ends will be square to each other for soldering. To resolve challenge (1) I had only annealed enough of the brass rod to wrap slightly more than one revolution around the wood buck. Doing this left the remainder of the rod stiff and springy. I found that by drilling and tapping a hole for a 6-32 bolt in the flat of the wood block, I could use the bolt to pull down on the stiff part of the brass rod to tighten the ring against the wood form. For challenge (2), I set up my Sherline mill with a thin saw blade to slice through the brass coiled around the wood buck leaving the ends of the ring square to each other. With the annealed brass it was easy to persuade the ends to lie in the same plane.

Now I needed to assure that the ring was as perfectly round as possible. To do this I used a 2.5” radiator clamp around the ring, squeezing it tightly against the hardwood buck. This helped to eliminate any small imperfections in the ring and also minimized the remaining amount of spring-back in the brass.

Next I needed a way to hold the two ends of the brass ring in position for hard silver soldering. A piece of MDF, some sheet metal, three 6-32 screws and washers worked well. The MDF was drilled and tapped for the screws as shown in the photo below. The sheet metal was used as a heat barrier between the brass and the MDF. When the brass ring was held by the three screws/washers, I was able to precisely align the ends of the brass ring for soldering.

After obtaining some Weldcote “56CF” high silver content hard solder and borax based flux, I thought it best to practice on some scrap brass rod since I had never hard soldered anything before. I used a jeweler’s mini torch on my Oxy-Acetylene set. The test went quite well and the joint was very solid. Now it was time to try it out on the brass ring for the steering wheel. Hmmm, brass melts pretty easily! Turns out that I had way too much O2 in the mix giving too high a temperature. That and the fact that I kept the torch in one place too long while trying to take a photo at the same time damaged the ring. Oh, well, another part for the scrap heap!

I annealed more brass rod, bent another ring, cut it to size and decided to try the MAPP gas torch for silver soldering. That worked better as it did not overheat and melt the brass. In fact, the solder joint worked quite well, needing very little cleanup.

Using the radiator clamp again with the brass hoop on the wooden buck helped to make sure that the rim remained round after soldering.

Next: Thinning and shaping the wheel rim and making a fixture to hold the rim for machining the finger crenelations.
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Last edited by oldtribefan; Jun 03, 2012 at 09:58 PM.
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Old Jun 03, 2012, 10:44 PM
BabyBootLegger
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United States, CA, Alameda
Joined Nov 2010
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Oxygen-free 101 Copper rod is the best soldering and malleable metal that you can use. You can cold roll it.
A really great way to replicate the steering wheel is to cnc machine it 6% oversize and make an RTV mold, then produce some lost wax models and cast in silicone bronze. A production run of 3 dozen in one ceramic stucco mold would be a proper number.
Each steering wheel, with the center hub would cost around $20.00 each, less the mating of the wire spoke bores and the soldered stainless steel wires.
The steering wheel bores could be made with a mill, drilling from the outside diameter and towards the central hub. These would make splendid kits for the builder.
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Old Jun 03, 2012, 11:28 PM
oldtribefan
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United States, GA, Kennesaw
Joined May 2007
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Quote:
Originally Posted by sunworksco View Post
Oxygen-free 101 Copper rod is the best soldering and malleable metal that you can use. You can cold roll it.
A really great way to replicate the steering wheel is to cnc machine it 6% oversize and make an RTV mold, then produce some lost wax models and cast in silicone bronze. A production run of 3 dozen in one ceramic stucco mold would be a proper number.
Each steering wheel, with the center hub would cost around $20.00 each, less the mating of the wire spoke bores and the soldered stainless steel wires.
The steering wheel bores could be made with a mill, drilling from the outside diameter and towards the central hub. These would make splendid kits for the builder.
Great suggestions, Sunworksco. Thanks! I might make one master and try this when I am done with the one for my friend.

Kip
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Old Jun 04, 2012, 12:08 AM
BabyBootLegger
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United States, CA, Alameda
Joined Nov 2010
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Hi Kip,
I can refer you to my RTV mold and lost wax model maker in Northern Ca. If you would like. I have a high production silicon bronze casting company that I use here also. They charge for the casting is what the silicon bronze will cost, which is a deal. You could do a hundred small marine deck fittings in one large ceramic stucco flask. This really makes the fittings affordable. The detail is very fine as well.
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Old Jun 04, 2012, 02:59 AM
Sea Dragon-Lover
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PDX, OR
Joined Dec 2002
10,479 Posts
A fantastic build thread.

I almost want to build one myself,... but what would I put it in.

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Old Jun 04, 2012, 05:44 AM
Registered User
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Sydney Australia
Joined May 2009
753 Posts
no Umi, you've got it the wrong way round, make the steering wheel then build a boat around it!
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