One off Risers...

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Prof
Founder, Choppers Australia
Posts: 5896
Joined: Sat Oct 22, 2005 3:54 pm
Location: Willunga, South Australia
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One off Risers...

Post by Prof » Sun Feb 24, 2019 3:55 pm

Dropped in on a customer recently and he was trying to find a set or risers to suit his custom Triumph. Needed them up 3½" and back 1½"... had a problem on top of that. His bars are powdercoated so instead of being 7/8" diameter (22.2mm) they are 23.5 mils.

Ten years or so ago, I had some riser blanks made up, but they got the holes slightly too large and the cutting required a lot of finishing, so ended up getting used for other things.

I had one 7/8 set left and figured I could sort something out for him. Hours involved would make them highly expensive so I suggested a reasonable price and perhaps a few trades down the track...
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Did some sketches for him and he chose 'B'...
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Marked out for the clamping bolts. Auto punched and centre punched then use a centre bit to keep everything spot on...
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Squaring up in the drill vice. Use a piece of white card/paper behind so you can clearly see that the fine gap is the same width all the way up...
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Using 5/16 UNF so appropriate drill bit is used all the way. Then an 8.5mm hole drilled half way. Here checked for depth. A handy tool that will be regularly found at swap meets...
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Drilled and tapped. Countersunk allens need trimming and a counter sunk hole needed in the risers...
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Here allens have been shaved on the lathe and counter sinking done...
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Line up and fit nicely. It common when tapping female threads to get them slightly off square. I this happens, the can work the tap back and forwards to one side to square the thread up. I you are careful final thread will still be fine...
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Now to mill out to 23.5mm. Using a drill bit to enlarge a hole by only a mm will damage the bit, so will use a milling cutter on the rotary table. If you don't have equipment like this, a die grinder or round file is the only answer.

Riser is centred on the rotary table with a machined up plug and clamped REAL tight...
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Removing the plug is easier if it is threaded, so a bolt can be used to pull it out...
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Checking with a a piece of round bar machined to 23.5mm...
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Careful marking for cuts to create the top clamp...
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Cut very gingerly with a 1mm angle grinder blade...
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Risers need to be angled rearwards 30mm. Will do one angled cut and then weld the two pieces together. A right angled line is marked and then the angle worked as if a 'v' was to be cut out (right mark to red dotted line). Instead it will be one cut and then the bottom piece will be turned 180 degrees...
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Cutting in the mitre saw...
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Bottom of risers need to be drilled and tapped to take 1/2" BSW bolts (English bike). With short pieces such as these use the drill bit to get them square...
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Drilled and tapped...
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Set up for welding... note angled cuts so weld will fully penetrate...
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Both welded on three sides. Front of risers need to be curved. This done and grooves cut to take weld...
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Finished. Risers will be painted and new owner will do final finishing...
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Begining and end...
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This was a time consuming job and not at all economical for me to do, but took it partly as 1. an interesting exercise, 2. to help out a customer and 3. to show readers just what you can do with some knowledge and patience...

Hope you found this interesting a perhaps picked up a few pointers for your own workshop and the confidence to do some fancy fabbing.
Chopit'nrideit... Prof

TriNortchopz
Posts: 69
Joined: Sat Feb 24, 2018 5:41 pm
Location: Haines Junction,Yukon, Canada
Interests: Choppers, nature, learning more about choppers

Re: One off Risers...

Post by TriNortchopz » Mon Feb 25, 2019 5:19 pm

Nice Prof, you helped me to learn a few new things again with your custom fabrication.

Prof
Founder, Choppers Australia
Posts: 5896
Joined: Sat Oct 22, 2005 3:54 pm
Location: Willunga, South Australia
Contact:

Re: One off Risers...

Post by Prof » Mon Feb 25, 2019 9:43 pm

Glad to be of help
Chopit'nrideit... Prof

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