Building a Bicycle Frame with Dave Yates – Day 4
Day 1 – Day 2 – Day 3 – Day 4 – Day 5
The main frame was finished yesterday. Today there are lots of details to add:
- Brake bridge cut, filed and brazed
- Bridge for mudguard cut, filed and brazed
- Bottle bosses drilled and silver brazed
- Rack mounts brazed
- Gear cable stops silver brazed
- Cable guide silver brazed
- Seat tube cut and filed to lug
- Head tube cut to lug
- Forks shot blasted
With the frame out of the jig now, the detail can be added. Two jigs are used to ensure the holes for the two bottles are drilled in the right place.
The walls of the 853 down tube are very thin, as little as 0.4mm away from the butted ends. For this reason the brass with its melting point of around 820°C is a bit risky. Far more expensive silver solder has a safer melting point of around 600°C so is used for the braze ons.
Again, silver solder used for the cable guides on the under side of the top tube.
Here's the cable guide for the rear derailleur on the bottom of the chain stay.
Shot blasting does a great job of cleaning up the joint of flux and any surface oxidation.
By the end of day four, the frame is almost finished!
Is silver solder ( Johnson Matthey Silverflo 55 & Easy-Flo Flux) suitable for the the larger joints, apart from the cost?
I want to modify a bike frame in to a long, and only have propane heating avalable.
Thanks
Will
OK so I tried this.
Silver braze will only just melt with a propane torch, it takes a long time to get up to temperaturem and the results are blobby to say the least.
Just about manged to stick two bits of 3mm steel together, build a bicycle I don’t think so.