Almost jigless bicycle frame building

Step 9 Pieceing together the front triangle

Now we will join the two halves of the front triangle together. Again, I am skipping the mitering and other steps.

At the front of the jig under where the head tube will end up, drill and tap a set of two holes to hold leveling bolts.

Using the two leveling bolts under the head tube, and either another leveling bolt or tube lift under the down tube, set up the down tube in its approximate position so that it is the correct height off of the jig face. Use welder's magnets to hold this in place

Then lightly clamp the seat tube to the jig and nudge it into place against the down tube. Double check that your down tube and head tube are at the correct height.

Next stand back and sight down the head tube and make sure it is parallel to the seat tube. You can fine tune the leveling screws to get them parallel. If you have a digital angle finder, it will be very easy to get the two tubes parallel.

Now set the angle between your seat and down tubes. Double-check by measuring the distance between your seat and head tubes, where the top tube will eventually go.

When everything has been double-checked and looks good, tack the down tube to the bottom bracket.