Front triangle tacked and brazing begun.....

On the previous post I ended by mentioning that the seemingly simple task of brazing the front triangle turned out to be not as straight forward as I might have otherwise expected.....

The reason for this is the material from which I made the jig. To save money I made the jig out of wood, however it has been a month or two since I made the jig and mounted the aluminium fixtures on to it - in the correct location I may add.

The issue is that, having re-measured the jig prior to continuing with the frame, it would appear that the jig has swelled ever so slightly. This in turn put all of the aluminium fixtures out of position!

Having re-located the fixtures to the correct position I then continued with brazing up the BB shell - see pic below:

 
Next up I added the top tube and down tube to the jig, tacked it all together and fully brazed the seat tube to the top tube.

Tomorrow I will be finishing off the main triangle brazes and shaping the rear triangle tubes ready for their joining to the main triangle.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Internal cable routings finished & seat-tube slotted....

Having an excess of holiday I decided to take a week off and hit the frame hard - as such I have finished the internal cable routings in the top tube - what a nightmare this turned into...

The stumbling blocks I came across when doing this were:

1. Making the holes in the frame tube for the internal tube to poke out of.

To do this I drilled a hole perpendicular to the tube surface where I wanted the centre of the internal tube to exit the frame tube. I then angled the drill bit to cut an elliptical slot, this sort of worked however every time I got a nice ellipse on one side but then on the other side I ended up with an asymmetric cut-out.

2. Brazing the internal tubes into the frame tube.

This was fine at one end, but when doing the other end I didn't account for how much distortion you would get. Routing internal tubes through a straight frame tube should be straight forward enough, however I'm routing them through a curved tube (just to make things more difficult).

When I tried to re-bend the internal tubes away from the inner wall of the frame tube (so they don't hit one another when the bike goes over bumps) I cracked one of the internal routings - big fail!!

3. De-brazing the internal tubing while brazing on the exit surrounds.

Unfortunately when I was brazing on the frame stiffening bits, which go around the internal tube exits, the braze on the internal tubes softened allowing the internal tubes to move ever so slightly.

Anyway - after all of these issues were overcome I got the tube finished and also cut the slot in the seat-tube for the seat clamp - see pic below.

 

Next I will be tacking and brazing the front triangle, but as it would turn out this would not be as plain sailing as I might have at first thought......

Internal cable routings started......but not finished!!

So before being able to join the front triangle together fully I needed to tackle the internal cable routings.

The main reasons for running the cables inside the top tube is that it will make fitting a frame bag easier and look cool!!

I did a lot of research into internal cable routings on the Internet and to be honest I didn't find out a great deal!

As such it looked as though a bit of experimentation was going to be the order of the day.

The first challenge was to bend the internal brass tubing at each end in order for it to exit the tube - this seemed straight forward enough - however the first attempt turned into an experiment into discovering the melting point of brass - it is low!!

The next try went much better so I thought I would take it to the next level and have a go at brazing on one of the cable exit shrouds - this resulted in the internal brass tubing melting!! This was becoming frustrating.

After a bit more of a play it looks as thought I was holding the heat on the tube for too long - by waving the heat in and out to locally heat the section being joined it meant the whole assembly didn't get as hot and only the bits I wanted to melt, melted.

Top Tube in Position With Guide Tubing Showing

The First Brazed Routing - 2 hours!!!

Next I need to braze the other three internal cable routings and shape the rear seat and chainstays.....

Front Triangle - done stamp!

This afternoon I managed to get into the shed and mount the seat-tube support onto the jig - it then seemed only fair to shape the seat-tube and top tube and fit them to the jig also - see below:

Front Triangle

 

I'm going to weigh all of the individual parts tomorrow but a rough guess so far puts the frame at just under 2kg without the braze.

Tomorrow I'm going to have my fist shot at internal cable routings.....

The first two dots have been joined......

As described in my last post, the next step was to start joining all of the various "hardpoints" of the frame together with the tubing.

I still need to finalise the seat-tube, as such this one wasn't an option to shape, so instead I started work on the downtube, see pic below:

Downtube Done

Mitre to headtube - this one took 53 minutes, next time I think I'll do the hard mitre first and then the easy one.

Mitre to bottom bracket shell - the easy one!

One thing that sprang to mind while shaping the downtube is that before I braze it in place I will measure the length and maybe trace the mitres so that it will take me a fraction of the time to shape this tube on frame number two.

This did make me think that, should I wish to start making frames more regularly, some kind of automatic mitre-ing device would come in very handy indeed!

Next up I need to finalise the seatube and get hold of it so I can cut in the top tube.

Frame Jig Complete

A late night last Friday combined wiht a very late night last night has resulted in the frame jig being completed - see picture below.

Here we have (from the bottom clockwise) the seat-tube locator, the bottom bracket shell mount, the headtube mount and the drop-out mount.

Close up view of the drop-out mount.

Close up view of the headtube tooling.

Next up was to accurately mount this lot onto the jig back-board. In order to do this I printed out a 1:1 scale plot of the frame and the tooling.

I set the centre of the bottom bracket and this formed the datum for the location of all of the other aspects of the frame.

Next was to set the sliding drop-outs to horiontal and the rest was easy!

Marking Out

Mounted Tooling

Next up is to start joining the dots!!!

Frame Stay Tooling & The First Bent Stay!!

The next step in the build has been for a while to pluck up the courage to start practicing with bending the tubing for the seat and chain stays.

This has been for me the most intimidating part of the build as it was the part I knew the least about and the lack of information on the Internet regarding techniques other people have successfully employed only served to make this task event more daunting.

I did find one picture of a stay bending setup on the net which was comprised of a set of form tools mounted in a fly press. This seemed pretty simple and after a quick chat with Piet (now my full time wood turner and general jig building consultant!!) we decided on a plan to make a set of tooling.

The picture below shows the turned piece of wood which will be used to form the basis of the bends in the tubing, for initial tests this will be mounted in a vice and the tube pulled around it to form the bends,

Turned Wooden Form Tool & Bar Clamp

Because I was so keen to test the tooling and also wanted to see if I could get away without needing a fly press I modified the turned block to incorporate a clamp to hold the tube during bending.

The next step was to have a play with bending a tube.

Tube Being Bent

This technique definitely requires some honing however the results of the first bent tube were pretty encouraging.

Chainstay Number One!!

At the moment these test pieces are being done using cheapo seam welded tube of the correct diameter. I need to do a couple more tests to accurately determine how far the centre of a bend ends up being from the mount in the form tool and I should be good to go on the real things!!

Next up should be a finished set of stays and even maybe all the bits on the jig ready for some brazing action!!