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!!

I just couldn't resist.........

For those of you aren't aware of the Chris King Cielo bikes some of them come with some pretty nicely carved out dropouts - as such I couldn't resist the temptation in emulating them on the first run of element frames - check out the pictures below:

I'm not sure I'll be doing this by hand for all dropouts - they do come out pretty nice but it takes ages!!!

Paragon Dropouts Added to CAD Model

Having spoken with the splendid chaps from Paragon Machine works it turns out that they provide step files for all of their machined parts available on the website - this makes it super quick, easy and most importantly accurate to simply smash the parts into your CAD model - which is what I did on Friday - see image below.

Now I really need to crack on with making the drop-outs a tad lighter and shaping the seat and chainstays!

Drop-Outs Sorted

So having tried in vain to get my own design of sliding dropout manufactured I turned instead to the splendid chaps at Paragon Machine Works in Richmond, CA.

The drop-outs arrived on Tuesday and I couldn't resist getting the stainless steel bits super-finished - check out the pics below....

Left Hand Drop-Out::

Riight Hand Drop-Out::

So as you can see all of the bits are really nicely made, now all I need to do is jig them up ready to be joined to the rear triangle.

Check out paragon machine works for these and more splendid bike frame building supplies -
http://www.paragonmachineworks.com/.

Top Tube Bending - Complete!

Having researched tube bending companies on Google I compiled a list of likely candidates (about 7 in all) - the first of which was a company called Pipecraft based in West Sussex (http://www.pipecraft.co.uk/).

I spoke with a chap called Andy who was so helpful I didn't even bother phoning the other companies on my list!

Having discussed my requirements (and essentially because I am generally interested in all things engineering) we decided that it was probably best for me to pop down and visit Pipecraft with my tubing.

This enabled me to watch and learn about the process of forming the tube and also served as a splendid opportunity to get a proper feel for their manufacturing capability for use on future projects.

In the end Andy rolled my 4130 tubing on a ring roller, we experimented with both sand filled and empty tubing and it turned out the bend was so shallow sand was not required to support the tubing - see pics below:

Andy in action on the ring roller!

Andy (with mesmerised Dad in background) demonstrating a tube mitreing belt sander.

All in all an excellent visit, 5 shaped top tubes and lots learnt about tube bending, shaping and fabricating.

Everyone at Pipecraft couldn't have been more helpful and I couldn't have wished to work with a more open and generally welcoming group of people - contact them for all your tube shaping needs ;) 

Tube Bending Pre-Work!

One of the design features of the Element frame is a very slightly curved top tube.

There are various reasons for this design choice the main ones being:

• it results in slightly more vertical compliance in the front triangle - aimed to provide a more comfortable ride over multi-day events while maintaining lateral stiffness and hence frame responsiveness.
• it enables a slightly larger frame bag to be fitted to the frame (essential for balanced bivvy bike setups)
• finally, and arguably least importantly, it differentiates the frame from anything else currently on the market!

 In order to achieve this "shaped" top tube it was necessary to cold form the tubing - I did a lot of research into this with various techniques being suggested including:

• fill the tube with soapy water and freeze it prior to shaping (the soap apparently acts to stop the ice crushing and cracking up under load).
• fill the tube with Bendalloy prior to shaping
• don't bother filling the tube with anything
• fill the tube with water and then pour in fine sand - the water acts to ensure no air is trapped in the filled tube.

In the end I decided to sand fill one tube and to not fill one tube and test bend them back to back.

In order to stop the sand coming out during shaping it was recommended I bung the ends of the tube with wood.

For this I turned to my friend Piet from work who not only has a wood lathe but is also pretty handy at using it!!

We used some old South African railway sleeper wood (Piet is originally from SA) and proceeded to turn the bungs on the lathe - see pic below:

Piet in action on the wood lathe!!

The finished bungs prior to parting off and finishing.

The bung in situ - job done!

Many thanks to Piet for showing me how to make the bungs on his lathe, putting up with my slightly optimistic manufacturing tollerences, and for providing some splendid Portuguese red wine to oil the wheels of creativity!!

The next step is to take the tubing to a company called Pipecraft to get it bent.