Mountain Bike Frame Building

Long time no update....

2010-02-05T05:37:00.000-08:00

Its been ages since I've updated this page, figured I'd shed some light on whats happened.

I finished the first frame, which looked good but had some obvious first timer mistakes. I ended up making the effective top tube measurement too short for my liking, I took off too much material when making my top tube miters ... this also affected the headtube angle. I decided to give it the destruction test to see just how good my braze welding is. After some hammering and prying in the bench vise I found that all the tubes failed and the brazing held together in the extreme tests. This leaves me to believe that my frame would have held together great during normal riding conditions.

After this I took on a few other projects including repairing and old GT Talera frame, and restoring an old dirtbike.

2010 is starting to look good for frame number 2. I'll be cleaning up the shop and restocking my supplies in the coming weeks. I'll also be drafting my plans for the "mark III" frame (MK I was the first draft that never made it past the sketch pad, MK II was the first frame I actually built) and selecting my tubing and small parts (braze-ons, dropouts, etc). When this frame is completed it will be painted and built to ride, no more test welds, destruction tests, mass confusion. Once the weather turns warmer around here (no heat in the shop) and I have my materials I'll be firing up the torches. I'm hoping to have the MKIII frame completed by the end of April 2010. I will also be updating this page more regularly.

Fire 'em up!

2009-06-11T16:43:00.000-07:00

Fired up the torches and made some real progress today. Things are beginning to come together and my brazing is looking good. Also learned a few lessons 1) pre-heat is key, always preheat the tube so that the flux turns glassy-looking all at once. 2) Be liberal with the flux, you can't have too much, always re-apply after tacking and after tinning.

Using the Tubemiter.exe template for the seattube/BB junction.

Seattube is mitered and fitted, covered in flux and ready to braze.

A liberal amount of flux. I use Unibraze Nickel Silver paste flux.

The seat tube/ BB assembly post brazing. I've used regular old low fuming bare bronze

Sexy fillet weld :D

Soaking the assembly (after its cool to the touch) to remove the flux. Even the most hardened on flux can be easily removed by soaking the tubes in hot/warm water for about 20 min.

Rough cut with a hack saw on the down tube to meet the head tube. You can see where I traced out the tubemiter template with a sharpie.

A nice sharp file and some arm strength will have that rough cut looking like a spot-on miter in no time (about 10min actually). The head tube is ready to braze now.

Bitchin!!! Hopefully I'll get some more done tomorrow.

Printer working - mitering time

2009-06-09T15:22:00.000-07:00

I got my printer all hooked up and printed out my miter profiles using the tubemiter.exe program. These handy printouts should get my miters 95% of the way, then a little tweaking to get them perfect. Lets cut some tubes!!!

Straight as an arrow..... almost.

2009-06-09T13:15:00.000-07:00

Measured the bow in the tubes today using some homemade v-blocks and my dial indicator. The top tube and down tube have a 0.018" bow in them, which is about 0.4572 millimeters, which seems pretty damn good considering they are the Nova house brand tubes. The seattube has a 0.008" bow to it (0.2032 mm) which is also quite acceptable. I marked the high spot of the bows and will position the tubes so that the bows go towards the inside of the front triangle and the tubes run straight side to side.

The next step will be to get my damn printer hooked up so I can print out my miter profiles from the tubemiter.exe program and begin fitting some tubes.

Tubeset arrives!!!!

2009-06-05T18:43:00.001-07:00

I finally ordered the tubeset and got it in the mail today from the good people at Nova Cycle Supply. I selected one of the cheaper (i.e. affordable) kits for my first frame and will go with fancier tubing as my skills progress. Its a Nova 4130 Cromo oversized kit, also got the braze-ons and such I needed as well as a set of super sexy Breezer dropouts.
Let the building begin!!!!!

Been a while.....

2009-05-13T15:39:00.000-07:00

Been a while since I've updated this thing..... I'm laid off and have to conserve so a set of tubes and braze-ons is out of the question for a while. But, with all the time off, I've been riding ALOT hahhaa. Happy Trails.

Test Fillets

2009-03-02T17:20:00.000-08:00

I have not updated my blog in a while, been kind of sidetracked with moving soon and such, but I did manage to do a few test fillets. I did these with flux coated bronze (I will be using bare bronze and paste flux when building the frame) and some mild steel. I destroyed one of the "T" mitered joints and have only been able to tear/buckle the steel tubing and not the braze. Guess I did ok? I'll have to work on making them prettier and getting the perfect bead all the way around with good penetration.

First couple

Fillet #1

And now #2
Mitered Fillet

Mitered Fillet #2

Step #2 - Tooling and Jig

2009-01-30T08:23:00.000-08:00

I've finished building up my jig using drwelby's design on the Instructables Website (click for link). I got away with building it from scraps and end-cuts from work so it cost me $0 to build..... SWEET!

I added a bunch of extra threaded adjustment screw holes to help fit designs with shorter tubes and different head angles.
Pictures of the dummy axle setup - the large washer represents the axle / hub centerline

I also picked up some various tools needed to get the job done including: A hacksaw, angle finder, square, 2 6" C-Clamps (I welded a piece of 2"x2"x1/4" plate to the clamping surface for holding the Bottom Bracket), a measuring tape with Metric and SAE increments, a Vernier Caliper (also with Metric and SAE), and a set of files. I'm waiting on more half round files.

I also got my O/A setup, a Harris style torch with a cutting and 3 welding tips, including hoses, gauges, etc.

Next time I'll be building my tubing blocks.... stay tuned!

Step #1.5 - Final Draft

2009-01-24T06:22:00.000-08:00

I just finished up the revised final drawing of the MK II frame design and included all the angles for my miters. My previous BikeCAD design was not suspension corrected and had some steep angles and such. I've done all my measurements in metric because I live in Canada EH!

Thanks to the guys at the MTBR.com Frame Forum for some pointers on improving my design.

Click the picture to make it bigger.

I'll go over the setup of my workspace and tooling next.

Step #1: Design Process

2009-01-23T15:39:00.000-08:00

I've been a mountain biker/enthusiast since early 2000 and have had my fair share of different bikes, steel and aluminum, hardtails and full suspension. I've always toyed with the idea of building my own frame and finally decided to go through with it this year.

The purpose of this blog is to show my progress and to reference the steps and information needed for other first time frame builders. I am also doing this the 'cheap' route and keeping all my tooling costs to a minimum to build a frame the most affordable way. I'll add all the links for information and resources along the way in the relevent sections. I'll also update this blog with each step I take.

After many hours spent doing some web research I decided to go ahead with the design process and start the ball rolling.
Some vital information can be found in the FAQ section at the MTBR.com Frame Building Forum
Also some great drafting advice from Ivy Cycles

I decided that I wanted to make a fillet brazed steel frame and that I would go with an oversized steel tubeset for added strength / stiffness (I'm a 240lbs clyde). Butted steel tubesets can be had for cheap compared to some Ti / Aluminum sets. Also, setting up to braze is much cheaper than buying a TIG welding setup. Its going to be a heavy duty XC / All-Mountain-ish build.

I went ahead and measured up my current ride, a 2008 GT Avalanche, and drafted it out. I then went ahead and tweaked a few measurements to fit me better.

An anglefinder and a good math set (compass, protractor, etc) is vital to correctly draft out your design and accurately measure all angles and tube lengths.

I then went ahead and plugged all the info into BikeCAD from the bikeforest.com website and came out with my design. I also had to input all the tubing diameters to keep things on track. There are alot of dimentions to take into consideration including fork length, headset stack height, bb drop, etc. BikeCAD is pretty simple though, you just plug in your desired criteria and out comes your design. From here you can re-draft and finalize your design.

Afterwards, I drafted my frame design out again and finalized the measurements and angles.

Step Two will be required tooling and jig construction........