Fillet brazed steel bikes, handcrafted in Oklahoma.

Archive for February, 2012

Upsize the fantasy, yo

Recently framebuilding icon Richard Sachs posted on his blog something called “downsize the fantasy” in reference to over reliance on machinery. Well, since the machinery is half the fun for some people I just have to poke a tiny bit of good-natured fun;) I’ve slightly upsized my fixture footprint recently.

Although I can make a 90degree miter like this faster with a half round file, this was an initial proof of concept for me.

This one is the one I was interested in, making an angled cut with just a couple of minutes of set up time. In the next few days there will be a tail on the fixture to keep the cuts in phase.  I’ll be installing a chunk of round stock that’s the same size as a bottom bracket shell on an adjustable slide so I can cut tubes to the right length without a ton of setup or trial and error. I have to set the angle with a big protractor, so it’s not totally pro. I works, it only takes a tiny bit of math and rotary tables are frakkin expensive. That part of the fantasy will have to wait a while.

Blurry pic, but you can see how tight the fit is. It’s also the right angle. I’m hoping that will speed things up just a bit, and more importantly save me some unintended shoulder workouts and worn out half round files. Those files, incidentally,  cost more than a decent hole saw and probably last about as long.

Anyway, I should have some frame stuff posted soon.

Boxes and chips

So I’m getting things rolling again after a winter slowdown. Boxes of stuff have been showing up and projects are being worked on.

First, is some nice tubing from True Temper that will make a geared 29er and a geared 650B. It’ll be my first 650B, so I’ll probably get myself a set of wheels and build my next single speed that size.

Next, boxes of parts and tooling.

Goodies from Paragon Machine Works and Enco industrial supply.

Now we have something I’ve been wanting to do for a while, and it took a 5/8″ ball end mill to do it.

I’ve used a wood form to bend my seatstays with until now, it works alright but it’s not an exact science and it can yield a few scrap pieces now and then.

So my plan was to build a set of dies to use with my arbor press, and without a rotary table for the mill I had to use a slightly more labor intensive method.

I bolted down the chunk and cut a groove with the 5/8″ ball end. Then, with the rear bolt acting as a pivot point I loosened the hold downs and rotated it just a tad. Tighten it back down and cut a groove slightly out of line with the first. Repeat until your groove is on a radius. Use a round file to make any final touches to the groove and you’re set.

Now the tube is completely supported on the inside of the bend area, and you’ll have a wrinkle free bend. I’ll be very happy to break this bad boy in on a pair of race bikes for my East Coat Test Organization (ECTO) or more commonly known as Flying Dog Racing of Fredrick, MD.

That’s it for today, more will follow fairly soon.