bonnie & jason

Bike build part deux – tube notcher

By jason, November 25, 2008 on 11:38 pm | In biking | No Comments

There are going to be lots of bike build posts in the future so for those of you looking for Alissa pictures, feel free to gloss over these. On to the topic of the day! I got the bench grinder bolted to the work bench and bought some c-clamps and other hardware to make the Grizzly tube notcher work. This tube notcher is a cheapo version of the “Ol’ Joint Jigger” and it shows in the quality. I had to clean up and grease the saw shaft because it was kinda rusty and did not twist freely in the bushings. Also, the degree scale is pretty much worthless because 1) there is no arrow pointing at the scale to begin with and 2) the hole saw shaft isn’t really square to the tube fixture. I made it work by making my own arrow and calibrating the shaft to the fixture. Finally, the adapter that connects the shaft to larger hole saws was drilled eccentrically so that the saw would wobble when rotated. To Grizzly’s credit, they’re sending me a new one gratis. In the meantime, I was able to use the adapter that came with my Rigid Hole Saw kit.

The other thing I wanted to be careful about was the tube fixture. It’s not defective, but given bicycle tubing is pretty thin, I didn’t want to dent it by tightening down on the clamp too hard. So I just cut a couple pieces of angle iron and used them in between the fixture and the tube to distribute the holding force across a larger area.

Anyway, after I got the notcher ready to rumble, I clamped it to the work bench, tightened up the 1/2″ drill to the shaft, and went to town on a test cut.

Here’s the result:

All in all, it did a pretty good job. It only took 30 seconds to do and this was slow since I was experimenting with how hard to push. I did notice that the tube seems to be sitting a bit low compared to the saw so the cut is offset a couple millimeters. That might be because of the angle iron I used to support the tube. I need to dig into this a little more before I make the actual “money” cut. Otherwise, the cut is pretty clean. If it wasn’t for the offset issue, a few minutes with a hand file and this tube would be ready for brazing. All in all, I’m pretty happy with the purchase. Without this, I’d probably have to spend quite a few hours calculating, rough cutting, filing, and cursing all the miters I’d need for the bike. Now, those hours will likely be turned into minutes. Yay tools!

Next on the list of things to do is to fix the offset problem, make the “money” cut, and try my first braze of the seat tube to the bottom bracket. (As soon as my silver, flux, and welding goggles arrive.)