Alex Wetmore is always busy with something…

The next step in building my frame is attaching the seatstays. Before doing that I needed to make sure that the chainstays were properly aligned. It will be much more difficult to correct axle alignment issues once my seatstays are attached to the frame.

Whenever I have the bike on the alignment table I double check the head tube and seat tube alignment. This is how I setup the bike:

The frame is connected to the table at the bottom bracket. The bottom bracket post is machined to be exactly perpendicular to the table, and the table is a flat reference surface. If the frame is aligned then it should all lie in a plane exactly parallel to the alignment table.

The first check that I’m doing here is comparing the plane of the head tube to the plane of the seat tube (I’ve already checked that the seat tube is square to the bottom bracket shell).To do that I’ve rotated the frame so that the head tube is over the alignment table and the bottom of the seat tube is also over it. My head tube is 33mm in diameter, while the seat tube is 28.6mm. To make alignment checks easier I put a dummy steerer inside the head tube (that has a 1″ or 25.4mm diameter) and then put a sleeve over the steerer which makes it 28.6mm in diameter. That looks like this:

The pointy thing coming down from the top is a scratch gauge. I set it’s height so it just barely touches the sleeve. When you draw it across the sleeve you can just hear it make a scratching noise. It is important to check both sides of the steerer to make sure that it isn’t twisted with respect to the seat tube. At this point in the build it would be very difficult to correct that, but when the frame was just tacked (before final brazing) it was easier.

Then I slide the scratch gauge over to the seat tube and compare it. In this case it is perfect, I also get just a very light scratching noise:

Now that we’ve double checked the front triangle alignment it is time to take a look at the chainstays. First I check to make sure that they are centered with respects to the seat tube. To do that I use this alignment gauge that I had made (I copied the design from Martin Tweedy) and a height gauge to hold it. In this photo I’m aligning the height gauge with the seat tube. Notice that the frame has been rotated on the alignment table to put the chainstays over the table.

This is what the chainstays look like when I slide the alignment gauge over. Clearly they aren’t centered:

The alignment gauge has steps for dropout spacings of 100mm, 120mm, 130mm, 135mm, and 145mm. This bike will have a 135mm Rohloff hub, so I cold-set (bend) the stays to make them work with the second largest steps:

Now we know that the stays have the right spacing and are centered on the seat tube. We haven’t checked to see if they are in line with each other. To do that I use a square placed on the table. This is how the setup looks:

This angle doesn’t tell us too much, but looking from above we can see that they aren’t properly aligned:

It just takes a little push to eliminate that gap.

On a final alignment I’d also use the Park dropout alignment tools to make the dropouts square with each other. I don’t need to do that at this point though.

The whole process is iterative. After every change I need to go and double check anything connected to what was changed. In the process of cold setting the rear dropout spacing I could easily bend the chainstay up so that the dropout is a millimeter or two out.

This is obviously only showing a little bit of the alignment process, but it covers the basics of how I use the alignment table. You can also see why a larger table would be nice. I have to rotate my frame many times to compare everything. A 2×3′ table allows you to check the whole front triangle or the whole rear triangle without rotating the frame. A 3×4′ table is enough to check alignment of the whole frame without rotating it. My table is 8″ wide by 32″ long.

I have nothing finished to show, but I have progress on the deck, cargo bike, and my bicycle jig.

The deck is half done. We were hoping to finish it this weekend but the 90F weather kept us off of the roof. We’re also waiting on 5 more boards to be delivered. The new decking is Tigerwood (from Ecohaus) and I really like how it looks so far. We’re using hidden fasteners called EB-TY. It took us a little while to figure out the best way to build the deck (especially because we are doing it in sections so that it can be disassembled), but now it is going pretty fast. Hopefully we can finish it up next weekend.

I’m embarrassed to show these photos of the cargo bike and fixture in progress because they show how much of a slob I can be about my workspace. The basement is a disaster, but I never feel like stopping work to tidy up.

The CAD drawing has been updated. There are a few changes and I switched the drawing to much easier to work with software (TurboCAD, I was using QCad).

/P>

Real progress on the cargo bike is occuring on two fronts. The first is building tooling that will be used on any frames that I built. I have most of the front triangle fixture completed. I’m building my fixture around a milling table that is 9 inches by 36 inches with 3 T-Slots running the length of the table. This table is accurately machined flat (not as perfectly as a surface plate, but well enough for bicycle frames) so I can also use it as an alignment table.Everything will be modular so that I can use the same base for building forks, rear triangles and other things.

Here is the table setup as a front triangle jig:

The bars under the seat tube and head tube are made from pieces of 80/20. They have T-slots in them too and are connected to the table using some brackets that I made. The brackets connect to the 80/20 usingT-Nuts that 80/20 sells and to the T-Nuts for the milling table. The milling table T-Nuts are setup for 1/2-30 bolts that are huge, but I bought some reducing bushings from McMaster-Carr that let me use smaller bolts. I can adjust them to any angle (using a protractor to check the angle) and then lock them into plate.

The tubing is held in these towers which are also primarily 80/20 with tube holding cones that I made on the lathe. I got the idea for these towers from a bicycle jig on Instructables, but changed the setup to be height adjustable. I shouldn’t need to adjust it once the whole thing is dialed in.

The bottom bracket is held in place with a vertical post and cones which sit on it. This is sort of an exploded view, with the top cone loosened. Everything is clamped in place with two clamping collars.

The other progress is on the cargo bike itself. As you can see in the first photo the donor frame has had it’s paint stripped (where I need to braze to it) and the headtube and downtube have been cut off.

The cargo tube on the cargo bike has some really tricky mitering. I built a fixture to do this miter (and others) on the lathe. This is what the mitering fixture looks like: (I’ll take some photos of it in use next time I’m using it).

It mounts to a T-Slot in the lathe’s compound slide. I can set the angle to on the compound slide to my miter angle and then use a hole saw to make the cuts. That block was made on the lathe and boring a 1.75″ hole took a long time. I’ll be able to use it for other tubing sizes with some reducing bushings that I need tomake. The mitering fixture works really well,but I need to tweak it a bit to get it better centered. Right now the miters are about 1mm off of center.

In that photo you can also see one of my test joints (I’ve made three of these and cut the other two apart). I’m pretty happy with the brass penetration that I’m getting,but the brazing looks a little sloppy and will require cleanup work. I’m getting better with practice, these big joints are a lot different than the little ones that I make for racks.

The joint is neat because the smaller tube completely pierces the larger one. When looking at it from the end you can see light coming around the smaller tube: