Bentech Step 2-1/8

Main tube with head tube clamped in the jig.
The drill thing is what I used to drill the hole for the head tube.
White u-strip will be welded on for the idler wheels
to get the chain up and out of the way of the front fork.

Here the u-strip has been welded on ...
and you see the two chain idler wheels.
The idler wheels were skate wheels that I turn on my drill press.
the blue thing is just a temporary spacer ...
because I didn't have another 2" x 5/16' bolt.

Here's the current status of the main tube ...
the portion to the left of the head tube will be shortened a bit
when it is tweaked and bored for the bottom bracket.

Bentech Step 2

The main tube has been shortened, I marked the centerline of the sides of the tube, marked the head tube points, center-punched them, used a 1/8" drill bit and drilled pilot holes, then used a bi-metallic holesaw with a 1/4" center bit to drill from each side ...
to drill out the hole for the head tube.

Here I've tack-welded the head tube into postion. You may be wondering how the decision was made as to how much of the head tube would protrude above or below the main tube ... I took off the front end clamps, loosened the 2 clamps to my right, rotated the front end of the main tube 90° up, tightened down the 2 clamps to the right, inserted the head tube so it rested squarely on the surface of the jig ...
I tacked on one side, then directly 180°opposite on the other side. Then the two opposite ones for front & back.
The white u-bar will be the bracket for the chain guide idler wheels.

Here's a view of my welding ... dressed up by the hand grinder.
The head tube is now firmly in place.

Bentech starting

I've built one of these before.  This was made with a muffler pipe and a Huffy Mtn bike (the Huffy front forks became the rear forks on the Bentech SWB).  I had USS (under seat steering) on it.  It ended up being a favorite bike due the ease of transporting it and because of sitting high enough that I was quite visible in traffic.  That's very important when you are riding through a BIG city.
Anyway, back to construction ...

Here's the maintube (muffler pipe again) clamped in the jig.
This tube is a little long ... I could only buy a 10 ft. length,
so I had it split into two 5 ft sections ... a muffler shop did the bend for $2

This is just the start ... shortening & drilling comes next ...

Changed Front Crank/Gears

The DeltaWolf trike had the the single speed front ... 38 teeth
which came off his sister's bike.
But there were all kinds of problems climbing hills.
So I ordered this new 3-ring front crank 152mm 48-38-28 teeth.

From this view you should be able to see the 3 rings of teeth ...
the chain is currently on the smallest one ...
Which should allow him to climb hills better.

Here you can see the added front derailleur ...
with 3-click twist-grip shifter on the handlebars.

Not Much Different ... But Changes

The Mach2 doesn't really look much different from last time ...
Still waiting on cables ...
Having ridden it several times ... I made some small changes
that are important to me.

It seemed like a good idea that the steering could be moved up and down ... But after riding it several times ... all that movement really irritated me. So, I pulled out the delrin (plastic) plug and cut the middle out of some funky handlebars. This foto shows that piece welded in where the delrin used to be ... and clamped solid at a good ride-able height. Just one less moving thing ... and it rides better because of it.

Even though the seat support bracket was hose-clamped to the main tube ... it tended to rock from side-to-side. If you off-balanced, it would roll to the side (like a horse saddle that wasn't properly cinched) ... and down I'd go. I centered it where it felt right ... then tack-welded it at the corners so it wouldn't move anymore. Way much better!

Mach2 - First Ride

At this point I finally put a chain on the Mach2. There's also a skate-wheel idler roller (red) to keep the return chain from flopping. I finally rode it for the first time. I like the way it handles.

No brakes ... No shifting gears ... Still waiting on cables so I can connect those up. I have some issues with the front forks ... may change them for another set. I'm going to make the steering solid so it doesn't move up and down. The seat base needs to be welded to the main-tube.

Its currently only for flat-ground ... no hills ... no speed ... yet. :-)

Jig - Update

The blocks are mounted on the jig.
The tubing lays in the center of the blocks
and is clamped by screwing down the top half.

I've lifted the tops off ...
and you can the bottom half's are screwed to the jig surface.
Nest Step: get 1-3/4" muffler tubing

Bentech SWB Jig

2 x 4's aren't necessarily 8 ft. long anymore ... so the foundation of the jig ended up being about 46" long. That was on the left side ... where the overlap won't matter all that much. The holes drilled in the plywood are used to insert clamps to hold the main tube firmly in place for little operations such as drilling or welding. There's one 2 x 4 block on top ... I need 8 of them. More about this later ...