Alex Wetmore is always busy with something…

The Fork Fixture Kit is sold as a partial kit.  Custom and harder to source parts are included, but you need to supply the rest.  This helps to keep costs down.

Features:

The steerer clamp is secure and fast to use:

The blade support is used to make sure that the crown and blades are square.  You can push it down and out of the way when you are brazing the fork.  You can adjust the pivot bolts to allow it to stay in place and to be moved by hand:

The dummy axle holder has three bolts.  The deeply recessed one is used to move the holder up and down on the riser.  The other two bolts lock the dummy axle in place:

You can arrange the jig with the fork facing up or down.  There is plenty of room for high rack forks either way, how you use it is up to you.

Assembly Instructions:

Kit Contents:

• A piece of extrusion which acts as the V-block to hold the steerer.
• A piece of extrusion with a 1/2″ hole in it which acts as the fork blade support.
• Pivot places for the fork blade support.
• A dummy axle holder.
• A 101B-style toggle clamp and a bracket to connect it to the V-block.

All parts are supplied in the raw machined form.  You want want to deburr the sharp edges with a file or light sandpaper. 

Note: There are two variations of the dummy axle holder.   Early kits have a 2″ long version with a groove milled into the back.  Most kits have a 3″ long version with two 8mm pins.  Both versions work and perform identically, but you’ll see both used on this page.

Shopping List:

• From 80/20  (80/20 Surplus on eBay is an easy source, total under $60+shipping):
  • 25x 3286 T-Nuts
  • 4x 4367 15-series 4-hole joining plate
  • 24 inch section of 1530 extrusion (the fixture’s backbone)
  • 8-12 inch section of 1515 extrusion (the riser for the dummy axle)
• From a well stocked hardware store:
  • 25x 1/4-20 x 5/8″ socket cap bolts
  • 3x 1/4-20 x 7/8″ socket cap bolts
  • 4x #10-32 x 7/16″ bolts (or M5 metric equivalent)
  • 4x #10-32 nylock nuts (or M5 metric equivalent)
  • 6″ rod or thickwall tube (it needs to be true and accurate to size, don’t buy junk)
• From Anvil Bikes: ($35 + shipping)
  • A 100mm front dummy axle (or make your own on a lathe, which is what I’ve done). 

The dummy axle needs to have a 1/2″ diameter and 1.35″ long clamp section.

You can use the “light” or “regular” extrusions from 80/20 for this project.

Assembly:

This is what it looks like when you have all of the parts laid out together.  We’ll build the kit from the rear of the fixture to the front.

The first step is to assemble the #4637 joining plates and fasteners.  Use 4 1/4-20×5/8″ bolts and 4 3286 T-Nuts with each plate:

Next put the V-block onto the backbone piece of extrusion and connect them with joining plates.  The exact location of the V-block is not important, but it should be near the rear of the long section of 1530 extrusion.  The V-block holds the steerer, and you may want to scoot it forward for very short forks:

It is important that these two parts are perfectly aligned.  You can check for this with a straight edge.  You can also look for gaps between the V-block and backbone.  Carefully check both sides and make sure that your straight edge can’t rock between the extrusions.

Put the 6″ 0.5″ rod through the fork blade support and secure with the set screw at the end of the support.  The rod and extrusion should be square to each other.

The pivot plates are partially assembled in the kit.  You may want to disassemble them, oil the pivots, and deburr the holes.  Then you should install 4 1/4-20×5/8″ bolts and T-Nuts through the remaining holes.

Attach the pivot plates to the fork blade checker as shown in this photo.  The smaller T-Nuts go into the 1″ extrusion, the larger T-Nuts go into the 1-1/2″ extrusion.  The heads of the pivot bolts face to the outside:

 

Slide the lower portion of the pivot assembly over the 1530 extrusion.  Carefully check to make sure that everything is square before tightening the bolts:

Put the other two pivot plates onto the end of the 1530 extrusion and arrange the extra two T-Nuts so that they are facing up:

Slide the riser into the joining plates and carefully tighten all fasteners.  Use a good straight edge to make sure that the riser is square and aligned with the backbone:

Find the dummy axle holder in your kit:

Cut the two halves of the dummy axle holder in half and file off the bridge of metal that held them together.  The wider portion of the holder with the two 8mm pins in it is the bottom.  Put a 1/4-20 x 7/8″ bolt through the unthreaded hole and attach a T-Nut:

Put the dummy axle into the dummy axle holder and secure it with 2x 1/4-20″ x 7/8″ bolts:

Slide the dummy axle holder onto the fork fixture.  The recessed bolt will tighten it into place:

Assemble the 101B toggle clamp onto the toggle clamp holding plate with 4x #10-32 bolts.  The bolt heads go into the recessed on the holding plate:

Put 2x 1/4-20 x 5/8″ bolts through the two plain holes and attach T-Nuts to the other side:

Attach the clamp plate to the upper slot on the V-block.  The pin on the toggle clamp can be used to adjust for different steerer tube sizes.

Here is a photo of an assembled fixture with a fork on it:

Easy Upgrades:

Clamping Arm

Make a clamping arm for your bicycle stand.  Get a piece of steel that is 3″ x 3″ and 3/16″ or 1/4″ thick.  Drill 4 1/4″ holes 0.75″ from each edge (making a copy of one of the joining plates) and then drill a 1/4″ hole in the center with a hole saw.  Braze a section of tubing to the plate and mount the plate to the center of the backbone.

Don’t forget to measure twice, cut once.  Two of my holes are off by 1/8″.  It doesn’t really matter.

If you don’t have enough T-Nuts for the clamping arm you can get carriage bolts that fit into the extrusion slots at a hardware store.  The slot is 5/16″ or 8mm wide.

Rake Reference Lines

Mark the center lines of the steerer tube on the riser block to make it easy to measure fork offset.  You can do this by putting a tube the same diameter as your steerer into the V-block and marking the top and bottom on the riser.  Measure to the center and scribe a line there for 0mm offset. 

The witness mark down the center of the axle holder can easily be transcribed to the side of the axle holder:

Better Steerer Clamp:

This one comes from Jeff Lyon. Remove the rubber cap and braze on a section of angle steel to get better clamping of the steerer: