Introduction

The 2D LibreCAD file long_reamer_facer.dxf contains a static design for an extra long reamer/facer rod attachment for use with cargo bike head tubes or any other long head tube. It is intended to work with the Park Tool HTR-1(B) head tube reamer/facer set.

The document long_reamer_facer.pdf contains the final drawing, print this for your reference at the machine shop.

Here is a preview of the current design:

Design Notes

The design is currently a WORK IN PROGRESS. It has not been tested.

Materials

• 3ft (or longer) length of ACME 5/8-8 steel or stainless rod. This will do: https://www.mcmaster.com/#98935a829

Instructions

1. secure access to a large lathe, collet chuck, draw bar, and 5/8" collet.
2. chuck the ACME rod in the collet with about 1.5ft stickout.
3. drill a center hole on the end of the rod and secure the end with a live center.
4. install cutter for turning while feeding towards the left.
5. turn down a 27mm length from the end to ⌀11.11mm.
6. install cutter for grooving:
   • side relief on both left and right sides.
   • 8° end relief
   • 0° side rake
   • 10° back rake
7. groove a 5mm segment to ⌀8.85mm. Make sure the step between the grooved ⌀8.85mm segment and stock diameter is faced.
8. install cutter for turning while feeding towards the left.
9. turn down the entire length of exposed ACME thread to ⌀15.48mm.
10. if you have DRO, zero your X axis.
11. pull back the live center and face off about 2mm from the end.
12. make a small bevel on the end.
13. remove the ACME rod from the collet and reinsert it the other way. Grab it in the collet on a turned segment, but near the transition to factory finish. This is not super great for the collet, but oh well.
14. drill center hole and stabilize rod end with live center.
15. turn the entire exposed surface to ⌀15.48mm, or X position zero if you have a DRO.

Software

The design was developed using LibreCAD 2.0.4 (for the drawing) and FreeCAD 0.17 (for the initial outline).

License

This is essentially a copy of the Park Tool HTR-1 shaft with a slight modification (longer ACME threaded section). Therefore, I can't claim any ownership of the design, nor anybody else unaffiliated with Park Tool.