3" Burrell Traction Engine build.

   Cutting The Modified Square Thread-Brake (Part 4).  Me aged: 53 Software Engineer Machinist, with zero tolerance to mistakes.. Simple Idea: Making a Tap from a Threaded Rod Hello everyone—just sharing a simple idea I’ve been trying. Instead of scrapping a brake rod, I decided to practice screw cutting and then use the best threaded piece to make a tap. The goal is to create a matching internal thread for a nut. The brake rod has been completed (As above) but this has taken a few practice goes before committing to this. The results of which I am very pleased with and the square threads look the part as compared to just cutting a metric thread of say 8mm.  What I did Cut an external thread on the rod Used a 4 mm ball-end cutter to make three flutes Offset the cutter slightly to give a bit of rake Cleaned up the edges with a file Case hardened the tool The idea behind it If the external thread is correct, turning it into a tap should produce a matching internal threa...

  Screw Cutting The Square Thread-Brake rod (Part 3). Hello again. (To put a face to the Blog)   The brake rod threading is still very much in the practice stage—we’re now on part 3. Screw cutting is proving to be a real skill to master, especially when it comes to achieving the correct thread form and overall appearance. The latest attempt (shown above) still isn’t quite right, but it will be used as the basis for making a tap. The plan is to produce a clean, symmetrical thread, then mill flutes into it and case harden it. This tap will then be used to cut the bronze nut so it matches the thread that will be machined onto the brake shaft. The current issue is with the pitch-to-width ratio. I used a 1.5 mm cutter for this test, but in hindsight it really needs to be closer to 1.25 mm to achieve a proper 50/50 tooth-to-gap ratio, which I wasn’t able to get here. The drawing specifies 10 TPI (2.5 mm pitch), and while I’m close at 2.55 mm, the groove width of 1.6 mm is too larg...