…Know this, my beloved brothers: Everyone must be quick to listen, slow to speak, slow to anger…
Good advice if you’re an instructor!
Bob Rolph is one of the Course Tutors at Axminster Power Tools for the engineering courses and he was our instructor. Amongst screaching noises and burning smells, he certainly manifested the above qualities!
Mrs Linn and I arrived a few minutes late as we lingered over breakfast at Pestoller House Bed and Breakfast in Axminster, talking to Adrian and Caroline, the hosts. What a lovely place they have! Everything just as you like it. They’ve really thought through what makes a good B and B.
At APT, they have a fantastic set up for teaching. They have a central break out area surrounded by four classrooms. Two for woodworking machines, one for routing and one for engineering.
In the engineering room there was five lathes, clean and ready to go. Here’s a picture…
Bob went through Safety first. Always wear eye protection and use the guards on the machine. No droopy cuffs, ties, long hair or beards. This isn’t prejudice against corporate drone/hippy crossovers, but just means those things should be tied back.
Next he went through some maths. Yes, maths. Much to Mrs Linn’s disgust (she would love a world without maths) there are some calculations to be done. This is just to find the correct rotation speed for a given diameter of metal rod. Basically, the smaller the diameter, the higher the rpm. Also, if you want to reduce the diameter by an amount, you move the tool inwards by half the desired amount. D’you know, I spent a good half hour – with many attempts at diagrams – trying to explain why to Mrs Linn. Eventually, I had to have extra beer…
First we learned to set the cutting tool to the correct height. It must be exactly on the machine’s axis. Too low and it leaves a nib in the centre; too high and it doesn’t cut properly and can overheat.
Next, we learned to “face off”, which means putting a metal rod in the chuck and causing the tool to move inwards across the end, squaring the end of the rod to the axis. This is only a 0.5 mm shaving.
Then we turned the rod to smaller diameters. We bored a hole in both ends and tapped one of them.
We took a second piece of rod and turned that to precisely to fit in the holes of the first piece; one end with a screw, one end plain.
Finally, we “knurled” the middle portion.
This is The Thing we ended up with…
The marks on the smallest diameter of the main piece were caused by me forgetting to support the end opposite the chuck whilst knurling. The pressure of knurling was trying to pull the whole piece out of the chuck’s three grips, causing the marks.
On the smaller piece, the end opposite the threaded end was turned to a precise piston fit…
Bob finished the two days by showing us how to sharpen the tools on the grinder.
Here’s a picture of the knurling tool, which impresses the criss cross grip into the middle of The Thing by brute force…
The key components haven’t changed much in all these years. What has changed is how the speed is controlled. The modern lathe; easy to operate precise electronic control. The old lathe; pulleys, belts and a gearbox.
We had great fun and I thoroughly recommend the course.
Big Bad is doing his best at the moment to delay things, but I’m cleaning up a tool holder and a chuck this week. A few bits and bobs after that, then maybe we can have a go at cutting something?