CNC?........ No skill required!
A very pleasant and light evening, just as well as I had to drive on my own for the evening due to holidays and baby-sitting! All the workers were there putting out the chairs and tables and our speaker, John Scott, from the Bedford club getting set up at the front.
In his absence, Rob had given some 'elpful ints' to Roger E for filming the evening and Roger was also tasked with taking photos of the members and the items on the back table.
The bell was rung and our Chairman opened the proceedings with updates on the progress that had been made during the day on moving our two Puffing Park containers to their new positions, one by the station and the other inside the track area. Photos are there for the looking and only a few of us feel guilty as we were not there.
Our Chairman introduced John as our speaker for the evening, and some may recall seeing John at previous evenings. It is always nice when the speaker stands confidently before you and you feel relaxed and interested in the subject matter. John proceeded to put most of the questions up on the screen that we might ask and that he would cover in his talk.
Like many present, he was committed to getting something to work and then improving it and making sure it would perform well. Once I had oriented my X, Y and Z axis I started to see what he wanted to do and how he going to do it. He was keen to show that the C (in CNC) did not stand for computer and although a program or sequence of instructions needed to be written the resultant was to control a sequence of events to allow a process to be started and completed.
As John talked he handed out for inspection objects illustrating what he was saying. The edited film shows the equipment he used but also showed how commercial production had gone further even to having five axis of operation in a single machine tool, expensive stuff! The Z axis previously mentioned was to raise and lower the rotating cutting tool. Wood first comes to mind but by carefully allowing for cutting time metal could also be shaped.
John had scheduled his evening talk into 2 parts and so we broke for tea and biscuits.
With part 2 we were invited to see how John had taken a standard milling machine and attached motors to the winding handles but still keeping the manual controls. However, the motors had to give an exact degree of incrementation to the tool and this is where stepper motors play their part, so that the program sequence could be accurately adjusted during the work.
Many of us thought about backlash being a small problem, but it appears that this had been attended to by a continuous balled nut. The nut had a procession of tiny balls in a circular travel within the nut and these positioned the nut on the threaded shaft and all back lash was gone.
This was a whole new concept to me and a sample nut on a threaded shaft was passed around with a warning of dire implications to not screw the nut off the end: fascinating! The material to be worked on had to have a start point which could always be referenced back to and then what might have been done by hand was turned into a series of movements which would go through and repat the same process as many times as required.
Advantages were that the sequence of operation could be planned before actual work was started and there were even programs that could emulate the process on the screen so that the finished article could be seen. It also meant that if expensive material was used there would not be any expensive mistakes.
It was an interesting evening and John was plainly enthusiastic about the subject, a great educational evening, not a single boring moment and ably presented. He was thanked for an interesting evening with a round of applause.
The video's of John's talk are on the club's YouTube channel. Filmed and edited in two parts.
Click on the links below to view the videos:
There were a few members items on the back table and lots of chat and there were two visitors who I hope we shall see again. Thanks go out to all the members who make our evenings go so well, and also our IT 'B team' who set up all the AV, and we all enjoyed great tea and coffee from the catering team as well!
I promised my wife I would not drive in the dark, and it was light when I climbed in to go home and ,as I pointed out, the house lights were on when I arrived home, so technically I was in the clear.
I hope to see you all next month, so until then drive carefully, stay out of the sun and keep well.
Roy
12/07/2025