Introduction

CNC lathes have been part of engineering and manufacturing for 70 years or more – quite amazing!

Why has it taken so long for the idea to filter into the hobby and designer/inventor markets you may ask?  Well, as always the primary reason has been cost. Most of the machines that industry use have always been costly due to the nature of their capabilities and accuracy. As a consequence they can cost hundreds of thousands if not a million pounds or so but, you invest in a superbly engineered machine tool that have state of the art electronics, hardware and software specially designed for that machine.
Even in the 1980’s when hobbyist CNC systems were venturing into the market, the price and limited capabilities of the machines were restricting factors due in part to dedicated electronics and software having to be designed for each type of machine. Also, the cost of such things as stepper motors were still extremely expensive and didn’t provide the size to power ratio that we are accustomed to today as there wasn’t a mass market for them at that time. That was the case until more recent times where there has been a staggering growth in the need for motion control products which has led to a wide variety of smaller CNC machines becoming available and with the introduction of the internet there have been many free open source developments for CNC.

So, why should industry have all the fun?  Well, times are changing and now you can have some of that fun too and enjoy new levels of creativity but at a fraction of the cost.

This CNC conversion kit has been carefully designed for the Myford Super 7 lathe so that it doesn’t distract from the lathes original appearance or need any major modifications doing to the lathe itself. So, the lathe could always be put back to it’s manual condition if CNC isn’t for you, which I would find hard to believe! It also aims to achieve as much accuracy as possible  from this design of lathe through the use of robust castings and good quality parts that can stand up to the higher demands expected of CNC.  Believe me, at the start you will probably be content watching the lathe take small depths of cuts and cautious feed rates,  but after a while this becomes tedious and there is a natural curiosity……. ‘how far can you push this machine’……….I’ve been there myself and in the aid of research and development used some punishing test routines on my prototype machines. I am pleased to say that the original machines are still a good workhorses to this day after many years of use!
The precision components and castings within the kit have all been carefully machined  to high standards  and make up a unique design that transforms the original Myford  lathe from it’s humble beginnings back in the 1940’s to a 21st century manufacturing machine capable of many operations and speeds that would never have been thought possible.  The creative possibilities for turning and screw-cutting are endless.

Some of the benefits of adding the CNC conversion are:

  1. Parts can be repeated easily at anytime

  2. Digital readouts are built into the software packages so there is no need to add linear scales to the slideways.

  3. Work and design methods start to become more ingenious and creative

  4. Minimal backlash can be achieved by using pre-loaded ball screw nuts which allows better directional accuracy.

  5. By using ball screws, the efficiency of converting motor torque into linear motion of the slides is greatly increased. ( a standard lead-screw and clasp nut arrangement may only be about 45% efficient whereas a ball screw can be in the region of 95% efficient !)

  6. No need for a costly gearbox with additional gearing for metric conversion.

  7. No need for a taper turning attachment

  8. No need for a ball turning attachment

  9. Provides a far wider  range of screw-cutting pitches than the standard Myford could ever achieve. A standard lathe would have been able to achieve a maximum pitch of 3.175mm (0.125”). Some of my CNC threading demonstrations have shown example pitches in the range 0.25mm (0.0098”) to 25.40mm (1.0”)

  10. Multi-start threads can be cut with ease. (https://www.youtube.com/watch?v=58FSddYEzmc) this video link shows one of my 10 start thread examples.
  11. Threading close to shoulders without the need for an undercut can easily be done

  12. Lathe alignment errors could be compensated for using either mathematical functions or by a simple offset using either addition or subtraction of the amount of error along the length of the axis to be corrected in the case of linear moves.

  13. With additional forward and reverse switching (maybe using a MESA breakout board), rigid tapping could be performed

  14. Peck Drilling for automatic drilling routines. (great for deep hole drilling or just for the fun of it!).

  15. By fitting a vertical milling attachment perhaps like the Myford Rodney mill/drill, the lathe now becomes a CNC milling machine!  Ideal for a clockmaker, or where workshop space is limited.

 

I hope that you enjoy the new creativity and fun that using CNC adds to your engineering projects.

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