Woody – Page 28 – Woody's Workshop

August 3, 2021

Rear Parting Tool Post on Myford Super 7

I’ve been meaning for some time to make a rear tool post for my Myford Super 7 when parting off material. There are various comments on the web about how a rear mounted blade is the best way to succeed for this activity.

Hemmingway Kits here in the UK offer a kit of materials and instructions based on the Geo. H Thomas design as detailed in his ‘Red Book’ (ISBN 1-85761-000-8). This seemed like a good route to take.

The kit arrived with all the materials and documentation needed including a casting for the body of the post. You do have to make a couple of cutting tools as part of the activity but again the material is supplied for this. I found that having access to the Red Book in conjunction with the Hemmingway kit notes helped me better understand what was involved.

Having the Tormach CNC mill allowed me to depart slightly from the intended construction but it all came together very well. I had some Myford Aqua blue paint to hand from my Clough42 Electronic Leadscrew control panel enclosure and this finished off the project nicely as shown below. However I do need to crop back the excess on the rear of the blades before blood is spilt.

Hemmingway rear tool post parting tool holder — The finished rear parting tool holder made from the Hemmingway Kit

Trial cuts have so far been excellent. I can now use the power cross feed when parting brass which is a major departure. Overall a good addition to my workshop assets and a relaxing pleasure to make.

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July 11, 2021July 12, 2021

How to square up a scrap piece of stock ready for machining

Can’t Remember How to Square Up Material Stock ready for CNC ?

I sometimes have to dig deep in the odds and ends heap of rough bits of materials to use on a project. This results in having to square up the find so it can be easily programmed into Fusion CAM. I always have to scratch my head on the process which is well documented by Tom Lipton and This Old Tony among others. What I needed was something to pin on the wall to remind me.

The result of this frustration is a write up and a graphic which you may find useful. Here is a screenshot and the link below it provides both this document and the write up in a ZIP file.

Squaring Stock

Hope that helps and if it isn’t well explained let me know and if it was useful also let me know.

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July 5, 2021July 5, 2021

Myford Super 7 backlash solution with thrust bearings

One Job Leads to Another

I had a job for a customer that needed two M18 screws cut on the ends of a shaft. I have never cut anything that size before but fortunately I have installed the Clough42 Automatic Leadscrew system fitted to my Myford Super 7 Big Bore lathe.

I tried some trial cuts using the Geo Thomas ‘Red Book’ top slide method but I found there was so much backlash on both the top slide and cross slide that I was struggling for consistency. In the end I did a hybrid cut ‘nearly there’ using the ALS using plunge cuts and then I finished with a nut die that was happy to start on the part cut thread . This gave me a clean finish to the thread and I was relieved to get the job done. Note that my S7 is a ‘metric’ version but the leadscrew is Imperial so screw cutting using the ALS entails keeping the half nut engaged and reversing the drive.

With the job completed my thoughts came round to giving the Super 7 some TLC to try to improve the backlash issues. I found various discussion threads about fitting thrust bearings to the cross slide and top slide but all referred to EBay thrust bearings that were no longer listed. After some investigation I found Simply Bearings had two suitable items in stock. The NTA916-TRA916 is a 9/16″ core diameter bearing and washers suitable for the cross slide and the NTA815-TRA815 is a 1/2″ set for the top slide. I ordered two of each set.

The attached PDF link below gives details of how I implemented this modification.

Myford Super 7 Thrust Bearing Mods

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June 25, 2021

Tormach PCNC440 Z axis oil manifold access

Turning a Dribble into a Flow

The right hand side oiler for the Z axis on my 440 has always had a poor oil feed to the slideway. I had tried to clear all the pipework that is easily accessible but with no improvement. I was conscious that deeply embedded in the spindle assembly was an oil manifold that fed the left and right slideways and the ball screw. Could this be the source of the problem and how was I going to get at it without a major strip down of the Z axis spindle assembly ?

Looking down from the top of the spindle assembly I could just see the manifold in a hole in the casting. If I could get to this I might just be able to work on it without a major strip down.

First of all an apology that I do not have any photographs of what follows as I was so engrossed and so grubby that I left my phone secure and out of the way. The process will become obvious as you progress and is not overtly difficult.

The stripping process was to remove the two screws holding the door interlock switch, remove the four screws holding the wrap round cover, remove the holding pin on the power drawbar and remove the two bolts holding the spindle motor. With all these fixings and parts freed off it is possible to lift the outer cover up and over out of the way and to lay the spindle motor inside it. It is tight to shimmy the cover around the power drawbar body flange but it is possible without removing the drawbar piston assembly.

With all this removed it fully reveals and gives access to the cavity containing the manifold. It is a short term joy because it is pretty much impossible to undo the right hand side oil feed as this is from the end of the manifold.

Light bulb moment – if I drilled two 6mm holes in the assembly casting opposite the two hex head screws that are holding the manifold in place, I could get a hex driver T bar to remove these screws and free the manifold from the casting wall. This would allow the manifold to be moved to work on it.

Here is a drawing to help locate the two holes giving the distance from the back and bottom of the casting. (The lower black and blue assembly is my fogbuster mounting).

Once the manifold is free to be moved around it is possible to remove the right hand feed pipe and remove the associated length of pipework to clean it. I found the manifold end of the pipe had not been cleanly cut and was restricting oil flow.

A word of warning – the oil feed to the ball screw is a semi rigid pipe and this terminates in the side of the ball screw. Do not overstress this length of pipework or there will be tears.

Assembly is the reverse process. Apologies once again for the lack of supporting pictures.

I can report my right hand side Z axis slideway oil flow is much improved.

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June 24, 2021June 24, 2021

Adapter plate for a Tormach microARC to mount a Xin Dian centralising vice

I’ve made mention in another post of the arrival of the Tormach microARC to use on my Tormach PCNC440 CNC milling machine. The microARC provides a 4th axis facility.

To date I have used this with the supplied chuck but there have been a couple of instances where a vice style stock mounting would have been useful. I am indebted to David Loomes for bringing the Xin Dian centralising vice to my attention.

This is available from various sources on the Internet and at a delivered price of less than GBP100. It is a lovely little vice. It is supplied with an industry standard backing plate which is held in place with four M6 cap head screws. The supplied backing plate is not suitable for mounting on the microARC .

A 3D model of the microARC is available as a Fusion file and this with some careful measurement allowed me to model a mounting plate for the Xin Dian to fit onto the microARC face.

As a secondary activity I edited the Fusion file to provide a simple sub-mounting plate for the Xin Dian vice on my PCNC440 tooling plate.

Details of both these mounting plates are contained in the PDF link below.

xin dian vice mounting plates

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