Author Topic: Myford Super 7 Tailstock Micrometer Dial  (Read 1360 times)

Offline Graham Meek

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Myford Super 7 Tailstock Micrometer Dial
« on: September 20, 2018, 10:43:59 AM »
Hello All,

It has been a while since I last posted, and my apologies for that.

Following a request from a Forum member I have been working on the design for a micrometer dial for the Myford Super 7 Tailstock handwheel.

George Thomas came up with an elegant design some years back. While it was graduated 0 to 0.3" and gave 0.001" per division using this in conjunction with the barrel markings in eighths would not have been easy. Easier if the barrel had been graduated in tenths of an inch. Of course it did nothing to help those with a metric lathe.

I have worked out two designs and the schematic is shown below. A metric version graduated 0-10 mm per rev has an error of reading plus by 0.000127 mm per rev. The imperial version is graduated 0-0.500" and has no error. This is always assuming a true theoretical pitch of 0.300" on the tailstock feedscrew.

Both dials have a friction Zero setting as used on my Apron handwheel design. I have also added an oilite bearing to reduce the need for constant oiling as well as a Needle thrust race to compensate for the reduced Handwheel boss diameter when ejecting drill chucks , centres, etc.

As yet I have not detailed all the parts, but I have had the maths checked as regards the gear ratios.

My best regards
Gray,

Offline Jasonb

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Re: Myford Super 7 Tailstock Micrometer Dial
« Reply #1 on: September 20, 2018, 02:04:34 PM »
That's quite a steep pitch screw on the Myford, never knew they were that coarse is it multi start? I'll stick with my Far Easten machine with it's 10tpi tailstock screw and 100div handwheel.

Offline Graham Meek

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Re: Myford Super 7 Tailstock Micrometer Dial
« Reply #2 on: September 20, 2018, 03:01:24 PM »
Hi Jason,

The Myford tailstock thread is a 3-start thread, the thread form is Acme but follows the proportions of a 10 TPI thread form. I know that sounds like a contradiction but I could not see any other way to describe it. This does give a very sensitive feel when drilling with small drills. From what I remember that is, as I have not owned one for a thirty plus years. My Maximat Super 11 came with a 2 mm pitch thread and is fitted with a dial as standard. This is a good compromise as far as I am concerned.

My best regards
Gray,

Offline Graham Meek

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Re: Myford Super 7 Tailstock Micrometer Dial
« Reply #3 on: September 23, 2018, 03:51:54 PM »
Just to let those of you who may be interested in this design know, I am writing an article on these dials. As regards when and which of my usual magazines will publish first I cannot say. A lot will depend on how soon I finish the prototypes.

I have also been asked if these dials will be available commercially?
Whether the ME suppliers will manufacture this dial alongside the Handwheel Dial for the same lathe I do not know. I express the usual caveat about no financial involvement in this. No doubt if there is a requirement for the dials the need will be met.

My best regards
Gray,

Offline Don1966

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Re: Myford Super 7 Tailstock Micrometer Dial
« Reply #4 on: September 23, 2018, 05:46:42 PM »
Interesting design Gray I did make one for mine years ago from George Thomas design and had started the carriage micro dial but have never completed it as of yet. Love the addition of the bearings in your design.


Don

Offline Graham Meek

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Re: Myford Super 7 Tailstock Micrometer Dial
« Reply #5 on: September 24, 2018, 06:22:39 PM »
Hi Don,

Thanks for the kind words of encouragement. I fitted a needle roller thrust race in exactly the same way to supplement the ball thrust race on my Maximat not long after it was delivered, (1986). The difference this makes when ejecting tailstock tooling is very noticeable. From this point of view the fitting of the thrust race alone is a worthwhile improvement.

My best regards
Gray,

Offline Graham Meek

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Re: Myford Super 7 Tailstock Micrometer Dial
« Reply #6 on: September 26, 2018, 02:45:49 PM »
Has anyone any pictures of the Super 7 tailstock dismantled by any chance.

I am wondering if Myford had a short register for the bearing housing to locate in the tailstock body.

Also has anyone ever measured the "effective diameter" of the 1.375 x 20 TPI thread used on the bearing housing.

My best regards
Gray,

Offline Graham Meek

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Re: Myford Super 7 Tailstock Micrometer Dial
« Reply #7 on: October 11, 2018, 01:06:39 PM »
Since the last post things have moved on a pace. Thanks to help and information from several forum members I have been able to make a start on the prototypes. The bearing pieces are finished machined and the dials require engraving, stamping, blacking and finally grind to reveal the scale.

The large ring in back ground is a gauge ring made to suit the thread dimensions.

I am indebted to John Slater who has produced some excellent 3D views of the assembly which I think might help to explain what is going on inside the dial.

My best regards
Gray,

Offline Xldevil

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Re: Myford Super 7 Tailstock Micrometer Dial
« Reply #8 on: October 12, 2018, 12:28:46 PM »
Regarding your thoughts about a commercial version of this very great upgrade for Myfords,
I would ask the people of Hemingwaykits.
Maybe they have interest to make some kind of DIY kit available .

Offline Graham Meek

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Re: Myford Super 7 Tailstock Micrometer Dial
« Reply #9 on: October 13, 2018, 11:12:50 AM »
I must apologise for not getting back to you sooner, yesterday was not a good day.

I am reluctant to comment on the commercial side of this design, other than I am not connected in anyway with my designs that are on sale. I have always given my designs via articles for people to make their own versions. Increasingly today many would rather purchase these items ready made. I did for a number of years make the Handwheel Dial for the S7 for Neil Hemingway to sell and made over 500 in my time, but my health issues got in the way some years back. Given the success of the Handwheel dial for the S7 I see no reason to see why this new design will not follow suit.

My best regards
Gray,


Offline Graham Meek

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Re: Myford Super 7 Tailstock Micrometer Dial
« Reply #10 on: October 27, 2018, 10:04:53 AM »
Hi All
I have managed to complete the gear cutting this week and started on the graduations on the dial. A test rig was made to check the meshing of the gearing at the correct centres. This test rig was also designed so that a check could be made on the gearing ratios once a dial was graduated. The first photograph shows the marker pen dot at zero, although the camera could have been a little more in-line. This was after 5 complete turns of the screwdriver slot. The slot in the sleeve gear and the screwdriver slot were aligned to start with. As can be seen from the photograph they are in alignment again.

The second photograph shows the metric train after 4 rotations, the dial is reading 30.50. The reading should be 30.48, but given that I am only working by eye to a pointer on the screwdriver slot on this one I am not too worried about the error. The dial however should read plus as the gear ratios dictate this. Once I have numbered the dial I intend to carry out the same 5 turn check which should show 38.1 in theory.

My best regards
Gray,

Offline Admiral_dk

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Re: Myford Super 7 Tailstock Micrometer Dial
« Reply #11 on: October 27, 2018, 03:40:36 PM »
I can't say that I will need them, as I have a different lathe - but that is a very nice design and beautifully made  :praise2:

Best wishes

Per

Offline Graham Meek

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Re: Myford Super 7 Tailstock Micrometer Dial
« Reply #12 on: October 27, 2018, 04:35:26 PM »
Thanks Per,

I don't own a Myford either, but I wanted a challenge at the time and I am glad now that I made them.

It finishes off my foray into attachments for the Super 7 and I am sure the prototypes will go to good homes. Hopefully later this week I will be posting photographs of the finished dials which I have just completed today.

5 turns on the metric dial does read 38.1 as far as I can ascertain with my jury setup.

My best regards
Gray,

Offline Graham Meek

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Re: Myford Super 7 Tailstock Micrometer Dial
« Reply #13 on: October 28, 2018, 03:22:11 PM »
Today marks the completion of this project. The two assembled dials are ready to fit. Maybe in due course my collaborators will send me some photographs of the attachment in-situ.

My best regards
Gray,

Offline Graham Meek

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Re: Myford Super 7 Tailstock Micrometer Dial
« Reply #14 on: November 05, 2018, 09:52:47 AM »
Well just when you think you have finished a project someone asks but will it fit my lathe.

In this case the Myford Super 7's big brother the 254. It turns out Myford used the same, or similar parts so what fits the S7 will fit the 254 as regards this attachment.

The only detail change regarding the design is to alter the shape of the dial to match the 254 dials. There has also been a detail change since the first schematic, in that the tailstock handwheel has been reduced to 23 mm diameter. It was felt there was insufficient material left at the root of the sleeve gear teeth. Sometimes when the gear cutter is past its best, especially with brass or bronze there is a tendency for the material to be pushed away from the cutter. With thin wall sleeve gears this usually means distortion in the bore.

My best regards
Gray,