Graham Meek?s Super 7 Tailstock Dial

[Mike CrossfieldParticipant @mikecrossfield92481]

Question about machining sequence

[Mike CrossfieldParticipant @mikecrossfield92481]

Having recently completed my last major project I have started building Graham Meek’s Super 7 tailstock dial (MEW 279/280). At the moment I am puzzling over the best machining sequence for the main body of the device (the Backplate). There are some critical dimensions and concentricities, and few clues in the articles as to how best to achieve them. I would be very pleased to hear from Gray or and/or anyone who has successfully constructed this useful accessory.

Thanks

Mike

 

 

 

Edited By Mike Crossfield on 26/10/2020 07:43:51

Edited By Mike Crossfield on 26/10/2020 07:45:34

[Graham MeekParticipant @grahammeek88282]

Hello Mike,

From memory the machining sequence went something like this.

The Face and Outside diameter where the dial goes were turned. The main bore was drilled, bored and reamed to take the Oilite bush. Then the counterbore to clear the input gear was also machined at this point.

The part was then reversed in the chuck, (I used soft jaws for this operation), the part is then brought to length. The boss diameter was then machined, along with the blend radius and chamfer. The thread diameter is then roughed out and the undercut for the thread machined to size.

Griping on the roughed out thread diameter in a chuck on the milling table the Idler gear pocket was machined using coordinates. The part was then mounted on a spigot mandrel by the main bore, (dial end nearest chuck). The thread diameter is finished machined and the thread screwcut to the 3 wire dimension in the text.

Hope these notes help?

Regards

Gray,

[Mike CrossfieldParticipant @mikecrossfield92481]

Hello Gray,

Thanks very much for the prompt and very helpful reply.

Just what I need.

Best regards

Keep safe

Mike

[Graham MeekParticipant @grahammeek88282]

Hello Mike,

You are welcome, if I can help you further in the future just ask.

Regards

Gray,

[Mike CrossfieldParticipant @mikecrossfield92481]

Hello again Gray,

I have cut the input gear and the idler gear (imperial) using cutters made according to the dimensions in Figure 5 in MEW 279, allowing for the drawing error noted in MEW 280. However the meshing, although close, doesn’t seem to be quite right. I made the cutters very carefully using the DRO on my mill. I don’t think I made any significant error, and I suspect there may be another drawing error in Figure 5. I think I can see in photo 6 In MEW 280 another cutter dimension (0.55 versus 0.62) in your original drawing which is different from that in Figure 5. If you wouldn’t mind I’d be very grateful if you could check that all the Figure 5 cutter dimensions are as you intended.

In view of these problems with the Figure 5 cutter dimensions, it would be reassuring if you also check that cutter data in Figure 6 is as you intended. I’m sorry to bother you with this, but I don’t know how to calculate the cutter dimensions for myself.

Many thanks

Mike

[Martin KyteParticipant @martinkyte99762]

Hi Mike

You may have found it already but the original build thread is here including all the drawing dim queries

Meek Tailstock thread

I'm very pleased with mine so well worth persisting.

regards Martin

[Mike CrossfieldParticipant @mikecrossfield92481]

Hello Martin

The thread you linked to is the one I started when I pointed out two obvious drawing errors, and I am very familiar with it. However no other errors apart from those I pointed out were mentioned. I now think there is at least one more, which is why I am now querying the MEW drawings again with Gray.

Regards

Mike

[Martin KyteParticipant @martinkyte99762]

OK no worries, didn't realise it was your thread.

regards Martin

[Graham MeekParticipant @grahammeek88282]

Hello Mike,

I have just rechecked my drawings and the dimension is 0.55 mm. You say the gears are close, but not right. In what way? Are they too loose, or do they bind? Will one gear run smoother if it is turned over, (symptom of an offset cutter)?

As regards what appears in the Magazine, my copies were loaned to a friend pre-Covid outbreak, so I cannot currently access them. If you can scan your copy and jog my mind I would be grateful. I have checked all the photographs submitted but cannot see any reference to 0,62 mm.

Regards

Gray.

[Mike CrossfieldParticipant @mikecrossfield92481]

Hello Gray,

The gears I cut ran very smoothly together, but had what seemed to me to be excessive clearance when set up at the specified spacing. Turning one over made no difference. I set them up in my clock depthing tool so that I could play around with the gear spacing and I found that the teeth bottomed out before the play reduced to zero.

Photo 6 in the magazine shows your test rig and your prototypes. I noticed that the hardware was laid out on the gear drawings, and in the top right hand corner of the photo I could see the dimensions for the idler gear cutter. This shows an offset of 0.62 rather than the 0.55 detailed in magazine Fig. 5. I haven’t yet made a new cutter using the 0.62 dimension, but I think it will reduce the clearance I am seeing.

I would be happy to scan the Figures from the magazine showing the cutter dimensions so that you can check them against your originals, but I don’t know if this will upset the magazine publishers? Perhaps somebody could advise?

Best regards

Mike

[Mike CrossfieldParticipant @mikecrossfield92481]

Hello Gray,

I have sent some drawings to your gmail address.

Best regards

Mike

[Mike CrossfieldParticipant @mikecrossfield92481]

Just to draw a line under this, Gray has very kindly checked the MEW drawings against his originals and confirmed that, apart from the two errors noted in MEW 280, they are correct.

Mike

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