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Warrington Model Engineering Developments

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Roderick Jenkins24/05/2019 12:22:25
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1780 forum posts
459 photos

There does seem to be a bit of a problem here: You can't actually mount a 17 Tooth gear on a standard Myford stud and keyway:

17t gear.jpg

Rod

Hopper24/05/2019 12:43:15
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3743 forum posts
76 photos

Unless it used a non-standard key that did not stand up so far above the stud?

Philip Cooper 124/05/2019 13:52:13
7 forum posts
9 photos

Hmm, I did wonder if it might be a bit tight, the smallest standard part is 20t.

Rod, many thanks for looking at this, I appreciate you taking the time. I’ll play around with some of the combinations that have been suggested, plus those from the Martin Cleeve book on screw cutting. Most of my metric stuff Is just a few standard pitches, so I should be able to find some workable solutions.

Thanks again to all.

Philip

Brian Wood24/05/2019 14:19:15
1985 forum posts
37 photos

Rod,

Thank you for taking the trouble to check that point, I too had wondered about it but dismissed as I assumed the seller of the kit would surely have considered that point, having made the metric table almost completely dependent on having a 17T gear in the chain.

You will perhaps have seen my offer to Philip to recalculate the table using other gearing, so it might become academic anyway.

And in answer to Hopper's thought, the key might in the end be too shallow to sensibly drive the gear without either the key being plucked from the slot or the gear fatiguing at one or both of the keyway corners in the wisp of material left to contain it

I think in the end that mystery will not be solved and other means will be needed to get round it anyway.

Regards

Brian

Clive Foster24/05/2019 15:06:25
1868 forum posts
59 photos

Not familiar with details of Myford construction but could the kit have included a replacement stud of smaller diameter allowing the 17 tooth gear to be fitted. Presumably with a sleeve to allow a standard gear to be used when needed.

Clive

duncan webster24/05/2019 15:17:14
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2255 forum posts
32 photos
Posted by Clive Foster on 24/05/2019 15:06:25:

Not familiar with details of Myford construction but could the kit have included a replacement stud of smaller diameter allowing the 17 tooth gear to be fitted. Presumably with a sleeve to allow a standard gear to be used when needed.

Clive

On the sleeve with the key machined into it, you could machine half te key away (lengthwise) and loctite a 17t unkeyed gear on

Roderick Jenkins24/05/2019 15:21:49
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1780 forum posts
459 photos
Posted by Clive Foster on 24/05/2019 15:06:25:

Not familiar with details of Myford construction but could the kit have included a replacement stud of smaller diameter allowing the 17 tooth gear to be fitted. Presumably with a sleeve to allow a standard gear to be used when needed.

Clive

That's my best guess. There is a patent number on the photo: Michael, where are you?  I think the whole thing is too well thought out not to have a solution.

Rod

Edited By Roderick Jenkins on 24/05/2019 15:24:42

Brian Wood24/05/2019 16:16:22
1985 forum posts
37 photos

Rod,

I tried finding the Patent but no banana, all UK patents start with GB2 in a 9 figure number and the search will not accept GB2 grafted onto the one shown.

The one shown is App No which I take as Applied for but it might even be a fake to look realistic; getting a patent in any country is an expensive business and would take up a fair chunk of any earnings the attachment might have raised.

The 17 T gear might have been a special fitting, brazed onto the other gear behind it, and used as a pair with the woodruff key removed from the shaft

And who is Michael?!!

Brian

Roderick Jenkins24/05/2019 16:49:42
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1780 forum posts
459 photos

Michael Gilligan (MichaelG) is our resident search engine and patents hound. The Carlsberg of searching wink

Brian Wood24/05/2019 17:00:59
1985 forum posts
37 photos

Ah, but of course---I should have known. Maybe he can succeed where I failed

Brian

Michael Gilligan24/05/2019 17:23:58
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14150 forum posts
616 photos
Posted by Philip Cooper 1 on 22/05/2019 11:22:52:

Please see below a few pictures ...

dsc_8371-r.jpg

.

Rod,

I've only just seen the cry for help

Happy to have a look, but I should mention that [ignoring the typo] Patt App. No. 80 31849 may, or may not, have produced a patent ... it's a Patent Application reference.

MichaelG.

.

Edit: Bingo !! ... Here is the Patent

 https://worldwide.espacenet.com/publicationDetails/originalDocument?CC=GB&NR=2059524A&KC=A&FT=D&ND=3&date=19810423&DB=EPODOC&locale=en_EP

 

 

Edited By Michael Gilligan on 24/05/2019 17:29:30

Roderick Jenkins24/05/2019 17:34:52
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1780 forum posts
459 photos

Thank you. You never disappoint angel

Rod

Philip Cooper 125/05/2019 11:31:33
7 forum posts
9 photos

It was fascinating to read the patent application, thanks Michael for tracking it down. Unfortunately no clues about using the smaller gear, metric seems to get only one brief mention.

Below is a picture of the stud/sleeve/key arrangement. It might be possible to make a stepped sleeve that would allow the use of a gear with a reduced bore.

dsc_8395-r.jpg

Still going to be tight, but worth investigating. Rod has very kindly made a couple of 17t gears, one of which is un-bored so could be adapted for use on a stepped sleeve, so I may now have a potential solution that would retain the originality of the unit.

Brian - Thank you for the offer to recalculate the ratios. I'll try and establish the constraints on gear size for each position to see if this could be an alternative way forward.

Thanks again to all for your inputs.

Philip

Brian Wood29/05/2019 17:31:14
1985 forum posts
37 photos

Hello Philip,

I have two alternatve gearing tables, both avoid the use of the awkward 17T gear, but as usual I cannot find the button that allows me to insert the images and post them here

They are on my Album or I can send them to you by email. If that is your preferred route contact me at

I have become quite interested in this device, Mr Pugh is, or was, a clever man and I appreciate his thinking that led to creating it

wood_y(at)btinternet(dot)com

Regards

Brian

Brian Wood30/05/2019 18:21:14
1985 forum posts
37 photos

Philip,

I've sent you a PM. Look in your inbox

Regards

Brian

Bazyle30/05/2019 18:28:20
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4762 forum posts
187 photos

One whacky solution to the keyway problem is to make the key bigger and serve as the actual tooth.

Philip Cooper 103/06/2019 09:34:58
7 forum posts
9 photos

Some photos below of the solution that I arrived at, using the 17T gear that Rod very generously made. The mounting stud is 0.375" and the standard Myford change-wheels are 0.625", so I bored the 17T to 0.500". This was then Loctited and pinned to a stepped sleeve, the other end of which was milled for a keyway to take the standard gears as required. Seems to work fine, usable on Stud 1 and Stud 2. Thanks to Brian's mathematical prowess I also have a set of alternative gear combinations to make finding a suitable set-up even easier.

Thanks to all for your help, the generosity of Forum members is amazing. I hope to be able to make a similar contribution at some time.

Philip

dsc_8405-r.jpg

dsc_8407-r.jpg

And in place on Stud 2:

dsc_8399-r.jpg

Roderick Jenkins03/06/2019 18:02:31
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1780 forum posts
459 photos

yes

Rod

Michael Gilligan03/06/2019 20:18:36
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14150 forum posts
616 photos

Nice job, Philip & Rod

MichaelG.

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