Myford ml7 21 tooth change gears

Hello all (and seasonal greetings)

This is my first post on the forum. I recently acquired an old, but quite well kept, ml7. It came with a huge number of extra bits and bobs, and a standard set of change gears. The gent who owned it had died, so his wife was selling up. I'm a novice with only a little experience with lathes, however i feel the best way of learning is by doing. I'm in the middle of a project and want to do some metric thread cutting, however i can't find any of the fabled 21 tooth gears to get the job done. Does anyone know where i could get some? or failing that does anybody have any experience in making gears. I have a little emco unimat 3 that i could potentially use to mock up a tooth cutting system with in conjunction with the ml7.

Cheers all

Ed

Hi Ed,

Metric screwcutting on a Myford has been discussed earlier on this forum, a few links:

***Link***

***Link***

***Link***

If you want to buy changewheels, manuals or thread charts, check out Myford Ltd.

Thor

Hello Ed, I have given up completely trying to send the Myford chart to you by this means, the magic word 'insert' is not visible at all, clicking OK adds a string of numbers but the whole message disappears when I try to add posting

Sent me a PM please and we'll do it by email Brian

If you can save a graphic as a .jpg file then it can be posted as a "photo".

Hello John,

Not today it seems, I've usually had no trouble, but patience ran out

Brian

Ed It would help if you gave some idea of where you live Some one may have 21 tooth gears spare

Roy

The 21t is usually on ebay. When the price is really silly it means not in stock until more come in. Might be worth messaging him to ask about the price - he might not have bothered to update yet>

John

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This note is primarily intended as an option for the newer hobbyists. Ed's situation brings to mind a similar issue that I faced a few days ago. I have a Myford Speed 10 with imperial leadscrew for which I have a set of imperial and metric gears. I wanted to install an Anschutz adjustable rear sight aperture on the target sight of my Walther KKM. To do so I had no suitable die so I needed to machine a 10mm X 1.0 adapter bushing to fit the larger Walther profile. When I pulled out the set of metric gears (that I have previously used) I discovered I had 2 X 65 tooth gears but not the required 63 tooth gear. A bit of online research and I discovered this NthreadsP gear calculation program at the following site. **LINK** I was able to set up a gear train to work with my 25 tooth spindle gear that provided a margin of error less than 0.7%; an entirely acceptable factor for this application. Maybe not accurate enough for the international space station (or Neil's telescope appendages) but definitely suitable for my needs. I loaded all of my available 29 gears (both imperial and metric) into the NthreadsP program which now sits on my PC desktop just a click away. ~ Bill

Hi Ed

There are available 21T, 63T and 127T gears on the web as are the associated gear train charts, these three I've found are an absolute god send for almost direct conversion gears the use of which are accuracy dependant, I have both ML10 and ML7 lathes and when using the 127T on the lead screw have left off the gear train cover so no loose sleeves at this end during use, well worth the investment, It's worth noting sometimes its more efficient to buy than make as a novice, I have all manner of rogue numbered gears some of which are off old Boxford lathes which I've found (dare I say this) are the same or very similar (Birch me now).

Rufus

Hi Ed

Hope this is of use

Hope these serve many

Rufus

Rufus Roughcut:

The source of your tables appears to be the ME article by Professor Cane at page 282 of issue 3628 which is well worth reading.

Just to pickup on a post above. Myford ML7 gears are 20DP whereas Boxford gears are 18 DP. That is for the mainstream machines last century. The very new Boxfords as with the far eastern machines from the last 20 years are module gears and the very first wartime Myfords were 14DP. You can't mix and match.

I wonder if the OP has search ebay uk for myford 21T and messaged the seller about the price if it's £900 odd. I did and bought one shortly after at the real price. That wasn't much at all.

John

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I fully agree with what Bazyle says and would like to add that Myford change wheels are also 14.5 pressure angle whereas modular wheels are 20 degree.

However if you are really, really stuck the 1.25 mod gears as fitted to the medium sized Asian imports do fit at a push. 20 DP being equal to 1.27 mod.

Not an ideal engineering practice but one that could get you out of a hole in a rush.

John W1:

Having noticed these "£900" offers on eBay in the past and been curious as to what lay behind them, I wonder if you can enlighten me?

It's been mentioned before - the supplier just inserts a 9 into the price when they are out of stock, and removes it when back in stock.

It saves deleting and re-inserting the item, so £57 becomes £957. I wonder if anyone has actually bought anything at the higher price?

Phil

LOL he has currently sold 910 of them !!!! Best to ask about them. Maybe he only obtains them when he's sure some one wants one.

John

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Thank you both for the explanation. I have only sold one or two items on eBay and can't claim any expertise; but I do wonder whether it might be possible (and simpler) to list the number in stock as nil.

.

Rufus,

Thanks for posting the charts, which are admirable for most practical purposes.

... As stated in the introductory note; they give very close approximations.

With the greatest respect to Prof. Crane, however ... I am surprised by his assertion that the 0BA pitch can be produced exactly. ... It is clear, from his 1mm approximation, that [as we know] this conversion is not exact.

[The sleight-of-hand comes from his use of two decimal places in the second table.]

MichaelG.

Edited By Michael Gilligan on 28/12/2015 15:42:33

Michael Gilligan:

"this conversion is not exact"

As you may know, his article elicited at least two lengthy and learned letters tp Postbag: one from GHT and another (quite critical) from A.Shackell. I did find the article interesting, however, not least because of the light it throws on the computing scene at the time.