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

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

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

Roy

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

Hope this is of use

Hope these serve many

Rufus

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.

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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.

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

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.

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.

.

Thanks for the information, ega,

No I did not know that. … So far as I recall, I have never read the original article, or the subsequent correspondence.

My sole reason for mentioning it was to reduce risk of modern readers relying upon the statement as 'fact'.

What does surprise me [in the context of engineering/computing] is that he works to four decimals of mm, but only two decimals of inches. … Please forgive my ignorance of the article: Does he explain that oddity?

MichaelG.

Neil Wyatt:

I sometimes think Postbag should have been called Punchbag!

Michael Gilligan:

Please see my PM.