Myford Ml7 Technical Drawings

[Howard LewisParticipant @howardlewis46836]

Purely an aside, Try finding a Tap for 6.354 mm x 1.27 mm, or 0.907 mm pitch!

Or looking for 0.236 x 25.4 " one!

I'll settle for 1/4 BSW or UNF, or M6

If a machine was originbnally made to Imperial (Or Metric ) dimensions, best to stick to those units.

Yes, Ive come across some hybrids, 3/8 BSF at one end of a stud and 3/8 UNF at the other, or 5/16 BSF bolt with a 5/8 A/F head, but those wouldn't have beeen my choice.

Yes, we quote BA sizes in Imperial, but really are Metric (O BA is 6 x 1, with succeeding sizes decreasing by a factor 0.9 ) The odd ball feature is the 47.5 degree thread form,, but that might be the Thury parentage to differ from both Whitworth, and Metric form

Measuring items in units which were not used originally just makes for complications

Witness film speeds in Russian Gost units rather than Scheiner or ASA

DON'T mention Weston or Hurter and Driffield, or the A/F sizes for Whitworth form fasteners!

Howard

[David-Clark 1Participant @david-clark1]

Hi Howard, I think converting threads directly is a stupid idea and doubt that was what the original poster meant.

Yes, metric dimensions would be fine but threads should be suitably selected for the jo.b in hand wether they are imperial, metric or measured in bananas.

[HOWARDTParticipant @howardt]

A design is basically imperial or metric, not both. While you can use threads of one in the other, where I use metric fasteners in my imperial engine builds, you shouldn’t convert dimensions unless you merely want to use measuring devices in the other standard. Trying to round dimension or use material sizes will create all sorts of problems with fits and clearances. Metrication or imperialisation needs to be applied creating a complete set of new working drawings with all the fits and clearances worked out to ensure a working model.

[JasonBModerator @jasonb]

I think this is an original Myford drawing for the spindle nose, not sure how easily those -ve figures would translate to modern H & h fits. Certainly easer to see how many thou under or over you can be than having to go looking up charts and working out what the tolerences are in microns.

[Alan DonovanParticipant @alandonovan54394]

Hello.

First.

To follow on from JasonB’s comments on the dimensioning of Myford parts. Myford (Beeston) used a ‘metal off’ system of tolerancing for all their manufactured parts. This was to enable the engineer actually cutting the metal to have a target dimension to achieve, but if he/she went over that dimension they would almost certainly still be within tolerance.
It also removed the need for the operative to undertake the mental mathematics needed with the plus and minus tolerancing systems, where maths errors can lead to potentially higher scrapage rates for components.

As we all understand, it is easier to remove excess metal than replace what we removed in error.

Second.

If I remember correctly, I think there was reference in this thread to wax(?) printing components to investment cast in metal. Would this require two CAD files? The second file to print an enlarged wax component to allow for casting shrinkage.  Plus the additional metal (wax) for where machining is required.

All the best to everyone. Alan

 

Edited By Alan Donovan on 18/09/2023 07:44:49

[JasonBModerator @jasonb]

I think most people making their own patterns would print in somnething like PLA which is the usual basic filament material and then after some surface prep use that as the pattern. One or two may CNC cut the pattern.

You would ideally want a STL file for printing and STP or STEP if CNC cutting with suitable allowance for shrinkage of the chosen metal, machining allowances added to all faces to be machined including draft angle, core prints added as required and then suitable core box drawings/files to form the cores in. If the part needed to be split in half then you would want two files and need to include pins/sockets to locate the two halves together. Then there would be a separate machining drawing required.

[smavParticipant @smav]

Hi. Would the drawings for the ml7 tailstock clamping plate and Gibs plate be available?  I inherited an ml7 but they are missing. Many thanks.

[Andrew TinsleyParticipant @andrewtinsley63637]

The answer to the OPs original question is YES PLEASE. I am ambidextrous and use metric and imperial measurements without any faff!

Instead of complaining and nit picking why not be grateful for a generous offer?

Andrew.

[John Haine]

On John Haine Said:

I have a S7 but can’t see any need for a set of engineering drawings. The main dimensions of interest are for interfacing accessories, usually to the spindle nose or carriage, and they can be measured in a trice. Likewise individual parts. Interesting that everyone leaped into the debate about dimensions and threads without answering the initial question!

Mind you, I suspect that Myford might like an accurate and detailed CAD model!  I wonder what state the “original” drawings are in?
Edited By John Haine on 16/09/2023 10:36:15

As most Myford owners know, Myford Limited is associated with RDG Tools.

I had cause to call them about 5-6 years ago to inquire about the centres of the mounting holes on the back of the bed, normally used for the taper turning attachment etc, I was making a mounting plate for ArcEuro’s digital scale for the Z axis carriage travel.

The helpful chap I spoke to said that might be difficult, I asked “can’t you just have a look at the drawings” he said we haven’t got the drawings we didn’t buy them as part of the Myford sale.

Whether that has changed nowadays I have no idea.

[Michael GilliganParticipant @michaelgilligan61133]

I can’t vouch for its accuracy, but here’s a contemporaneous discussion about the 2011 sale

https://www.polytechforum.com/modelengineering/the-myford-sale-51465-.htm

MichaelG.

[BazyleParticipant @bazyle]

Are there no copyright issues?
I expect there will be a bunch of small parts that people want to know about for replacements and modification. For example you might know a gib screw is 4BA but not know how long it is. Also what the spacing is of gib screws because you were considering modifying for a lock screw.
I spent a little time this evening trying to find the dimensions of a different lathe change gear cover (to see if there would be room to open it if in my workshop) and couldn’t even find online a picture of the end view – how useful a dimensioned drawing would be.

So a set of drawings could be useful. I don’t think this site hosts pdfs so I suggest the Groups.io/g/myfordlathes as a host. NOT FACEBOOK

[smav]

On smav Said:

Hi. Would the drawings for the ml7 tailstock clamping plate and Gibs plate be available?  I inherited an ml7 but they are missing. Many thanks.

I think this 3-year-old thread was resurrected by smav with his request, above;

The parts you describe are, I think

Clamp Plate – P/no. 70/1514

Gib Strip – P/no. A2136

The gib is available from Myford for £12;

https://www.myford.co.uk/product/m27-gib-strip-a2136-2/

or from their Ebay store – can’t remember what it’s made of, or whether it’s ‘hard’/ground.. anyone?

The Clamp plate is a simple rectangle of steel with a threaded hole and rebates on the top edges – unless anyone beats me to it in the meantime, I will go and measure-up (both parts) this evening after work..

[Bazyle]

On Bazyle Said:

[…]

So a set of drawings could be useful. I don’t think this site hosts pdfs so I suggest the Groups.io/g/myfordlathes as a host. NOT FACEBOOK

This site DOES host PDFs … you just need to upload them to your ‘Documents’ Gallery

MichaelG.

[noel shelleyParticipant @noelshelley55608]

Only last week I had an example of the “bad idea ” of mixing metric and imperial threads in the same machine. My colleague told me that a certain thread was 10mm, he had tried a 10 mm nut on it ! It did indeed fit, but was sloppy. Knowing the engine was American and therefore UNC I checked OD and pitch. 3/8″ unc ! Had I took him at his word I would have destroyed an irreplaceable part for 50+ year old engine . Convert the dimensions to metric if you wish but to mix threads in the same machine is not a wise idea. Noel.

[smav]

On smav Said:

Hi. Would the drawings for the ml7 tailstock clamping plate and Gibs plate be available?  I inherited an ml7 but they are missing. Many thanks.

Bump.

Zombie thread alert.

[DiogenesParticipant @diogenes]

It’s such a pain working in mixed measurement systems 🙂 Try these

 

[Nigel Graham 2Participant @nigelgraham2]

I can see one source of worry immediately… Does the length of the gib, for example, have to be to 2 decimal places? (I doubt it!). Why not 113mm?

 

My thought irrespective of any machine, is as far as possible:

– keep the dimensions consistent with the original: if it is made to inches, use inches (decimals for anything machined); if metric use mm.

– keep the threads consistent with the manufacturer’s chosen standards.

There is nothing to stop the builder converting the units if necessary, usually to suit his own facilities, but at least the manufactured dimensions in either standard are likely to be round numbers.

While mixing fasteners leads to awkward use and servicing.

For example, the commercially-made rear tool-post on my ML7 has two 1/4″ or 5/16″ BSF T-bolts in its projecting foot, and a 17mm A/F nut on its central column. I have not measured the column thread, which should be M10 for that nut. The fixed-steady clamp stud is about the same size but uses a BS or AF spanner. I would not expect such needless inconsistency on commercially-made accessories for the same machine.

 

Sometimes you might not have much choice as the range of readily-available BA and BS thread fittings diminishes. I used M6 cap-screws screws on an accessory I made for my Harrison L5 lathe; but in such cases it is best to be consistent across the accessory itself as far as possible.

Similarly, the set of small-thread T-nuts I made for my Myford VMC mill has M6 threads; easy to equip and compatible with an Arc-Euro M6 clamp-set that neatly fits the BCA jig-borer table. The full-diameter, commercial clamp set that fits the mill uses 3/8″UNC nuts, fitting T-slots of odd width neither one thing nor the other; the machine itself uses BSW / BSF.

 

Really, the original question is rather academic. When we make accessories to our design we measure the relevant parts of the machine anyway; if we use a published design that’s been done for us. You don’t need know the headstock sizes to make something to clamp to the saddle.

Besides, I very much doubt any machine-tool manufacturers publish full sets of detailed, dimensioned drawings of their products: the most will be enough outline dimensions to aid installation and use, and exploded parts-diagrams.

 

Perhaps the moral is that you’ll not please everyone every time!

Just be thankful we’re not calling for all those umpteen-sixtyfourths from random data-edges as we see on some of the older model-design drawings.

 

 

 

[Diogenes]

On Diogenes Said:

It’s such a pain working in mixed measurement systems 🙂 Try these

[…]

Succinct 

MichaelG.

 

[Andrew TinsleyParticipant @andrewtinsley63637]

Mixed measurements are not a problem for me, But I suppose it can be challenging to people raised on only one system.

Andrew.

[Andrew Tinsley]

On Andrew Tinsley Said:

Mixed measurements are not a problem for me, But I suppose it can be challenging to people raised on only one system.

Andrew.

Lucky Andrew!  But I fear he’s missed a trick.   The problem with mixing systems is conversion factors – an extra step in the sums are more work and go wrong.   Calculations foul up if:

• a conversion is left out
• the conversion factor is wrong  (misreading it, or a typo – 24.5 rather than 25.4)
• the extra complicated arithmetic is done incorrectly
• the human does not notice the error because the answer is in the system he’s least familiar with

Imperial Measure, the Foot-Pound-Second system, is bad because it’s riddled with internal conversions.  Blame it on history: the base units were set arbitrarily before it was realised they are interrelated.

Imperial is mostly harmless in the workshop, because it’s only used in simple form.  Unfortunately, serious disadvantages emerge when Imperial measure is applied to the complex maths required in science and engineering.  The problem became apparent around over 200 years ago.  Steam engine design requires force and motion calculation, and Imperial’s internal inconsistencies makes these much harder.  Mph or feet per second.  Inches, yards, miles of chains?  A Horsepower is 550 ft-lbs/s.   HP only makes sense as a measure of output power, so what about input? Foot-Tons, Foot-pounds, or inch/ounces?  Lots of fractions.  Imperial measure is an incoherent mess, and it doesn’t cope at all with electricity!

Better was needed, specifically a system that eliminates conversions.  Metric base units were carefully chosen to be coherent, and everything scales in tens.  There are few internal conversions – no need to know that 60mph is 88 feet/s etc.

Took decades to fine tune metric.  Centimetre-gram-second metric (CGS) was found to generate very small and very big numbers that aren’t human friendly and complicate the maths, especially in the days of slide rules and log tables.   Switching to metre-kilogram-seconds fixed most problems.

Unnecessary conversions being evil, might be expected that the disadvantage of allowing Imperial and Metric to coexist would be obvious.  But no, traditionalists were so set in their ways, the UK allowed just that.  Worst of both worlds, because we’re saddled with the need to convert between Imperial and Metric, with poor results.  A toxic decision that damaged British manufacturing.  Most countries took a hard-line and forced metric through, giving their industry a significant advantage over ours, especially when it comes to foreign trade.   Customers in metric countries do not want BSF, BSW and BA fasteners!

Conversions cause expensive mistakes: Mars Orbiter ($330M), aircraft running out of fuel,  Concordski, buildings wrong size, and more. Bottom line: avoid conversions.  And if you do have to convert, take care.

Dave

 

 

[duncan webster 1Participant @duncanwebster1]

I think we should all switch to the furlong firkin fortnight system FFF much more rational than traditional imperial.

Before anyone points out that our American friends use imperial, they also play rounders as a national sport, and US science uses MKS

[howardbParticipant @howardb]

“Customers in metric countries do not want BSF, BSW and BA fasteners!”

I know from past experience that BSP pipe fittings are widely available in the Netherlands, due, so I was told, to british built ships historically being maintained in Dutch ports.

BSP domestic plumbing fittings are standard in France, but they are cleverly disguised.

1/4″ BSP = 8/13 French designation

3/8″       = 12/17

1/2″       = 15/21

3/4″       = 20/27

1″          = 26/34

1 1/4″    = 38/42

1 1/2″    = 40/49

British Standard Pipe (BSPP) parallel thread fittings and adapters are, by far, the most popular, with prominence in the UK, European, Asian, Australian, New Zealand and South African markets.

[JasonBModerator @jasonb]

BSP under the name of “G” thread is used throughout the metric world.

1/4 x 32 UNEF is also used worldwide for glow and miniature sparkplug threads

And there are several more like back nuts for electrical switches, vamera mounts, etc.

[Nigel Graham 2Participant @nigelgraham2]

A common criticism of the older units was their supposed anthropocentric origins – which would be logical, after all.

SI is both! The dB scale for sound pressure in air, and the mathematical definition of the candela, are based on the sensitivities of the human ear and eye, respectively. (Sound levels in water are mathematically “pure” as their 0dB is equivalent to 1 micro-Pascal. In air, it’s 20µPa. The Pa is absurd for “ordinary” pressures like domestic plumbing, car tyres and locomotive boilers.)

The c.g.s. system may have been unfriendly as being too unwieldy to relate to human activities, but I don’t think the SI is much better. The Newton and Pascal are particularly unworldly, and the Radian that simplifies Theoretical Mechanics is hopeless for practical angle measuring. This may be why schools and the rag-trade insist on centimetres whereas everyone else using the units properly, counts in thousands and thousandths of metres.

Network Rail still uses Miles and MPH, and I think the Yard and Chain. (The mile and yard are still statutory for road use.) Air and marine navigation uses the Nautical Mile and Knot – but those are based on sea-level lomgitude divisions. Land is still sold in acres, judging by auction notices dotted around the countryside. Horses are still Hands high; organ-pipe fundamental lengths still in Feet and fractions thereof (not inches).

Oh, and mine’s a Pint, thankyou!

 

Really, all units of measure are arbitrary even if the system holding them is numerically consistent.

Steering back to the original question, what matters far more than which dimensions we use is our consistency in any one project; and dimensioning drawings with regard to making the components.

 

I use either Imperial or Metric according to purpose.

[Alan JacksonParticipant @alanjackson47790]

If anybody dares or is naive enough to draw up a Myford ML7 in metric and/or imperial dimensions, It can be seen that they will be hounded into oblivion trying to cater for the desires of the recipients of the drawings. Judging from the comments in this thread.

Alan

[Author]

Posts