Difficulty with setup

[Southernsandman]

I have a difficult thread that I need to set up on my myford and I hope that your combined knowledge will
Crack it my thread form is a 10 WF .

 

[stevehuckss396]

I think it's a whitworth form thread. British used whitworth threads. They are alot like imperial but might be 55 degree unlike imperial 60 degree but I would need to do some checking. You might need 55 degree cutter.

 

[fcheslop]

I have a few early tools over 130 years old that are stamped W F ,Whitworth Form from the days when whitworth was the only standardised thread .
I think its to show the tool is to the standard
55 degrees for Whitworth and British Standard Fine and just to confuse during ww2 they shaved a 1/16 of the bolt head

 

[goldstar31]

It's 55 degree Coarse Whitworth Form obtainable from 40 and 50 gears of preferably 20DP pitch.

After saying all this, you have all this information on the 'casing' of both the ML7 and Super7.
These- and a block of gears divisible by 5 should be standard on your lathe. If you eventually need to go 'Metric'
a correct transposing gear of 127 of 20DP will not fit but an approximate 63 or 21's can be used.

Two things which I would commend are a thread gauge which are cheap and would have answered your question and will in future be used to check the setting up of your 'banjo' and Martin Cleeve's book Screwcutting in the Lathe.

Again, my best wishes to Frazer and a comment to say that have a form tool which could be too much of a strain on a Myford leadscrew.

 

[BaronJ]

Hi Guys,

That thread chaser could easily be used to cut the thread once the lathe is set up for ten threads per inch.

Use it just as you would for single pointing but ensure that the body is at exactly 90 degrees to the work. The reason for doing this is that the cutting teeth on the end of the chaser are sloped down to the right. So the initial cut will be done by the first tooth and the other teeth will come into effect as each cut removes material.

The second tooth will barely scratch and the third tooth won't until a few thou of feed is applied, and so on until full depth is reached.

Thread chasers are very good for cutting full form threads.

 

[goldstar31]

John
Your eyesight is obviously better than mine

Cheers and thanks

Norman

 

[Southernsandman]

Hi Guys,

That thread chaser could easily be used to cut the thread once the lathe is set up for ten threads per inch.

Use it just as you would for single pointing but ensure that the body is at exactly 90 degrees to the work. The reason for doing this is that the cutting teeth on the end of the chaser are sloped down to the right. So the initial cut will be done by the first tooth and the other teeth will come into effect as each cut removes material.

The second tooth will barely scratch and the third tooth won't until a few thou of feed is applied, and so on until full depth is reached.

Thread chasers are very good for cutting full form threads.

 

[Southernsandman]

I new It was worth getting some help.ill sort it tomorrow with some luck. I was using the thread chaser to figure out the T P I and what sort of tool to grind but I dont really do much free cutting with threads on my machine.

 

[BaronJ]

Hi Southernsandman

If you have ever seen a Coventry die box, you will note that they have four threading dies in them. The dies can be obtained in a multitude of threads. Properly mounted they make superb single pointing tool bits for cutting threads. One of the features of chasers is that the threads produced will be of exactly the correct form.

There were many millions of them made, and scrapped because no one wanted them any more. Without the Coventry die boxes the war effort wouldn't have been as effective.

 

[goldstar31]

I totally agree with Baron's observations about Coventry boxes. Historically, we Brits had Whitworth Coarse and Whitworth Fine with an 'electrical' dash of British Association threads

However all this very inconclusive dialogue had my back to crests on threads or in some cases, their absence.
I seem to recall when I made my Quorn tool and cutter grinder in the days of Yore that Professor Dennis Chaddock 'truncated' the threads on the measuring ( I think that's right) spindle. Again, in Screwcutting in the Lathe that Martin Cleeve truncated his tailor made special screws for industry on his much modified Myford ML7- and then he made his own micrometers on it. Then Norman Tinker on his original Tinker used his Myford leadscrew to calibrate his tool and cutter grinder. I note that on the Canadian Guy Lautard version that those notes are absent.

And then- oh dear- no one has got on to Jo Blocks. I have a set but nothing fancy or NPL quality.

Somewhat quizzically

Norman

an

 

[BaronJ]

Hi Guys,

FWIW "Tracy Tools" in the UK, stock both the dies and a handle so they can be used as a hand chaser. there are pictures on their web site of them. Whilst I would not advocate using the handle in the tool post of a lathe and would use a specially made holder for them that would stop them from twisting out of line.

Disclaimer ! I have no relationship with "Tracy Tools" other than a satisfied customer.

 

[goldstar31]

I suppose confession is good for the 'sole'( Dover or Lemon) but I have a two ended die holder which I made with a Number 1 Morse Taper and fitted a jumper sleeve to work in a Number 2 tailstock. As I have 'new-ish' Myford Super 7B with the power cross feed( and probably a decent coat of paint) to arrive shortly it is probably time to tart things up a bit and go into the 20th Century from the Dark Ages.

 

[fcheslop]

Cromwell Tools in the UK are currently selling hand chasers at a discounted price
I have hand chased fine threads in brass in a former life but always found it a butt clenching experience
We used to polish the threads to a near perfect fit although sometimes I think it was just to keep the apprentice busy.

 

[Charles Lamont]

I regularly finish external threads with hand chasers. I have sawn off the handle tangs and use them in a toolholder. I find they have to be skewed very slightly to ensure cutting on the first tooth.

 

[Apprentice707]

The Whitworth form of thread was devised by British Engineer Joeseph Whitworth in 1841 and established the first thread system in the world and continued in common usage by British manufacturers until the early '70s. My 1960 Myford Super Seven has BSF and BA threads. I am a traditionalist and have a good stock of British Nuts and Bolts and threading equipment so I still use them on my projects. Let us hope Brexit sees the reintroduction of these threads (Heh Heh).
Seriously I have some Coventry die head cutters that I use as chasers. I believe Tracy Tools in the UK sell these and a holder to make them handheld chasers.

Cheers

B

 

[RonW]

Gents,
This is probably a little off topic but back in 1963-4 I attended a demonstration at a trade show in Salisbury, Rhodesia (now Harare, Zimbabwe) where a local trade school demonstrated a "thread swirling system" of cutting threads on a lathe. In comparison to single point threading the results were spectacular. I have never seen or heard of it since. Has anyone, maybe Norm in his vast experience, ever built a device to do this. There was recently a short video showing cutting threads using a vertical mill but obviously computer controlled.
RonW

 

[holmes_ca]

When I left school at fifteen my first job as a Turner Improver was at a small shop in London UK machining water pump castings and one job was on the production line chasing brass shafts and I found that slow rpm was not good it went 100% better with a higher speed, that was 70 years ago, don't ask what the speed was, but I got pretty good at it,

Edmund..........Alberta

 

[goldstar31]

Has anyone, maybe Norm in his vast experience, ever built a device to do this.

RonW

I am quite baffled to be associated with full size, 12" inches to the foot sort of thing. Maybe there is confusion with another Norman Atkinson who wrote the biography of that great engineer Sir Joseph Whitworth.
As I have said- far too many times that I was a 'bean counter' until the age of 55 and at that point had enough of my version of the rat race and retired- for longer than I had ever worked.
As a MODEL( Apologies Cogsy but the message must be forced home) engineer, it seems fairly easy to assume that with sufficient horse power, people can move away from single point machining. I'm always ashamed to find that I agree with a leading expert in model engineering that people 'ask the the same silly questions and get the same silly answers' I'm like him, I spend far too much time having to work things out for myself.
As both gentlemen have have Myford ML7's, it is fair to mention that another L7 owner made a good living out of his highly modified lathe- screwcutting- and probably very little in royalties. As far as I am aware he bought half a Myford and added a One horse motor and a half horse one and drove his version with old traditional line shafting. He was too poor to finalise Patent applications or bu any tools and made and describe how he built up his workshop with fabricated mild steel sections rather than castings which he hated.

Thinking back, people do create threads with dies and looking a m sets of BA ones, they cut threads- one following the other whilst my other assorted stuff is three fold. Harking back to the 7 Series Myfords, the tailstocks have three start threads in the tailstock poppet. No doubt that they were cut at -one operation.

Returning to myself, I have travelled fairly extensively in Europe, a bit in America and Canada and not enough in the Far East. In the UK and Europe we bought property but Far from the Madding Crowd of Industry. On my wife's death, I sold up, ensured that my grandchildren would also benefit as well as my children with better educations that I was previously subject to. As a bean counter, I am constantly aware of the problems of inheritance and simply and also the need to extend charity to those who haven't been quite as lucky as myself.

So I've little time to brood especially on questions which have been discussed time without number- and which are still largely ignored.

Now at almost 90, I have real problems which only the fortunate amongst you will experience.
I hope that this goes somewhere to clear the matter and frankly, if it doesn't, it's only a hobby and should be treated as such.

Norman

 

[David Shealey]

Cromwell Tools in the UK are currently selling hand chasers at a discounted price
I have hand chased fine threads in brass in a former life but always found it a butt clenching experience
We used to polish the threads to a near perfect fit although sometimes I think it was just to keep the apprentice busy.

Being in the USA, the use of "Thread Chasers" was not something I was familiar with. I looked at Tracy Tools, and created a link on my desktop to them. Some nice stuff there. US suppliers want an arm and a leg for Metric Drills, Tracy is less expensive, not sure what shipping would be though.

I also tried looking at Cromwell Tools, but that is blocked by my security system as a dangerous website.

 

[Cogsy]

I also tried looking at Cromwell Tools, but that is blocked by my security system as a dangerous website.
View attachment 113900

Seems like they have an SSL issue so they are vulnerable to being 'hacked' but there is nothing actually malicious about the site. Should be quite safe to browse normally. You can check the report here : https://www.ssltrust.com.au/ssl-tools/website-security-check?domain=www.cromwell.co.uk