1/2 threads on Myford super 7

[rodders]

I have a myford super 7 set to imperial with a quick change gearbox fitted. i am trying to find info on how to change the TPI available beyond what is offered on the gearbox ie how do you get 11.5 tpi. Is it necessary to change the tumbler gear to achieve this and if so where is it documented? Any help on this would be appreciated.

 

[SandyC]

Hi Rodders,

Is it necessary to change the tumbler gear to achieve this

Not quite that simple I am afraid...

You will need a changewheel banjo arm and a set of changewheels to get what you want.

There are a couple of good (free) programmes available for calculating the required train, however, you will need to input the necessary info about your particular gearbox.

The link below will take you to the download page and it also gives quite a good amount of info for the 2 programmes.

http://www.lathes.co.uk/latheparts/page14.html

I hope this is of some help.

best regards.

SandyC

 

[Dunc1]

Since I don't own a Myford I can't verify that this will work. It is from Screwcutting In The Lathe by Martin Cleve and it suggests 2 possibilities for 11-1/2 tpi using an 8 tpi leadscrew. Assumes gears 20-20-75T by fives are available. The lower setup requires a 38T gear (don't know why this is specified - perhaps it is an optional gear not in the usual change gear set)

40----A----50
65----75
This didn't display properly: shift the lower row (65----75) left until 65 is under 50
55----25 30----38
20----50
Again, a hiccup: move the 30----38 on the top row to the right. Move the bottom row (20----50) so that 20 is beneath 25 & 50 is beneath 30.

Reading from left to right the columns show:
first driver, first quadrant stud, second quadrant stud, lead screw.
The dashes connecting gear-pairs indicate that they are in mesh; superposed gears are coupled/keyed together on the same shaft.

Aside from the user manual (should be on the net) there is a book by Ian Bradley. Aside from its existence I have no info. Looking up "Myford" on Amazon got me the title/author combo.

 

[Dunc1]

Edit of previous post did not work

Since I don't own a Myford I can't verify that this will work. It is from Screwcutting In The Lathe by Martin Cleve and it suggests 2 possibilities for 11-1/2 tpi using an 8 tpi leadscrew. Assumes gears 20-20-75T by fives are available. The lower setup requires a 38T gear (don't know why this is specified - perhaps it is an optional gear not in the usual change gear set)

40----A----50
65----75

What I typed into the reply box does not display identically here.
I edited my post (tried to) but it didn't display.
In the above you must rearrange the schematic to place the 65 directly beneath the 50.
Then the instructions below will make sense.

55----25 30----38
20----50

Ditto here: display hiccup. Rearrange the lower row to place the 20 directly beneath the 25.
You will need to shift the "30----38" to the right so that 50 displays directly beneath 30.

Reading from left to right the columns show:
first driver, first quadrant stud, second quadrant stud, lead screw.
The dashes connecting gear-pairs indicate that they are in mesh; superposed gears are coupled/keyed together on the same shaft.

 

[dsquire]

Edit of previous post did not work

Since I don't own a Myford I can't verify that this will work. It is from Screwcutting In The Lathe by Martin Cleve and it suggests 2 possibilities for 11-1/2 tpi using an 8 tpi leadscrew. Assumes gears 20-20-75T by fives are available. The lower setup requires a 38T gear (don't know why this is specified - perhaps it is an optional gear not in the usual change gear set)

40----A----50
...............65----75

What I typed into the reply box does not display identically here.
I edited my post (tried to) but it didn't display.
In the above you must rearrange the schematic to place the 65 directly beneath the 50.
Then the instructions below will make sense.

55----25 ...30----38
........20----50

Ditto here: display hiccup. Rearrange the lower row to place the 20 directly beneath the 25.
You will need to shift the "30----38" to the right so that 50 displays directly beneath 30.

Reading from left to right the columns show:
first driver, first quadrant stud, second quadrant stud, lead screw.
The dashes connecting gear-pairs indicate that they are in mesh; superposed gears are coupled/keyed together on the same shaft.

Hope this helps.

Don

 

[rodders]

Thanks guys you have been most helpful
Rodders