screwcutting chart - newbie help needed

[shazzbat]

I've sorted a few miscellaneous problems with my TDS1/1GBL as mentioned in my previous topic, and have started thinking about how to cut threads. looking at the chart fixed to the gearbox cover, I've acquainted myself with the dial selector and lever, left right and centre, quad gear in/out, and which stud gear to use (from reading other's posts I appear to have a complete set).

That covers the outsides of the chart, so to the main field. The numerals are in groups of three in each box, and to the right of the chart (see pic) are three glyphs, repeated in 5 rows. From a casual glance at these, I assumed that the top one referred to screw diameter, the middle one to the pitch of the thread, and the bottom one to thread depth. However, I can't see this being right, as looking at the top left box, this would mean the maximum screw size would be 7.0mm, and it would have a pitch of 2.14mm, which is clearly ridiculous.


So what do these figures reference, and how for instance would I set up to cut a 10mm thread with a 1.5mm pitch?

TIA
Steve

[LesT]

Hi,

Firstly you are responsible for the diameter of the item you choose to thread, also for the tool angle and other settings. You are also responsible for the depth of thread that is cut.
The lathe leadscrew only moves the saddle,toolpost etc along the bed.

Refering to the chart in your previous post:

The "Stud Gear" for a particular selection is made by replacing whatever is fitted in the drive train with the gear as listed. The are identifies by letter and should be held on a parking stud under the end cover.
The "Dial reading" is the selection on the rotary selector, (Note that the gear lever on the left selection must agree with this).
The "Top lever" mounted on the top of the gearbox gives three speed selections of Left,centre, and right.
The "Quadrant sliding gear" is the big knurled knob under the end cover which slides a gear in and out of mesh on the drive to the output shaft.
And finally....
The three figures given on the rightmost column are, from the top down, for a) threading. b) surfacing (cutting an outside diameter of a shaft) c) facing (cutting the face of a plate or disc).
Note that b) and c) don't use the leadscrew but use the layshaft and require the appropriate selections to be made.
I hope this is helpful. (and that I've got it right !, although I'm sure someone will point out any mistakes ).

Cheers,

Les.T.

[Pete.]

LesT is bang on - for screwcutting you only read the top number. That is the pitch of the thread you will cut.

You find 1.5mm on the plate, then go up the columns to the top and work your way down.

Stud gear D. On the end plate should be a stack of gears A-G, find D and fit it on the geartrain.
Dial reading 1. Select gear 1 on the gearbox.
Sliding gear in. On the end geartrain you push the knurled knob which had 2 large gears behind it inwards.
Lever right. The left lever can be left, middle or right - you choose right.
Note you must also move the right lever to select screwcutting, so that the threaded leadscrew turns when the lathe is running.

Now you will cut a 1.5mm pitch thread when you engage the leadscrew.

[shazzbat]

Thanks both of you. I'll give it a shot when it's not so bleeding cold.

Steve