[boxcarmj]

Is there a relationship between the spindle gear (40T) and the leadsrcrew (12TPI)? Is there a formula I need to work out? Thank-you Mike.

[RotarySMP]

Your question is not clear.

[boxcarmj]

Hi Mark! My question is not clear, as I'm not sure how to ask it. I'm tring to figure out what gears I would nee to build a QCGB for my lathe. Any info is helpful. Thank-you Mike

[Al_The_Man]

I agree with Mark, there is not enough info, if you are looking for a drive relationship between spindle and saddle (leadscrew), then their is more mechanics or gearing required?
You have only specified one gear.
You lead screw is going to provide .08333"linear travel/rev, but what is between spindle and screw? What is the 40T attached to?
Al.

[hoss2006]

Hi Mark! My question is not clear, as I'm not sure how to ask it. I'm tring to figure out what gears I would nee to build a QCGB for my lathe. Any info is helpful. Thank-you Mike

have you seen Swarfrats quick change gearbox?

<Mini Lathe Gearbox>

or Richard Hagenbuch's gearbox.
he has all the gear sizes charted in the pdf.

http://homepage.mac.com/bhagenbuch/m...es/WebQCGB.pdf

Hoss

[RotarySMP]

Those projects from the Swarfrat and Richard Hagenbruch certainly are cool, but just CNC'ing the thing is easier than that, and then you can have any thread pitch, or feedrate you want just by typing a line.

[hoss2006]

Those projects from the Swarfrat and Richard Hagenbruch certainly are cool, but just CNC'ing the thing is easier than that, and then you can have any thread pitch, or feedrate you want just by typing a line.

Not everyone is into CNC that's why swarfrat and Richard did what they did
and why I provided the links seeing thats what the OP is looking to build.
CNCing and learning how to run a CNC lathe isn't quite the simple a task as you make it sound.
Hoss

[RotarySMP]

Hi Hoss,

You are right about that, and I certainly respect those mechanical solutions, but wanted to offer up the alternative. I have CNC'd my 7x, and it was less work than it appears Swarfrat invested in his gearbox, and gives much more flexibility.

Plenty of the home machining I do is not the easiest or cheapest way, but done because I want to. Wanting to do a QCGB is a great goal.

[hoss2006]

Hi Hoss,

You are right about that, and I certainly respect those mechanical solutions, but wanted to offer up the alternative. I have CNC'd my 7x, and it was less work than it appears Swarfrat invested in his gearbox, and gives much more flexibility.

Plenty of the home machining I do is not the easiest or cheapest way, but done because I want to. Wanting to do a QCGB is a great goal.

I agree with you, the OP has me thinking of making one for my G0602 now.
I may CNC it some day still but a QCGB would be cool to have right now.
Some things I just prefer to do manually.
Hoss

[boxcarmj]

Thank-you. I will study the two links; I'm building this because I think it is the best way for me to learn how it works. Also more time than money LOL! Mike

[Johann ohnesorg]

Hy Mike,
as always, there are more ways to skin the cat.

First of all, get exploded views from Norton boxes in case you only want to alter feed in a certain range. This is the cheap solution, uses two shafts and a few stacked wheels with a long woodruff key.
One step up ladder (a huge one) would be something like the Myford super seven gearbox. Again, there are exploded views and a detailed manual hidden somewhere on the internet.
In case you only want to change to certain threads pretty fast, it pays to make a spare Banjo and buy a few extra gears to set it up to the most often cut thread. You take out one Banjo, install the other and presto...
The ELS has the huge advantage that it will cut both metric and imperial without a hassle.

As it seems, you´re still checking what you need. A very good book on the topic is screwcutting in the lathe from special lnterest books, costs 10 bucks. After careful reading, you will know all you need to know to calculate the geartrains for given pitches/leads. It´s written hands on in laymans terms. Not too fancy, not too much calculus.

Cheers,
Johann

[boxcarmj]

Johann Hi! I must apologize for being so late with my thank-you. I'm a lot closer to the goal though, Thanks MIKE.

[Johann ohnesorg]

I must apologize for being so late with my thank-you

Well, I guess we never were in a hurry here... at least I´m not. :cheers: