Thread: lathe al 336 threading

You could always buy an imperial leadscrew to go with your new lathe.

There is a well known author who doesnt have much time for these new fangled gear boxs you speak of and says that they are a step backwards. He believes we should all be using change gears.

Stuart

Mine has a imperial lead screw and you still have to change gears for different threads as seen in the photo. I would like to make another small gear box to save changing them and have been thinking more about it now CTC has cheap gear cutters.

Dave

Dave do you use a 120/127 gear to get metric?
I have a metric leadscrew. The gear boxes must be almost the same.(just the last two columns or maybe the plate is wrong lol, would be interested in seeing the rest of your metric plate Dave especially D4)
I would have thought if you get a lathe with a imperial leadscrew the gearing would be easier to set.

One of these days I'm going to take the gearbox off so I can count the teeth and work out all the ratios.

Stuart


oops forgot pic

Sorry for the blurry picture.


Dave

At least your guys left out the non-metric metric ratios lol
Unless of course you want to cut a .5625mm pinch thread, C2.

Stuart

the al336 lathe i looked at had an imperial lead screw and the pictures posted seem to be from al335 or al336.as the z gear looks like the one you change.The norton box has been around for about 40 years or more on lathes such as Hercus ,sheriden .nuttal and many others and is fast and easy.The first lathe i had at 16 years old(1948)was an Advance 3 1/2 inch by 21 inch made in Melbourne sold by Alfred Stewart.This had a stack of gears to change for each pitch.It was great later on to graduate to a Hercus with power feed etc.Good to have other points of view.

My lathe comes from Gasweld, it's not from H&F's. They are similar in design but mine is a lot better finished and a different lever set up in the bottom box as well as a few other things.
I understand what your saying about the gear change and it is a pain to change in the middle of a job. One day I will get around to making a separate gearbox for it.
It seems we are stuck with it until the manufactures change it. I come from a manual change Hercus so it was a big step up.

Dave

Hey Dave J, thanks for the PM, but I just don't get the chinese manufacturing business. As I mentioned in my mail, my new one is a Toolex from Gasweld and looks like yours other than the gear box looks like the Hafco model, four drums not two.

Yet they all have the same modle number on the front. CQ6230A. Just like this one: http://http://cgi.ebay.com.au/36-X12-GEARED-HEAD-METAL-LATHE-W-COOLANT-LIGHT-STAND-/270658395485?pt=AU_Hardware&hash=item3f047f5d5d#ht_750wt_1117

which has a buy now price of $3200, he sold one yesterday at auction for $2800. This front panel is like mine, just green like yours.

Tony

That surprises me they have changed because they have sold this same type of lathe for around 15 years that I can remember.
Gasweld may have changed their supplier or the supplier has changed gear boxes. I haven't been in their for a few years so I will call in and have a look at what the Newcastle store stock is looking like these days.
The website has only just been upgraded and it is still showing a lathe like mine with the same controls.
https://www.gasweld.com.au/products/580713
$3195 for the lathe and $395 for the stand, I think it was around $3400 when I got mine for $3000 cash.
Other guys down south have tried to barter with the price but got no ware, but up here they seem to.

Dave

Dont mean to hijack the thread but I this query about my lathe that has confused me for a while. It has a metric leadscrew and a quick change gearbox to cut metric threads from .2 to 3.5mm. However, on the end of the lathe it also has a gear on a quadrant that you can shift in order to cut imperial threads from 8 - 56 TPI using the same quick change gearbox.

How does this work? Are the metric threads accurate and the imperial threads an approximation?

Originally Posted by 19brendan81

Dont mean to hijack the thread but I this query about my lathe that has confused me for a while. It has a metric leadscrew and a quick change gearbox to cut metric threads from .2 to 3.5mm. However, on the end of the lathe it also has a gear on a quadrant that you can shift in order to cut imperial threads from 8 - 56 TPI using the same quick change gearbox.

How does this work? Are the metric threads accurate and the imperial threads an approximation?

What happens is that there is usually a 127/120 tooth or 127/100 compound gear that gets introduced into the power train, this has the effect of introducing some permutation of a 25.4 ratio into the gear-train (as in 25.4 mm = 1") which allows you to cut threads of the opposite system. Some lathes have a 63/50 gear which is not quite 25.4 but close enough for most purposes.

The downside is that the thread chasing dial will no longer work in this mode and so the half-nuts can't be disengaged between passes. The lathe needs to be stopped and reversed back between passes with the half-nuts engaged the whole time.

Dave Surely the gearboxs for USA lathes would be set for imp threads. I wonder how hard it would be to get hold of one of those?

Brendan Got a picture of the gearbox?

Here is a pic from the manual.

Thanks for the info Gavin.

Brendan, It looks like you have an 81 speed gearbox, Daves and mine only have 50 speeds.

I think some of the threads of the "other" system will be approximations(if they were exact why have two leadscrews?), but without knowing the gearing its hard to be sure.

Stuart