NGC question for the machinists

[Canuck750]

I have a question regarding the power feed options of the lathe I have (shows my total ignorance of how these things work) that I hope someone can explain.

My lathe has a lever that switches the power feed from the lead screw to a second rod of similar diameter located directly below the lead screw but this rod has a continuous slot at the 12 o’clock position running the length of the rod(below this is a third solid rod which remains stationary).

I assume when driving the lead screw (provided appropriate change gears are used) and positioning the two transmission levers in accordance with the charts a know thread pitch can be cut.

My question is what is the purpose of the second rod with the slot? Is this drive not for screw cutting but just to control the feed speed of the cutting tool?

If I got that right (likely not) does this mean the spindle rpm is totally independent of power feed on this setting?

Thanks in advance

Jim

[lucky phil]

I have a question regarding the power feed options of the lathe I have (shows my total ignorance of how these things work) that I hope someone can explain.

My lathe has a lever that switches the power feed from the lead screw to a second rod of similar diameter located directly below the lead screw but this rod has a continuous slot at the 12 o’clock position running the length of the rod(below this is a third solid rod which remains stationary).

I assume when driving the lead screw (provided appropriate change gears are used) and positioning the two transmission levers in accordance with the charts a know thread pitch can be cut.

My question is what is the purpose of the second rod with the slot? Is this drive not for screw cutting but just to control the feed speed of the cutting tool?

If I got that right (likely not) does this mean the spindle rpm is totally independent of power feed on this setting?

Thanks in advance

Jim

It's the drive for the carriage and cross slide. Yes feed speeds are independent.

Ciao

[Canuck750]

It's the drive for the carriage and cross slide. Yes feed speeds are independent.

Ciao

Thanks Phil!

[John A]

I thought you were going to ask how do you take a piece of round stock and make a square block out of it on a lathe.

[Moparnut72]

I would like to see a picture of that lathe.
kk

[Canuck750]

I would like to see a picture of that lathe.
kk

I will take a pic tomorrow and post it.

[ridingron]

I will take a pic tomorrow and post it.

I think he meant a machine that could make round stock square. Just guessing. 

[reidy]

To make square stock from round on a lathe is easy.
Firstly mount your piece of round stock on a face plate. Face of the side to make it flat. Flip it over with the flat side on the face plate and do the other side. Then rotate it 90 degree to do the third and flip 180 to do the last.

Steve   

[Mike Tashjian]

Owning a nice lathe is a great start to making parts and tools.  I suggest getting a book and course or two to operate it safely.  Every course I have taken stressed safety and it has paid dividends.  Youtube has many videos that will help you get an idea of operating your lathe too.  But personally, I liked the hands on courses making projects with assorted machines. 

[Rick4003]

The Second rod does drive the feed for the carriage and the cross slide but it is not independent of the spindle speed. You have a separate gearing that drives the second rod that is also driven in relation to the spindle speed. So you would have the tool move 0.2mm pr revolution of the spindle. There is a different table showing you what the feed rates will be at different settings.

The lead screw is mainly used for thread cutting and not for normal power feed. As I understand it. Or that is how my lathe works.

[Michael Moore]

Most lathes will do a LOT more feeding for facing/turning than they will threading.   You don't want to wear out the  leadscrew and nuts by using them to do power feed, you want to save them for doing accurate threads.  You'll see older/smaller lathes that have only a lead screw that gets used for both threading and feeding and so wears out much sooner.

[Canuck750]

I played around with the power drive setting, leaving the lead screw stationary and adjusting the spindle speed and gear box. This now makes sense to me, thank you for the explanations.

 I have been practicing turning mild steel to an accurate diameter and today started to work with aluminum and brass. I have some work to do on tool grinding to stop the endless coils of aluminum spinning off! 

It’s all very interesting to watch the videos and attempt to put theory into practice. It’s mesmerizing watching a round piece reduce to a pile of chips, it takes little to amuse me.