[Newbie] When Is It Good/safe To Engage The Power Feed Lever

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dave_r_1

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On my Force International lathe, which seems to not be a 'basic' model, as it has a power feed bar and a thread screw for the saddle, and an interlock between the power feed lever on the saddle and the half-nut lever. However, the saddle does not have a clutch lever.

For making a relief cut or a smaller diameter part in the middle of a shaft, should I stop/restart the lathe when engaging and disengaging the power feed lever because it has no separate clutch lever? Or would it just be part of the machines design to permit engaging/disengaging it with the lathe running?
 
Thanks.

Yup, it engages and disengages nice and smooth. I was concerned it would be something like the gearbox, which explicitly warns not to change gears while running.
 
The feed lever is designed, even intended for operation while the feed shaft (spindle) is turning. The slip clutch on the feed rod will activate on either the carriage or cross slide travel (in practice it is unlikely the clutch would slip while facing).

Whether the clutch will actually slip or not (on longitudinal feed) may be iffy, and you should check/confirm the function before you depend on it.

I have 2 lathes and on the larger one, when I set the carriage stop, it may well push the stop. The clutch is adjustable, and I have messed around with it, but I still do not trust it. The smaller lathe is a higher end machine and the stop does not need to be cranked down tight, and the feed will kick out smoothly and repeatable.

You should play around with the clutch and your carriage stop. Learn how it works on your machine. The invite to stop by here and check out some other machines and setups is still open (only 90 minutes down the road).
 
When I engage/disenage the power feed using the lever, it certainly does so smoothly, but I'd have to look at the saddle more closely to see if there is any kind of clutch adjustment, and it wouldn't be expected to be commonly adjusted, as I've seen pictures of other lathes where they have a separate lever just for adjusting the clutch.

I will give the carriage stop a try and see how it interacts with the power feed. I know it doesn't play well with the carriage when using the threading screw, as it seems that something is going to break anything slips. My carriage stop isn't the easiest to use, as to tighten it, the two allen-head bolts are on the bottom of it, and the thread screw is just in the way when using a regular-length allen key.
 
The clutch / feed trip is arranged differently on different lathes. On my Enterprise lathe the slip clutch is on the feed rod, right where it comes out of the feed gear box (easily accessable to adjust). On my S&B the feed kicks out when there is enough resistance to the travel of the carriage, and to adjust it requires taking the apron apart - quite a job.

You are correct that one does not ever use a stop when using the threading screw. It will break something.
 
IMG_0498.jpg

Now I'm at this stage of threading. I'm using an 'E'/C6 bit, so it's a proper 60 degrees, and I used the tool for making sure it's square to the rod, and the relief at the end seems to have helped with not killing the tip of the bit [it looks a little worn, not busted off like the first one]. The compound slide is set to 60 [with 0 being parallel to the work]. But they aren't coming out right.

I've got a feeling that:
1) I need to use a higher RPM, for this I was using under 100 RPM [mainly so I could make sure I stop before running into things]
2) I have to make sure to take backlash out of the saddle movement, as I'm using the motor in reverse with the half-nut engaged to go back to the beginning.

But I don't know why the angles on the thread appear off [as I think they should look like a nice equilateral triangle from the side], and they dont...
 
Chipper5783 said:
The clutch / feed trip is arranged differently on different lathes. On my Enterprise lathe the slip clutch is on the feed rod, right where it comes out of the feed gear box (easily accessable to adjust). On my S&B the feed kicks out when there is enough resistance to the travel of the carriage, and to adjust it requires taking the apron apart - quite a job.

You are correct that one does not ever use a stop when using the threading screw. It will break something.
Click to expand...

Evidently I have to find out where Tom of "Tom's Technique" youtube videos lives, so I can steal his lathe. It appears to have a carriage stop that also works with the thread screw, as well as a fancy way of reversing the thread screw without having to stop & reverse the headstock. And some kind of quick mechanism for getting the tool away from the part and back again without changing the cross slide or compound slide handwheels. He manages to make doing it look trivial...
 
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Threading is frequently done at low rpm, sometimes between 40 and 50 rpm. Use the appropriate fishtail to set the angle of your bit perpendicular to the work surface. Keep practicing!


Steve Shannon, P.E.
 
The trailing edge of the threads look nice and smooth, but the leading edge frequently has parts that look like swarf got mashed between the cutting tip and the part or a little bit of the part tore. It's my understanding that this is generally due to going too slowly through softer steel, and this is on a 3/8" rod, so the tool speed will be pretty slow.

And I did use the fishtail tool to align the tool tip with the rod, so it's perpendicular to it.
 
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