Threading on a PM1127 lathe - turning instead of threading

[Mitch Alsup]

You can't use the threading dial for metric threads. You can use it for inch threads, but you don't have to- it's optional
Mark

ABomb79 showed how to use the threading dials on a metric thread with inch lead screw a couple weeks ago.

As you near the end of the thread, you perform the usual fast turn of the cross slide dial to pull the tool from the work; and as fast as possible, turn the motor off.
Then reverse directions and when the threading dial reaches the correct number you re-engage the half nut; and let the carriage carry the tool past the start point.

I thought this was both clever and handy.

 

[markba633csi]

For a beginner this may be a bit much to digest, but yes there are moves that allow using thread dial for metric

 

[epanzella]

I was threading 1/2" stainless yesterday using 24 tpi. This takes patience. I was going .005 at a time and it took a long time. I would've been taking larger cuts if I was working with mild steel.

I also ordered a center gauge today from Amazon.

When you first start a thread you can use heavier cuts as only the very tip of the tool is engaged. As the cuts get deeper and the tool load increases you can reduce DOC. You should really buy the book titled "How to Run a Lathe". Trying to learn all the ins and out of a lathe a post at a time is confusing at best.

 

[Pcmaker]

On the feed rate chart, when it shows 0.0025 does it mean 0.0025 per revolution? I like using the auto feed and I'm getting rough finishes when I have the threading gears on. I want the feed rate to be very slow for a better finish. At least, I'm getting better finishes this way.

 

[jbobb1]

Yes, you are correct.

 

[epanzella]

On the feed rate chart, when it shows 0.0025 does it mean 0.0025 per revolution? I like using the auto feed and I'm getting rough finishes when I have the threading gears on. I want the feed rate to be very slow for a better finish. At least, I'm getting better finishes this way.

Not threading gears, change gears. You use change gears for both threading and feeding. For threading the carriage is driven right off the leadscrew by the halfnuts. When you release the halfnuts and use the power feed lever it adds nother stage of gearing inside the apron that slows it down to feed speeds like .0025/revolution.