Crashing a micrometer stop?

I think we are all a bit respectful of the "crash" potential while threading. I know I am.
I learned by incident that I have the clutch in the apron almost exactly like the picture mksj posted.
I was threading and got to the end or under cut section and the thread or half nut lever was stuck.
The QCTP hit the chuck outside the jaws so I didn't have a bad crash. Thanks to the clutch I had very little damage.
I stepped on the brake almost immediately.
After reviewing what happened, my under cut was not adequate in size or depth.
Lesson learned.
 
Graham, the single biggest aid to threading comfortably and safely is practice. Your half nuts will disengage instantly and the saddle will stop instantly the moment you move the lever, you'll see.

Whenever possible, a thread relief that is 2-3 threads wide is recommended. The depth of this relief is about 0.005" deeper than the minimum diameter of the thread. This relief is usually more than enough to stop in time provided you are not threading at insane speeds. You will learn to pick a spot where the tip of the tool just enters the thread relief and your hand will kick the half nuts out of engagement and the saddle will stop at the instant you do. With repetition, this movement will become subconscious and you won't need to even think about it much.

I joked a bit about using your "brain" in my previous response but it really is true. You will find that with enough practice, screw cutting on the lathe is a fun, stress-free activity. You don't need a carriage stop; you simply need to stay focused. Try not to worry too much about it - you will do just fine.
 
The 9A is fun to cut threads on. Here's a pic from last weekend. I needed a bolt for the carriage lock that would hold the wrench that also fits the feed reverse. The machine had an allen head bolt when I got it. So I would have to look for the allen wrench as well as the wrench that fits the feed reverse. Now it will be right in front of me. The machine didn't have a thread dial either. This one seems to work until the right one comes down the pike. I'm no pro at threading but I have fun doing it. 20191110_071145.jpg20191110_092413.jpg20191110_134930.jpg
 
Chuck K said:
The 9A is fun to cut threads on. Here's a pic from last weekend.
Click to expand...
Woah Chuck.. Most excellent pictures!
I can see TWO machines in there, the one behind clearly a bigger, more beefy sort.
Great idea for the carriage lock. I can understand how easy it is to always be hunting down the right Allen wrench.
I have sets of Allen key wrenches, one a full set in a plastic case having both metric and imperial, and a couple of those plastic storage bins where goes all others I rescue or tidy up. I attach the right size Allen key to certain tools so I don't have to go hunting for them. The circular saw has a special storage place for it's wrench, etc.

Of those that get muddled together, the attempt to separate metric from imperial did not work well. Some I have put little printed labels on, covered with transparent sticky tape (cellulose?). Others have dabs of colour coded paint, and some have colour coded heatshrink idents miss-applied from electrical cable marking kit. Since I acquired the South Bend(s), I have had to get used to 3/8" and 1/2" and 9/16" etc. all over again. Last I used those units was in a previous century - a previous millennium even! It's going to take some patient sorting and a caliper to separate the imperial Allens from the metric. They all look much the same!

I take it you also have a mill, to make the square head on your lock-bolt.
 
mikey said:
Graham, the single biggest aid to threading comfortably and safely is practice. Your half nuts will disengage instantly and the saddle will stop instantly the moment you move the lever, you'll see.
Click to expand...
I am totally looking forward to getting to the point I can get some of the "practice" working the half-nuts lever. Right now I am up to the armpits in iron stuff part-way through adventures with paint stripper, wire brushes, and yuk little heaps of tear-off paper towels that I am sure are becoming a fire hazard! I seem to spend a large fraction of "messing with machines" time just cleaning up after me. When I have the parts in fit condition to assemble, I will post more. I wanted to be taking photos of the stripdown detail, but one Samsung Galaxy7 nearly ended up in the dirty paraffin solvent! I need stuff like that so I know how to put it together again. :hate:
 
I take it you also have a mill, to make the square head on your lock-bolt.
[/QUOTE]
You have to have a $5000.00 mill if you want to make a $5.00 bolt. LOL
 
You must log in or register to reply here.
Back
Top