Crashed my lathe

[zippyslug31]

I just started learning SPTing... lots to remember such as getting the correct change gears, lathe speed, doing the "3 handwheel mambo", oh yeah and don't forget to look at the thread indicator before engaging the half nut!

Needless to say I was a bit preoccupied and managed to clobber my compound with the chuck. Took a couple of pea-sized chunks out of the compound and have a new scratch on one of the way facets. Double

I had to hone down a couple of interfering burrs, but now all 3 handwheels run to their full ranges without any issues. The chuck seems to turn freely by hand, but is there anything else I should inspect before trying to fire the lathe back up?
I think I'm just going to try my threading operation at least once more (with the stock pulled WAY out, away from the chuck) just to make sure everything that is in my current setup all works without any new clunks or weird noises.

Additional thoughts and bashings? I'm kicking myself at the moment.

 

[GeneT45]

Just go for it. Seems like you covered your bases. The machine is probably fine, other than the obvious damage to the compound, which are a common feature on many lathes...

Try 'air cuts' ahead of time and spin the chuck with the toolpost at the 'leftmost' position before starting, then get back in that saddle!

GsT

 

[Jake M]

Needless to say I was a bit preoccupied

I know it works best if you can remember ALL of the things, and the last thing you want is one more to remember...... But this is something I do that actually works for me when I'm working uncomfortably close to the chuck. Threading or power feeding- For me, it actually takes some of the mental stress off. I set up a carriage stop. Before starting any powerfeeding, I work out the maximum carrage travel I want (and compound infeed if I'm threading), and move the carriage to the left most extreme that will ever see. Then a whisker further, but still not sharing space with the chuck jaws, and set a carriage stop right there. It will NOT stop the carriage (maybe yours would?), but it gives me an EASY reference to know when to stop. Very easy to see exactly when it's just about to hit, and stop it right there. If the first thirty five of your threads cut fine, the last six or eight will be fine too, take your eyes off, and watch the stop. So much less going on, and so much more precise of a visual.

Honestly, with practice, it does get easier to "see" the precise tool position under the chips and oil, but I still set it up that way more often than not. I don't get the willies like I do when I'm watching the compound being .050 inches off of the spinning chuck and no real way to judge it. I just ride in the last bit with my hand on the power feed (or threading) control, and my eyes on that stop.

I suspect I won't use that "beginner's crutch" forever, but for me it's a good one. I'm still using it more often than not. It keeps my nerves in check, so I don't make bad decisions under pressure. I'm not saying it's a good solution for you, but I'd suggest that you consider it, maybe try it for a couple of practice runs. One hand on the appropriate control (thread or power feed), and eyeballs on the stop. At that point in the operation, those are ALL that matter. The coolest part about this, unlike most advice regarding machine tools- This one won't cost you a nickel.

As for your lathe..... Ouch. But it happens, and you've done the right things. Everything is still there, nothing seems broken (except the broken parts... But you know what I mean....). The thing to do at this point and start it up, verify functionality, and take it as it comes. Depending on the severity of the crash, it'll probably be fine. But after careful inspection, the next step is to run it.

 

[pontiac428]

If you want to practice threading with a padded suit on, it's good to run the cut with a sharpie in your toolholder instead of the tool, and practice that. Less going on, easier to learn and follow the motion, don't matter what speed you run since you're not cutting, so you work it at your own speed and build up.

 

[homebrewed]

There's nothing wrong with finishing the threads by hand. There are many designs out there to turn your spindle into a hand-driven job. That's about the ultimate in control.

In some cases I have set up a test indicator on a magnetic base to more accurately monitor the carriage/cutter position. A DI is pretty sensitive so the setup works best at very low RPMs or with a handwheel-driven spindle. I used this approach to cut some .7mm threads for a project that used an R/C servo and I needed to attach something special in place of the servo horn.

 

[OTmachine]

.

In some cases I have set up a test indicator on a magnetic base to more accurately monitor the carriage/cutter position.

I use a Mighty Mag with a 1” travel dial

 

[GL]

Seems like you avoided the full stop train wreak type crash. Those can really hurt things - gears, pins, keys. A couple of gouges on the carriage or compound make it look like many lathes in a high school metal shop. They seem to continue on.
Single point threading is easy -all you have to do is 17 things, in the right order, at the right time (the three hand wheel mambo was a good description). But it becomes easier with practice. Far away and that pen trick are good thoughts. Slow everything down to get the rhythm and reduce the pucker factor. Setting a stop has its own crash risks, but setting up a dial indicator that starts moving a little early also gives a visual indicator that the end is near. You don’t need to watch the lathe, just need to know when to pull the lever. The Joe Pie thread away from the chuck is another cool option if you don’t have a threaded chuck (he has a video). The horse is waiting to be ridden. You will be so much more confident when you get it. Some never try, but it’s kind of one of the rites of passage. Good luck.

 

[talvare]

For any threading job that requires the cutting tool be in close proximity to the chuck, I use the method of threading away from the chuck. Takes all of the stress out of the job.

Ted

 

[sdelivery]

Second that Talvare

 

[wachuko]

I just started learning SPTing... lots to remember such as getting the correct change gears, lathe speed, doing the "3 handwheel mambo", oh yeah and don't forget to look at the thread indicator before engaging the half nut!

Needless to say I was a bit preoccupied and managed to clobber my compound with the chuck. Took a couple of pea-sized chunks out of the compound and have a new scratch on one of the way facets. Double

I had to hone down a couple of interfering burrs, but now all 3 handwheels run to their full ranges without any issues. The chuck seems to turn freely by hand, but is there anything else I should inspect before trying to fire the lathe back up?
I think I'm just going to try my threading operation at least once more (with the stock pulled WAY out, away from the chuck) just to make sure everything that is in my current setup all works without any new clunks or weird noises.

Additional thoughts and bashings? I'm kicking myself at the moment.

I have nightmares about this…

Whenever I build the courage to do threads, I will try to learn to do it like Joe Pie described in his video…