Carriage stop "STOP" - why not?

[ScrapMetal]

I need to spend more time in front of the lathe 'cause it seems I have too much time on my hands otherwise and I start "thinking"...

Okay, it has come to my attention that if you were to be a bit careless when threading or having the clutch engaged you could easily allow your carriage/tool post/etc. run smack into the spinning chuck. While I haven't seen it in person I imagine this is what would be called a "bad thing". :biggrin: Since this is a "bad thing" why isn't every lathe outfitted with a device to prevent this from happening?

It would be simple enough to incorporate, just make a moveable carriage stop with a built in kill switch. When you do your initial setup for cutting you move the kill switch/carriage stop to the point you do not want the carriage to go past. If you happen to slip up after that point the tool post would never make it into the chuck as the power would be cut when the carriage hits the stop/switch. Being moveable it could be reset at any point depending on your tool setup or even moved out of the way if need be.

It would be very simple to fab up and certainly wouldn't cost much especially considering what the aftermath of a "bad thing" would cost.

Am I missing something basic that makes this impractical?

-Ron

 

[BRIAN]

Hi Ron
I use this system on my 7x12 now I have converted to belt drive, and dont have to worry about slowing the DC motor before switching off, to save the speed controller ( it blew up any way ).

The adjustable rod is set to trip a micro switch, that is inline with the safety gard trip.

It works very well and makes threading to a stop a doddle.

Also as I have a young helper in the shop it is safer,and gives me peace of mind when I allow him to use the auto feed.



I hope this helps BRIAN.

 

[Al 1]

Why not install a spring on the end of the rod that activates your switch before the rod bottoms out?

 

[ScrapMetal]

Rick,

What you say makes sense I had no doubts that I wasn't the first to consider this but I may not have been clear on what I was thinking of it's implementation.

I think I already spoke to "if one sets the stop to take account of this you tend to lose working area where it is most valuable" by making the emergency shutoff moveable/removable. (ie. Make it like a standard movable stop with a button on it.) If one really needed to work that close to the chuck it would still be possible.

As for the the lathe being high speed and still turning after the power is cut, I'm sure I wasn't as clear as I intended. I was thinking of this "kill switch" as just that, an emergency kill switch in the case of a runaway carriage and not as an actual working "stop" for cutting to a shoulder or threading. It could be set up to shut off when the tool or QCTP gets to within say an eighth of an inch from the spinning jaws. It might not prevent nicks and such but could prevent a complete catastrophe "bad thing" :biggrin:.

Where I was thinking it may be a drawback is that a person may come to rely upon it and not pay as much attention to their cut. :thinking:

-Ron

 

[Tony Wells]

I've seen some rigs with air cylinders set up to kick out the halfnuts and the tool also, used for threading API tool joints. I wish I'd paid attention, I'd like to set up one of my lathes just for that.

 

[GK1918]

Ron I know I posted this somewhere, but I will say whatever works for ya. First off I always make a relief cut down to
the root of the thread with parting tool. Theres a lot of things going on while threading. So I made a stop out of
wood 1/4 rod Horizontal about a foot soldered a wire and spring to end of rod wired in series with an smoke detector
from the junk box. Degut alarm (only for speaker) its 9Vt always on works perfectly. As soon as spring hits carriage
slam half nut off. (blindfolded) course you gotta sand just a spot on carriage where spring hits. I only found a spring
same size as rod. I got this idea from first job running a loom. With all that noise and distractions of 20 very loud
looms running, If only one (end) out of a million broke, a thin piece of metal (heddle) droped, grounded and rang a
large bell, then you slam machine out of gear, if not you made a smash rendering woven section junk. So in fact the
machine relied on your hearing same as a lathe crash. Has to be wood or plastic its insulated always on no on off
switch, can be put on the right for left threads (I have already crashed into tailstock not paying attention) beleive me
this will get your attention. Heres a quick drawing or later ill get a picture. sam

 

[Tony Wells]

My Acer lathe does have a stop system that it primarily intended to provide repeatable feed stopping. I allows for 4 different positions, depending on the selection of which cam is aligned to push a dog underneath the carriage. The lathe originally was equipped with a 4 way tool turret, so the idea was to set cut limits for each tool in the too post. I suppose it could be set up to prevent a crash while feeding, but is not involved when threading. It is not intended a a failsafe to prevent you from running over the chuck in all cases.

On some thread I was asked to up a few pictures, so I did. I don't have the link to it at the moment.

 

[ScrapMetal]

Any pics of that Rick? Love to see them.

-Ron

 

[Tony Wells]

I've spent many an hour on turrett lathes, WS and J&L mostly, and they are covered up with stops to make production. Kind of cool at first, but then rather dull work, especially if you have a bar feeder and a rack full of material.

I wish I had one in my shop now.. These days they are still good for some things, I have in mind mindless drilling of cut to length bar stock. I do a lot of hollow work, being as it is all (nearly) downhole stuff.

 

[ScrapMetal]

It's this new fangled internet stuff, everybody wants pics. :biggrin: 'Course us older guys aren't used to taking pics of everything as pics (used to) cost lots of money. (Anyone else see in the paper where Kodak is going under?) Now it doesn't cost anything to take pictures and people have their "cameras" with them 24 hours a day. Definitely a strange new world.

-Ron