# Carriage Stop For Threading



## Buffalo20 (Jun 30, 2017)

Again, I have to say, I do many of the shop procedures, based on what my grandfather, showed me. He and his 2 brothers ran the local machine shop, in the rural upstate NY state, village. Probably because they did small production jobs for the local mills, doing multiple parts, I was taught to use a carriage stop, when threading on the lathe.

So I have had a carriage stop on all of the lathes, I've owned. I had mentioned the stop in a thread a couple of days ago and I thought I show it.

The way I was taught, was to get the shaft ready to thread, bring the tool in to just touch the work, while stopped, set the stop, set the compound (set at 29.5 degrees) dial at zero. Advance the compound, start to thread, at the end of the thread, back the carriage out, stop and reverse the lathe, when past the end, stop the lathe, turn the carriage to the stop, advance the compound, the start threading again, repeat as/if necessary.

To me the stop, takes one element, for error out of the picture. As I thread about one a month or so, usually on a piece, I can't screw up, to me the carriage stop is a tool to make it easier to finish the job, without screwing up. Can I do it without it, yep, maybe its a unnecessary crutch, but for me it works.

Its nothing more than a couple of pieces of steel, welded together and a 7/16"-20 coupling nut and a piece of 7/16"-20, B-7 hardened all-thread, made to fit on the travel rest mounting point

1 - the pre-existing travel rest mounting point
2 - on the lathe
3 - one side
4 - the other side








Edit -title says carriage stop, in fact it's a cross slide stop..........


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## Ken from ontario (Jul 1, 2017)

I have been looking for ideas on carriage stop(auto feed) for a small lathe and the simplest I found is this one:https://mynewlathe.blogspot.ca/2015/01/mini-lathe-diy-autofeed-stop.html

The most ingenious auto feed carriage stop by James pvill who is a member here:


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## Buffalo20 (Jul 1, 2017)

The video was interesting, thanks for posting. That system releases the half-nut, which I never do, the way I was taught was to keep the half-nut engaged unit you finish the thread. Again, removing a chance for error.


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## Ken from ontario (Jul 1, 2017)

Buffalo20 said:


> The video was interesting, thanks for posting. That system releases the half-nut, which I never do, the way I was taught was to keep the half-nut engaged unit you finish the thread. Again, removing a chance for error.


I'm just learning  new ways to stop the auto feed, as you mentioned (when cutting threads)it may work best to leave the half -nut engaged but for other operations such as running two lathes  or machining multiple parts of the same length, it is a great system .


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## Ken from ontario (Jul 1, 2017)

Buffalo20 said:


> The way I was taught, was to get the shaft ready to thread, bring the tool in to just touch the work, while stopped, set the stop, set the compound (set at 29.5 degrees) dial at zero. Advance the compound, start to thread, at the end of the thread, back the carriage out, stop and reverse the lathe, when past the end, stop the lathe, turn the carriage to the stop, advance the compound, the start threading again, repeat as/if necessary.


Jack, I'm a novice and can't quite picture it in my head how your carriage stop works, is that C.stop for lathes with auto cross feed only?


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## Buffalo20 (Jul 1, 2017)

Ken,

I agree, I'm always interested in the ways, other people perform, their procedures. You never know when, you going to see something that will spark an idea or you learn their procedure is better than yours.

The 3 gentlemen, I learn from, all would be over 150 yrs old, half the equipment in the shop, was made before the Roosevelt administration, not Franklin, but Teddy Roosevelt. To those fine gentlemen, CNC would have been code for "Coffee 'N Cake". A lot of what I do, maybe old fashion, but for me it does work.


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## Buffalo20 (Jul 1, 2017)

Ken, 

my carriage stop, only takes the carriage back to the same starting position, every time. At the end of the thread, you back the carriage out, then go back to start the next pass, you turn the carriage into the stop, advance the compound, and cut the next pass. Repeating the procedure until your thread is cut.

I learned this way, doesn't mean is right for everyone, after almost 48+ years, to me it's second nature.


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## Ken from ontario (Jul 1, 2017)

Thanks , it's something I had never seen, but I'm just  starting to search for new idea/ designs like that,it looks like a great idea if used to make the same size threads repeatedly, as you said it"takes one element, for error out of the picture." I got it now.


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## mksj (Jul 1, 2017)

There are a number of different methods, but I no longer use the compound slide and just cut the threads by just advancing the cross slide. On larger 13" or bigger swing lathes the rigidity improves and I have not found any issues or difference in cutting threads, CNC lathes use a myriad of difference cutting algorithms. It also may vary by material. I will often zero my dials so that they indicate the start or end of desired thread depth. This way you have a reference point as to either where you need to back out to or you want to end up at.  If I use the compound then I do not use the carriage slide, if I am cutting with the cross slide, then I lock the compound. If you try to use both, probably more prone to errors, unless you use a system as noted above. Not disengaging the half-nut, the cutter speed change changes when stopping and it is difficult to gauge the final position. A mechanical system per the video is a snap action, which is important to prevent undue wear on the half nut. 

If you use a VFD drive you can use either a mechanical snap action limit switch to stop the lathe electronically or an electronic proximity switch to stop the carriage, the latter has a repeatable  accuracy that is +/- o.0002". Using electronic braking, stopping time is about 1 second. This method works very well to do the complete threading process without disengaging the half-nut, so no issues with doing metric threads, threading to a shoulder or internal;/blind threading. With this method, I find that just using the cross slide for threading gives pretty much the same exact stopping point with each pass. You can either use a DRO or indicator zeroed to either the start or end of the desired thread depth as a reference point. So only moving one dial back and forth.


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## higgite (Jul 1, 2017)

The OP's device is a cross slide stop, not a carriage stop. It makes it super easy to return the cross slide to zero if you thread using the 29 degree compound method. You don't have to remember how many turns of the dial that you backed the cross slide out when you finish a pass and return the carriage back to the starting point. Just crank it back in until it hits the stop, advance the compound and make the next pass. It's a neat contraption. Good job, Buffalo. You got my creative juices flowing to do something similar.

Tom


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## Buffalo20 (Jul 1, 2017)

Higgite, 

thank you, you are right, I called it by the wrong name, sorry brain fade.......

I put an edit on the original post


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