# The Retractor



## MrWhoopee (Jun 16, 2022)

View attachment The Retractor.mp4


Some people (no one here) weren't satisfied with the automatic threading stop for my SB Heavy 10. They felt that the tool should also retract to avoid the necessity of a thread relief.  I've always tried to fulfill people's unreasonable requests, so here goes. Please bear in mind that these things are designed on the fly, the unanticipated details and errors of one step influence the next.

Here's what we started with. The bearing is a guide bearing from a router bit.















I only needed one of these cams, but when I decided it needed another feature it was easier to just make another.









The additional feature on the cam was a .250 R. divot .005" deep at the high point, which provides a seat for the bearing when the tool is in the forward (working) position. Pushing the trip lever (bottom right of last picture) rotates the cam off center, then the pressure from the spring takes over, pushing the tool back as the cam rotates to its low point. The tool retracts 1/8", which should be plenty for all but the coarsest threads. A larger cam and some clearancing would allow for more retraction if needed.

This whole job would have been a lot easier with a surface grinder, but you work with what you have.  I spent way too much time lapping the tool shank to provide a precision slip fit in the carrier. I still have to make the trip stop, haven't quite decided how it will be attached to the lathe.   Video will follow once I've worked out those details.


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## benmychree (Jun 16, 2022)

It would be all the better if the device was made with an integral dovetail to fit the tool post, avoiding the excessive overhang of the attachment.


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## MrWhoopee (Jun 16, 2022)

benmychree said:


> It would be all the better if the device was made with an integral dovetail to fit the tool post, avoiding the excessive overhang of the attachment.


There is actually enough material to do that, but first I have to deal with inconsistent release. Going to start with a stronger spring and maybe a little fine file work on the cam to reduce the "neutral zone". I have considered other release mechanisms, but hoping I don't have to go that far.


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## markba633csi (Jun 17, 2022)

It's a lathe, it's bear-trap, it's a floor polisher... _all in one! _


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## MrWhoopee (Jun 17, 2022)

Well today is more promising than yesterday. I discovered some things about setting the stops that made a big difference. This is cutting 3/4-16.






This is just some nasty old black pipe, so the finish is less than stellar.


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## ConValSam (Jun 17, 2022)

What an excellent presentation from Kripke all the way to finished threads. My compliments.


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## MrWhoopee (Jun 17, 2022)

benmychree said:


> It would be all the better if the device was made with an integral dovetail to fit the tool post, avoiding the excessive overhang of the attachment.


Since the mechanics of this thing have worked out, I've ordered the dovetail cutter.


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## MrWhoopee (Jun 17, 2022)

ConValSam said:


> What an excellent presentation from Kripke all the way to finished threads. My compliments.


Why thank you. Trying to keep it entertaining and informative.


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## Tipton1965 (Jun 17, 2022)

Pretty cool!


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## Janderso (Jun 17, 2022)

MrWhoopee said:


> Why thank you. Trying to keep it entertaining and informative.


Oh man, that’s cool.


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## brino (Jun 17, 2022)

Very slick!

Brian


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## Winegrower (Jun 17, 2022)

Bravo!


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## Just for fun (Jun 18, 2022)

Very nice work, thanks for sharing!


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## Parlo (Jun 18, 2022)

Great presentation and design, thanks for sharing.
Could you have two stops on the threaded bar for the trip lever to run between. This could re-set the tool when the carriage is returned to the start position.


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## MrWhoopee (Jun 18, 2022)

Parlo said:


> Great presentation and design, thanks for sharing.
> Could you have two stops on the threaded bar for the trip lever to run between. This could re-set the tool when the carriage is returned to the start position.


The cam rotates180° for full retraction, so a second stop on the threaded bar would not be able to engage the trip lever. A second lever on the trip lever hub might, but it would likely only achieve 90° return at best and then would snap back to full retract under spring tension.

Thanks, you guys are giving me some ideas.


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## Janderso (Jun 18, 2022)

MrWhoopee said:


> The cam rotates180° for full retraction, so a second stop on the threaded bar would not be able to engage the trip lever. A second lever on the trip lever hub might, but it would likely only achieve 90° return at best and then would snap back to full retract under spring tension.
> 
> Thanks, you guys are giving me some ideas.


Are you going to patent this thing?
Send the specs to China for production?
Will you still speak to us when you are a multi millionaire?
I hope so


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## Parlo (Jun 18, 2022)

MrWhoopee said:


> The cam rotates180° for full retraction, so a second stop on the threaded bar would not be able to engage the trip lever. A second lever on the trip lever hub might, but it would likely only achieve 90° return at best and then would snap back to full retract under spring tension.
> 
> Thanks, you guys are giving me some ideas.


I thought it could retract with a 90 degree movement of the cam, so the trip lever moves +/- 45 degrees. It may need a flat on the cam and a stop pin to restrict the rotation of the trip lever to 90 degrees.
Perhaps the cam and follower could be vertical, the trip lever can then ride up and down adjustable angled plate cams?


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## MrWhoopee (Jun 18, 2022)

Parlo said:


> I thought it could retract with a 90 degree movement of the cam, so the trip lever moves +/- 45 degrees. It may need a flat on the cam and a stop pin to restrict the rotation of the trip lever to 90 degrees.
> Perhaps the cam and follower could be vertical, the trip lever can then ride up and down adjustable angled plate cams?


Because the cam is a round piece of stock, the retract at 90° will be less than 1/8" without changing the cam. A vertical trip lever has some possiblities, would require a different approach to the trip stop, perhaps a ramp sort of thing.


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## MrWhoopee (Jun 19, 2022)

Janderso said:


> Are you going to patent this thing?
> Send the specs to China for production?
> Will you still speak to us when you are a multi millionaire?
> I hope so


Unfortunately, my designs are so stupidly simple that there is nothing patentable about them. I don't see a vast fortune in my future. I'm happy just to be able to hang out here with you guys.

Back to the matter at hand, I've formalized the stop system, moved the reset lever to the top and added a short trip lever on the bottom.




The stop pivots up, out of the way, when not needed.




Once I realized that the disengagement of the half-nut did not need to be closely synchronized with the retract, I found the retract worked much better. There is a more or less fixed relationship between the two stops, so adjustment can be done by moving the the main (lower) stop bar in the support bracket.


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## MrWhoopee (Jun 24, 2022)

The retractor now has its own dovetail, no tool holder required. Turns out the height adjusting screw is perfectly postioned as a reset stop.


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## Janderso (Jun 24, 2022)

MrWhoopee said:


> The retractor now has its own dovetail, no tool holder required. Turns out the height adjusting screw is perfectly postioned as a reset stop.
> 
> View attachment 411482


Come on John, you owe Mrwhoopee an at a boy!
Well done sir!


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## Parlo (Jun 25, 2022)

MrWhoopee said:


> The retractor now has its own dovetail, no tool holder required. Turns out the height adjusting screw is perfectly postioned as a reset stop.
> 
> View attachment 411482


Very neat, looking more like a modified toolholder with a plate screwed on.


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## MrWhoopee (Jun 25, 2022)

Parlo said:


> Very neat, looking more like a modified toolholder with a plate screwed on.


I've been considering that very thing, but the last one I modified was HARD. I wasted a new carbide endmill. The slot is probably doable, the tapped holes would be another matter.


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## Parlo (Jun 25, 2022)

MrWhoopee said:


> I've been considering that very thing, but the last one I modified was HARD. I wasted a new carbide endmill. The slot is probably doable, the tapped holes would be another matter.


They are usually case hardened, a carbide slot drill, or drill can remove the case ready for drilling + tapping.


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## MrWhoopee (Jun 25, 2022)

Parlo said:


> They are usually case hardened, a carbide slot drill, or drill can remove the case ready for drilling + tapping.


That was what I expected, but was not the "case" for the one I modified. It was a knurling tool. I removed the ears for the knurls and extended the slot the length of the block. It was hard all the way down. Of course, they may not all be like that.


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## Parlo (Jun 25, 2022)

Sorry, I meant adding a plate to a standard quick release toolholder.


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## FOMOGO (Jun 25, 2022)

It's good to get lucky once in awhile. Seems it happens more often as I get older. Maybe He/She/It that runs things starts to give us a break as we get up there in age. Mike



MrWhoopee said:


> Turns out the height adjusting screw is perfectly postioned as a reset stop.


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## Dan Krager (Jul 18, 2022)

My purchase of one of these retractors arrived today and I'm thrilled.  I can't test it just yet because the Smithy is setup for gear cutting just now.  So later this week I'll see it in action.  Thank you Mr. Whoopee.

I couldn't find the post where a batch of these was offered for sale.



DanK


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