video of the design and construction of a spring retractable tool holder

[BoydAllen]

The majority of the video is about how it was made, part by part. If you skip forward to 29:30 you can see it in action.

 

[hoz53]

The majority of the video is about how it was made, part by part. If you skip forward to 29:30 you can see it in action.

Thanks for that Boyd- Both the video and the channel info. Hope youre doing well these days

 

[boltfluter]

What a cool video and a very handy accessory to have! Threading to a shoulder can be exciting, to say the least!

Paul

 

[jackson1]

Interesting video. Spent my life as a tool and die maker, so threading was not a daily occurrence for me, but cut enough from Acme's to sharp V. The video demonstration was done with aluminum, which is by nature quite forgiving. What I noticed is a bit of play (possible forward tool movement when locked in place). Have cut threads where the tool got sucked into the workpiece. Making blank cuts ( with no adjustment to the compound or crossfeed, using self ground HSS tool bits). Great piece of home style engineering. Could possibly work great when cutting internal blind threads. Thanks for sharing.

 

[GenePoole]

I just watched the end, so I don't know all the details. Do you still manually disengage the half-nuts?

I'd like to see how this does with steel. I think all that stick-out and all the tolerance stacking would not lead to a very good thread.

 

[Roeder]

As I understand it, the Hardinge tool maker lathe is designed to do much the same thing. It automatically simultaneously disengages the half nuts and retracts the tool. It allows for threading very close to a shoulder without a relief groove and at high speeds. The design is currently being manufactured in Taiwan and sold under several Brand names. Even though the Taiwan copy is priced at about half the original, it is still pricey and too small for most gunsmiths. A shop would be well equipped to have one along with a larger machine.
https://www.grizzly.com/products/South-Bend-Super-Precision-Digital-Threading-Collet-Lathe/SB1009

 

[hpshooter]

"As I understand it, the Hardinge tool maker lathe is designed to do much the same thing. It automatically simultaneously disengages the half nuts and retracts the tool."

When Hendey lathes were being built they featured an auto reverse that could be used for turning and threading, required backing off the cross slide and setting your desired depth of the next cut before you hit the auto advance trip. They also offered an optional cross slide retract feature, manually operated, that worked well when using the auto reverse. Hendey was very proud of the auto reverse set up for threading which is why finding a Hendey with the optional threading dial fitted is somewhat rare. I havw a Hendey cross slide with the retracting mechanism in it tat was salvaged from a damaged lathe that is on the round-to-it list to fit to my 12x30 Hendey. Lots of info on threading with a Hendey auto reverse on the Practical Machinist antique and vintage forum.

There are plans on the net for manually retractable tool holders that utilize an eccentric cam to withdraw the tool that have fewer sliding surfaces to be fitted than the self retracting one.

 

[Alex Wheeler]

I thread at 260 rpm, its very easy to do manually. I used to run 375 and you have to be a little quicker. I know guys that run 500 plus. You can get a great finish at any of those speeds, and even less if the setup is right. I dont like engaging the half nuts at 375 and up on my older lather, it seems abusive. At least in my experience, rigidity in threading is extremely important to prevent chatter. I doubt any of these setups would work well in larger od and coarse threads in steel. But it wouldnt be the first time I was wrong.

 

[hogpatrol]

Pretty slick.