Single Point Thread Chasing on a Manual Lathe

I had a small threading ob come up where the customer wanted two new shoulder bolts to match the shoulder length of an original part which requiring machining the threads further back. I show you my techniques on how to line up on an existing thread and progressively cut them to match the original. I understand that after filming this video some of this may be hard to understand or even see in the video so I would like to revisit this subject and film it again in more detail.
#abom79 #singlepointthreading #manualmachining #machining

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[joepie]

Greetings Adam. Congratulations on the new shop and expansion of your machining capability. You should be very proud. Now for the hard part. Your setup was destined to ruin the original threads from the start. Locating the threading tool on the right side of a 60 degree thread with the compound set at 29 1/2, doesn't work the same for chasing as it does for cutting a thread from scratch. To simplify, imagine 2 cars on the freeway side by side, but the one on the right (original thread profile) is slightly ahead of the one on the left. Now the car on the right turns 30 degrees to the left while you only turn 29.5 degrees to the left. A collision will occur. Exactly the same thing happen to the original threads on this rework. I don't have the parts to inspect, but I'd bet ya dinner, the original thread PD is now smaller than additional threads you just cut. Align the 'V' first as deep as you can then back out the tool and creep back to that position. I hope you accept this in the good faith it was offered. Stay well.

[VacFink]

The close up showing the tool tip riding in the previous thread was fantastic. Great explanation.

[rickhand]

On my badly worn Sheldon lathe I engage the half nuts then push the saddle to the right (for right hand threads) when lining up the tool with existing threads. It must be a joy to use a tight, high quality machine like that! Another great video!

[willjosephson]

Thanks in particular for showing what's important and what's less important. Knowing that is what comes with your years of experience, and what really helps the rest of us be better. Thanks as always.

[timthetoolman]

Exactly the kind of content I come here for. Thanks Adam!

[patrickirish]

I am a level 3 machinist apprentice and I have to say I've never seen a thread chased this way with a compound at 29°. Fresh threading yes 29°, but for chasing, I alway set my compound 90° aka so the ways of the compound are parralel with bed. Then I engage split nut, and feed back and forth with compound using a dial on compound to show when I hit either side of the thread wall. Then I split the difference, do an eye check and this ensures youre in the bottom. Then some guys like to take some pressure off one cutting edge of the tool which is fine and would be acheived by moving compound in direction of chuck maybe 0.002". Then use oil and gradually feed in using the cross slide over multiple passes until you gently clean it up.

[mudgutsisgeordie]

Those camera angles were perfect. Seeing that back edge just clear the existing thread and start to cut the new one was amazing. Your content never gets old!

[KimbrellBrad]

Critical technique there Adam. I've done it and destroyed my workpiece and done it with perfection (likely by accident LOL). Great video and glad to see you are back home.

[tomkennedy]

I'm glad you have a new shop but I just enjoy the videos of you working from home better but I wish you all the best in the new shop

[bigdatapimp]

how can anyone think that videos of cutting soap and other BS is satisfying, when there are videos like this that exist? This is a billion times more satisfying to watch.

[ThomasLips]

It took me watching the setup two times to understand what you were doing with the cross feed and compound. I got it after the second run through. Thanks for sharing the information Adam!

[imbok]

It's always good to see a 'Hey Man' job turn into a learning opportunity. Thanks for sharing.

[rexmyers]

Your camera angle REALLY helped me to see what needs to be done to make it all work. Thanks

[matspatpc]

Nice. I had to do something similar - I thought I'd cut a deep enough M18 x 1.5 thread on a custom bolt I was making, and found that it wasn't quite far enough - so I had to pick it up again, and do another few passes on it. I just made it up as I went along, nut cam up with more or less the same method - using the compund-slide to adjust the position sideways and cross slide for depth. It worked! ;)

[phrozenwun]

Really enjoyed to display of skill and technical know how! Thank you for sharing your knowledge of such an involved process - keep up the good work!

[howardtoob]

The close ups are really helpful.
Your explanation of how to pick up the existing thread is the best I've ever seen.

[steveb]

Hi there and greetings from down under, I work for a valve manufacturer and cut threads on a daily basis have done for 30 years, there is no need to turn the top slide around to halve the thread angle. Keep it set to 0 and engage the halve nuts then simply adjust the top slide unit the tool lines up with the existing thread happy days, I hope this comment might speed things up a bit for you. Cheers

[DownToNerd]

That PM lathe looks so smooth to operate.

You probably heard it before but congrats on the new shop Adam! Thinking back to the first few videos and seeing what the new shop looks like now. The progress made is amazing!
Thank you for your content.

(edit spelling)

[ukp]

I know cutting threads every day, normal for you, but it's still magical to watch the threads being cut. Especially when they match up, with existing threads, on the right hand side.
Great video Love from Scotland 5* 😁

[darkmann]

That golden-coloured knob on the toolpost looks very nice!