Single Point Thread Chasing on a Manual Lathe 

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.

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

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!

Thanks for the video Adam

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.

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

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.

Excellent ! Just finished a 0.46-24 brake tube nut for my 63 Split window vette single master cylinder. It's the original date coded Master from GM that came on the car. Typically it's a 7/16-24. Not sure what happened or why this Weird thread made it onto a production car, but here I am, making a custom nut for the damned thing out of 12L14 9/16 hex stock from McMaster. This technique would have saved half the time and material knowing how to pick up a thread last week to adjust the length or fit. Thank you Adam for all the great content over the years.

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.

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! ;)

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!

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.

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!

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

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

Thankyou for the education.

Spot on as always Adam

For a gear head lathe that one is sure quiet. QUALITY.

Thank You. Always the best.

Thanks, this helped a bunch with an assignment in my machining class

Thanks man! Liked this one a lot!

Fascinating and very informative Adam Thank you.

Really nice job. I could watch you n your work all day. Thanks

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

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!

Thank you for these videos I am learning a lot.

Thanks, great video. I really appreciate the up close video during the cut. Also the shot when you're making the second bolt and we get to see how you're manipulating all the controls is really impressive and helpful to really understand what's going on.

Hobbyist lathe operator here, I've chased a thread on my lathe one time in the past, and this looks much easier than how I did it. Thanks for the education.

THANKS FOR SHARING

Particularly good one Adam, thank you

Great detail. Thank you.

Great wrk. Always a pleasure watching you do your thing

The lathe looks amazing

Great job thanks for teaching!

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* 😁

Great video Adam, thanks for sharing.

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

Great job as always 👍

Close up shot is fantastic

Superb filming - so great to see the cutting process

Great video, and perspectives... 🙂

Thanks Adam, I have a project coming up similar to this and have been thinking of how I was going to do it. Your timing making this vidio is perfect for me! Thanks

Great video and work!

Thank you for sharing!

Thanks very useful and good camera angles

Good camera angle, especially on the first bolt. Enjoyed. Thanks.

Thank you Sir for sherring your expertise

Good job thanks for sharing

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)

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

Super helpful! Thank you as always! -CY Castor

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

I bet Joe really likes having you so close now!

Very interesting video.Thank you.

Interesting camera angles thanks for sharing

Thanks for sharing

Kind of magical seem the transition between the factory and new thread…

Outstanding video! Really good camera work on this one. Gives me confidence when doing my own work when I learn how from you!

Great Video

Top job,Adam. One additional little tip I use is to blue the original thread with Dykem and it makes it easier to see where the tool is initially making cutting contact with the thread flanks....it does help getting the alignment spot on.

I'm looking forward to see more video like this even i don't have lathe now once you showed me i really would like to buy one and start to do my little DIY work

Excellent tutorial and remember to remove all backlash if using an old worn lathe.

That Precision Mathew Lathe is sooo quiet

Very cool. Not sure I got the hang of it... but it's a wonderful demonstration of skill! :)

Hey Adam. I think you changed from advancing at the angle to advancing on the vertical. That is why you started to cut the original threads.

Thanks ☺️

Good job

cool video!

Did any one notice when the thread was first being chased that there was light showing either side of the cutting tool? If you are going to go in at 29 and a half degrees to only cut on the left side of the tool then surely the right side has to be within a thou or less of the left side of the thread( to the left of the peak) otherwise if there is say 8 thou gap to the right side of the tool then the centre of the new thread being cut is 8 thou to the left all the time. Also as the tool got deeper did anyone notice that the original thread was being cut and chips were coming off. Which to my mind says my original statement was correct Adam was off too far to the left when he set the tool up to the original thread.

great lession, i just had to do the same on my p & w clutch rod, i think i got luckey !!!!

Worked at a shop years ago where we frequently had to pickup & chase existing threads on cylinder rod ends, SKF nut threads on shafts and rolls because of damage. Was always my job because I was the young apprentice.

Nice work Adam!! Ive always wanted to know how to chase a thread.. Cheers

that old bolt sure took a beating

Interesting! Never seen that done before. Without knowing anything about the application, I won't comment on the rolled vs cut thread question. Bolt torque, etc. Don't know if it has to be exact because using a castle nut means you may have to go a little tighter to get the pin hole lined up (never back one off to do that). Mechanical Engineer (now retired) IRL BTW. 😁

Thank you for sharing!!👍🏽👍🏽👍🏽👍🏽👍🏽👍🏽👍🏽

Thanks for making the video! I've is been wondering for awhile how to find a new thread.

Alternatively, turn the chuck by hand (with the half-nuts engaged) far enough to remove backlash in the gear train. Then, with the work stationary, line up the RH flank of the tool with the RH flank of the existing thread. Rotate the chuck by hand a little and tweak the cross-slide and top-slide settings if necessary.

Good to know better than making a new part

Really interesting video Adam. As interesting as the main subject is here, it's actually helped me visualise the effect of using the cross slide as you feed it in, it really helps you see how it appears on a fully formed thread. Must admit, I still haven't mastered the cross slide on single point cutting, don't know why it puzzles me so much.

Not me Adam you do it how you want I'm watching good job as always

Good content

Hola buen día saludos desde Riosucio caldas Colombia

Nice work, you really clearly showed how the compound advances along the thread profile and it helped my understanding a lot!

I would propably just have prepared that thread similar to how you did, but then cut it with a die. Should work pretty well since the existing thread gives you a nice start. But doing it this way gives you a way nicer thread, so thumbs up.

Internet engineers out in force in this one .

i have a chart that shows infeed at 30 or straight for all thread pitches. so far it has not failed me. for normal threads i have not needed to test fit

Nicely done

I needed (2) 5/16-18 socket head cap screws 2" long with the thread all the way back to the head . They don't come that way. I did just exactly as you did . The main advantage to using the compound is your cutting on the left side of tool only. When you use the cross side you cut on both sides of the tool. That creates twice as much surface cutting and is more likely to cause chatter in the thread . You must use another depth for the compound than the double depth marked on a thread gage. My machiest hand book has the correct depth setting for the compound.

It's funny even though I KNOW I can engage the half nut on every other number of the thread dial, I still only go on the same number every time, just to be safe lol 😆😆

I can't seem to locate the correct threading bar and bit for the Walter tool you used on their site, Great video , thanks so much👍👍

Now, this is interesting.

Nicely done. Best thread chasing video on the net

This is an excellent video. I finally understand the use of the compound for thread cutting. Beautiful!

I have picked up a thread 3 times, almost back to back on customers parts, I was terrified, still am... but it can be done !

nice trick to know. I'm a bit puzzled by the tiny gap one could see on the close up views to the right side of the tools with the original thread : would that not mean that there is a slight misalignement of the tool with the existing thread (i.e. when one is plunging at 29°1/2 without touching to the right, when bottoming the right of the original thread will still remain a bit further away on the right side of the tool) - should not the tool be in light contact of the right thread trailing surface rather than a few thou away?

How can your eye even see that small detail? I'd need three magnifying glasses to even see the tool tip let alone making chase a thread. The closeup footage helped explain this really well.

you can see on the 5th thread it still flat thats where its binding up

That Walter tool must be good quality, it hurted my eye watching how deep cut you made few times.

Why did the threads at the transition from old to new break? If you were matching the existing threads why did you cut them as well while cutting the new ones?

Hello you mentioned the nut may have a burr on it. it is so close but just not there. I mite try running a tap in the nuts just to make sure . Thanks for the vids .