South Bend Lathe Feed Screw - Acme Threads & Involute Gears!

In today's video I'll be making a cross slide feed screw for a South Bend 9" lathe.
This feed screw will work for either a South Bend 9a or 9b lathe, as it includes the involute gear used for the power feed.
This project involves a good deal of work, has some challenging features, and everything needs to remain concentric.
I'll do my best to give an overview of the entire process and all of the different operations involved.
I will cover turning, grooving, single point threading and acme thread, and cutting a gear on the vertical milling machine.
I hope that you enjoy the video, and please don't hesitate to ask any questions you may have in the comment section.
Who am I?
I'm a hobby machinist, with a passion for old machine tools and manual machining.
I am here to share and learn.
Being self taught, much of my limited knowledge, has come from others sharing their experiences online, just as I am doing now.
My hope, is that by putting my work in front of much more knowledgeable machinists, we can all learn something new together.
My Lathe: MSC / Prince 9517350 - 13x40 Manual Metal Lathe
My Milling Machine: Bridgeport Variable Speed Series 1 "J Head"
My other Milling Machine: Brown & Sharpe No. 2 Plain "light type" Universal Milling Machine
CREDITS:
Music and Sound Effects courtesy of www.epidemicsound.com
/ @hersch_tool

[@larrypalmer7136]

Very well done! Nice voice over with clear and interesting information and an appreceated understated delivery.

[@hersch_tool]

Thank you very much! I really appreciate the feedback!

[@macsmachine]

You’re a natural on many fronts: machining, teaching, speaking. I enjoyed the video.

[@hersch_tool]

Wow, that is VERY kind! Thank you so much! I'm glad that you enjoyed the vid, thank you very much for watching!

[@marcosherculano5944]

Thank you so much for the video , it gave me a better understanding to do it. My lathe is a copy of south Bend Lathe model A. I'm from Brazil, and may God bless you.

[@hersch_tool]

You're very welcome. Thank YOU so much for watching!

[@appalachianbushcraft3959]

More videos man!!! Atleats give me one a week lol. I need something to watch on this cold winter day!

[@hersch_tool]

Lol, thanks very much! And I'm working on it. ;) Actually, I'm always working on a video lol... 😬 There's a new one coming soon I promise!

[@zoltannagy1813]

Nice work. Keep the videos coming in the new year.

[@hersch_tool]

Thank you very much! And I definitely will keep them coming. Thank you for watching!

[@manmachinemake3708]

Great job ! I did a replacement crossfeed screw & nut for my 1956 S.B. 14-1/2" but used off the shelf ACME stock and cut/pinned it on the old front half. Long story why, but it was only meant as a temp fix. Still, it works great. You just found a source of income while providing greatly sought after parts for the hobby. Best would be to offer the matching nut that was cut with a tap which was made on that same lathe of yours. That way, the threads all match the same leadscrew. Hint, hint !

[@hersch_tool]

Whatever gets the job done, I used acme stock when I made the screw for my old leblond. And yeah that's a great idea! now I just need to find the time to make enough of em to get rich! Haha 😂 thanks very much for watching btw!

[@manmachinemake3708]

I machine obsolete replacement parts for Delta / Rockwell power equipment. I do the final work for a local business. He has made an amazing career out of providing those parts to the community.

[@hersch_tool]

@@manmachinemake3708 this is a legitimately great idea 🤔

[@eyuptony]

Excellent. Love your commentary on que. Good to see a follower rest being used while performing along screw cutting operation. Enjoyed.....Tony

[@hersch_tool]

Thank you very much 🙂 and thank you for the feedback, I'm trying to find a good balance of giving useful info while also not getting to "boring" or "tedious". And that follow rest really worked out well! Happy Holidays!

[@smashke]

Man, you continue to impress, both in ability and production . Looking forward to your expanded content including tutorials. I also enjoy the “tips and tricks” you cover while making these project videos, very helpful. What’s routine for you can be an “a ha” moment for others. Keep up the great work!

[@hersch_tool]

Thank you so much. I'm really glad to hear that your'e enjoying the vids and getting something useful out of them as well. That just makes me feel great to hear. I am overwhelmed with gratitude for all of the kindness and support that I've received for the channel. So again, thank you, and happy holidays as well!

[@sky173]

Nicely done. I have a Logan that needs this done. It should be a great project later in the year. Thanks for sharing. New sub.

[@hersch_tool]

thanks! it's a great way to refresh these beautiful old machines. thanks very much for the sub!

[@jeffanderson4979]

Well done dude. Yeah, last time I used my follow rest, it worked out great

[@hersch_tool]

thanks very much, and thank you for watching!

[@Awegner176]

Theads are not defined by minor diameter unless your inserts are ground for one, and only one, thread pitch. Most inserts accommodate a range of thread pitches. A good fit on a thread is most contingent on pitch diameter. Using an acme tool with a broader or narrower flat on its edge will result in a looser or tighter fit respectively if you plunge to the minor diameter. In my experience, using thread depth as your gauge can get you in trouble and should be avoided. Thread wires, ring gauges, or even thread mics are a better approach.

[@hersch_tool]

These inserts cut only 10 tpi acme threads, hence why I specifically called out the use of a form tool. So I'm plunging to ~1/2P. But thread forms still confuse the heck out of me lol. Thanks very much for watching btw!

[@Awegner176]

@@hersch_tool Well made video, regardless. Keep up the good work! I'm known as "the thread guy" at work, so please excuse me if I came off as harsh.

[@hersch_tool]

@@Awegner176 oh no worries at all. in fact the opposite, i have a lot to learn and very much appreciate any info that you offer. i'm serious, thread forms are difficult for me. i spent a lot of time in handbook for this vid and still feel like at the end of it all i was kind of just winging it lol.

[@FullSendPrecision]

Nice little project. Came out beautiful!

[@hersch_tool]

thank you very much! and thank you for watching 🙂

[@adamandrews2528]

Nice filming.

[@hersch_tool]

Thanks very much

[@DK-vx1zc]

Great job! great narration and videography!

[@hersch_tool]

Thank you very much! And thank you for watching!

[@Warped65er]

Nice project, and well done.

[@hersch_tool]

Thank you very much!

[@pikeyMcBarkin]

Holiday episode! YEAH!!

[@hersch_tool]

Haha, thanks! Happy Holidays!

[@tuck1963]

Nice work!

[@hersch_tool]

Thank you!

[@foogee9971]

Hey David, i am a little bit late, got my family around.....merry christmas and all the best to your family & loved ones! 🌲⛄🎄 ...another nice Video...as always! : )

[@hersch_tool]

Merry Christmas, and a Happy New Year to you and yours as well! 😉

[@parnuzutech]

Nice work 👍

[@hersch_tool]

Thank you!

[@life.is.to.short1414]

Great job

[@hersch_tool]

Thanks!

[@patrickbeaumier8616]

Really nice job. well done. 👍👍👍

[@hersch_tool]

Thanks very much!

[@martinchabot_FR]

You got a new subscriber sir, I really like your restoring video and wait for more!

[@hersch_tool]

Thanks very much for the sub! And than you for watching!

[@edsmachine93]

Very nice work. Thanks for sharing the process. Merry Christmas. Have a good evening.

[@hersch_tool]

Thank you, and you're very welcome. 🙂 thank you very much for watching, and merry Christmas!

[@ralphpavero7760]

Good tip on the tread relieve have a merry Christmas and happy new year

[@hersch_tool]

Thanks very much. :) And a Merry Christmas and Happy New year to you as well, thank you for watching!

[@larrywiggins9946]

Great job Happy New Year

[@hersch_tool]

Thanks very much 🙂 happy new year!

[@chadstrand7868]

very nice work

[@hersch_tool]

thank you very much!

[@michaelnoyes4817]

you made that look easy as, merry xmas

[@hersch_tool]

Hahaha, thanks very much. And merry Christmas to you!

[@McKildafor]

Thanks for the video. You got a new sub.

[@hersch_tool]

Thank you very much! I appreciate the sub, and thank you for watching!

[@kentuckytrapper780]

Excellent job man, merry Christmas and happy new years..

[@hersch_tool]

thanks very much, merry christmas and happy new year to you as well!

[@RustyInventions-wz6ir]

Nice work

[@hersch_tool]

Thank you very much!

[@ferrywobma1836]

Beautiful end product. However, I don't have a Southbend Lathe myself, so it's interesting to show this newly made lead screw next to the old or damaged one. Please show us the differences. Greetings from the Netherlands.

[@hersch_tool]

I'll try to make a short so that you can see a worn feed screw. It looks basically the same, but the acme threads get worn out causing a lot of play and backlash. Cheers 🙂

[@annacalise8336]

I loved this one, my only complaint is that I think it was to short, you know when your really into a video and aren't ready for it to end lol, that was this one, and the quality of work was excellent, keep the great content coming my friend! Hope you and your family have a Merry Christmas and a Happy New Year!

[@hersch_tool]

Thank you very much! I am glad to hear that you enjoyed it. I really appreciate the compliment and the positive feedback. That is what really makes all of it worth it and rewarding for me, so thank you. And merry Christmas to you and yours as well!

[@mechaform]

Neat trick with the planer gauge. I’ll file that one away for future ref.

[@hersch_tool]

Thanks! I hope it's helpful. And thank you very much for watching!

[@user-gt3xz6wo3o]

Very nice~ bro

[@hersch_tool]

Thanks very much :)

[@andrewyanke1787]

Cheeehoooo! Standing in front my lathe for this one.

[@hersch_tool]

Nice! Thank you for watching!

[@JourneymanRandy]

Nicely done. My 14.5inch South Bend takes a 11/16" 8 acme. I can't get it anywhere. Because is so worn out cutting threads is out of the question. I might swa it for 5/8" 8 acme. The nut for the 13" is 5/8" 8 and is available. What do you think?

[@hersch_tool]

As long as you're using the same pitch, which you are, then the dials will still read correctly. You might want to check other dimensions though to make sure "everything" is going to work and fit. For example, the power feed gear size and location, the diameter length, and locations of other features, like the part that rides in the bushing and where the dials and hand cranks connect, etc. And you might have to either or trim, or pack out the nut a bit so that it lines up correctly. South Bend made weird small incremental changes to things over the years, so basically just remember to check all the details and confirm that it will either work, or that you can at least make it work with modification. But in general yeah, there's not really any problem with changing to a slightly different size thread of the same pitch.

[@raindeergames6104]

What funky insert are You using for turbing down the OD? Its breaking chips nicely.

[@hersch_tool]

Yeah, those inserts are fantastic. They are Swiss style front turning inserts. I got a crazy good deal on a whole pile of Swiss style CNC tooling from someone on Facebook and they were included. The tool holders are TFT style holders made by NTK. And the inserts are TFX inserts. The only problem is, they are difficult to find for a hobbyist. Pretty much the only place I've been able to get them is when a pack will randomly pop up on eBay.

[@JT-uf4pg]

good video, got to follow your work. will you make parts for your viewers? would like you to make both lead screws and nuts for my SB 10L lathe.

[@hersch_tool]

Thanks very much! You can send me an email, we can discuss in private. Thanks for watching btw!

[@col2lin]

You makers/fixers tend to over look us that either don't or have little knowlage of what & how you get your results (in your case I like what I see, how & the finished item), tend to ask "what do you want see" forgetting that I just want to see what you are doing it isn't boring I most likely haven't seen what you are doing before. Thanks.

[@hersch_tool]

Thanks very much. This is really helpful feedback. I've had a lot of conversations with my wife about my videos, about how to make them interesting, even for folks who've maybe never done, or even seen some of these techniques and machines before. As usual, she makes everything that I do better than it would be without her... 😅 Thanks very much for watching!

[@robertharper8776]

Thanks for a great video. I have to make same leadscrew for my model c im coverting to a model b I'm waiting for a good deal on involute cutters.

[@hersch_tool]

Yeah they can be pricey. If I can offer a bit of my personal experience, be wary of the import "sets" of gear cutters. I've tried them and the profiles seem very hit or miss. I got this cutter from McMaster and it's pretty decent. Good luck with your project, and thank you for watching!

[@robertharper8776]

@@hersch_tool thanks for the advice I've had bad experience with cheep seems like the only one that is reputable is vevor stuff and shars.

[@hersch_tool]

@@robertharper8776 yeah I've had good experience with both of them as well

[@Raul28153]

that saw is made from the exact same castings as my RongFu saw

[@hersch_tool]

Yeah a lot of the import tools are made from the same castings with a different paint job and name slapped on the side. Jet, HF, Grizzly, RongFU, etc etc...

[@MynyddMunro]

Hi mate, what involute gear cutter did you use? Thanks

[@hersch_tool]

20dp 14.5pa cheers

[@311Bob]

Does it really matter if it's left or right if you also make a carriage nut too?

[@hersch_tool]

Not really insofar as it'll still work. But your dial will read "backwards" if that matters to you. Also it might feel weird if you've spent much time at a lathe as usually they are left hand so your muscle memory might be confused.

[@kendion4597]

What did the cutting tool look like for the acme thread?

[@hersch_tool]

I talk about the tool I used in the vid, it's a TNMC insert for 10P acme threads. :)

[@user-gt3xz6wo3o]

Which mini lathe do you recommend? ​

[@hersch_tool]

I would recommend something a little bit bigger if you can manage to find space for it. 9" or 10" swing is usually a manageable size machine but still packs enough rigidity to give you a good experience. Just make sure that you pick a reputable company if you're buying new. If there is a second hand market in your area, either Facebook marketplace, craigslist, etc. Then I'd recommend checking that out as well. You can often find a great deal on a machine that someone else has either grown out of, or just decided that the hobby wasn't for them. And the second hand machines will also normally come with tooling, which is a very big bonus because tooling is easily the most expensive part of the hobby once you get going. Thanks for watching btw!

[@devmeistersuperprecision4155]

What did you use for alloy? How are your nuts?

[@hersch_tool]

I used 1144 stress proof. Also lol my what? 😂

[@dennistennyson8856]

What was the material That you used. It seemed to be free machining.

[@hersch_tool]

It's 1144 stress proof. Thank you for watching btw!

[@syldysnya]

New video!

[@hersch_tool]

Thanks for watching!

[@grntitan1]

Well executed. What was the steel?

[@camillosteuss]

Yeah, the alloy would be interesting to know... I would expect something in the range of Merilo steel alloy, prehardened to around 50hrc... It doesn`t stress deflect(well, it does, but on a very small level), it`s practically a toolsteel alloy designed for gear and die making... It`s ridiculous stuff... And it machines amazingly if the machine is anything in the range of a decent southbend or other, let alone bigger machines... ¬edit, he did reply to another dude below, its stress proof 1144... definitely not sihard 2842, but i`ve heard that it is a decent steel to use for parts such as these... And i can`t bemoan the use of the alloy, as getting specific alloys in smaller quantities in some places can be hard/impossible and damn costly...

[@hersch_tool]

@@camillosteuss yep, it's 1144. it's fairly decent for this kind of application as it doesn't move around on you after machining. like you said, especially for a home shop where some of the higher end materials can be difficult and expensive to get your hands on. thanks for watching!

[@camillosteuss]

@@hersch_tool Don`t thank me for watching... I`m on a shop hiatus, so i can either pick my nose or work on my car(just spilled 1l of automatic gbox oil on the rear carpeting, permanently ruining it, so that`s a new issue before i`m even done with the primary`... Shop related videos are helping me in not contemplating a makeout session with a gun... All the best...

[@hersch_tool]

@@camillosteuss looool, sheesh man. Yeah, maybe put the oil jugs down for a while and watch more vids... ;) Seriously though, I do appreciate the support. I just feel like I really need to express my gratitude for that, it's genuine.

[@camillosteuss]

@@hersch_tool Nah, there ain`t enough oil rags in the world to save car interior from gearbox oils or even just the engine oil... And i chose the worse option of the two... Luckily i didn`t spill it over the seats, as i can rip the entire interior carpeting out, toss a match on it where the oil spilled and just snag some well preserved interior from a totaled twin vehicle... It`s just going to be a fucking pain in the ass taking two whole car interiors apart just to be able to reassemble one of them... Regarding the appreciation of watching, i understand, but since we both share the love of machines and try to make videos, I think it ``goes without saying`` ;) you have interesting projects, and even tho i have seen similar components, it`s always nice seeing someone do nice work on a nice part... All the best!

[@tomnorton8218]

I'm a newbie? What steel did you use?

[@hersch_tool]

1144 stress proof. Thanks for watching!

[@ellieprice363]

@@hersch_toolWhat is the appropriate hardness of 1144 stress proof? Thanks.

[@larrybud]

Great stuff. Do you have Patreon?

[@hersch_tool]

Thanks very much! I don't yet have Patreon, but I hope to get stuff like that set up in the new year. I really want to work hard to expand the channel in 2024 🙂

[@larrybud]

@@hersch_tool Please start one, you deserve more support.

[@hersch_tool]

@@larrybud thank you SO much. That is incredibly kind. Really, I can't tell you how much I appreciate you saying that. This whole experience of starting this channel has been amazing, and that's because of all of the kind support and encouragement that I've been getting. Again, thank you for all of the support, genuinely thank you. Look for hopefully a lot more to come and ways to support the channel in the new year. My wife is going to be helping me with some of the technical stuff, so hopefully we'll be able to get all sorts of cool things happening. And happy holidays btw. :)

[@hitnmiss49]

What is that lathe tool?

[@hersch_tool]

Which one?

[@hitnmiss49]

The one you were turning with. Looks like the insert mounts vertical.@@hersch_tool

[@hersch_tool]

@@hitnmiss49 oh that is a swiss front turning insert. it's an excellent tool but it's difficult to find inserts for it. the tool holder is "TFT" style i believe