Single Point Threading an Internal Left Hand 5 Pitch Acme Thread for a LeBlond Lathe Nut

[@BillySugger1965]

I know nothing about Leblonde lathes, but wouldn’t you want to ensure that the threaded hole is bored to intersect the mounting boss at right angles? Or am I overthinking this?

[@TopperMachineLLC]

I read the title and immediately thought "yuck"! You did a great job on that.

[@rodsolomon4503]

Why didn't you align the bore of the ACME thread with the threaded post on the bottom of the nut?

[@petemclinc]

I would have done this totally different and began in a vertical mill, finding center and squaring up off the threaded post with a DTI. Drill, ream or bore an undersized thru hole at the proper offset and then go to the lathe and indicate the bore in X/Y. Bore to finished OD and commence with threading. No worries.

[@7LegSpiders]

Every other comment has criticism, but your's has a solution.

[@shubus]

We're all feeling better seeing that part number being stamped in.

[@walnutclose5210]

Doesn't the axis of the lead screw threads have to be coplanar with the axis of the vertical boss? I really don't see where the setup accomplishes that.

[@stevestrohacker8436]

You got me, Keith. It always messed with my mind that by accident, I'd hit the rapid traverse lever on the lathe. Just as I thought that you sped up the video and I jumped...lol. bugger!

[@williamsquires3070]

One nice thing about machining that bronze is the nice little chips that result, making it easy to evacuate the chips through the drill flutes. 😊

[@ron827]

Transferring the part number is a nice touch.

[@fpoastro]

How are you sure the lead screw hole is at a dead right angle to the threaded shank?

[@rustyshackleford928]

You had me at hypotonus. And at 18:46 JK thanks Keith. love your work.

[@mwoliver]

Maybe just me, but I would have found the center of the hole in the existing nut, referenced from the machined flat, and used that to layout the center of the hole for the new nut, again referenced from the machined flat. The new casting is admittedly oversized and using a sloppy half-the-width measurement as a basis for laying out the hole center referenced from the radius of a rough, oversized casting just doesn't give confidence that this nut wouldn't end up binding. Maybe just me and maybe my reasoning is flawed. EDIT: Two followup comments. One, my comment was meant for those who don't know any better so that they think about their layouts and setups. Two, my comment was in the context of the external threading and machining having been completed already, which was the improper sequence in the first place in my opinion. That said, none of us are without fault and (again) my initial comment was meant to be constructive for new guys who don't know any better. 👍🏻

[@littleworkshopofhorrors2395]

My very thought on the matter.

[@ton146]

Me too. Was wondering how Keith would establish the distance of the hole from the machined face but he did not use that as a reference. Dont know the lathe concerned but is there a risk of binding at the extremes of cross slide travel?

[@littleworkshopofhorrors2395]

@@ton146 if it is out of line it will reduce the backlash, for a few days!

[@CameronMcCreary]

The most accurate method I use is to drill, ream and thread then, set the part up between centers on the granite block and measure for the outside dimensions. Now I machine the outside dimensions using the threaded hole for referencing all the final dimensions.

[@mwoliver]

@@CameronMcCreary Yep, start with the threaded hole and build from there. You're spot on.

[@steveshoemaker6347]

Excellent work....Thanks Keith.... Shoe🇺🇸

[@russellherold272]

You are the man Keith! Thanks for sharing your knowledge and your years of experience. I am 78 years young and would NEVER, EVER lean on your on your ability, judgement and expertise. Keep em' coming. YEA!!!!!

[@ccrider5398]

While you have cut many threads of many sizes on your channel ( I even remember a left hand acme lead screw that ABOM did for you at the museum) I don't recall an internal 5 pitch acme cut in reverse feeding in. A lot of left handed threads are cut outwards from the chuck. Thanks for sharing this rarely video taped procedure. Interesting there wasn't an oil port for that nut/thread. I also liked your craftsmanship in stamping the part numbers onto the nut. Since you were returning the original, you might have left that out, but worn-out loose parts often get lost in a shop. I'm still awaiting machining of precious metals in your shop! Thanks for your videos.

[@Sizukun1]

I commented on part 1 and I'm glad to see you stamped the part number on. Not that you didn't film it before my comment!

[@appalachianbushcraft3959]

A coaxial indicator would made for an easy setup. Even if it doesnt need to be perfect, just my ocd talking. Love your vids Keith, been watch for a long time....

[@oldschool1993]

A bit tricky building a nut to fit a lathe that probably has a lot of wear in the carriage and working off a nut with worn out threads. The vertical alignment can be adjusted by adding shims or removing some material, but the side to side alignment is not adjustable and if the hole is off center or not straight through the casting it will bind. The hole should be centered on the the vertical pin, not just halfway between 2 sides of a rough casting. To be sure the hole goes through straight, flats should be machined on the three sides to be equal with the centerline of the mounting pin.

[@gilbertgassmann91]

Completely agree with you, Keith should not have centered the bore on raw foundry faces. It should have taken the axis of the crankpin as a reference and been parallel to the machined bearing surface.

[@24681359David]

As long as the hole is straight and the thread has a few thou clearance, it's not going to matter as long as it's close. If it were this tricky just adjusting the gib on the cross-slide would cause a bind.

[@oldschool1993]

@@24681359David Probably right for most folks, unless he is like Keith and will spend a year scraping all the ways to within 0.0001"

[@walterplummer3808]

Good morning Keith. Thanks for all the work making the videos. Have a great weekend.

[@dcpower777]

I love Tap Magic

[@williamgamache2882]

Once again another great video... Thanks Keith !!!

[@takedeadaim8671]

Nice job Keith

[@geraldharkness8830]

excellent work keith

[@johnrice6793]

Very nice. You are an accomplished fellow indeed. 👊🤜🤛

[@daveentwistle8535]

Thanks Keih, as a newbie, one question: when holding the rough casting in the four jaw, how do you ensure axial alignment - or did you just guess it would be within tolerance?

[@Paul-FrancisB]

the same as @MikeOliverKT2T comment, the thread alignment should strictly be to the machined faces, i.e. the bottom face and cylindrical register. This would ensure alignment with the lead screw once fitted to the slide, rather than inferring by referencing both to the cast surfaces that are not critical dimensions.

[@chuckinwyoming8526]

I saw this potential problem too. You could run an indicator along the flat turned in the first video. Or clamp a parallel on the face to extend the flat and run an indicator on the parallel.

[@johng8473]

I am thinking you may still not have a good fit when installed. The center of the Acme thread hole should be the same as the shoulder of the machined stub in one axis, and the other axis should be measured off the flat around the stub. The outer dimensions do not matter at all.

[@UKDrew]

Hi Keith, you made a lot of effort to make reference surfaces, But then didn't use them...Unless i missed it ?

[@curtkuhns]

Thanks for another interesting video Keith. -Curt

[@monadking2761]

We had to replace the block nut and the cross-slide on my lablond as well. except we purchased a left hand brass long nut and milled down the outside. The cross-slide wears more in the middle since that is were it is used more. We also purchased a left hand acme shaft that matched the nut size and milled it down for bearing mounts and handle. We used our old parts as reference. The outer ends of the shaft hardly wear. That is why you might have more back lash in the middle when you checked the block. Nice video as usual.

[@migueltorres6073]

Thanks Keith for the video. Another great job

[@Siskiyous6]

Very nice work!

[@dannyl2598]

Thank you for the video Keith. Looks like you are taking more backlash out of this than you had hoped for.

[@timf6916]

Good job

[@michaelhallas6450]

Very Nice . Kieth my question is do you make a video on the 1st part of the machining of the nut with the external threads ?

[@jamesdavis8021]

I don’t think I have not had to take a little more.Much better than taking too much

[@davidlostumbo6845]

Nice job

[@ThePottingShedWorkshop]

Surely ACME is 29deg, trapezoidal (metric) is 30deg, so if you feed the compound in at 15deg the thread will not have the correct form.

[@masteruniverse3506]

Great work!

[@wilsonlaidlaw]

Keith, I just hope you don't end up like Steve Watkins, after cutting the LH internal thread (I think his was square thread, pre-Acme), he then found that the lead screw from the shaper was a two start thread.

[@paulterhaar4218]

Well that was dumb thinking of me that Keith would forget stamping the partnumber. Last but not least. 😅

[@tedmiles2110]

It is nice that you can do a job for somebody local. TM Long time viewer

[@rw3dog]

Great work ! I love the threading job.

[@WillyBemis]

Thank you Keith!

[@geckoproductions4128]

Interesting video, thank you

[@RRINTHESHOP]

Nice job Keith. Came out great.

[@robertlevine2152]

Keith, I was wondering, if you already established the center of the nut when you machined the threads for the nut. Why not transfer that center to the face of the hole you were drilling? When I drew parts as a draftsman many years ago, we drew off a datum point. Since you machined the off sticker ( please excuse my lack of terminology) first, the datum would be the center and face of the face. Dimensions for x. Y and z would be measured from the centerline and face of the screw. By establishing multiple centers off different surfaces you compound errors. Bob

[@24681359David]

The biggest problem with this is the fact that Keith was working with a worn-out nut. That's all he had to work with. Depending on how wornout the nut is, his method of going off the outer dimensions of the casting may very well have been more accurate than trying to decipher where the centerline of the screw sits in reference to the original nut to transfer those dimensions over to the new one.

[@thefirstcalled]

Thank you!

[@csnelling4]

Thank you Keith 🥰🥇

[@tomswindler64]

Great video as always,👍👍👍😎😎😎

[@melshea2519]

Happy Friday Keith! 😊

[@6NBERLS]

Most excellent.

[@elsdp-4560]

Thank you for sharing.👍

[@GWBoen]

Great informational video as always Keith

[@barrystevens2780]

Wouldn't you want to add the Ackme thread measured from the locating shoulder on the part to its mounting position at assembly

[@scottthomas5999]

Nice job. Not an easy operation.

[@johnkraus728]

Many comments about the thread hole alignment. I was going to ask, as well, why not reference from the machined threaded stud? I'd be concerned about the load it would put on that long leadscrew if not perfect. Thanks for sharing, Keith.

[@Heretic_Dezign]

I can only concur with others, personally I would have placed the centre of the leadscrew hole to match the centre point you put in the thread you machined, on the East/West plane and taken centre on the North/South plane from the flat machined surface

[@VictorAndDad]

Keith. What kind of leblond lathe was the cross slide nut for? I have a leblond Regal 13 inch I'm restoring.

[@Henning_S.]

As far as I know the lathes with serial numbers starting with ND are Heavy Duty models, so the part number with ND is probably also for a heavy duty model

[@azarellediaz4892]

20:58 At this time stamp looks like the threads are full of swarf, was this due to roughness on the finish or actual brass chips?

[@jonareli]

Tight

[@jerryWallis-k3w]

did the threads get shortened for the nut that holds it on?

[@CameronMcCreary]

I was wondering Keith; do you ever use fixtures for stamping the numbers/letters into the parts so the characters are spaced properly? I always make and use stamping fixtures when stamping or pressing numbers into metal and wood.

[@par4par72]

As an apprentice, I was required to Lap Nuts with a dedicated Lap mandrel ID then run the Screw thru the nut. "Zero fit".

[@thepotterer3726]

What's the range of that internal micrometer, you are using on the bore?

[@howardhughes6311]

Nice job EXCEPT Acme threads are 29 deg.

[@Videowatcher2.0]

I hope it's a single leed, use a dead center to indicate to center punch

[@toddbishop9412]

Ring finger is looking good....

[@userunavailable3095]

You should put your name on there with the serial number, my friend. I can see someone trying to puzzle out, a hundred years from now, why LeBlonde made one part that was clearly better quality than all their others, and why the number stamps don't match all their others.

[@mark-]

that's how it's done 😊👍

[@belatoth3763]

Everybody tried to find out how he will maintain symmetry, squares and align with the fixing nut's symmetry. And he marked it like it was a piece of sqare iron for a shelf 😂, aligned the raw casting with the jaw with protector 😅. Funniest guy, it must be a joke.

[@MikeB0001]

Yeah...I don't think this nut will work out well for the local guy.

[@5axmachine167]

I notice you never use air to blow off chips. It's a very good practice, especially before performing any precise measurements. Any reason why?

[@millwrightrick1]

Blown chips can end up in the more delicate parts of your face, even with safety glasses on.

[@markschweter6371]

@@millwrightrick1 And the machine's works... Mr.Pete always rails on about that.

[@chrissmith513]

That's Amazing 👍👍👍

[@briancarruthers1738]

Oil hole?

[@olens.6987]

What is half of 1 1/2 ?

[@petemclinc]

1/4.

[@CHICOB4261]

So 1 1/2 or 1.50 so half would 3/4 or .75?

[@charlesmiles9115]

😛😛😛😛😛😛❤❤❤❤👍👍👍👍👍👍

[@willemvantsant5105]

29 degrees for acme thread. If your insert is 30 degrees you are cutting metric trapezoidal thread, not an exact match for the acme spindle. Good enough for the purpose.

[@ellieprice363]

The carbide ACME insert would be 29 degrees. He didn’t make it clear but the compound was probably set at 14.5.

[@FireGodSpeed]

Normally i don't critique someone but Keit come on.. "right on the money"- when we clearly saw it was going further.. and why did you drill it out to 9 thou under? LIKE WHAT you need a minimum of 20 thou if not more to get it actually cleaned up. Now you got a hole which is wider in one direction then the other.....(you could hear it clearly when he was making the scratch pass when threading). Disappointed to say the least

[@fredhoyt6900]

Did you say, "half of inch and a half is inch and three quarter."?

[@user-fu1bh3dt2c]

If this thing works even halfway right it will be yet one more proof of the old adage that it is better to be lucky than it is to be good. I couldn't believe what I was seeing here. He has a presumably good and true reference point to start from yet he ignores it and approximates from a rough casting! A pipefitter or a rough carpenter might be able to get away with this sort of stuff, but a machinist, not so much. As it is, the hole is not aligned in either axis and it is not even truly round as you could hear the intermittent cut as he was threading. What a mess.

[@Henning_S.]

I also noticed the intermittent cut but I think the part may have moved in the chuck because the second threading pass started good but became more and more intermittent at the end. So the part may have tilted in the chuck, the front end was just slightly off center and the rear end was worse.

[@TonyUrryMakes]

Funny. I asked you for help on exactly the same part, and was told the tap to do it was too expensive. Now internal threading is feasible but wasn’t a couple years ago. I got my Leblond running anyway- but it would have been nice to have this instead of having to use the cast iron part Leblond sells now.

[@user-fu1bh3dt2c]

Seeing how he made this part I suspect you dodged a bullet.

[@gordonburns8731]

"Where I'm at"!? As such? As so, yes, as such yes, like such, definitely is that English, ending a sentence with a preposition? clearly so! it's not 'Where we're at", it's "I do not follow idiots, who can't speak the English language.

[@petemclinc]

My English teachers always said, "when you state where you are at" you are behind the at...

[@briancarruthers1738]

Half of inch and half is inch and three quarter? 😅

[@jozefa1234]

this all sucks, no way that this nut will work properly, tolerance wil need to be 0,001 and now 1/16 at the best

[@justinl.3587]

There is no way that ACME thread is perpendicular to the existing machining on that part. But hey, this is the "Eyeball it" machining channel. 🤡

[@W4BIN]

I don't understand why he calls it a half nut, it looks like a nut to me. Ron W4BIN

[@minbannister3625]

Stop wearing that shirt.

[@johncloar1692]

Thanks Keith for the video. Another great job.