When the Screw... SCREWS YOU!

In the culmination of months of work making my own gear cutters we are back on the gifted lathe refurb making… another lead screw. Only this time it has an integrated gear. And is hardened… and is also… brittle. VERY brittle.

#inheritancemachining #machineshop #hobbymachinist

Thank you again to the Micrometer level Patreon members listed at the end of the video!

TIMESTAMPS

0:00 It was all for a reason
1:46 Heritage
3:42 I'd Tap That
6:51 O1 Kenobi
8:34 Hidden Enemy
10:50 Countermeasures
12:08 Screw This
14:17 All Geared Up
16:58 SMH
19:19 It's gettin' hot in here
22:18 Time to Bow Out

FAQ
Editing: Final Cut Pro X
Intro Song: Way Back Way Back When (Instrumental Version) - Gamma Skies

This video is sponsored by MyHeritage.

© 2024 Inheritance Machining, LLC. All Rights Reserved.

[AlexMusayev]

On the bright side, two halves of this shaft fit into the box of shame easily.

[ryanvandyke]

Hi, heat treat metallurgist here. There are three constants in life: death, taxes, and distortion during heat treatment. There are a couple things you could do different on the next one...

Stress relieving before machining will absolutely help. The material will move less as stresses are relieved while heating up in heat treat. Do not machine, stress relieve, and then heat treat... Every time the material is heated and cooled, stresses are relieved. When there is a change in stress, there is a change in strain, which equals movement. Only stress relieve if you're going to be doing subsequent machining operations.

When heated before quenching, hang the part vertically. A lot of the bowing you saw after quenching is actually from the part bowing under its own weight since it was suspended horizontally. When quenching, only agitate the part up and down. Agitating side to side in the quench tank will cause preferential cooling on one side, which leads to bowing. If possible, you should heat your quench oil to 150-180F. The additional heat will reduce the quench severity and help with distortion.

Even with all of these steps, you're still going to have to straighten after quenching. Your best bet will be to straighten and then heat to temper. This can be achieved by clamping and tempering, where you clamp the part between two flat surfaces so that it "takes" a flat, and then temper. You'll need to go above 500F to see any significant "taking" of the flatness. But, your lead screw does not need to be 60+ HRC, so that shouldn't be an issue. It can be difficult to clamp and temper round parts, though. Alternatively, you could also use your V anvils and the hydraulic press to press the shaft just past flat and use your torch to heat to a nice, deep blue. This will relieve the stresses put into the material by elastically deforming it, and it should "take" some flatness.

Hope this helps!

[jeffwxyz]

I used to work for a machine tool rebuilder. We would chase the worn screws in the lathe so the profile was even through the whole length of the screw. Then make a new nut with a matching profile to fit the screw. You end up with a screw with a non standard acme profile, but the lead is consistent which is the important part. It also saves a lot of time!

[probiwan]

I love that this video ended failure and not only success. That's as real as you get in this trade.

[KyleMc]

Hearing "easy for the hydraulic press" immediately after hardening I knew exactly what was coming... Might be worth it to straighten it after cutting everything and then anneal it to remove the stress from straightening and machining. After that anneal the hardening step shouldn't bend it and you'll end up with a straight, hardened, finished product.

[MyTubeSVp]

Anyone else sat on the toilet screaming “stop, it’s gonna shatter!!” at the screen?

[flameboy]

The image of you “literally” being dragged down a “literal rabbit hole” has made my day!
Keep up the great work, love the videos and your honesty.
Always remember, those who don’t make mistakes don’t make anything!

[johnryan]

Sure I speak for everyone here, when it snapped we all felt that in our hearts

The relationship you have with your wife is truly wholesome

[beachcomberbob]

You didn't hear me screaming at the screen "Follow Rest!!" on your first cuts.

[PatrickHoodDaniel]

There are so many videos out there that show perfect outcomes, but they never show the failures. This video is so incredibly valuable. Showing what happens to materials when cutting or bending during certain states is worthwhile to document, and it is also quite exciting to view.

[Lilac]

This channel is what inspired me to learn machining. Because if you, I'm going to a trade school as part of my high school curriculum to learn precision machining and get industry certified. Thank you for making these videos.

[keithlincoln]

"It's moving, not progressing " my new headstone!

[TakeMyLunch]

"Should be no match for the hydraulic press"
Me: "Oh no."

[kngjulien_]

Me at 22:50 : wait didn't he just harden that shaft?
Me at 23:10 : he sure did! 😅😂

[ethanhancock]

As a few have said before me, stress relieving the material after machining and hanging the material vertically while heating will help. Also, instead of relying on the press to straighten the shaft, additional spot heating can be used for straightening. Heat a small spot cherry red at the low side at the start (vertex?) of your bend and when that spot cools it will shrink and pull the shaft in that direction. "Fire the mountain, peen the valley" is what the old fellas say.

[ujnawierzbie]

I love the new format you introduced, with your wife being present, and more open style of communication/storytelling. It's unique and very easy to follow :)

[jakeoshay]

"speaking of girth I have something to show you" sounds like a wild pickup line

[letsfoolgravity]

"Hahaha, you have to make a whole nother tap?"

"I *get* to make a whole nother tap."

[matthewheaton]

To fix that follow rest problem you could leave a dummy end on. I do this a lot. Just leave whatever length you need on the end smaller than the minor diameter. When done part it off and face.

We do 98 inch helical shafts and we always heat treat them vertically. It doesn’t stop the warpage all together but it greatly improved it. Another thing we do is stress relief before machining.

Hope the next one works out!

[Baerenbruder]

As a person who has nothing to do with machining I highly respect you for showing all your failures along the way to what is essentially a boss fight.All the episodes lead up to the restoration of the lead screw and I am hyped to see our protagonist come back from a temporary setback!!!!