Building the most accurate DIY CNC lathe in the world [video]

You can see a guy following Dave Gingery's instructions to make a lathe bed here [1]

And as you say, a granite surface plate is needed. Of course, Gingery's books only claimed to set up a metalworking shop starting "from scrap" and "simple hand methods" and that "it isn’t long before the developing machines are doing much of the work to produce their own parts" [2]

Of course, to truly make a lathe from scratch, you must first create the universe.

[1] https://www.youtube.com/watch?v=zPGZg45dGXA [2] https://gingerybookstore.com/MetalWorkingShopFromScrapSeries...

Yeah, that's a different book, _Foundations of Mechanical Accuracy_:

https://mitpress.mit.edu/9780262130806/foundations-of-mechan...

The three plates is the foundationiof accuracy but no tools are needed to create them. you need a lathe to create a lathe - but a lathe can build itself as by the time you need a lathe in construction you already have enough of a lathe built for that next step.

Does anybody actually use the three plate method with granite? It was originally done with cast iron, and I thought cast iron was still the standard material. The plates are covered with dye and rubbed together to find the high points, which are then scraped off, instead of being removed by the rubbing directly.

Granite is a common material for modern surface plates (and a good one because it doesn't rust and doesn't raise burrs if it's chipped), but I believe these are still made using cast iron reference plates.

Oh yeah smart guy? Well how do you make the granite?

Lathes can certainly make cylinders, and a tube-based lathe bed is not a stretch.

A lathe can't replicate its own assembly, of course. It can't seat the spindle in the constraint bearings, for instance.

A CNC (without the word lathe) can make most of itself, and possible all. Nope: certainly all, if two of its dimensions fit within its work volume.

A lathe is the only machine you need. Those flat surfaces are easy to create with basic hand tools. (easy - but expect to spend a month if creating a flat surface is your full time job)

My pleasure!

I found a copy of Vol. 2 ages ago and gave it away, and was glad to be able to purchase the updated all-in-one leatherbound edition.

That said, there is a certain charm to the originals with their typewritten text and hand-inked illustrations.

You can buy the full series. Or check the likes of amazon. The books were first written in 1980, so they are fairly widespread. You can find plenty of youtube videos of people trying to make them, and once in a while forums dedicated to people making them (and suggested upgrades). They are not the best machine cools you can get/make, but they are serious tools and better than most DIY attempts (though the video here is better than most DIY attempts I've seen)

This guy is quite interesting, because he starts from scratch without reading or experience, so you end up with a really wonky machine, but it's wonky in unusual ways that really make you think. Like the sibling comment says, it's obvious he hasn't read the Gingery books. This sounds like I'm throwing shit, but I'm not - it's actually how I work a lot of the time. Making a mistake gives you a deeper understanding of the issue than you would typically get from doing things the right way. For example, he overheated the gravers while sharpening them, which made them soft, and now he gets to learn about annealing and temper. And indeed, in the comments, he gets:

>Just for future reference on making gravers, you were correct that you do not want to get the pre-hardened steel red hot or it will lose its heat treatment. However you have to go much further than that and not allow it to heat above the desired temper temperature. For instance if it was previously tempered to a straw (yellowish brown) color but then while grinding it the steel turns blue, that means you have reduced the temper to a lower hardness. So you need to keep the steel cool and never let the temperature go beyond the desired temper temperature. You can think of it this way, hardening the steel makes it as hard as it can get (but too brittle to be good for much), then tempering reduces the hardness but makes it stronger, and this effect continues the hotter you temper it.

n.b. this sort of thing is absolutely endemic in the world of 3D printing, which is why most videos are fairly useless to learn from, but the comments are invaluable.

Also Maxim Kachurovskiy: https://www.youtube.com/watch?v=lnFw8G95LGo

Someday when I have time, after I fix my little rowboat, and sew the clothes/bags I want, and fix the porch, and, and, and...

For now there's satisfaction watching others do some of the project I haven't made time for.

While interesting he hasn't read the gingery books and has made several 'mistakes' that gingery tells you how todo better. Though there is plenty of fault to pick in the gingery designs they show a clear understanding of how to do things and the mistakes are compromises based on materials available not a failure to understand precision.

Not CNC, but I am addicted to the Cutting Edge Engineering channel:

https://www.youtube.com/channel/UC2wdo5vU7bPBNzyC2nnwmNQ

Why cast such negative aspersions on a stranger doing good work?

If you are smart and patient you can find good used machine tools for very cheap (relative to their new cost). I would guess that buying a new Honda Civic costs more than what this person has in their shop. And if you bother to watch the video, you see at the end that he takes what he makes home to a different shop, implying that this is a shared or borrowed set of machine tools. Buying a bunch of tools that will hold their value while producing more value is not a sign of being reckless with someone else’s money.

Would you make such judgements about every Honda owner for spending a five figure sum?

No, good thermal management with a chiller, active thermal compensation, and glass scales make um precision on that scale reasonable. 10-100x better? Sure, you’re getting into machines where the room to keep them happy is significantly more expensive that the machine…