Good reading, and a lathe problem

[nickel-city-fab]

Wow I just found some more good reading -- All of Euclid's Elements (13 volumes) on archive.org. From the classic 1800's translation by Sir Thomas Heath, published 1908. Very handy for machining, in general. Link: https://archive.org/details/thirteen...ge/n8/mode/2up

Basically its just Geometery and layout, how to make any shape and any size using just a compass and ruler like Euclid did 2500 years ago.

The reason I went looking for a book like that is to answer a lathe question: How can I take a piece of round stock and turn it into a hex stock using only the lathe with 4-jaw? Accuracy doesn't have to be great, certainly no better than you would get with hot-rolled. Lengths no more than (say) 6 inches or 150mm. Round to be any diameter initially.

How would you do this?

[danlb]

Assuming the piece would fit in the 4 jaw sideways, you'd face the first side and then rotate 60 degrees. Assuming that it would not fit in the chuck, fasten it to an angle plate fastened to the cross slide and use an endmill or flycutter in the chuck to cut off one side at a time. In either case I'd leave a collar on the end to preserve the original spacing so that as long as I'm cutting to the same depth each time I don't have to calculate the offset.

With or without measuring devices? With protractors, dividers, calipers and things it becomes much easier.

Dan

[nickel-city-fab]

Assuming the piece would fit in the 4 jaw sideways, you'd face the first side and then rotate 60 degrees. Assuming that it would not fit in the chuck, fasten it to an angle plate fastened to the cross slide and use an endmill or flycutter in the chuck to cut off one side at a time. In either case I'd leave a collar on the end to preserve the original spacing so that as long as I'm cutting to the same depth each time I don't have to calculate the offset.

With or without measuring devices? With protractors, dividers, calipers and things it becomes much easier.

Dan

That's pretty much what I was thinking -- yes, with dividers and a ruler. I would chuck it sideways in the 4-jaw, face one side. Flip 180 and face the opposite side. Then use a large nut against the face of the chuck to establish the hex. Face that side, flip 180 and face the other side. Repeat...

Actually you can make most any shape or angle with just the dividers and ruler. Once as a student, I made my own fishtail gage that way, perfect 60 deg every time. A lot cheaper than Brown and Sharpe, too.

[Baz]

Actually I don't think you can make any shape. like that. I believe the first one you can't do is quite low, like under 20 and there is a mathematical proof for which ones cannot be achieved. There was a programme on the BBC radio within the last two weeks about the mathematician who proved it.

[Bented]

Polygon turning
Fast yet unlikely to meet the expectations of the .0005 accuracy sought by many hobbyists.

[nickel-city-fab]

Polygon turning
Fast yet unlikely to meet the expectations of the .0005 accuracy sought by many hobbyists.

yeah, hobbyists are a strange bunch. I'd be OK with .020 or so on this, like a chunk of hot roll rusting away in a corner. It doesn't have any critical fits for what I'm thinking of.

[nickel-city-fab]

Actually I don't think you can make any shape. like that. I believe the first one you can't do is quite low, like under 20 and there is a mathematical proof for which ones cannot be achieved. There was a programme on the BBC radio within the last two weeks about the mathematician who proved it.

I recall hearing similar, but I can't recall the details. Lately I've been interested in how many ways one can divide the circle, using technologies that have been available since the beginning of time. Its not hard to do squares or triangles, or anything based on them. But what would I do to get all 360 degrees with just a can of layout blue, a scriber, a ruler, and dividers?

[JoeLee]

Assuming the piece would fit in the 4 jaw sideways, you'd face the first side and then rotate 60 degrees. Assuming that it would not fit in the chuck, fasten it to an angle plate fastened to the cross slide and use an endmill or flycutter in the chuck to cut off one side at a time. In either case I'd leave a collar on the end to preserve the original spacing so that as long as I'm cutting to the same depth each time I don't have to calculate the offset.

With or without measuring devices? With protractors, dividers, calipers and things it becomes much easier.

Dan

that would be my first thought, unless you mount your work between centers, lock the spindle and mount a shaper bit in the tool post, then run the carriage back and forth feeding the cross slide in .001 increments and shave your flat sides.
What what I do this?? Absolutely not but this is just a thought.

Some people use their mills quill for broaching, sort of the same idea.

JL....

[nickel-city-fab]

that would be my first thought, unless you mount your work between centers, lock the spindle and mount a shaper bit in the tool post, then run the carriage back and forth feeding the cross slide in .001 increments and shave your flat sides.
What what I do this?? Absolutely not but this is just a thought.

Some people use their mills quill for broaching, sort of the same idea.

JL....

My back already hurts... yes you are right, I totally wouldn't have thought of that. I bet it gives a nice finish too, and it pretty accurate over short distances. (modulo tool/part deflection)

[754]

I need to know diameter and length of part..

[nickel-city-fab]

I need to know diameter and length of part..

Say for example 6" long and 3/4" dia. But it could be anything. I'm looking for creative ways to do the work holding and setup, the actual sizes and numbers don't matter.

[darryl]

You'd be laying something across the chuck, between the jaws, to back up the piece you're machining I'd assume- you need the alignment in both directions, rotation plus parallel to the chuck face. Something straight, and the right height to place the workpiece where you want it as you tighten the jaws. If you use a piece of wood, you can put two screws on one edge of it to keep that piece centered in the chuck hole. That way you can leave the piece in there for continued support as you do the machining.

[754]

If I was using the compound as a shaper I would likely use a 3 jaw chuck, could hep with the indexing.
if lathe was big enough I would probably hold it in a 4 tool post on the side, and flycutter in the chuck.

[MattiJ]

Use large-ish lathe and offset the round stock by 6 feet.
if the final part has 1/4” hex sides nobody is going to notice that the sides are not flat and actually have 6 feet radius

[Mcgyver]

. Lately I've been interested in how many ways one can divide the circle,

And hobby machinists are a strange bunch? lol sorry couldn't resist