Need Help!- Manual Mill threads

[ngwanhoe]

Hi is there anyway that I can mill threads (female and male) with a manual milling machine?

Infos
40mm diameter female and 40mm diameter male side.

[Ed from NY]

Well, you can not circle around the part like with a CNC mill. If you use a rotary table or if you put the part on the spindle there is no way to synchronize the rotation with the Z-feed. The only thing I can think of is if you can rotate and advance your part against the cutting tool with some sort of jig driven by a screw of the same lead... the jig would rotate the part and feed it at the said lead. If you can make that rigid/precise enough it might work, but you probably would need an even wider screw/thread driving the jig which makes the whole thing not very likely.

[Kiwi]

Post withdrawn.

[ngwanhoe]

Originally Posted by Kiwi If the full depth of thread is cut with one pass, the Z feed does not need to be in sync with the rotation of the rotary table.

What kind of tool do that?

What you meen is attached the special tools to the spindle and rotate the work on the rotary table around the tool?

[M250cnc]

Originally Posted by ngwanhoe What kind of tool do that? What you meen is attached the special tools to the spindle and rotate the work on the rotary table around the tool?

Ed is correct the Z has to move in sync with the rotary table.

The only way to accomplish this is to connect the rotary table via gearing "THE CORRECT GEARING" so as you turn the rotary table the Z moves in tandem.

This was commonly used on dividing heads geared to the X axis on milling machines.

With CNC you don't even need the RT as the CAM will interpolate the XY & Z

With Kiwi's method all you will achieve a set of grooves, not a thread.

Phil

[Kiwi]

Originally Posted by ngwanhoe What kind of tool do that?

Single tip thread cutter.

Originally Posted by ngwanhoe What you meen is attached the special tools to the spindle and rotate the work on the rotary table around the tool?

Have the part being rotated by motorized rotary table at a known speed.
And the cutter rotating in the spindle, traveling down the side of the part at a set automatic feed rate to suit the pitch.

[M250cnc]

Originally Posted by Kiwi Have the part being rotated by motorized rotary table at a known speed. And the cutter rotating in the spindle, traveling down the side of the part at a set automatic feed rate to suit the pitch.

Eureka

A request for a how to on a MANUAL MILL

Kit needed a MOTORIZED Rotary table with a known speed, and a manual mill with an infinitely adjustable precision Z axis feed

Phil

[Kiwi]

Originally Posted by M250cnc ..A request for a how to on a MANUAL MILL

Many manual mills have power feeds, the same as manual lathes.

[awemawson]

Encoder on the spindle. Stepper motor on the rotary table. Electronics divider between the two as per John Stevensons horizontal mill used to cut gears. Set the downfeed at a suitable rate and make sure your maths is right in the divider!

[Geof]

Originally Posted by awemawson Encoder on the spindle. Stepper motor on the rotary table. Electronics divider between the two as per John Stevensons horizontal mill used to cut gears. Set the downfeed at a suitable rate and make sure your maths is right in the divider!

Encoder on the spindle is irrelevant because the synchronization is between the rotation of the rotary table and the downfeed.

[ngwanhoe]

Ha. its all boiled down to electronic control or motorise z axis and rotary table. Oh well, I think its better to buy a lathe.

Thanks guys or gals.

[fizzissist]

Simple.

No sophisticated electronics needed, just some good ole' American ingenuity.

Assuming a plain old vertical knee mill....

Mount a flat plate on an angle plate (vertically) equal in length to the dia x pi, and in width to the length of the part at an angle equal to the angle of the thread pitch....picture cutting a threaded tube along its axis and unrolling it flat. That's what you're going to make.

Using a single point milling cutter ground to the thread form, mill slots along the part at intervals equal to the thread pitch. You'll probably need to make multiple passes.

Unmount the part, form it around a mandrel till it's round and the proper diameter. Weld the seam, and finish file the joint.

Use the same process for the female part, and when done, use lapping compound to work them together so that they fit and match.

(before some of you laugh....I've essentially done this once...just to see if it could be done. It can.)

There are older mills out there that have dividing heads that are driven by the table, so you can coordinate the linear motion with the rotary, allowing you to make cams, gears, or as here..threads. Used to have one, a Cincinnati #3. Big, old, ugly, cumbersome. But it worked.