How would you machine these tube ends to shape?

We're going to have to start charging you..... :) For approximations to what you want to do, get an indexer (spin fixture, cheap as imports), mount work with axis along X on a BP, and move in and out in X with suitable diameter cutter, and suitable angular increments. You can soften edges by also fudging in Y.

Difficult to do on a manual lathe, as they don't index. Mebbe a Smithy or sumpn might do this. Ideal for a VMC w/ a 4th axis, or a multi-axis cnc lathe, but you'll proly be banged hard. My buddy in Brooklyn? :)

"Proctologically Violated©®" wrote in message news:LLcKh.13$ snipped-for-privacy@newsfe12.lga...

My baby Atlas does! ('Course, it doesn't have degree marks, but there is an index plate on the boss gear. 'Course, it ain't real TIGHT when indexed, and there's no spindle lock to keep it on the mark, but WTH.... )

Actually, I've done a little bit of non-critical indexing with it. As long as a few thou off the angle is OK.

(now... how to get the tailstock drill to rotate .... )

LLoyd

That's what the handwheel is for, right? ;-))

Nick

Both ends of a single tube need to be cut this way, and the shapes need to be oriented in a specific relationship to each other?

The sinewave cut you describe is often referred to as a fishmouth, as used to join two sections of tube to form the junction of a T (90 degrees) or other angle. Fishmouths are generally cut with a rotating tool.. a drill or holesaw. The resulting tube end shape is fairly symmetrical (gradual transitions). The fishmouth would give you the basic rough shape. Using hole saws to cut thru pipe or tubing generally requires a ridgid setup in a very strong drill press or a vertical mill.

Perhaps a shaped grinding wheel would remove the additional material, leaving the final shape you want. A cheap diamond dresser can be used to shape a grinder wheel. For numerous workpieces, the wheel will most likely require reshaping.

Getting both ends of a tube to line up properly, for finishing, would typically require some method of indexing the workpiece as suggested. A simplified method of checking rotational position, is to attach a perpendicular fixed rod to the end of a workpiece (pointing straight down), and also attach a string (with a small weight), so that the correct position is indicated by the rod and string being in alignment. Various other methods can be implemented, such as a degree disk and a pivoting pointer. Flat blocks can be clamped to the workpiece near each end, and adjusted so the flat blocks will be indexing references for each end.

A lot depends on the accuracy that you desire. Machines can reduce the effort required, but you might end up needing to file a profile that the available machines can't produce.

Making a gage or a "master pattern" that slips over the tube ends can eliminate a lot of guesswork/rechecking.

WB metalworking projects

Are you just cutting tubes to fit sideways onto other tubes, the classic fishmouth cut? If so, in that size range you can likely just use a 3/8" or

If not, I suggest you give us more information about what you are making, perhaps at a somewhat higher level.

Having a lathe's apron feed in & out on every revolution is the wrong approach.

GWE

snipped-for-privacy@yahoo.com wrote in news: snipped-for-privacy@o5g2000hsb.googlegroups.com:

Is the intent to have the end of the tubes mount at a right angle (or some other angle) to another tube or rod? If so, this is called a "fishmouth". There are devices called "tube notchers", that mount in a drill press (or a mill), that use an appropriately sized hole saw to cut the tube. Or there are computer programs (Winmiter.exe or Tubemiter.exe) that create a paper template that can be wrapped around the tube, and allow you to grind (with a bench or right-angle grinder) the tube end to the desired shape. This is the easy way to go for only a few pieces. I've never used the tube notchers, but have made many tubing projects with the computer generated templates and a small 4-1/2" grinder.

Ken

Easy enough, after inserting the bit in the chuck, tighten being sure to use each hole to snug the bit. Next reverse the chuck key and turn 1/4 turn in the other direction. You may not notice the drill rotating at first but as soon as you make contact with the rotating stock, you should notice a steady rotation.

For the small-volume prototyping you mentioned maybe you could shape a small cheap rotary grinding stone to match the profile you need, then fix up a jig to slide those drilled parts across it. Or you could have a carbide or HSS cutter custom ground to the profile for use on your mill.

--I'm assuming you're going to weld or braze the sections together, yes? Getcher self a copy of one of the free tube notching programs and you'll be able to wrap a paper template around the parts, tape it on, then grind to the line. If this is a production volume situation you should get a hydraulic tubing notcher, the kind that uses an insert to keep the tube from being mashed when you notch it. Milling can be made to work but you'll find that the notches created this way tend to be off kilter due to milling forces.