Cutting brass tube

I will have to cut several different sizes in length of 3mm internal brass tube, in the past I have done this on the lathe with a 3mm steel rod inserted and pulling back on the tube with the and rod using a parting off tool, Is this the best way to do this.

Bit unclear the description but if it works for you and is safe then stick with it.

Brian

I made a mistake on the post. I insert a steel rod in the tube then support the brass using the steel rod when using the parting tool. But I would like to know how others on the forum cut tube and be accurate on different short lengths.

On small diameter/thin walled brass and copper I use a jewelers piercing saw which have very fine blades and give a nice smooth cut with no burrs.

Alan C.

Turn it in the lathe and use a Dremel or similar with a cut-off disc.

Rough cut with razor saw and then face off the ends to required length in the lathe

Extruded aluminium mitre box and razor saw work for me.

OK so the picture shows a piece of brass angle being cut but the principle is the same.

If it works for you Alfie - then sure - parting-off is fine but there are other ways to do it (as suggested above).

To my mind, one consideration is the 'fiddle' factor. If you are only doing one or two lengths, then your way is simple and presumably uses the kit you already have. If you have a large number to cut then there is the hassle of stopping the machine (OK if you have a clutch), easing the chuck off, re-setting the work to length (and any required internal support).

I have a very simple table-saw, which is just a steel square with a 'built-in' toolmakers clamp and a length-setting gauge. Once set up, I can run the cross-slide back, unclamp the work, slide the material forward, re-clamp and take another cut with the cross-slide. It's quick and accurate enough for my needs. I've used it for brass strip and rod too but not for tube (as yet). If I needed the tube internally support, I would find a way to clamp the inner support material further back and then I could slide the tube forward without needing to cut the support too (I hope that makes sense - the first cut would simply set the internal support bit to the correct length). I use the finest slitting saw I have. I have several 'tables' (with different depth slots & v-guides on each edge) - they bolt to the normal tool-post support instead of the QCTH base I (used to) use...

This may explain it better.. (P.S. I like it when other folk post photos - so I try to do so myself too)

Regards,

IanT

Alfie,

If you want to control squareness and get a good finish the method you described is likely the best. If you grind your parting tool on a slight angle it will leave the cut off piece nearly burr free. If you are using a collet to hold the work I think you might be able to eliminate the rod through the center.

The original question was how to cut 3mm brass tube and the use of a saw with big teeth could easily crush the tube.

Edited By Paul Lousick on 10/08/2017 22:40:03

Regarding the post from John Reese about using collets for holding the tube, can I use a E 32 thats on the mill and knock that into the tapper on the lathe, or will I need a special type of lathe collet chuck.

The ER32 should work fine. Just be sure that the tubing extends all the way through the collet. You will probably want to use the collet chuck without a drawbar so the work can pass through the headstock. Be sure the taper is seated firmly to minimize chances of the taper loosening. A better setup would be a flange mounted collet chuck mounted to a backplate that screws onto the lathe spindle. As you already have a taper mount collet chuck it makes sense to try it.

When I used to make my own fuel tanks for control line aircraft I used brass shim and 1/8" tube. To cut the tube I scored round where the cut was to go by rolling the tube between a scalpel blade and the bench, then gently bent the tube in different directions around the score, not actually introducing a bend but just straining the tube walls. After a minutes or so the stress concentration caused the tube to fracture around the score line giving a clean break.

I use one of these with a razor saw. The combination of a length stop and a simple clamp (just press down on it with your thumb) make it very easy to use.

Neil

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