Know exactly what you mean and faced same problems for 20 odd years needing precise accuracy as an end product.

Its more down to batch produced since since had same tubing from same supplier over time. Bores will be different as will be o/d. Up to twenty one years ago used to buy BS1474:HE30TFT66082? by the tonne, tolerance for an extrusion was +/- 0.1mm, more often than not on the undersize since less material for same cost of product. Theres not many extrusion mills knocking around though could be imported.

I don't buy much 5/8" o/d usually larger thick wall to bore out and turn o/d. Some of it well over 30% runout.

Finding reasonably concentric bore to o/d you will have to visit places or take a punt. The only advice I can give is buy or try as many different suppliers, some maybe better than others. Last year dropped on some critical 15mm bore bore that had to slide over cock on 15mm dia with minimal tolerance bonded, 5/8" no good too much clearance. Got it offf ebay last year but 18 o/d x 1.5mm. First bought a short length then bought the rest at longer lengths.

Other than that dependant upon lengths, turn o/d concentric to bore.

Hello Norman,

I'd love to read an article on making tin whistles. I have several, though I can't really do them justice). I would really like to make a very big one I have long fingers

I couldn't put it in MEW but I know Diane occasionally covers musical subjects in ME.

Neil

Norman,

I forgot to answer your specific question …

Wyevale Garden Centre, Otterspool Road, Marple [Stockport]

… But, as you will have seen, the manufacturer [?] does deal direct.

Note: I haven't tried machining it yet, but the quality of the sawcuts suggests th material is good.

MichaelG.

To the OP:

All extruded tube in the UK will be made to BS EN 755, The dimensions to BS EN 755 Part 9. The tolerances on the form are dependant on the alloy being extruded. 6063 is easier to extrude and is in 'Alloy Group 1', while 6082 is in Alloy Group 2. For 6063, the tolerance on the wall thickness allowed by the standard will be +/- 0.2mm for the size tube you want, giving a minimum wall thickness of 1.01mm. With 6082 the tolerance is wider, at +/- 0.3mm, meaning that 0.9mm is within tolerance if you don't measure the last 0.01mm.

Now, it's in tolerance, but may not be acceptable… I've had this a lot at work, putting machinings into extrusions & often needing to have a thicker wall than I need so it can be machined to a known size – at the sizes I work with, the thickness can be +/- 0.6mm, which makes a heck of a difference.

Regards,

Richard.

No, we don't extrude ourselves, but have a fair few extrusions made by specialists like 'SAPA'.

The Aalco website is slightly confusing in that it gives general information. Unfortunately the extruders extrude to specific standards rather than to the general info, hiding behind the figleaf of the standards. The standards do give them a lot of leeway. When it comes to hollow products, they also make the mandrel up the middle to form the hollow as large as possible. This way as it wears the wall thickness starts at one limit and slowly wears, and as the mandrel gets smaller, the thickness goes up. Starting at minimum thickness means that they get more extrusion for the weight of aluminium and the mandral lasts as long as they can manage.

Cold drawn tubing is more accurate, but I've never heard of cold drawn aluminium, just brass/steel/stainless.

Regards,

Richard

.

^^^ one last attempt at helping ^^^

Now I will