(An introduction to common home workshop materials)
In the previous article I had a look at ferrous metals. Typically, they are off-the-shelf bar stock items, and relatively cheap. Unfortunately, a large portion of the non-ferrous metals, specifically the copper alloys, are expensive, and I can honestly say I seldom buy bar stock. As a rule, all sections above 20mm are cast for purpose or I use the runners from my castings as machining stock. With this in mind the copper alloy section will deal more with first principle alloying elements. Any good metals sales person will be able to supply the closest equivalent (at a premium!). A few years ago I bought a drawn section of phosphor bronze for use in a rather rough bearing application. It lasted six months before it had worn to a point that it was causing mechanical issues. I promptly removed the bearings and replaced them with risers from a tin bronze casting I had done and the bearings are still going two years on.Aluminum
The most well-known and common non-ferrous metal is aluminum and its respective alloys. The weight to strength ratio is superb, they melt easily and machine beautifully. In fact, it is easy to obtain a mirror finish if the cutting tools are sharpened correctly and you can keep the swarf from rubbing on the machined surface. Aluminium is also highly conductive and works well as a heat sink or electrical conductor.
Figure 1: Small aluminium heat sink
Copper alloys
The copper alloys are numerous, both in chemistry and application. I’ll have to limit this section to the four alloys I commonly use. The cheapest is brass, which I typically mix to 60% copper, 2.5% lead and the remainder zinc. The lead improves the machinability. This is a general rustproof metal for any non-bearing application, typically for ornamental fittings or airtight castings.
Figure 2: Brass castings

Figure 3: Standard bearing bronze valves

Figure 4: Tough bearing bronze

Figure 5: Alumina bronze casing
Stainless steels
The two most common stainless steels are SS304L and SS316L. I prefer SS316L. It is slightly easier to machine, and safer in small boiler applications. Machining stainless steels require lots of cutting fluid and generally, you’d machine at half the cutting speed typically used for mild steel. Stainless steel rubbing on stainless steel should be avoided at all costs; it tends to cold weld. This can be avoided if dissimilar materials are used. Even stainless nuts and bolts will seize if heated or over tightened. This cold welding occurs when the extremely thin oxide layer, which gives it its corrosion resistance, rubs off resulting in metal to metal bonding. Stainless steels can be readily TIG welded, but care needs to be taken to prevent sensitization of the welded area. This can result in corrosion or sensitivity to chlorides which would ultimately cause cracking. If the correct filler rod and correct welding amperage (to minimize overheating) are adopted you shouldn’t have any issues. A quick check for sensitization is to see if the weld has become magnetic. If it has, it’s probably been sensitized. I once found a couple of discarded coffee bodums (the plunger type). The centre shafts made a few steam valve spindles (being of a good quality free machining stainless steel) and the strainers made a nice filter for a tender I was busy with. If you keep an eye open you’ll be surprised by how many materials are just thrown away.
Figure 6: Stainless steel steam valve spindle.
Differentiating between materials
Often you come across materials where you’re not entirely sure of the grade. I recently machined a piece of mild steel hollow bar that was anything but mild. If you do a search for differentiating steels you would come up with the “spark” test. Basically using a bench grinder you can determine the type of material by the characteristics of the sparks. I have personally never used this method but I’ve added the chart for reference. My methods are a little more pragmatic.
Figure 7: Spark test chart (internet ref.)

Figure 8: Tin bronze left, commercial gunmetal right
Grear article, but you do not mention where one can obtain the items. In particular I am looking for brass bar stock.
Thanks
Hi Bashir,
Thanks, I’m glad you enjoyed it!
I have tried a few suppliers for brass bar stock, and have found that non-ferrous metals gives the best service; they are very helpful. If you want cut lengths you might battle to source a supplier, they are generally unwilling to cut to size for the smaller diameters or sections and when they do you could just as well buy the whole length.
Hope this helps,
Metals Centre cc in Selby will cut most popular sizes as well as sheets and plate to size.
try Metals Centre cc in Selby/Booysens. Full range of Ferrous and Non ferrous and they will cut to size. 0114934930
Hi there, just wanted to mention, I loved this post. It was helpful.
Keep on posting!