About Bolts, Screws and Fixings used in DIY Loudspeakers
Amongst the vast number of available fixings, QTA systems have selected a few which are useful for Loudspeaker construction. Most popular are screws but depending upon cabinet material and access, bolts may be better. MDF, the material of choice? is constructed from wood fibres. It is easily split when screwing it's edges and needs pilot holes. In addition, the faces are hard and difficult to screw without pilot holes. Repeated use of screws can strip the wood leaving useless holes. Bolts compress the material but need rear fitting access or the use of accurately aligned wood inserts. So.........Choose carefully.
Pan Head Wood Screws
Wood Screws: Pan Head. Mild steel. Better grades are case-hardened and have hard tips. Available in cross-slot and / or Posidrive / Phillips heads. Finish is usually Bright Zinc Plated, known as a BZP finish. Other options include chemi and oil finish, known as Chemi-Blacked. Occasionally a spray paint finish is used.
Pan Head Machine Screws
Machine Screws: Mild Steel. Pan Head Screws, plated (BZP) and fully threaded. Posidrive head. Many other varieties are available in different materials including Stainless Steel and Brass.
Button Head Bolts
Button Heads: Usually High Tensile steel or Stainless steel, often supplied in self colour. The heads have a hexagonal recess which requires an Allen key or hexagon Bit to tighten. Some are available with Chemi-Black finish. Note: Chemi-black finish is a 'cosmetic finish'. In a damp environment it WILL eventually corrode.
Socket Cap Head Bolts
Cap Head Bolts: Same material toughness as Button Heads, Note: Bolts usually have (20 - 25)mm threaded body length only. If you find you need a longer thread, carefully select the correct Bolt length. Bolts with a fully threaded body are known as SET Screws, NOT Bolts. Also available in a variety of materials and finishes.
Nylon Cheese Head Screws
Nylon: Made from hard Nylon. Being non-ferrous and therefore non-magnetic they are useful for fitting Air Cored and Ferrite Cored Inductors without influencing their magnetic properties. They have only moderate strength, and should not be over-tightened as they will stretch. Available with Washered Nuts i.e. integral nut and washer or with separate washers and nuts.
Assorted Washers for Kits
Washers: Two basic types, Plain and Shakeproof. Plain washers can be of type A or B. This defines the outside diameter relative to the internal diameter. Type B have greater load-spreading ability because they are larger in overall diameter so..... But not here. Subsets of Shakeproof are Spring, Crinkle and Wavy. Wavy washers are only available in Stainless Steel. Crinkle can be defined as Internal or External which defines the location of the teeth. We have internal. See the Pic.......... There are many others but......