ATK303: Compression spring 12.7

Length 12.7, Diameter 10.4, Wire diam 0.81, Solid Len 3.5, Tension 2.16N/MM

  • Manufacturer: Various
  • Product ID: C2-2737-2M (Flexosprings version)

A 12.7mm long compression spring used in the Clinch (fire) button design.

Supplier Links

https://www.flexosprings.com/search-products?sku=C2-2737-2M

Indicative Pricing With Allowance for P&P

Springs are probably the most difficult and expensive things to source. This is a stock spring available from many different manufacturers (see below on what aspects are critical) and although they are not expensive you’ll probably get hit hard for P&P.

Flexospring charge £8.63 for this spring + postage but they require a minimum order of £9+p&p, so you’ll have to buy other stuff off them to complete your order. As an indicative price I’ve gone for £10 effectively for this spring.

£10

Substitutions

Although these are commodity items you may struggle to find an exact duplicate unless you buy from flexospring. If you want to vary any of these dimensions these are the consequences.

  • Length 12.7mm – A bit longer or shorter is fine
  • Outer diameter 10.4mm – Do not go any wider. The cavity for the spring assumes this
  • Wire diameter 0.81mm – This affects the inner diameter which is also critical or the spring will catch
  • Solid length 3.5mm – Shorter is fine, you could go as long as 4mm.
  • Tension 2.16Newtons per mm – Not so critical. This effects the feeling of pressure needed. I chose this pressure to give a nice strong but not too string operating force of around 15 Newtons. = 1.5Kg

ATK302: Extension Spring 38.1

Length 38.1, Diameter 9.5, Wire diam 1.6, Max Len 49.3, Initial Tension 36.68N, Tension 9.69N/MM

  • Manufacturer: Various
  • Product ID: s48 (Ashfield Springs version)

A 38.1mm long extension spring used in the Spitfire flight stick for the pitch spring.

Supplier Links

https://www.ashfield-springs.com/shop/extension-springs-3-10mm

Indicative Pricing With Allowance for P&P

Springs are probably the most difficult and expensive things to source. This is a stock spring available from many different manufacturers (see below on what aspects are critical) and although they are not expensive you’ll probably get hit hard for P&P.

£7

Substitutions

Although these are commodity items you may struggle to find an exact duplicate unless you buy from flexospring. If you want to vary any of these dimensions these are the consequences.

  • Length 38.1mm – Do not go any longer. You could maybe go shorter by 1 – 2 mm
  • Diameter 9.5mm – Do not go any wider. You could go narrower by 0.5mm
  • Wire diameter 1.6mm – Not so critical but if massively affects the tension
  • Max length 49.3mm – Longer is fine, shorter is less fine as you’ll overstretch it but you may well get away with that on the few occasions you go max roll.
  • Tension 9.69Newtons per mm – Any less and the pitch resistance will feel very week. Any more and you’ll stress the design more than I have tested it to. If you’re feeling brave try a stronger one

ATK301: Extension Spring 31.8

Extension Spring Length 31.8, Diameter 9.5, Wire diam 1.42, Max Len 42.28, Initial Tension 10.5N, Tension 6.98N

  • Manufacturer: Various
  • Product ID: AM 3310 (Flexospring version)

A 31.8mm long extension spring used in the Spitfire flight stick for the roll spring.

Supplier Links

https://www.flexosprings.com/search-products?sku=am3310

Indicative Pricing With Allowance for P&P

Springs are probably the most difficult and expensive things to source. This is a stock spring available from many different manufacturers (see below on what aspects are critical) and although they are not expensive you’ll probably get hit hard for P&P.

£9.50

Substitutions

Although these are commodity items you may struggle to find an exact duplicate unless you buy from flexospring. If you want to vary any of these dimensions these are the consequences.

  • Length 31.8mm – Do not go any longer. You could maybe go shorter by 1 – 2 mm
  • Diameter 9.5mm – Do not go any wider. You could go narrower by 0.5mm
  • Wire diameter 1.42mm – Not so critical but if massively affects the tension
  • Max length 42.28mm – Longer is fine, shorter is less fine as you’ll overstretch it but you may well get away with that on the few occasions you go max roll.
  • Tension 6.98Newtons per mm – Any less and the roll action will feel very week. Any more and you’ll stress the design more than I have tested it to. If you’re feeling brave try a stronger one