MATE Building Instructions - Page 11

 

Converting the MATE from metric to Imperial

The "MATE 2cc DIESEL" was originally presented in Metric form. Because this is the official Australian Standard, it was hoped that the MATE would be attempted by a number of beginner (and most probably younger) machinists who would have learned to use the metric system as a matter of course.

So I make no general apology for using the Metric system. However I realise that some, possibly older builders, and in particular those in the United States, may be inconvenienced.

The following conversion notes have been written to make life a little easier for Imperial builders.

DAVID OWEN, "MATE" designer. March 1990.

IMPERIAL CONVERSION

All metric dimensions are easily converted with a pocket calculator. Divide mm by 25.4, or multiply by .03937 (use the constant function) and round the result off to three decimal places. For example:
8mm x .03937 = .31496 = 0.315".

[Ron: Divide 8mm by 25.4 and you get precisely the same result: 0.31496. Call me lazy. Why memorize two magic numbers when one will do? Repeat after me: "twenty-five-point-four". You don't even have to remember when to divide by it, and when to multiply. If you pick the wrong one, you get a rediculous answer, so know you need to do the opposite!]

To avoid confusion, go through the drawings and mark each dimension, thus converted, in red.

The following notes cover specific areas of conversion to a suggested Imperial alternative. The original metric dimension is shown in brackets, with the imperial dimension following right on, thus....bore (13.3) 0.524", tap (M5x.8) 10x32 UNF. An underlined dimension, eg 0.400", indicates alteration to a convenient size, rather than an exact (rounded) conversion:

VENTURI, Part #2

  1. drill the cross hole (3) 1/8".

BACKPLATE, Part #3

  1. screw-cut the thread (1P x .61D) 24TPI.

CRANKCASE, Part #4

  1. screw-cut for backplate (1P x .550) 24TPI.
  2. cylinder hold down...drill 4x holes (2.3 x 10D) #43 x 0.400" deep on a (25.2) 1.000" PCD. Tap (6BA) 4x40 UNC.
  3. transfer passages...drill 4x holes (5 x 18D) 3/16" x 0.700" deep on a (15.5) 0.590" PCD.
  4. mounting holes...drill (3) 1/8".

CONROD, Part #5

  1. ream ends (4) 5/32" and (5) 3/16".

WRIST-PIN, Part #6.

  1. use (4) 5/32" drill rod stock.

CRANKSHAFT, Part #7

  1. turn end (5) 0.187" and thread (M5x.8) 32 TPI to suit 10x32 UNF Nut.
  2. turn crankpin (5) 3/16" to suit wrist-pin big end.

NEEDLE VALVE ASSEMBLY! Part #17

  1. spraybar body...turn (3) 1/8" and thread (M3x.5) 5x40 UNF.
  2. shoulder nut and collet...tap (M3x.5) 5x40 UNF.

CYLINDER, Part #11

  1. use 3/32" centre-cutting mill for exhausts.
  2. use 5/32" centre-cutting mill for transfers.

PISTON, Part #12

  1. drill (3.9) #25 for wrist-pin and ream (4) 5/32".

COOLING FINS, Part #14

  1. drill 4x (2.7) #32 holes @ 90 spacing on (25.2) 1.000" PCD.
  2. c/sink to (20) .080" deep with (5) 3/16" slot drill.
  3. drill for compscrew (4.3) #21 and tap (M5x.8) 10x32 UNF.

COMPRESSION SCREW, Part #15

  1. use (5) 3/16" drill rod and thread (M5x.B) 10x32 UNF.

CYLINDER SCREWS, Part # 14

  1. use (6BA) 4x40 UNC screws.

CYLINDER LAP, Part #188

  1. drill (4.3) #21 and tap (M5x8) 10x32 UNF.
  2. use (M5) 10x32 UNF socket head grubscrew.

CYLINDER SCREW JIG, Part #1Bc

  1. drill 4x holes (2.3) #43 on (25.2) 1.000" PCD.

 

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