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FIGURE 13

Thick Section Butt Joint Techniques

Fixture

3M #670 tape cut after cement is cured

Fill level will shrink when cured

Cellophane tape (try tape to see if cement cures against adhesives)

Processing Steps

  • 1.

    Use PS-30 or Weld-On 40 or 42.

  • 2.

    Cut must be sharp (sawn or routed).

If material is stress free, no annealing necessary. 3. Cement against saw or rout cut surface.

FIGURE 15

Capillary Action Cementing with Unthickened Cements

Use a hypodermic needle, eye dropper, or other convenient dispenser.

Parts should fit without forcing or flexing before cementing. There should be no visible gaps.

Do not attempt to cement parts when the temperature is less than 65°F.

Clamping pressure used to hold pieces being cemented together should not exceed 1 psi. Joint should set in 2 to 5 minutes.

FIGURE 14

Technique for Inside Joints

Cementing technique for inside joints that cannot be routed and finished.

Outside open V-joint which may be routed

3M #670 Tape (Reinforced cellophane)

1

  • 16" Keep tape back so

Cemented area

a radius of cement is left.

  • 1.

    Thin PS-30 or Weld-On 40 or 42 15% with MMA.

  • 2.

    Mix with component "B"– degas cement and pour in area left by #670 tape which is to be cemented.

  • 3.

    Float vertical piece on cement. (If heavy, support weight with a fixture.)

  • 4.

    Clean off excess cement with a spatula that has a radius on tip to create a radius of cement.

  • 5.

    Let cure and cut carefully along tape edge and remove tape.

27

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