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On the Amiga 500, 500+, 600, and 1200, what size screws were used to hold the chassis together? Is it the same size screw for all, different screws per machine, different screws front and rear, or were all the holes designed to work with more than one size screw depending on what the factory happened to have in stock?

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  • On the Amiga, if it was not Phillips, it was either Allen Key, or Torx.
    – Brian White
    Commented Jun 20, 2017 at 4:11

2 Answers 2

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I compiled the table below from A500 Plus Service Manual and other sources:

Bottom Case Top shield & RF Disk drive assembly
Type Torque (Torx?) #5 X 3/8 LG Torque (Torx?) #5 X 5/16 LG Metric M3 X 8.0 Self Tapping
Qty 6 4 4
Diameter 0.125" (3.18 mm) 0.125" (3.18 mm) 3.0 mm
Length 3/8" (9.53 mm) 5/16" (7.94 mm) 8.0 mm
~Pitch 22 TPI (1.15 mm) 22 TPI (1.15 mm) ?
McMaster id 92470A125 92470A122 ?
Subst. type Pan Head 2.9 x 9.5 self tapping Pan head 2.9 x 8 self tapping /
Subst. Diameter 2.9 mm 2.9 mm /
Subst. Length 9.5 mm 8 mm /
Subst. ~Pitch 1.1 mm (DIN 7981) 1.1 mm (DIN 7981) /
Subst. McMaster id 94997A250 / /

On my Amiga 500, the shallowest rear screw hole is 11 mm deep, and the shallowest front screw hole is 9.3 mm deep, so a 9.5 mm screw in front seemed to risky. I used 2.9x6.5 screws in front, and they seem to fit well.

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There is very little information online about this, so I have scraped around and put this together:

The screws on the Amiga 500 and 500+ were often Phillips (requiring a #2 Phillips head screwdriver[1]), but hex-socket (Allen key) screws were also used[4].

trall measured the external case screws on an A500 case that appear to be original. They are Torx T9, the rear three (3) are 9.0mm long at the shank and 13 threads/inch. The front three (3) are 7.5mm long, and two (2) of those are 13 threads/inch and one (1) is 29 threads/inch.

Most of the screws for the 600 and 1200 are six millimetres long[2] and appear to be Phillips screws[3] as well, however there are shorter screws for the lower front edge[5] on these machines.

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    A good answer to any question about screw sizes would include the thread pitch and shank size, for example here. You can't go buy the correct screw without this information.
    – Robert Harvey
    Commented May 26, 2016 at 18:44
  • Note to go and buy a screw you also need the diameter... Also note that 13 TPI works out to ~0.5mm pitch in metric. My guess would be those are standard M3 metric screws.
    – tofro
    Commented Feb 9, 2017 at 12:15
  • After all, the Amiga was produced in times when the US where still trying to go metric :)
    – tofro
    Commented Feb 9, 2017 at 12:23
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    @tofro 13 threads per inch is 0.5mm???? I don't think so. Work it out.... 25.4 / 13 = 1.95mm. Definitely NOT 13 TPI ! With a 0.5mm pitch it would be equivalent to ~50TPI, but that simply doesn't exist. Yes of course the fine pitch threads are metric M3. Here is a standard thread chart for reference... mdmetric.com/tech/tict.htm
    – len foster
    Commented Oct 2, 2018 at 18:06

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