anyone have a working Apple 40 meg tape drive?

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Sat Aug 30 17:21:01 2003

> I think I've come up with something that will work.
> The outer and inner cross section of the roller is .7" and
> .5" so I dug around at Weird Stuff to see if any old DC2000
> drives were close. The Colorado 250 appears to be, and with
> a bit of work with a small flat blade screwdriver I was able
> to remove the rubber from the .5" shaft. Now, I need to clean
> the goo out of one of the MCD-40 mechanisms and try it.

To somewhat change the subject, I've just rebuilt the roller in an
HP9810's card reader. The OD of this is 1", and there are 2 rollers on
the spindle (about 1/8" thick with an 1/8" gap between them). Of course
the rubber had turned to goo.

What _I_ did (and it depends on having a reasonable workshop) is make up
a puller that would fit under the rollers and pull them off the shaft
using a screw against the end of the shaft to provide the force. Once
they were off, I machined a piece of brass rod 7/8" in diameter to have 2
grooves for 1" O-rings in it. Then pressed that onto the reader's shaft
with a suitable drift and a bench vice.

The result works fine. If anyone wants to try this, I'll include the
files below on how to do it :

Firstly the tools :

Puller tool to remove HP9810 card reader roller
-----------------------------------------------

2 pieces of steel, 2.5" by 2"

Top plate, 3/8" thick :
4mm holes at (0.25,0.25), (1.25,0.25), (2.25, 0.25), (0.25,1.5), (2.25,1.5)
10.6mm (M12 tapping size) at (1.25,1.5), Tap this hole M12 (1.75mm pitch)

Lower plate, 1/8" thick
4mm holes at (0.25,0.25), (1.25,0.25), (2.25, 0.25), (0.25,1.5), (2.25,1.5)
1/8" hole at (1.25, 1.5). Mill 1/8" slot to nearest long edge (about 0.5"
long).

5 pillars, 2" long, 3/8" diameter steel. Drill 3.5mm and tap M4 in centre
of each end.

Assemble with M4 bolts through 4mm holes in plates to ends of pillars. Fit
M12 bolt to tapped hole in top plate.


Drift to refit roller
---------------------
1.5" length (or thereabouts) of 7/8" brass rod. Face off both ends,
centre-drill, and drill 3.2mm hole. This should be a sliding fit on the
roller spindle.

-----------------
And now how to do it

Take off the drive belt from the LHS.

Then undo the 2 screws and remove the head. This is not essential, but
you'd feel a right idiot if you damaged the head in subsequent work!.

Remove the top left and bottom left card sensor bulbholders from the
plastic frame, leave them hanging on the wires.

Remove the screws from the pillars connecting the 2 sideplates. The front
bottom one on the right hand side, all the others on the left (you have to
frob one of the top ones to get it clear of the pulley).

Separate the plates, and slide the 2 left hand card sensor photodetectors
out of the plastic frame also. Contine separaing the frames and remove the
pinch roller/pressure pad assembly.

Remove the rear cover from the motor (2 tiny screws, you need a nutdriver
a few sizes smaller than most people have!).

Undo the 2 screws holding the wires to the brushgear.

At this point the 2 plates can be completely separated, set the right hand
one (with the cableform, etc) aside.

Remove the motor brushes (one more screw each) to protect them.

Remove the screw holding the lower front pillar to the left plate, remove
it with the card guide.

Rmeove the roller from the shaft using the puller tool. If
necessary, file off any burrs from the end of the shaft. Carefully
slide the roller shaft out of the side plate and recover the metal strip.

Make a new roller as follows :

1" (or so) length of 7/8" (actually 0.87") brass rod. Face off both ends.

Centre-drill one end, then drill 1/8" (or 3.1mm). Check it will fit onto
the roller shaft (but not over the knurled part)

Turn a 0.06" deep groove (so 0.75" dianmeter at base) 0.1" from the end
and 0.25" from the end. Part off a total of 0.35" of the rod.

    --------------- <--------- ) 0.1"
    ) ( <--------- )
    | | 0.15"
    ) ( <--------- ) 0.1"
    --------------- <--------- )

Fit 2 O-rings (1" OD, 0.75" ID, 0.125" think) into the grooves. Check
overall diameter of roller (should be 1")

Refit roller shaft through metal strip (DON'T forget this!) and left side
plate. Press new roller onto shaft using a suitable drift and bench vice.

Reassemble the other parts of the reader.

-tony
Received on Sat Aug 30 2003 - 17:21:01 BST