HP 8640b

Take a look at Jose Gavila's web page describing a problem with his HP8640's gears....although he doesn't offer a solution for the broken gear he does describe a homebrew solution to fixing some of the fingers on the wafer. He may have some suggestions if you contact him.

Dino KLØS/4

They're Delrin ,and yes it's very common with the older serials, along with the little switch fingers falling off the plates, never to be seen again.

Let us know if you find an answer, I never did, mine's sitting in a heap in the garage :^(

Dan

eric van slee wrote:

They can be fixed. I had 2 cracked gears. Both are now repaired. I'll post pictures when I can (or when I remember).

1. Take photographs of the gear assembly before removal so you know how it goes back together. The meshing of the gears must correspond to a starting point, so also record the position of the front panel dials before disassembly. Be sure to record the position of the clear plastic switch armatures.

1. Tear it apart and remove the cracked gears. The gear cracks because the delrin gear shrinks onto the brass center piece. If you just glue it together, the gap between the gear teeth on either side of the crack will be excessive.

2. Remove the delrin gear from the brass center piece and file the center hole in the delrin gear to enlarge its diameter. Leave a little extra space around the brass center piece for the glue. Make sure that the gap can be closed. Leave the filed area slightly rough for good adhesion. You may also need to enlarge the hole around the set screw for clearance with a small round file.

1. Glue the gear to the brass center piece with 24hr epoxy (not the 5 minute type). Clamp the gear in a vice, glue clamp, or whatever, being very careful not to crush the gear teeth. Be sure the crack is closed, properly aligned, and that no glue slops between the teeth. Do it right the first time. Keep warm, and wait 24 hours for the mess to dry before even looking at the results.

Thank you, This seems a good advice that I will try. And I am interested in the pictures.

Eric "Jeff Liebermann" schreef in bericht news: snipped-for-privacy@4ax.com...