Sears Automatic 8mm threading sprocket

[David Hardt]

Hi, everyone,

Newbie to 8mm projectors here. Glad to find your site.

Found a Sears Automatic 8mm Projector at a Habitat Restore. Everything lights and turns except for the first auto-thread sprocket (see photo ).

I have the back off. All the appropriate gears turn for forward and reverse including the gear behind the sprocket that does not turn. The white gear pictured turns, but its axle/spindle does not turn. (Yes, i removed the two gears that were in front of it for clear access).

1. What might the issue be?

2. Repairable by a newbie?

3. If that sprocket needs to be removed, how do I do that? I haven't seen that kind of wire/slot/flat spring attachment before.

Any thoughts appreciated! Thanks!

[Nantawat Kittiwarakul]

Gummed up lubricant on the sprocket shaft maybe?

[David Hardt]

Perhaps a gummed up sprocket. I'd get better access to that shaft by removing that gear. How do I remove the "wire spring-like clip" that seems to be holding it on? And how would I put it back later? ! )

[Shane C. Collins]

I can't tell from your photo, but is that spring clip possibly a tension spring?

[David Hardt]

Well, maybe it is, to put pressure on that small flat metal piece. I thought it might be holding the gear on the shaft as a kind of clip. You can see in the photo that the shaft has a split end. The wire you see goes through that slit resting (or pushing against?) The metal piece and the gear. It does two or three turns around the shaft and ends by going through the slit in the shaft again.

Does that help? Would a different picture help?

[Shane C. Collins]

Well, maybe it is, to put pressure on that small flat metal piece. I thought it might be holding the gear on the shaft as a kind of clip. You can see in the photo that the shaft has a split end. The wire you see goes through that slit resting (or pushing against?) The metal piece and the gear. It does two or three turns around the shaft and ends by going through the slit in the shaft again.

Does that help? Would a different picture help?

Yeah I'm not sure how this set-up works but I'm sure someone here does. I've taken gears out from projectors in the past, but most of the time the gears were held in by c-clips. This arrangement is new to me!

[Tom Dennis]

If this is simply gunged, then try de-gunging before dismantalling.
Put some freeing agent [discussed many times on the forum] where appropriate let it soak and using the inching knob gently work the mechanism to free off, this may take a while and require several applications, but might solve the problem.

TOM

[David Hardt]

OK. I'll check into applying freeing agent. Thanks!

And yes, C- or E-clips on other gears, but not these two connected to the sprocket shafts..

[David Hardt]

Hmm, search on "freeing agent" doesn't give results. What other terms would I search?

[Ed Gordon]

Hmm, search on "freeing agent" doesn't give results. What other terms would I search?

Any cleaning agent that is safe to use on plastic parts. Gunk would work. https://gunk.com/product/gunk-multi-...cleaner-hdc32/

[Maurice Leakey]

David
Search for "Removing dried grease".

[Tom Dennis]

Good day David,
Further thoughts on your projector and there are many If`s.
the mechanism resembles a B/H autoload sold in U/K.I have been in my bitsa shelves to look at one.
If the nylon/plastic is degunged and the projector is still seized, then suspect the drive shaft linking the top sprocket to the inner mech.
If the projector construction is the same as a B/H and the main chassis is aluminium, the drive shaft steel then a bi-metallic reaction has occured.
If this is so then a few drops of penetrating oil will dissolve the crud.
In the U.K. WD40 or XC90 act as a lubricant and a freeing agent.
Putting a few drops on the shaft both front and back leave overnight if necessary repeat
Sorry about the If`s but I have seen this on various units usualy when subject to damp.


Regards TOM

[David Hardt]

Thank you. I will give these ifs a look.