No: 3 Extractor Gear Problems

[wlw-19958]

Hi There,


I recently purchased a #3 American 2nd Issue and it has a couple
problems. The extractor gear has broken off the spur that engages
the catch. So, I'm looking for suggestions on how and where to get
it repaired or find a replacement. There is a seller on GunBroker that
sells replacements but his are not exactly right. The gear teeth are
on his are not quite the same as mine. Take a look at the pics.

Any ideas?


Cheers!
Webb

 

[mmaher94087]

Webb, I'm afraid that I would take the chance on this cam gear. Although the teeth look 'sharper' than your original, the pitch and tooth count look correct. I can't tell you how to spend your money but, the worst case is that you will be out a few bucks and your revolver will still need the cam gear. I would risk the money, as IF it works, (and I think it will) your revolver will be fully functional. Let me know the seller as I may need parts in the future.

 

[wlw-19958]

Hi There,

Webb, I'm afraid that I would take the chance on this cam gear. Although the teeth look 'sharper' than your original, the pitch and tooth count look correct. I can't tell you how to spend your money but, the worst case is that you will be out a few bucks and your revolver will still need the cam gear. I would risk the money, as IF it works, (and I think it will) your revolver will be fully functional. Let me know the seller as I may need parts in the future.

Well, I am leaning in that direction but it didn't hurt to ask for ad-
vise. There was someone here that used a service offering "micro
welding" and I was wondering how much that might cost.

On my wish list is a wire EDM machine. I have NO experience
with one (yet) but it would be the perfect tool to make one of
these extraction gears. The hardest part will be developing the
program to guide the EDM wire to profile the part. I don't have
much CAD/CAM experience but it is a skill I would like to acquire.

It should be possible to weld-up the old gear and machine back
to its original shape but I don't own a TIG machine either. Its also
on my "wish list." I do have welding experience with Oxy/Acety-
lene but this part is made of high carbon steel and welding this
up will cause the steel to de-carbonize in the weld zone. This is
where TIG has the advantages of both a smaller weld zone and
shielding gas to exclude air (Oxygen) from the weld zone and pre-
vent de-carbonizing the steel.

Any of these ideas is going to be much more expensive than the
$200.00 (plus shipping) for the replacement gear. On the other
hand, buying a piece of equipment will be useful for other projects
and possibly produce parts for sale.

I am not an expert on these extractor gears but I have read that
S&W re-designed this part several times. The one advertised
on GunBroker is probably a copy of an earlier design (S&W was
constantly trying to improve the extraction system and make it
less prone to breakage). I think there was 5 or 6 different designs
used in the #3 American series.


Cheers,
Webb

 

[mmaher94087]

I agree that there were five or six changes to the (generally speaking) Model 3 size frame.

As for Micro-welding, the place that I have used has (had?) a $125 minimum. When I send them a project, I send them drawings and specific instructions for what I need welded as well as "DO NOT TOUCH THIS" instructions. I have sent good parts for reference too. I haven't been disappointed yet. I do all the cleanup/machining. They do the welding.

 

[wlw-19958]

Hi There,

I agree that there were five or six changes to the (generally speaking) Model 3 size frame.

As for Micro-welding, the place that I have used has (had?) a $125 minimum. When I send them a project, I send them drawings and specific instructions for what I need welded as well as "DO NOT TOUCH THIS" instructions. I have sent good parts for reference too. I haven't been disappointed yet. I do all the cleanup/machining. They do the welding.

That sounds like a viable plan. I have been a "Home Shop Machinist"
for the past 40 years and have the equipment to re-machine the
gear after having it built up.

After posting my last response, I had another idea on how to repair
this gear. I can grind the broken area flat (on the surface grinder)
and silver solder on a piece of similar tool steel and then machine
it back to its original form.

I think I will get one of those copies as a back-up and reference
for profiling out the spur.


Cheers!
Webb

 

[wlw-19958]

Hi There,


I pulled the extraction gear from another No. 3 I have for
comparison and I noticed something I find "interesting."
The two have significant differences. The cutout for the
gear catch is in a slightly different location on the gear.
See pics.

I wish I had more No. 3's to document the differences in the
extraction gears over the period the American model was made.


Cheers!
Webb

 

[mmaher94087]

Hummm, do the teeth align and, if so, can you post pix of the cutout for the gear catch with the teeth aligned?

 

[wlw-19958]

Hi There,

Hummm, do the teeth align and, if so, can you post pix of the cutout for the gear catch with the teeth aligned?

I knew someone would ask that. The gear teeth were aligned
when those pics were taken.


Cheers!
Webb


Edit: Second Pic Added

 

[mmaher94087]

The new gear appears to have a slightly bigger window ahead of the 'catch' point. I wonder if the window was lengthened to allow more time for the cylinder catch to enter the window to snag the gear.

 

[wlw-19958]

Hi There,

The new gear appears to have a slightly bigger window ahead of the 'catch' point. I wonder if the window was lengthened to allow more time for the cylinder catch to enter the window to snag the gear.

Depending which gear you're talking about, the two gears pictures
are from my small collection of No. 3's. The broken one is from
serial number 11747 and the gear next to it is from 25980. The
only other No. 3 American I have is an earlier model and doesn't
have the double wide first tooth.

I have ordered one of those replacement gears mentioned earlier
in this thread but I don't expect to get it for a week to 10 days
(I sent them a money order so I could save the 4% credit card
fee).

I agree the whole (later) gear has a longer notch (or window) for
the catch to enter. I can think of two possible reasons why S&W
did this:

(1) The gear catch could be having problems re-entering the
window after extraction, or

(2) The gear catch could have problems exiting the window due
to the smaller size.

I would like to see a monograph on the various changes the ex-
trasction gear went through during the period the American and
Russian models were being manufactured and the dates these
changes were enacted. Such a project would require a large
sample size of existing No. 3's to examine and there is always
the possibility the gear had been replaced at some point. But
given enough examples, a trend could be discovered.

I don't have a large enough collection to do this.


Cheers!
Webb

 

[mmaher94087]

My sample size would be one. Not much help. I would like to know how well the repro part works. I know the vendor stated that the part needs to be thinned to fit but are there any other problems?

 

[Exmilcop]

Talk about timing! I started a thread about a problem No.3 Russian that I'm trying to put to rights. I've ordered the cam from the gentleman in Wyoming and with the currency conversion and shipping, it's going to cost me near to $300. It would be a serious PITA if it doesn't work. I hadn't realized that there were variations in the internals even within the same model. Do any of you gentlemen know the trick to actually removing the cylinder from the frame? I know the retaining piece held by the top screw would retard the removal but can the actual cylinder be taken out?

 

[wlw-19958]

Hi There,

Talk about timing! I started a thread about a problem No.3 Russian that I'm trying to put to rights. I've ordered the cam from the gentleman in Wyoming and with the currency conversion and shipping, it's going to cost me near to $300. It would be a serious PITA if it doesn't work. I hadn't realized that there were variations in the internals even within the same model. Do any of you gentlemen know the trick to actually removing the cylinder from the frame? I know the retaining piece held by the top screw would retard the removal but can the actual cylinder be taken out?

I assume you are talking about the "New Model" Russian (a.k.a.
Third Issue Russian). Yes, the cylinder can come out. The large
screw on the top strap needs to be backed out enough to disengage
the cylinder retainer. The cylinder retainer is a piece in the top strap,
just under the barrel latch, that has a lip that comes over the back
edge of the cylinder to keep in place.

That retainer has to be pulled out. This retainer fits in a slot in
the top strap that is parallel to the bore. If yours are like my two
second issue Americans, that M--F-- is stuck like nobodies business.
I am doing the Kroil® Soak and prayer routine for now.


Cheers!
Webb

 

[wlw-19958]

Hi There,

I should mention there is a “latch,” under the barrel at the end of the
extractor housing that needs to be depressed. This latch is a rocker
type that holds the end of the extractor.

Cheers!
Webb

 

[wlw-19958]

Hi There,

The replacement extractor gear arrived today and I thought
some of you would like to see it and have a report on it. On
first impression, it looks very much like the original but careful
examination, there are some differences that are not obvious.

As pointed out in the listing, these are thicker than the
originals. The originals are .1545” to .1555” thick. The
replacement is .1625” thick (or about .007” to .008” oversized).

What isn’t apparent is the differences between this replace-
ment and the originals in other dimensions. The center hole
and bushing are larger in diameter. The center holes in my
originals are .3790” and the bushings are .3770” on the
outside diameter. The replacement has a .3825” center hole
and the bushing is .3793”. This shows the originals had a fit of
.0020” and the replacement has a fit of .0032”. This is a much
looser fit than the originals.

The center hole in the bushing different too. The originals
measure out at .232” and the replacement measures at .229”.
This can be reamed to the correct diameter but being the
outside diameter of the replacement is over .003” undersized,
I will make a new bushing that fits better.

The window for the catch is very close to the extraction gear
that is broken in my 11747 but the angles are off a little and
do not terminate in as sharp an angle in the vertex. But it
should work

As pointed out in my earlier posts, the teeth on the
replacement gear are formed with a slightly sharper angle
than the originals. I haven’t checked the working action of this
replacement gear because of the work needed to make it fit
but I will report later.


Cheers!
Webb

 

[wlw-19958]

Hi There,


Here are a few more pics.


Cheers!
Webb

 

[wlw-19958]

Hi There,


This is my final report on fitting the replacement extraction gear
to my No. 3 American 2nd Issue. I initially used my surface grinder
to thin the gear from .1625" to .1555" and found that there was still
a slight rubbing that prevented the gear from rotating back to its
starting point when the catch was depressed.

The hole through the center turns out not to be of uniform diameter.
I initially measured it at .3825" but it turns out the hole was tapered
(I assume the EDM wire wasn't perpendicular to the stock being cut).
It turned out it tapered from .3825" on one side and .3880" on the
other. Also, there was a burr in the hole at one point (I assume it
was caused by the arcing of the wire at the start/stop point when
cutting the hole). I ended up using a needle file to remove the
burr and honing the hole to remove the taper.

As I mentioned in my last post, I made a new busing for the center
hole that was much more precise fit (the old bushing was .008"
undersized). I used some W1 tool steel (which is as close as I can
come to the original type of steel used) to make the new bushing.
I hardened it in brine and tempered it in a saltpeter bath at 300°C.

After a trial fit and discovering I had to polish the sides down
.0005" (1/2 thousandth of an inch), to get the new gear to fit into
place and the extractor now works like it should. So the thickness
ended up being .1550". If you look at the pic, you can see the
rub marks.



Cheers!
Webb

 

[mmaher94087]

Absolutely great! It was a bunch of work on your part, but the results are stupendous. I can't wait to hear of your next project.