Weaver cracked gears....ugh!!!!

Perhaps NWSL might have just the gears...?

Maybe it's just me...but 88 bucks to get a pair of O scale diesels up and running doesn't seem too extreme.

Mark in Oregon

The problem with Weaver is that they did not age the plastic before cutting the gears.  You may want to ask NWSL if they still age the Celcon before hobbing.

The price of a gear might blow you away.  If you order a thousand they might be a buck each, but in onesies and eightsies they will be closer to $11 than to $1.

Also ask P&D about aging.  They probably got them from NWSL, and Raoul is the guy who tipped me off about aging (Raoul founded NWSL and always gave me a discount, not to mention a fun tour of the factory).

hi Bob and Mark just got off NWSL website. 9.99 a gear!

looks like going to purchase whole wheel/ axle a lot less work in the long run.

I can get the wheel off but getting back on might be a different story, thanks guys!!!

S&OSCALER.

In an O scale train magazine there is an article written by Brian Scace on replacement of cracked Weaver gears. The article includes the name and contact info of a company that sells whatever size needed for the job. I have the magazine somewhere on my shelf. I will see if I can either send you a copy of the article or send a link for it.
it was certainly more affordable than what you mention.
back to you soon.

Leroof.

@S&Oscaler posted:

hi Bob and Mark just got off NWSL website. 9.99 a gear!

looks like going to purchase whole wheel/ axle a lot less work in the long run.

I can get the wheel off but getting back on might be a different story, thanks guys!!!

If I may, having done a few of these myself...

Be very cautious when removing the truck sideframes, as the stem that holds them are very fragile and easily broken.

Mark in Oregon

Frank;

Stock Drive Components-Sterling Instruments has what you're looking for. That's where I bought my replacements. It is also where Brian Scace purchased the ones for his magazine article. I can probably give you the part number.

Ok Chris sounds great!

just email info, thanx

PRR Man,

I would appreciate if very much if you would email me the part number for the gears for the weaver axles also.    I have 10-12 RS3s and FA/FB units.

I am surprised that all 4 axle gears in both  units would go at once.     I have had 2 go bad at once early on, but usually only one at a time.

S&O Scaler

To take the trucks apart, I place the blade of a smaller (about 1/8 inch) screwdriver under the back of the pin in the middle of the bolster and twist it and push a little and the side frame pops off.   DO NOT PULL on the sideframes, that will probably just break them off the pin.

Is there a problem in posting sources/part numbers on this forum for others affected by this problem??

So far I'm reading of two sources, but no one wants to post the respective part numbers to facilitate ordering?

...Or did I miss something in the Forum rules against this sort of info being posted?

I worked at P&D when those sprockets were made THEY had them made because they used the Weaver drive train on their custom F3s. Even offered them to Weaver but they declined and continued to use the faulty ones. So every Weaver engine we sold had the sprockets changed before they left the store.

Edit I goofed P&D had the sprockets made locally.. I think the gears came from Weaver as Pat and Bob became good friends over the years. I know the completed chain drive assembly came from Weaver.

There’s no mystery about posting part numbers here. My info for Frank is at home and I’m presently at work.

Stay tuned.

i think the Scace article was about changing the sprockets that drive the chain. not the axle gears.

Apparently, P&D Hobby is not restocking many of these Weaver replacement parts as they run out of stock.  P&D was selling just replacement axle gears p/n 10021 up until a short while ago as I picked some up for a recent project for something like $4.00 for a 2-pack back in February.  When I just searched on their website, the Weaver content has been cut down significantly.  Maybe the current operators are not choosing to have replacements made (or just don't know how to go about getting them made).

Scott

Or maybe NWSL was the supplier, and after two ownership changes and price increases it is no longer economically feasible to produce these things.

The owner passed away and the adult kids are keeping the store open. It's very unlikely that more sprockets will be made.

A lot of times folks skip over posts.  I went back and re-read yours - it did not say there would be no more, and it did not say where they "had them made."

You just have to shrug when someone misses your post.  Happens all the time.

The sprockets were made locally. I did an edit on my post.

The axle gears were the items at issue - sounds like P&D had complete axle/gear sets, and I submit that if they still have them, time for Weaver aficionados to stock up.  Guarantee they will never be made again at any reasonable price.

I have to apologize. Dave’s comment had me realize it’s the axle gear. I mistakenly thought of tower sprockets. Which I have part numbers for.

To Bob’s point about missing the point!

I may have enough on hand to help Frank out. He is a fellow club member.

But tonight I’ll check the SDP-SI site for a compatible axle gear. If I find it I’ll post it here.

mea culpa.

S&OSCALER, Oh! I misunderstood as well. The  Scace article is in fact about the sprockets on the tower as mentioned above.

best of luck finding your solution in this case.

so sorry.

Ok mi thought I posted a response to my question but the place where I work the wifi is not too sporty!

so thanks to all, to dkdkrd I will post part no. for gears when I get them.

also not all gears on all axles were cracked, I thought it mine best to replace all since truck is apart.

they are a pain!!!!

thanks to all!!!!

for gears when I get

There is a guy in England named James who has 3D printed axle gears for the ROCO/Atlas/Red Caboose wheels.  I have a set installed in a Red Caboose GP9 project but haven't gotten around to running them.  They look suitable and installed nicely.  Pre shipping price from Shapeways is about $14 a set (4 gears).

I wonder if a 3D printed solution could be the future for Weaver gears

Here is the gear page from James' blog:

https://jamestrainparts.com/20...arossi-f9-revisited/

thanks Rick! I haven't decided which route I'm going to take, but this is another option!

so I measured  the axle gear on a spare I have. technically the gear is a worm gear, as it is driven by a worm.

it's important to measure the axle diameter. I found two different size axles w worm gears on them: .125" and .187". I think the wider axle is the OEM from Weaver, the narrow is a NWSL, as the wheels have a more narrow tread.

both gears are about the same O.D. .460". the OEM Weaver is slightly thicker than the NWSL. both have a low slope helical cut. (as worm gears should)

now I can search SDP-SI for a match.

@PRR Man posted:

so I measured  the axle gear on a spare I have. technically the gear is a worm gear, as it is driven by a worm.

it's important to measure the axle diameter. I found two different size axles w worm gears on them: .125" and .187". I think the wider axle is the OEM from Weaver, the narrow is a NWSL, as the wheels have a more narrow tread.

both gears are about the same O.D. .460". the OEM Weaver is slightly thicker than the NWSL. both have a low slope helical cut. (as worm gears should)

now I can search SDP-SI for a match.

Number of teeth on the worm gear??

I noticed P&D Weaver Parts inventory dropping a few months ago. If that is the case 3D printing will probably fill the void without much trouble.   Frank - I’ve had a weaver rs-3 apart on my bench for a year with the same problem.  When I get a chance I’ll see about doing a cad drawing of the gear.   Should be super easy.  Then print some in a high strength plastic    I’ll have to print some jigs too to maintain spacing when pressing on and off.   If we are successful I’ll find a way to post the STL file so anyone with a $150 FDM printer can make their own.  I don’t see a reason to monetize something so simple   This is the future.  There are a number of people that I follow on 3D printing sites and forums that have designed printed and built some fairly decent drivetrains on the cheap, and they are improving all the time.  Handicap will be the insulated steel wheel sets, which would involve a small cnc lathe, which most of us don’t have.  This is why most of the stuff to date used 3D printed wheels.

Blown away by the idea that a $150 printer can produce a plastic gear as strong as hobbed and aged Celcon!  That is a major breakthrough.

@bob2 posted:

Blown away by the idea that a $150 printer can produce a plastic gear as strong as hobbed and aged Celcon!  That is a major breakthrough.

But if you don't have the $150 printer (+ time , inclination, patience, yada, yada, yada to work your way up/down the learning curve thereof) the aforementioned $88 sounds like a bargain after all.  Even at NWSL's price for gears, only, ($9.95 each) one could invest in a quality wheel puller and still be ahead.

But, TEHO, of course...

so there are 20 teeth on the Weaver worm gear and 21 (!) on the NWSL.

based on 20 teeth, .187" hub bore and approx. .450" OD these are the SDP-SI choices. all much less than $9.99 each.

SDP-SI acetal worm gears

Based on the fact that these Weaver gears have a 48 Diametral Pitch (48 DP), then it is going to be one of the first two in the table in Chris' on SDP-SI acetal worm gears link.  You have to see if the worm is a single or double start or, which is even easier, get the gear ratio by spinning the drive shaft at the truck (not the motor drive shaft since there is a second reduction via the chain sprockets) and count how many turns it takes on the truck drive shaft to spin one of the wheels one complete revolution and then check against the SDP-SI table.  The first gear has a 10:1 gear ratio and second has a 20:1.  These two 48 DP gears have different pressure angles (20 degrees vs. 14.5 degrees), which you need to match to the existing worm so getting the worm gear with the same gear ratio as the Weaver stock gear is key.

Also, it looks like these SDP-SI gear drawings show a hub sticking out one side of them, which will need to be machined off to fit in the Weaver gear box but one of these two gears should work, depending on the results of the Weaver gear ratio test.  Based on the examination of some of my old broken Weaver axle gears, it looks there is the remnant of a hub on those too that was machined off.

Scott

Should have bought an MTH.

nearly all worms in vertical drives are double start. I once tried a test with a new single start worm and matching worm gear.

I did not find any hubless gears on the site.

also, there are gears with .1865" and .186 bores for more choices.

@Scott Kay posted:

Based on the fact that these Weaver gears have a 48 Diametral Pitch (48 DP), then it is going to be one of the first two in the table in Chris' on SDP-SI acetal worm gears link.  You have to see if the worm is a single or double start or, which is even easier, get the gear ratio by spinning the drive shaft at the truck (not the motor drive shaft since there is a second reduction via the chain sprockets) and count how many turns it takes on the truck drive shaft to spin one of the wheels one complete revolution and then check against the SDP-SI table.  The first gear has a 10:1 gear ratio and second has a 20:1.  These two 48 DP gears have different pressure angles (20 degrees vs. 14.5 degrees), which you need to match to the existing worm so getting the worm gear with the same gear ratio as the Weaver stock gear is key.

Also, it looks like these SDP-SI gear drawings show a hub sticking out one side of them, which will need to be machined off to fit in the Weaver gear box but one of these two gears should work, depending on the results of the Weaver gear ratio test.  Based on the examination of some of my old broken Weaver axle gears, it looks there is the remnant of a hub on those too that was machined off.

Scott

Good direction, Scott.  But I have a caveat...

Re the Nylon gears: Avoid them!  I notice that they show having an attached hub.  However, they also indicate "No Set Screw", which means the hub is for a different purpose.  And, IMHO, the purpose of the hub is to provide a better design for a press fit to a shaft w/ or w/o a knurl.

The use of Nylon in these applications...and their ultimate cracking/splitting failures...has been the bane of the industry across all scales.  Just look at NWSL's listing of replacements by scales, manufacturers, years-made, model i.d., etc., etc..  The use of nylon for these gears is akin to the zinc pest problem; maybe it's OK now, but odds are that with time, most are doomed to failure.

The reason nylon is a poor material choice for these gears...as designed...is that the material is hygroscopic.  It absorbs/desorbs water depending upon humidity, etc..  In fact nylon can absorb up to about 10% of its weight in water.  That adds stress for a pressed-fit part.  Then, too, the water can be desorbed, the gear 'dries out'.  That also plays poorly to the stresses in the design/fit.   And, if you've studied one of these split gears on an axle shaft, the split ALWAYS goes radially to the root of the gear teeth...the easiest path of stress relief.

The use of the hub on the side of the nylon gear is by design.  The hub...often equal to or wider than the face width of the gear teeth...provides a far better feature to retain the part with a press fit, knurled or not.  If that hub has to be cut off to fit the model application, you are removing the key portion of the nylon gear design that will provide the best durability in a pressed fit situation.

Acetal resins...Celcon (Celanese) and Delrin (Dupont) are brand names for this resin family...are not hygroscopic.  Water adsorption/desorption is not an application risk for these resins. 

So why do manufacturers keep using nylon for these (hubless) axle gears??  Nylon is cheap, cheap, cheap.  Also, nylon has low shrinkage as molded; meaning, die dimensions for molded nylon parts need minimal-to-no adjustment to yield an accurate part...especially important when molding gears. 

Molded acetal resin parts, OTOH, have a relatively high molding shrinkage factor.  To get an accurate final gear profile, for instance, the die profile must be altered to account for the shrinkage...not an easy task for die-makers.  Of course, hobbing (machining) the gears from acetal resin stock is the easiest way to ensure an accurate final part...and I'm quite sure is the technique used by NWSL.  Hobbing is NOT a low-cost way of making gears for volume applications...e.g., many model engines with many drive axles.

Acetal resin has that other advantage over nylon...it inherently has more lubricity; it's part of the 'slippery' family of resins. 

Then there's metal as an option for axle gears.   The gear tutorial in NWSL's website emphasizes the importance of being sure to use dissimilar materials between, say, worms and worm gears.  Most gear worms are made of steel.  Brass or bronze, then, is an ideal metal choice for a mating worm gear...the axle gear.  Brass gears tolerate press fitting to an axle very well...without a hub feature.  But, brass gears must be hobbed (machined), not molded.   Ergo, brass is not a low-cost choice for OE gears, especially in mass-produced 'toys'.

As for 3D printing of gears...we'll see how the technicals evolve.  Far be it for me to doubt the possibilities!

-----------

As a side note, I'm really surprised that, if this Weaver problem is that common, NWSL hasn't cataloged acetal and/or brass replacements by now.  Looking at the old catalog listings..O scale...on their website I did not find a Weaver listing.  Very strange.  Or, perhaps, it was dropped for some reason?

FWIW, always...and IMHO.

KD

Very informative.  Yes, the original NWSL first aged the Celcon, then hobbed it in long rods, then sliced and bored.

But brass is not a good gear material.  A model train worm gear will last about two hours with a steel worm.  You need a good grade of bronze.  Bronze will last almost as long as Celcon.

And I believe that by now most of the early Weaver gears are split.

@bob2 posted:

The axle gears were the items at issue - sounds like P&D had complete axle/gear sets, and I submit that if they still have them, time for Weaver aficionados to stock up.  Guarantee they will never be made again at any reasonable price.

I don't see them listed on the P&D site anymore.  NWSL lists them but they are $65 for a set of 4.  Yikes...

@bob2 posted:

But brass is not a good gear material.  A model train worm gear will last about two hours with a steel worm.  You need a good grade of bronze.  Bronze will last almost as long as Celcon.

From NWSL's 'old' catalog...

"For best gear life, the gears should be dissimilar materials with the driving gear harder. This is particularly important for high speed and/or high load interfaces such as worm to wormgear and less important in low speed situations such as idler gears between axles. Acetal is the generic name for the engineering plastic trade named Delrin (DuPont) and Celcon (Celanese). NWSL acetal gears are machined from stable, aged material to avoid the shrinkage and cracking problems inherent in inexpensive moulded plastic gears. Gears can be machined in material of your choice with appropriate handling and difficulty charges (ie. gears in bronze usually require a 50% surcharge compared to brass because of added machining time and tool wear)."

Actually, brass is an excellent gear material.  Per a phone discussion I had with Dave Rygmyr (previous NWSL owner) most of the concerns folks have with brass falls into two categories...first, that the brass gear was mated to another brass gear (both of which are destined to wear excessively [see above paragraph], but one will usually 'give out' before the other); and secondly, poor/improper lubrication (for which Dave recommended rail hobbyists use LaBelle #102 Gear Lubricant).   If you look at the catalog listing for replacement gears by product manufacturer (e.g., HO), especially Samhongsa, you'll find that NWSL recommended the use of brass for a large portion of the o.e. nylon gears.  To anticipate only a 2-hour life for an application using a brass gear leads me to believe there would be other problems in the mechanism, loads, lubrication, ...?  But, TEHO, as they say.

Again...FWIW.

Maybe Dave Rygmyr is more of an expert than Raoul Martin, or for that matter, Machinery Handbook.  But I can tell you I got the first NWSL brass axle gears, and right after that Raoul started making all gears out of Celcon.  Then I had a little cottage industry here replacing brass Sunset axle gears with new bronze ones.  We got the proper alloy out of the above handbook.

I have not seen a Sunset brass axle gear make it past the one hour point.  Early Big Boys, Challengers, Cab Forwards - all failed on the SDMRR Museum trackage after a couple laps.  Mort sent the bronze gears, and I replaced them.  As far as I know, since then Mort and now Scott do not provide brass axle gears.  Excuse the nomenclature - worm gears.

A most excellent read fellas. Bob2 I've always like others I've known hold your experience in high regard in these matters.

Thanks guys for the informative and entertaining thread.

Thanks for all the negative comments on any attempt to do things differently than they have been in the past.   I sort of remember NWSL being shut down for a bit recently, but I’m sure there are at least a dozen companies out there chomping at the bit to manufacture miniature gears in the wonder plastic Celcon for all those people out there with 1980s vintage o scale 2 rail locomotives.   I was just trying to think outside the box as I’m hoping I still have a few years on this earth, and anticipating/preparing for when these manufacturers are not around and I’ll have to figure it out on my own.   I have an old Weaver RS3 that I bought for $20 with two cracked gears.  I’ll give it a shot on that, and if it doesn’t work so be it, but I anticipate there will be a printer and a filament/material of suitable strength and characteristics in the near future, if what I have available in the 3d printing arsenal now doesn’t.    I’m not concerned with matching the strength, and am only concerned about the lower melting point of 3d printed plastic compared to something like acetal.  If these gears are going over 50 Celsius (around 120F) I’ll likely have some issues, although I might be able to push that up to 10 degree more.  .  I honestly don’t know how hot a weaver gear box gets?    But I will find out soon.    Since there are plenty of old school gear gurus here, I won’t bother to follow up on this forum, or link the STL file for the worm gear.  If you are interested in 3d printing in model railroading, you should know of the sites related to this specific subject and I’ll update there.