# The 312 engine that started my journey is running!



## shaker281 (Jun 22, 2019)

Three weeks ago I started my rehabbing of my three (sadly neglected) sets of American Flyers with what appears to be a 1948 312 steamer. I finally got everything together that I needed for a suitable rebuild. I thought this one would be the simplest of the three locomotives I needed to get running, but it proved to require more time and parts than the others (484 and 21165), though the 21165 reverse unit seemed to be a delicate task. 

I ended up re-using the original boiler front (after repairing the socket) and bought a NOS field winding and used cowcatcher along the way. I felt the wire to the winding was too frail to trust, as it had been poorly handled. I also replaced brushes, springs, smoke unit and the harness to the tender, plus lower reverse unit fingers. 

Problems I encountered along the way: Defective new lower fingers. These had an unreliable contact from the tiny grommets to the fingers and at first seemed like a cold solder joint. Once I figured out the problem, I swapped them for a spare set that I had on hand. Then I found a brush sticking in the brush tube. Then I had binding wheel linkage. And a missing armature spacer/washer. Fought me all the way! 

But, here she is and seems to be running reliably. And not looking too bad, either. The only re-popped item on the unit is the front truck. I still need to find the correct shoulder screw for the tender drawbar. Not wanting to spend $8.50 shipping for a .75 part! And I suppose it could stand a bit more "polishing" of the bright bits.


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## flyernut (Oct 31, 2010)

Nice. Polish the hand-rails with 2000 wet/dry paper, they will sparkle, or just buy new ones. Make up a list of parts you might need in the future and put that screw on it, and while you're at it, get several..Whenever I do a rebuild, I polish the inside of the brass tubes that the brushes slide in.. The brush must be able to slide all the way through. This will insure the brush springs put the proper tension on the armature face.


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## mopac (Feb 24, 2011)

Looking good. Speaking of armature face did you resurface yours. At least polish it up.
#312s are worth the effort. Good job.


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## shaker281 (Jun 22, 2019)

mopac said:


> Looking good. Speaking of armature face did you resurface yours. At least polish it up.
> #312s are worth the effort. Good job.


Thanks. Yes cleaned up the armature with the usual: toothpick and contact cleaner and 1000 grit sandpaper then more contact cleaner. It was shiny! I had even run a slimmed down q-tip through the brush barrel with contact cleaner previously. Second time's a charm though. Must've been a tiny bit of debris. 

I am pretty happy with the result. I may keep on the lookout for another steamer just to rehab. I've got a few spare parts at this point, LOL, and a bit more knowledge. 

Those lower fingers were bizarre. I literally had the meter probes 1/8" apart, from grommet to finger and no conductivity on either finger! Even after touching up the solder 3 times. I couldn't believe my eyes!


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## shaker281 (Jun 22, 2019)

flyernut said:


> Nice. Polish the hand-rails with 2000 wet/dry paper, they will sparkle, or just buy new ones. Make up a list of parts you might need in the future and put that screw on it, and while you're at it, get several..Whenever I do a rebuild, I polish the inside of the brass tubes that the brushes slide in.. The brush must be able to slide all the way through. This will insure the brush springs put the proper tension on the armature face.


Yeah, I am going to make up a list that includes a couple shoulder screws and armature washers and extra bits and pieces for repair/maintenance. 

And next time clean those tubes better.


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## mopac (Feb 24, 2011)

Before I install my fingers I bend them some so they contact the drum. Seems to work.
First time I installed fingers I did not bend them. They did not work. They were not contacting the drum. So I learned.
flyernut had told me to bend the fingers and I did not listen.


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## shaker281 (Jun 22, 2019)

mopac said:


> Before I install my fingers I bend them some so they contact the drum. Seems to work.
> First time I installed fingers I did not bend them. They did not work. They were not contacting the drum. So I learned.
> flyernut had told me to bend the fingers and I did not listen.


This was actually not the finger contact with the drum. These had no conductivity from the grommet hole to the fingers. I know it sounds weird, but it was proven with my meter. After touching up the solder three times (it looked fine the first time) I finally got wise. I could touch the solder, wire or grommet and get no signal to the fingers. Either finger!


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## AmFlyer (Mar 16, 2012)

Good work! You really sweated all the details. The whitewall wheel insulators look good with no sign of yellowing.


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## shaker281 (Jun 22, 2019)

I do not feel like my 312 is running as strong as it might. I plan to pull the chassis and replace the armature thrust washer with a more correct replacement. At that time I will clean the commutator again and anything else that needs touch up. The brushes/springs are new. Is there anything I should pay particular attention to? Is Challenger oil OK for armature bearings? 

Do people put oil (or grease) in the chuffer unit bore? I did not previously.

The reverse unit seems to be working well and all contact points were cleaned thoroughly. It is possible that my expectations are too high, I just feel there might be a little more in the old gal.


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## flyernut (Oct 31, 2010)

shaker281 said:


> I do not feel like my 312 is running as strong as it might. I plan to pull the chassis and replace the armature thrust washer with a more correct replacement. At that time I will clean the commutator again and anything else that needs touch up. The brushes/springs are new. Is there anything I should pay particular attention to? Is Challenger oil OK for armature bearings?
> 
> Do people put oil (or grease) in the chuffer unit bore? I did not previously.
> 
> The reverse unit seems to be working well and all contact points were cleaned thoroughly. It is possible that my expectations are too high, I just feel there might be a little more in the old gal.


I use different thickness spacers when there is a clicking noise, or there is too much movement in the armature when going from forward to reverse.. I don't believe changing them would make any difference in speed unless they are causing some binding in the rotation of the armature. Also you want to check to make sure the smoke gear is free and not bound up. I've found many steamers that would not run and the problem was a smoke gear that was froze up with old oil.. As far as the smoke piston chamber, I use a small amount of grease to lube and to act as a seal... And 1 last thing, it's great to clean the armature face but you should "re-face" it as well. Think about it, that engine has probably run forward for approx 90% of it's life, and the brushes have cut a micro-scopic groove in the face of the armature.. The most correct way to re-face it would be to chuck it up in a lathe and put a new flat surface on it. But what works just as well is a drill press or drill. I chuck up the armature in the drill press and fire it up. I hold a piece of sand-paper on the face as it turns and put a new, flatter surface of the face.. After I get the groove out, I use a piece of 2000 wet/dry paper to polish it even further. When I like what I see, I clean out the slits in the armature face and call it good. I also use that 2000 paper and polish both ends of the armature's shaft, using my dremel to clean out the gear teeth.. If all else fails, try a different armature.


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## flyernut (Oct 31, 2010)

mopac said:


> Before I install my fingers I bend them some so they contact the drum. Seems to work.
> First time I installed fingers I did not bend them. They did not work. They were not contacting the drum. So I learned.
> flyernut had told me to bend the fingers and I did not listen.


Told you so, told you so!!.... lol.:laugh:


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## shaker281 (Jun 22, 2019)

Ok, thanks. My smoke unit chuffer linkage was cleaned, but I'll grease the bore too when I open it up again. I did polish the commutator face with 1000 grit and it looked very smooth and shiny, plus cleaning the slits and then spraying the face with contact cleaner. It was pretty uniform when complete. But, I might chuck it in my cordless drill and give it one more whack. 

The reason I need to address the armature spacer is that I discovered a lot of play and realized that mine was missing completely. I think from a previous owner's maintenance. To get it running I used a similar sized fiber spacer and then ordered a couple different brass spacers from Port Line. 

Thanks for the advice/knowledge. I might be expecting too much from this old 312 possibly.


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## mopac (Feb 24, 2011)

Tell us what is not up to your expectation. What part of the performance you were hoping would be better. We might be able to help. I think you need at least one shim (washer) on each end of armature. I also put a small drop of oil on each end of armature as I reassemble. A drop or two on the oil wick. With the armature out check that the wheels roll easy. Grease can harden around the axles. The axles are hard to oil without one of those long needles on your oil dispenser. Make sure tender rolls good. Oil
those axles also. Another area I have trouble with are the small wires we are working with. My 336 was running great. It runs great in forward. It is now running slow in reverse. Problem is probably one of the tender wires. Small wire and a couple strands break and you will not get the full power to engine.

I have a couple engines with a lot of slop in armature. I have shimmed armature to take slop out and the engine does not run as well. I think some engines just like some slop.


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## shaker281 (Jun 22, 2019)

mopac said:


> Tell us what is not up to your expectation. What part of the performance you were hoping would be better. We might be able to help. I think you need at least one shim (washer) on each end of armature. I also put a small drop of oil on each end of armature as I reassemble. A drop or two on the oil wick. With the armature out check that the wheels roll easy. Grease can harden around the axles. The axles are hard to oil without one of those long needles on your oil dispenser. Make sure tender rolls good. Oil
> those axles also. Another area I have trouble with are the small wires we are working with. My 336 was running great. It runs great in forward. It is now running slow in reverse. Problem is probably one of the tender wires. Small wire and a couple strands break and you will not get the full power to engine.
> 
> I have a couple engines with a lot of slop in armature. I have shimmed armature to take slop out and the engine does not run as well. I think some engines just like some slop.


Seems to occasionally start out sluggishly. Doesn't pull longer trains as easily as I think it should. Top speed seems limited. I have solved most my track conductivity issues and think I am close to 90% efficiency there. My Alco is running pretty smooth and fast, so thinking the 312 is not fully up to task yet. 

Good info on the armature slop. Mine had a lot and that is when I noticed there should be a shim from online diagrams. It is possible that the temporary fiber shim I used is causing problems. Not greasing the chuffer bore could be causing some minor resistance, I am guessing. 

Everything else I will double check as I go. I must've forgotten to oil the wick, so I'll be sure to do that this time through. And double check wires and contacts.

Wheels were cleaned thoroughly along with axles and copper axle contact springs. All contacts were bent to give good pressure before reassembly. Still, I will go over everything with a fine toothed comb once my next parts delivery arrives. 

Thanks for the help and ideas.


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## AmFlyer (Mar 16, 2012)

The fiber shim may well be causing problems. It should not be necessary to lube the piston bore. I never have but some do. All my 312's run fast and the drive wheels will slip well before a heavy train will stall the engine.


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## mopac (Feb 24, 2011)

Well, we will see what flyernut says about your observance. Starting out sluggish and then getting faster sounds like there is still some hardened grease somewhere. As the grease heats a bit it gets softer. Just my opinion. flyernut is my AF guru so we will see what he says. He has rebuilt so many he has seen it all.


I agree, a fiber shim is probably not what to use. Oil all the side rod linkages. A 312 has a lot of linkage. After it is all back together. Turn over and turn armature with finger and see if you come across any resistance.


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## flyernut (Oct 31, 2010)

The fiber may be causing a problem, but was it running sluggish BEFORE putting in the fiber shim?? Sounds like it was...I think the armature has given up the ghost.. Do you have another armature to try?? Maybe from another engine??. Make sure the hole in the brush bracket assembly the armature shaft goes into is not burred, etc.When assembling keep the 2 screws that attach the brush bracket assembly just a tad loose, see if that helps.


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## dooper (Nov 9, 2015)

Did someone say there are two different 312's?


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## AmFlyer (Mar 16, 2012)

There are more than 2 variations of 312's. However if you are referring to the motor style with the shoulder brushes (rather than slotted) there are two styles of armatures (with and without an oil slinger) and two corresponding sizes of bakelite brush holders. 
Go to the Factory Service Manual, the Engines volume, page 57 of 255 and look at the footnotes. The armatures were assigned two different part numbers but both brush holder brackets use the same part number even though they do not directly interchange.


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## shaker281 (Jun 22, 2019)

flyernut said:


> The fiber may be causing a problem, but was it running sluggish BEFORE putting in the fiber shim?? Sounds like it was...I think the armature has given up the ghost.. Do you have another armature to try?? Maybe from another engine??. Make sure the hole in the brush bracket assembly the armature shaft goes into is not burred, etc.When assembling keep the 2 screws that attach the brush bracket assembly just a tad loose, see if that helps.


Because there were other issues such as defective replacement lower fingers, binding linkage and a brush that was not fully seated, I cannot really say what it might have done before I inserted the fiber washer to mitigate what I thought was considerable slop. Also, I am pretty certain that I did not lose any armature shims, so it may have been gone (or never there) before I started. 

I always intended to rectify the matter with the correct shims, but had to place an order, so I went ahead with the fiber shim as an experiment. The shims that I ordered (.010 & .020), or no shim at all, should address that concern. 

Mainly though, while I am in there, I want to do everything possible to avoid opening it up again. I did check the armature for resistance on all segments previously and they were all the same (IIRC ~ 1.3 ohms). I saw no excess wear on commutator or shaft, but I will use stronger magnification this time and check clearance from shaft to bearing as well. And I'll make certain not to over-tighten the brush bracket. 

Thanks everyone for the ideas.


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## flyernut (Oct 31, 2010)

My suggestion would be to pull all the linkages off and run the engine. Try to eliminate any area that could/would cause any type of binding, one area at a time, that would include linkages, smoke gear, piston lever, armature, brush bracket assembly, etc. Have you checked the field coil yet??..Internal breaks in the wiring?.Now to the shims. There are various thicknesses to the shims. As we know, Gilbert used shims to bring the armature in spec with the gears and field, and to eliminate slop. The armature plates should line up with the field coil plates such as in the picture.During mass production runs, there's always a little give and take, and to meet specs,items such as shims were used. I was a quality technician, finished product inspector, and a quality assistant on the films that were used in the SR-71 Blackbird spy plane during some of my 35+ years at Eastman Kodak. I also held a Top Secret security clearance during my service years.That and a dollar will get me a pop at McDonald s, but again,production runs will change. The old saying was don't buy a car that was made on Monday, or Friday, try to get one made on a Wednesday.. You'll find armatures with no shims on occasion, 2 at the chassis end, 1 at each end, etc.. My guess is a bind, a defective armature, and/or field coil... Swap out parts until you are happy with the running.I can look at it for you, no charge, if you'd like. I have spare armatures and field coils, some of which I have re-wound.


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## mopac (Feb 24, 2011)

I think the shims are more important to get that alignment you show in your pic. More so than the slop. Like I said earlier the slop does not seem to be a problem.

flyernut, I got that 302 smoking better. I put it back together yesterday and she would not run. Took the shell off again and she ran great. I think maybe the legs of the resistor were shorting out with the shell. Smoke box is really close to top of shell. I think I will try some black electrical tape amd put it back together today. I donj't run my trains fast. The 302 smokes great if I run fast. I will settle for some smoke and run slower. I really like that little engine.

I have hand wound the field coils also. And they work great. I never get all the wire back on but it does not seem to be a problem.


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## shaker281 (Jun 22, 2019)

Thanks for all the ideas! I was actually shooting for the exact alignment you pictured. The current shim leaves it a little forward of the optimum position when in forward operation. I will set it precisely for forward operation and reverse can play second fiddle, once I receive the shim washers. It appears about 1 field plate's width too far forward presently. Shimming properly should create less play overall, making the reverse/forward travel less severe. I will avoid being too tight as it would induce friction. 

The field is NOS and metered out at exactly 1.3 ohms. Just like the old one it replaced (which had a very fragile winding wire). Thanks for your very generous offer, I should be able to resolve with the info I have been provided, but will keep that as a backup plan. 

I will follow your advice and eliminate variables that might be causing binding. 

The only thing I haven't got a spare of is the armature. I'll examine it carefully, as stated above it did meter out evenly across all windings.

The more I think about it, where exactly is the oil wick on these things? I cannot recall seeing one. 

I am a big fan of the SR-71. Who doesn't love a plane that leaks fuel until it gets up to temp?


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## mopac (Feb 24, 2011)

Shaker, I have a 282 I have had since 1955 and for 25 years it would not run up to speed and motor got really hot. I had checked my armature with meter. 1.3 like you said. I did not think my armature was the problem. Well it was. I got a parts chassis off ebay and started changing parts. After changing armature she sprang to life. It was running at about half speed. After armature change she was a speed demon and motor never gets hot now. And my old armature checked out on meter. I have it in a baggy marked bad now.


Not saying a different armature will cure everything but possible. I bought 2 brand new armatures from a closed up train shop and I am still using the used one that came from the parts chassis. No reason to change it.


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## shaker281 (Jun 22, 2019)

mopac said:


> Shaker, I have a 282 I have had since 1955 and for 25 years it would not run up to speed and motor got really hot. I had checked my armature with meter. 1.3 like you said. I did not think my armature was the problem. Well it was. I got a parts chassis off ebay and started changing parts. After changing armature she sprang to life. It was running at about half speed. After armature change she was a speed demon and motor never gets hot now. And my old armature checked out on meter. I have it in a baggy marked bad now.


Well that is interesting! Good to know. Thanks. If all else fails, I'll source a replacement armature or a whole chassis, like you did.


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## mopac (Feb 24, 2011)

My parts chassis was 20.00 on ebay. Best 20 I ever spent. It was a motorized chassis.
So now I have wheels, motor parts. One disappointment was when I removed the brush cap it broke into about 5 parts. So I have bought a spare brush cap for about 4 bucks. I like having spare parts. A motorized parts chassis for a 312 will cost a lot more than my 282 chassis but still may be worth it. Although the motors may be the same. Be careful there are a few different armatures. They all won't work. Find a parts diagram for your 312 and it should have the parts number for your armature. I think my armature ended with 177.


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## AmFlyer (Mar 16, 2012)

Mopac it would have been XA11077. These have oil slingers and are 1950 and later plus some late production 1949 engines. Early armatures were copper colored, later were purple. All have wide pole gaps. These should measure 1.5 ohms. There was a later armature with the same part number that has narrow gaps between the cores. They can be interchanged with other oil slinger armatures. A good one will measure 1.6 to 1.7 ohms.


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## shaker281 (Jun 22, 2019)

In case I confused the issue re: resistance - field vs armature - I just measured my armature again. It is coming up 1.5 ohms across all poles. Both my field windings measure @ 1.3 ohms. My armature is copper colored.


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## AmFlyer (Mar 16, 2012)

1.3 Ohms is correct for the field in that motor.


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## flyernut (Oct 31, 2010)

shaker281 said:


> Thanks for all the ideas! I was actually shooting for the exact alignment you pictured. The current shim leaves it a little forward of the optimum position when in forward operation. I will set it precisely for forward operation and reverse can play second fiddle, once I receive the shim washers. It appears about 1 field plate's width too far forward presently. Shimming properly should create less play overall, making the reverse/forward travel less severe. I will avoid being too tight as it would induce friction.
> 
> The field is NOS and metered out at exactly 1.3 ohms. Just like the old one it replaced (which had a very fragile winding wire). Thanks for your very generous offer, I should be able to resolve with the info I have been provided, but will keep that as a backup plan.
> 
> ...


The oil wick is in the end of the brush bracket assembly. It's where the end of the armature will go into. The oil wick should be present there. You'd be surprised what a little drop of oil there will do for a sluggish engine.


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## mopac (Feb 24, 2011)

LOL, I was close on part number of my armature. I said 177 and is 077. I was going from memory. Always a dangerous thing to do.


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## AmFlyer (Mar 16, 2012)

You were 2/3rd's right, that is very good! I had to look it up.


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## mopac (Feb 24, 2011)

I have a 312 I believe to be a 48 or 49. It has slotted brushes. Bought not running
and have not worked on it. It needs a center driver (flangeless). Might try shoulder brushes and a newer brush cap someday. And a ending in 077 armature. It has been in storage since52. Very hardened grease.


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## flyernut (Oct 31, 2010)

mopac said:


> I have a 312 I believe to be a 48 or 49. It has slotted brushes. Bought not running
> and have not worked on it. It needs a center driver (flangeless). Might try shoulder brushes and a newer brush cap someday. And a ending in 077 armature. It has been in storage since52. Very hardened grease.


We have the parts..We can rebuild it...lol.


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## AmFlyer (Mar 16, 2012)

According to the Gilbert Factory Service Manual the armature with the oil slinger (-077) was first used in 10/49. With slotted brushes your 312 is likely 1948 production. Send it to Flyernut and get it running. Then there is that matter of an S gauge layout.


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## mopac (Feb 24, 2011)

LOL, yep Its coming.


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## shaker281 (Jun 22, 2019)

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flyernut said:


> The oil wick is in the end of the brush bracket assembly. It's where the end of the armature will go into. The oil wick should be present there. You'd be surprised what a little drop of oil there will do for a sluggish engine.


Mine must be missing, I haven't seen any wicks at all. Is this what we are talking about? I was imagining a washer-like piece of felt that slides over the rear armature shaft. I cannot find them in parts diagrams. Or even see a place they might go in the area of the brush holder.

https://trainrepairparts.com/diagra...ies-4-6-2-pennsylvania-k-5-pacific-locomotive


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## flyernut (Oct 31, 2010)

shaker281 said:


> ```
> 
> ```
> Mine must be missing, I haven't seen any wicks at all. Is this what we are talking about? I was imagining a washer-like piece of felt that slides over the rear armature shaft. I cannot find them in parts diagrams. Or even see a place they might go in the area of the brush holder.
> ...


Yep, that's the oil wick. Here's where it goes.


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## shaker281 (Jun 22, 2019)

Oh, I see. Yep, it was missing. Sorta obvious in retrospect. I'll order a few. Thanks as always. 

Found online that chassis mounting bracket that I was missing and ordered it too. No point in cheaping out now. And it did lean just a bit.


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## flyernut (Oct 31, 2010)

shaker281 said:


> Oh, I see. Yep, it was missing. Sorta obvious in retrospect. I'll order a few. Thanks as always.
> 
> Found online that chassis mounting bracket that I was missing and ordered it too. No point in cheaping out now. And it did lean just a bit.


For a missing oil wick, I bought a sheet of felt the correct thickness.. It will last me until I'm long gone....


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## shaker281 (Jun 22, 2019)

flyernut said:


> For a missing oil wick, I bought a sheet of felt the correct thickness.. It will last me until I'm long gone....


I actually knew I could do that and will snag a sheet of felt if I run across one. Truth be told, I just didn't feel like going shopping. And if I ask the wife to go to Michael's or Hobby Lobby, it is likely to trigger a spending spree, negating any potential savings to me. Could end up being the most expensive piece of felt ever!

BTW, I used your idea to (drill) chuck the armature and polish both the commutator and shafts. I'd actually done something similar when building pinewood derby cars with my son (axles), but it never occurred to me until you mentioned it. Great idea! Definitely better than the rudimentary job that I did by hand. Unless the armature is indeed faulty, this is going to be a great running unit when I am done.


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## flyernut (Oct 31, 2010)

shaker281 said:


> I actually knew I could do that and will snag a sheet of felt if I run across one. Truth be told, I just didn't feel like going shopping. And if I ask the wife to go to Michael's or Hobby Lobby, it is likely to trigger a spending spree, negating any potential savings to me. Could end up being the most expensive piece of felt ever!
> 
> BTW, I used your idea to (drill) chuck the armature and polish both the commutator and shafts. I'd actually done something similar when building pinewood derby cars with my son (axles), but it never occurred to me until you mentioned it. Great idea! Definitely better than the rudimentary job that I did by hand. Unless the armature is indeed faulty, this is going to be a great running unit when I am done.


I won my Pinewood derby race back in 1958 while a cub scout.I was dis-qualified as the winner as I had oiled the axles on my racer. I was given 2nd place and the 2nd place award was a AMT model kit of a 1958 Ford fairlane.


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## shaker281 (Jun 22, 2019)

flyernut said:


> I won my Pinewood derby race back in 1958 while a cub scout.I was dis-qualified as the winner as I had oiled the axles on my racer. I was given 2nd place and the 2nd place award was a AMT model kit of a 1958 Ford fairlane.


A 1958 AMT Fairlane is not bad.


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