Wombat C30T

 
  Neville John Station Master

Location: Sydney
I've had the C30t for quite a while since it's inception from Wombat models. My problem with it is the noisy mechanism.It sounds like it's a tractor on a farm! I don't recall it being like this when I first bought it. I have added weights to it to improve traction but I don't believe this has affected the running qualities.
It's dc and non sound. (Sorry but I'm old fashioned and started well before dcc!)
It's a great runner but a noisy one!
Does anyone have any ideas?
Thank you in advance.
Neville.

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  Oscar Train Controller

My thoughts without answers.  At a certain speed the chatter starts on both of mine, (edit)more in reverse.  I've left one unaltered and have heavily messed around with the other one, 3004. I thought perhaps the motor was to blame but with a Mashima and non accurately bored out worm the noise was worse.  I've had other variations of motors like custom skewed OEM and NWSL both using stock unaltered worms and the the chatter still exists above a certain speed.  

There is tape underneath the OEM motor which I thought may dampen vibrations and I have experimented with a layer of squished blu tac and other tape to no avail.  Then there are those four metal plates which I can't remember off hand exactly where they go, but I think they go between the sides of the metal gear housing and the body, and they might dampen noise. But from memory there was still noise before I took them out so i haven't put them back in.

Then there's the gears.  I've only once disassembled everything. The worm, worm gear, reduction and drive gears (not sure of exact names), they all seem finely machined and mesh really well and the chassis finely machined to accept shafts in the right spots. I really can't tell where the chatter comes from except to say I think the gears cause the noise but I don't know where or why.

I've thought that perhaps fewer gears would make a difference. I've an unassembled FSM Z25 kit that has a fine pitched worm and drive gear without idlers. I look forward to seeing if that type of setup is noiseless. On the other hand a Lloyds C30 with worm, idler and drive gear in a NWSL gearbox is smooth and quiet.  The major difference is it drives the middle axle which makes the gear box visible. So in that respect the Wombat does well to conceal the gears and any attempt to change the gears to a more direct drive setup would require major and accurate work I'm incapable of.

So I don't know.  I'll have another look at this one day but the only thing I'd be prepared to do myself that probably goes against any advice of the more experienced and manufacturers is to liberally apply heavy grease to the teeth of all gears.  I'm not recommending you or anyone to do it, but I'll give it a shot for the greater good. Soon. Cool
  a6et Minister for Railways

My thoughts without answers.  At a certain speed the chatter starts on both of mine, less in reverse.  I've left one unaltered and have heavily messed around with the other one, 3004. I thought perhaps the motor was to blame but with a Mashima and non accurately bored out worm the noise was worse.  I've had other variations of motors like custom skewed OEM and NWSL both using stock unaltered worms and the the chatter still exists above a certain speed.  

There is tape underneath the OEM motor which I thought may dampen vibrations and I have experimented with a layer of squished blu tac and other tape to no avail.  Then there are those four metal plates which I can't remember off hand exactly where they go, but I think they go between the sides of the metal gear housing and the body, and they might dampen noise. But from memory there was still noise before I took them out so i haven't put them back in.

Then there's the gears.  I've only once disassembled everything. The worm, worm gear, reduction and drive gears (not sure of exact names), they all seem finely machined and mesh really well and the chassis finely machined to accept shafts in the right spots. I really can't tell where the chatter comes from except to say I think the gears cause the noise but I don't know where or why.

I've thought that perhaps fewer gears would make a difference. I've an unassembled FSM Z25 kit that has a fine pitched worm and drive gear without idlers. I look forward to seeing if that type of setup is noiseless. On the other hand a Lloyds C30 with worm, idler and drive gear in a NWSL gearbox is smooth and quiet.  The major difference is it drives the middle axle which makes the gear box visible. So in that respect the Wombat does well to conceal the gears and any attempt to change the gears to a more direct drive setup would require major and accurate work I'm incapable of.

So I don't know.  I'll have another look at this one day but the only thing I'd be prepared to do myself that probably goes against any advice of the more experienced and manufacturers is to liberally apply heavy grease to the teeth of all gears.  I'm not recommending you or anyone to do it, but I'll give it a shot for the greater good. Soon. Cool
Oscar
My Wombat 30T is back in its box, I took it out only to have a bopeep, and take the tail rods off the cylinders as mine is a Superheated version which did not have them, and I have not tried to run it yet.

I purchased the 30T to use only as a shunting engine and a relay work to an abatoirs section works, so no fast running will be had.  But no looking at this point of time as to the problems mentioned here. Although I am wondering after reading what you have said regarding the Lloyds C30 and nil noise, with the wombats body off does the same noise take place? or closer to the quieter Lloyds model.

I wonder if there is some internal flexing with the motors mount as the speed of the model increases, that causes the motor or gears themselves to move a bit in a side ways manner. How that would affect the gears or even positioning of them and or the motor may be part or all of the problem.
  Oscar Train Controller

Apologies for the late reply, be warned, it's gonna be a long one.....

Regarding body off, definitely less noise. When I was experimenting months ago I noticed louder with the body on, quieter when off, regardless if it was an OEM motor, Mashima or NWSL. It was as though the body can act as an amplifier of sorts, similar to how baseboards can amplify track sounds.  During testing on a rolling road and body off, even less noise is transmitted, but the noise is still there.  Generally it's faint whilst starting, nearly disappears at maybe quarter pace then gets louder all the way to full throttle.

I'll post a couple of exerts from older videos demonstrating the noise. I must correct a couple of things though.  The noise is a whir sound not chatter as I described it in the previous post. Also, running in reverse produces a louder sound not less as I previously typed.

Now regarding the flexing motor mount theory you mentioned, I admit I was dismissive when I read it a few days ago. But I gave it some more thought after going out and cleaning the track to get the locos running and I remembered the test with the Mashimas and rebored worm many months ago that there was more noise at speed than OEM motor and stock worm.  The reboring excercise was inaccurate and from that I suppose anything messing with the mesh of worm and worm gear will lead to more noise.  

So I had a look at a couple of other gear arrangements. The Lloyds C30 has a flexible tube coupling between motor and worm's shaft compared to the wombat with worm attached directly to the motor's shaft. That highlights another major difference whereby the Lloyds C30's worm shaft is held in place by bearings and bushes fore and aft in the NWSL gearbox.  Similarly an unassembled Ezi Kits Z24 has the same in its NorthYard gearbox. This approach leads to a secured and constant meshing of the worm and worm gear.  The wombat on the other hand has the worm attached to the end of the motor shaft with nothing anchoring the rear of the worm.  So the worm's position relies on that motor retaining clip and chassis bulkheads to keep the motor in one place and by extension, keep the mesh between the worm and worm gear.  If there was any vibration or freeplay perhaps there'd be a magnification towards the worm.  But I hasten to add it all seems pretty solid.  Only when I have removed the forward bulkhead and packing tape beneath the motor did I see movement of the motor under the retaining clip.

An obvious fix to this would be to add 1mm shafting from the worm through a bearing placed in a hole drilled into the rear of the gear housing.  Easier said than done but it's an interesting idea.  

Whilst it's possible that vibrations of a fast spinning motor and worm arrangement of the wombat might cause some additional noise it's my belief that it's the rest of the gear train that causes the whir.  The Lloyds 30 as mentioned before is quiet.  The fixed position of the worm inside the gearbox meshes it to a helical idler gear then helical drive gear.  The worm is fine pitched and reduction is 28:1 with a bigger Mashima 5 pole skew wound 1525 motor.  The wombat has a 1015 sized 3 pole motor with coarser pitched worm.  The matching helical gear has a straight cut reduction gear attached that's meshed to a straight cut idler gear and straight cut final drive gear.  Reduction is 50:1.

My take on all that is more gears and particularly straight cut have more potential to be noisy.  The smaller motor spins faster for reduction to be performed by the worm, first reduction gear and the idler to get the slow speeds rather than just the fine pitched worm of the Lloyds example and a torquier motor.  I wish I had the Z24 going but I assume it would be quiet based on the fine pitched worm producing reduction alone with no idler.  The worm gear is also the final drive gear.

So barring major mods I go back to my initial thoughts into reducing noise by using a sticky thick grease. Research into what to use is continuing.

Here's those snippets demonstrating the whirring noise. Click the links for the short versions or fast forward to 12 seconds and 1:42 respectively.



https://youtu.be/m6Mu_TvpLtk?t=12



https://youtu.be/xXaxmlvipXg?t=102
  Oscar Train Controller

Did a fair bit of testing over the weekend, results were negligible. I used INOX MX6 and MX8 on two mechanisms a 30T and Ixion 32.  Briefly about the greases - MX6 food grade type, is synthetic PAO with PTFE.  MX8 is lithium based with PTFE and much thicker.

The 30T always had a quieter spot which I said was around quarter throttle but after remapping the chip to a straight line to mimic a lineal DC like response, I discovered the mechanism was quieter between 50 - 90% throttle. I used MX6 first which had no effect.  After trying to remove some I repacked the area with MX8 and whilst I thought there was some improvement, now I'm not sure.

The 32 had just MX8 applied, repacked twice and it made no difference.  The 32 has the gear noise form zero to full throttle.  

I videoed and compared everything but they don't capture what you can hear. It's a bit of hit and miss and sometimes unfairly exaggerated so I've not cut a video together.  In short, overpacking with grease didn't really improve anything.

I will leave some photos of the mechanisms though because there's one more thing I'd like to try.
Before I greased the mechs I took photos of them just to check they were the same.
The 30T had a little more factory grease compared to the 32 but both were lubed enough IMO.  With them appearing the same I wondered why they sounded different.  The idler in both mechs can slide laterally and the 30T's idler could move more readily compared to the 32.  Perhaps the 30T is more run in. But I would like to try and see if adding bushings, washers and a spring to keep the idler in place will make a difference.  

The first two pics show the 30T with idler in different positions and the last is of the 32 showing the same gear arrangement. Helical cut gear and attached reduction are easily visible in the last pic.


https://flic.kr/p/2kXHRvv
https://flic.kr/p/2kXDpLA
https://flic.kr/p/2kXDpMn
  Neville John Station Master

Location: Sydney
Thank you both for the replies and a thank you to NSW3802 for the pm's. It was suggested that I apply some oil to the gears which I've done by only taking off the bottom plate. ( Labelle 107 ).I think this has made a little difference although after reading Oscar's extensive replies, perhaps I'm kidding myself?
It was also suggested that I remove the body and apply some oil on either end of the motor and perhaps the top bearings associated with the gears. I'll get around to doing that soon.
Thanks again.
Neville.
  a6et Minister for Railways

Did a fair bit of testing over the weekend, results were negligible. I used INOX MX6 and MX8 on two mechanisms a 30T and Ixion 32.  Briefly about the greases - MX6 food grade type, is synthetic PAO with PTFE.  MX8 is lithium based with PTFE and much thicker.

The 30T always had a quieter spot which I said was around quarter throttle but after remapping the chip to a straight line to mimic a lineal DC like response, I discovered the mechanism was quieter between 50 - 90% throttle. I used MX6 first which had no effect.  After trying to remove some I repacked the area with MX8 and whilst I thought there was some improvement, now I'm not sure.

The 32 had just MX8 applied, repacked twice and it made no difference.  The 32 has the gear noise form zero to full throttle.  

I videoed and compared everything but they don't capture what you can hear. It's a bit of hit and miss and sometimes unfairly exaggerated so I've not cut a video together.  In short, overpacking with grease didn't really improve anything.

I will leave some photos of the mechanisms though because there's one more thing I'd like to try.
Before I greased the mechs I took photos of them just to check they were the same.
The 30T had a little more factory grease compared to the 32 but both were lubed enough IMO.  With them appearing the same I wondered why they sounded different.  The idler in both mechs can slide laterally and the 30T's idler could move more readily compared to the 32.  Perhaps the 30T is more run in. But I would like to try and see if adding bushings, washers and a spring to keep the idler in place will make a difference.  

The first two pics show the 30T with idler in different positions and the last is of the 32 showing the same gear arrangement. Helical cut gear and attached reduction are easily visible in the last pic.


https://flic.kr/p/2kXHRvv
https://flic.kr/p/2kXDpLA
https://flic.kr/p/2kXDpMn
Oscar
Oscar, looking at the last pic, I gather the gears are some sort of synthetic/nylon or something rather than brass gears that were more common in previous models as I have not purchased anyloco's for some time, the Wombat 30T being the exception, I wonder if brass gears may be better?  Other thing I notice and maybe the photo's angle but the 3rd pic looks to me with the large gear to have minimal distance between the side of the gear and the metal side of the chassis/gear setting, could that mean the noise could be the gear rubbing against the metal, as the model increases speed?
  NSWRcars Assistant Commissioner

I can't believe that Nylon gears would be noisier than brass. I am also not surprised that packing grease makes no difference.
I have a re-motored Ixion C32 (similar mech to Wombat C30T) and it is quite noisy, particularly in reverse, but otherwise runs well since fitting a Mashima motor.
If there is a significant difference in noise between forward and reverse then one must suspect the helical gear that meshes with the worm, this will be thrust either left or right depending upon the direction of travel.
  a6et Minister for Railways

I can't believe that Nylon gears would be noisier than brass. I am also not surprised that packing grease makes no difference.
I have a re-motored Ixion C32 (similar mech to Wombat C30T) and it is quite noisy, particularly in reverse, but otherwise runs well since fitting a Mashima motor.
If there is a significant difference in noise between forward and reverse then one must suspect the helical gear that meshes with the worm, this will be thrust either left or right depending upon the direction of travel.
NSWRcars
Sugestion only
  Oscar Train Controller

Regarding brass gears a6et, I haven't had any experience there but must admit I used to think brass must be better only based on a general view of anything metal must be better than plastic. Not always the case I suppose.  For example, a number of years ago my son and I dabbled with RC planes and there was a perception and some marketing that metal geared servos were superior.  I can't quote the article I read but I became convinced otherwise.  They were all noisy to be honest but plastic suited our needs and budget particularly as every plane crashed out of service before a servo failed.

Similarly during my search for greases to use on the wombat and assuming the gears were nylon, I read on an engineering site about the preference for metal worms on plastic gears. There was something about nylon on nylon create heat and wear prematurely. As for metal on metal, or rather brass on brass, I really can't speak to why that isn't used except that moulded gears are easier and cheaper to make than machined metal ones and generally speaking nylon and delrin too perhaps are proven and do the job for our purposes.  On many newer gearboxes I looked at online most were brass worm on plastic.  But there were always exceptions.  As to whether all brass would be quieter I wish I could test it but one would think metal would dissipate that heat from contact surfaces more easily.

About that third pic and the large gear - I'm pretty confident that the large final drive gear doesn't touch anything.  The axle sideplay is minimal and I just can't see where the gear could touch anything. On the other hand that lateral movement of the idler between the first two pics above has had me curious as to whether there's contact with the side of the helical and reduction gear combo.  Check the old pic below of 3004's gears which has received the most abuse. I'm sure I oiled this mech with Labelle 102 during the many motor swaps and the black is due to the brass/nylon contact.  But what's obvious in this higher res version below is the idler is picking up some of the blackened oil off the side of the helical gear, perhaps contacting it.  

Which brings me to your really good point NSWRcars. I never really thought about side thrust on this helical gear moving laterally.  Well I've just gone out to the shed to look at 3004 that's partially stripped at the moment and can confirm the helical gear does have lateral movement and in that loco moves quite easily. It seems pretty obvious now that the sides of the gears are touching. I'm not looking forward taking the gears out again or saying this'll cure the gear noise but if I can shim the helical and idler we may be onto something.  Wont be able to test till the weekend or early next week but perhaps we can tackle why slow motion point motors are so loud....

https://flic.kr/p/2kXNcMK
  NSWRcars Assistant Commissioner

Notice that the OP comments his Wombat is weighted. My Ixion C32 is weighted, as well as having the motor changed, and it has significantly increased tractive effort. It stands to reason that a loco weighted like this will be seeing higher forces in the driveline - including lateral thrust on the gears. I always assumed the noise of my C32 was related to the motor change, but now I wonder. Oscar, I look forward to your further work and investigations on the Wombat. As for my C32, I've had enough of fettling these locos, it can just growl around the layout for a while...
  Oscar Train Controller

Completely understandable NSWRcars, this process has taken hours for negligible results, plus there's a load of work to do to resolder things and put other bits back together.  I found too that once I put a load behind the locos it somewhat takes away the rattle and whir of the mechs. And speaking of adding weight, I've yet to make progress on that side of things but in this little adventure I cleaned track and wheels with kero for a change and both 30t's hauled more than I've seen them do before. For eg they lifted 3 x Lima 12 wheelers, 1 x Eureka 12 wheeler, 1 x Powerline FS and a Traino GHG up a 1:40 30" radius climb.  Did it slow, did it fast, did it from a standing start without wheelslip. I was really surprised. The 32 however struggled. I'll throw a clip in at the end.

Now, regarding shimming the gears. In a nutshell, results were meh. Because 3004 was already partly disassembled I used it as the test bed using a number of washer combos to get the worm gear/reduction combo centred and the idler fixed in place to avoid rubbing against the side of the worm gear or chassis and do it all without introducing drag.  For the most part I achieved all that except one thing still bugs me and that's the idler so far as it doesn't stay perpendicular to it's shaft.  It can't be a snug fit but it does need an extended hub that would reduce or eliminate the chance of wobble. I hope that makes sense, I couldn't really demonstrate what's still happening but anyway here's the photos.


The bags of goodies ranging from 0.3mm to 1.0mm thickness
https://flic.kr/p/2kYPVon

0.3mm stainless against the helical worm gear and 0.4mm brass against the reduction gear
https://flic.kr/p/2kYPVqS

Of the next three pics, the first two show possible lateral movement of the worm gear prior to shimming with the last showing a fixed more central position and no binding after washers were inserted.
https://flic.kr/p/2kYEQf6
https://flic.kr/p/2kYNp5s
https://flic.kr/p/2kYNp8y

The idler took ages to get right.  Firstly a single 0.3mm stainless washer was placed on the short side.  This being on the same side the reduction gear has a 0.4mm against the chassis. It effectively ensures a 0.1mm gap between the worm gear and the idler sides, so long as all the other spacers do their thing of course.
https://flic.kr/p/2kYKsPm

Regarding the other side of the idler, referring to the pic above, two 1mm nylon washers were the perfect size to maintain the distance between the idler hub and chassis, however....note their smaller diameter.  All the washers I purchased were 5mm OD which was too big for this side of the idler.  When trying to put them in they contacted the worm gear so I had to reduce their diameter.

This was done with them mounted on a nail in a vice and a file was used to ground them down to final size as shown in second pic below. Took a fair amount of cleaning up.  
https://flic.kr/p/2kYKsLL
https://flic.kr/p/2kYJkGW

It all turned easily without any binding and no lateral, or rather imperceptible lateral movement.  But that idler can lean over a bit. Those two nylon spacers and the idler are independent of each other, have all slightly oversized inside diameters to fit the shaft and the result is the idler can tilt off perpendicular.  I really needed to add tubing as the spacer here but had nothing on hand. But really the idler needs an extended hub, a thin tube that's attached to the idler to keep it upright and there's a possibility I'll look at trying to do that.  

For now here's the vids.  
First one shows Ixion 3258, Wombat 3036 and Wombat 3004 in accelerating from standing to full speeds, then backwards, then forward at moderate pace.  Then there's Auscision 48158 with a load, Casula CPH with SEM Black Beetle and lastly my long suffering Lloyds 3112 which I somehow got going again, making a fwd and rev pass.

Make of them what you will and I'll gladly take any criticisms or critique.
Keep in mind the following as to some issues I see with the tests:
- All using different decoders
- 3004, the test bed, did not have the body fitted due to too much rewiring to be done but no body typically means less noise IMO.  It has also a NWSL motor, not OEM. Pony tuck not added as well. Lead added to mimic body weight. Weight of lead was 55g, ,body is 57g.
- 3036 and 3258 have their gears packed with grease, so no longer OEM setup but I reckon nothing's changed from before.

The second vid is of the main three locos doing the 1:40 start to full speed with load for noise comparisons.



https://youtu.be/tKXIWi9dpPo



https://youtu.be/VFHjdB36Q_g
  a6et Minister for Railways

Oscar
Oscar, interesting to watch the tests and your mentioning of using Kero on the track and how it improved the haulage capacity of the models.

The model group I am involved in, uses CRC 2-26 in different areas, first off - its in a blue can and has a few different uses for modellers, I can testify to the success of it.

It is very much a lubricant, but also an enhancer for electrical areas, such as to enhance the conducting abilities for many things, for the modeller its an ideal just for lubrication of wheels and usual parts such as in the worms. Light spraying of track also makes for better traction especially if the loco's are somewhat prone to slip if the track is dirty.  I use a small block of radiata pine off cut and glue some cork onto one side once set, I use the CRC and wet the cork, then lightly rub it along the top of the track.  No more incidents associated with dirty track or the like.

Its not ultra cheap but lasts for a long time, in many different areas.
  Oscar Train Controller

It's an interesting topic a6et that has been solved but we still struggle with it by making incorrect choices.  A few youtube channels I follow like fishplatefilms, chadwick and model railways unlimited covered it over the past year with aussie made INOX MX3 getting some good exposure. I went with auto trans fluid prior to that but after not running anything for months, nothing would run.  Rather than use ATF again, for this latest running session I revisited the old MRH article that listed kero as the most non-polar and a near empty bottle was behind me. So that choice was easy. CRC 2-26 rates alongside ATF as semi-polar, so whilst not the best, they still work remarkably well as you and many other will attest to. FWIW kero, WD40 contact cleaner and CRC contact cleaner rated in the top 3 along with other brands for being the most non-polar.
  DJPeters Deputy Commissioner

I have been watching on you tube how some very noisy locomotives are quietened down some what, mainly British ones though, but on quite a few of these videos the actual worm gear on the motor shaft was not in the exact proper place on the shaft of the motor and therefore was not at the optimum place to mesh nicely and quietly.  So moving the worm gear a smidgen one way or the other might do it or else one end of the motor or its housing is too high and forcing the gears to actually fully contact and thus create a noise, fixing this angle in most cases fixed the really loud noise in the locos he fixed in the videos. You will never rid it completely of noise though.

On You Tube see a few videos by OO Bill and you might get an answer to your problems, it might be something else but it might help you find it.
  a6et Minister for Railways

It's an interesting topic a6et that has been solved but we still struggle with it by making incorrect choices.  A few youtube channels I follow like fishplatefilms, chadwick and model railways unlimited covered it over the past year with aussie made INOX MX3 getting some good exposure. I went with auto trans fluid prior to that but after not running anything for months, nothing would run.  Rather than use ATF again, for this latest running session I revisited the old MRH article that listed kero as the most non-polar and a near empty bottle was behind me. So that choice was easy. CRC 2-26 rates alongside ATF as semi-polar, so whilst not the best, they still work remarkably well as you and many other will attest to. FWIW kero, WD40 contact cleaner and CRC contact cleaner rated in the top 3 along with other brands for being the most non-polar.
Oscar
Thanks Oscar,  I had to change two taps the other day, and the water meter we have is one with a lever on the top, and you have to turn it 90 degrees to turn on/off, I could not budge it to turn the water lever off, I gave the lever a slight spray with the CRC, initially it did not want to move, a little more around the base & it opened a bit gingerly then close & open it, a 4 year old would find it easy.

Another item I have is a drill press that is rusted with the tray stuck fast, the CRC was another relief item there as well. I need to clean the shaft up, then try to sell it.
  Oscar Train Controller

Thanks for the heads up on OO Bill DJ. I watched a number of videos over the past few days and was amazed how noisy some of those worm drives are on those older hornby models. On the flip side, some with still coarse pitched worms but in newer models are very quiet and I reckon the difference between the old open frame and newer can motors must make a difference too.  Worm meshing was something I considered early on as there doesn't seem to be much of the worm gear exposed for the worm to grab on to.  I'm going to drill a couple of inspection holes to see how things line up but the shimming has definitely stopped the chance of the worm wheel/reduction combo gear from moving laterally.  

But I agree poor worm alignment will cause noise and as I noted I think in the other thread and NSWRcars thought too, when we put Mashima motors in and rebored our worms to 1.5mm both ended up slightly off centre and added to the noise.  To this end I may have good news.  I've ordered some worms from Germany. A worm for N gauge Minitrix part number W0456.  From what I can tell they're Module 0.4, 5mm diameter, 6mm long and have ID of 1.5mm. Wombat's were 5.3mm diameter but the threads are sharp so I'm conveniently ignoring that difference. Length is 9mm but the Wombat's only have about 6mm of actual thread.  If these fit and work they are my missing link to an "easy" 5 pole skew wound Mashima makeover a couple years back.

As for the gears and my shimming attempt, 3004 has had a lot of running along with the other two and although I reckon it's quieter it's not as good as I had hoped.  Slow speed is really good, much better than the other two but once there's speed there's a rattle and whir still.  Reading the old NWSL catalogue about gears and the effect of vibrations causing noise, to my mind it's a result mostly of that idler and freeplay. The shim and spacers I put around it don't quite act like a hub extension like I wanted.  I assume they hold the gear more perpendicular to the shaft but their inside diameters are slightly oversize like the gear's ID and since they're not attached to the gear they do nothing to stop the gear from moving up and down.


I'm still thinking of a way to prove this.  I was going to glue some tube to the gear to form the hub but I doubt I can be accurate enough to avoid the gear becoming eccentric. I'm unable to find a replacement with hub or correct bore and commissioning a one-off is unlikely. So the next step is to make it myself but I doubt that'll happen. Lathe, mill, tooling. Three little things I don't own....yet.  One day, maybe.
  a6et Minister for Railways

Thanks for the heads up on OO Bill DJ. I watched a number of videos over the past few days and was amazed how noisy some of those worm drives are on those older hornby models. On the flip side, some with still coarse pitched worms but in newer models are very quiet and I reckon the difference between the old open frame and newer can motors must make a difference too.  Worm meshing was something I considered early on as there doesn't seem to be much of the worm gear exposed for the worm to grab on to.  I'm going to drill a couple of inspection holes to see how things line up but the shimming has definitely stopped the chance of the worm wheel/reduction combo gear from moving laterally.  

But I agree poor worm alignment will cause noise and as I noted I think in the other thread and NSWRcars thought too, when we put Mashima motors in and rebored our worms to 1.5mm both ended up slightly off centre and added to the noise.  To this end I may have good news.  I've ordered some worms from Germany. A worm for N gauge Minitrix part number W0456.  From what I can tell they're Module 0.4, 5mm diameter, 6mm long and have ID of 1.5mm. Wombat's were 5.3mm diameter but the threads are sharp so I'm conveniently ignoring that difference. Length is 9mm but the Wombat's only have about 6mm of actual thread.  If these fit and work they are my missing link to an "easy" 5 pole skew wound Mashima makeover a couple years back.

As for the gears and my shimming attempt, 3004 has had a lot of running along with the other two and although I reckon it's quieter it's not as good as I had hoped.  Slow speed is really good, much better than the other two but once there's speed there's a rattle and whir still.  Reading the old NWSL catalogue about gears and the effect of vibrations causing noise, to my mind it's a result mostly of that idler and freeplay. The shim and spacers I put around it don't quite act like a hub extension like I wanted.  I assume they hold the gear more perpendicular to the shaft but their inside diameters are slightly oversize like the gear's ID and since they're not attached to the gear they do nothing to stop the gear from moving up and down.


I'm still thinking of a way to prove this.  I was going to glue some tube to the gear to form the hub but I doubt I can be accurate enough to avoid the gear becoming eccentric. I'm unable to find a replacement with hub or correct bore and commissioning a one-off is unlikely. So the next step is to make it myself but I doubt that'll happen. Lathe, mill, tooling. Three little things I don't own....yet.  One day, maybe.
Oscar
Oscar, you are doing a great job and makes for interesting reading.

I am wondering about how much space is between the motor/gears and the inside of the boiler, & while I'm a bit loathe to make this suggestion as it may not work.  So, here goes.  I understand that there are spray cans and also brush on insulation that could reduce the noise level to the outside, doesn't help the noise and reason problems though.

I have a suspicion that Jaycar and another company that is bigger but forget its name atm that could be of help in those area.
  Oscar Train Controller

I know the stuff you're talking about a6et. Honestly I don't think there'd be enough room for it to have an effect, not in and around the gears or on the chassis at least.  But for the room that is around the motor/boiler, possibly.  Though I'd rather fill that up with lead.  Weight or mass, in my opinion, will have a greater effect in sound deadening when it comes to softening the transmission of vibrations. I bought some modelling clay not long before this thread started to use it to create moulds for casting lead to fit in the boiler and around the motor. I did the same thing in 2019 but the clay went off, so don't hold your breath to see the results.... However, the motors spin fast and all of the ones I've tried- OEM, Mashima and NWSL, vibrate in the hand, Mashima the least. It's why I think that thin black cloth tape is stuck on the underside of the OEM motor to minimise vibrations. However, if lead on the chassis does subdue vibrations a thin layer of sound insulation may help too by subduing the amplifying effect when the body is on. I shall keep it in mind.
  Oscar Train Controller

I've another little update, this time showing gears in action.  My assumption is the difference in the diameter of the gears' shafts and the gears' oversized bores allow vibrations. Some vibrations might be against the chassis and others on the shafts. I start with the helical worm wheel/reduction spur combo, then add the idler spur, than the drive wheel. Each gear will dampen some of the previous vibrations but not eliminate.  It seems the cast gears including the fixed one on the wheel don't rotate perfectly round or may be out of round adding to changes in mesh and initiate vibrations.

This is all came about during fitting a 1015 mashima to one of the locos so it has a non OEM worm which I've detailed in the other thread I started and needs more updating which is in the works. It's open for criticism that this worm may affect the lateral movement of the worm wheel more than the OEM wheel and I could put an OEM setup in there again to prove it doesn't matter but we'll see. The main point is to demonstrate how the gears past the worm intereact and my aim now will be to replace the two main gears with either 3d printed, milled or cast replacements that have hubbed centres whose bores match the shafts more closely and will hopefully eliminate lateral movement and vibrations without adversely inducing a lot of drag.  

The chassis is filmed upside down and level with camera over the top.  The gear housing and motor are firmly clamped on the table which echoes the motor making it sound like R2D2.  Whilst the noise from the gears is the rattle and chatter that you'll be able to pick up, plus embarrassingly, some nose whistle which I'm blaming on the magnifiers pinching on my nostrils, or age.



https://www.youtube.com/watch?v=wtc4OqEu43U
  GoldenGirl Junior Train Controller

I've another little update, this time showing gears in action.  My assumption is the difference in the diameter of the gears' shafts and the gears' oversized bores allow vibrations. Some vibrations might be against the chassis and others on the shafts. I start with the helical worm wheel/reduction spur combo, then add the idler spur, than the drive wheel. Each gear will dampen some of the previous vibrations but not eliminate.  It seems the cast gears including the fixed one on the wheel don't rotate perfectly round or may be out of round adding to changes in mesh and initiate vibrations.

This is all came about during fitting a 1015 mashima to one of the locos so it has a non OEM worm which I've detailed in the other thread I started and needs more updating which is in the works. It's open for criticism that this worm may affect the lateral movement of the worm wheel more than the OEM wheel and I could put an OEM setup in there again to prove it doesn't matter but we'll see. The main point is to demonstrate how the gears past the worm intereact and my aim now will be to replace the two main gears with either 3d printed, milled or cast replacements that have hubbed centres whose bores match the shafts more closely and will hopefully eliminate lateral movement and vibrations without adversely inducing a lot of drag.  

The chassis is filmed upside down and level with camera over the top.  The gear housing and motor are firmly clamped on the table which echoes the motor making it sound like R2D2.  Whilst the noise from the gears is the rattle and chatter that you'll be able to pick up, plus embarrassingly, some nose whistle which I'm blaming on the magnifiers pinching on my nostrils, or age.



https://www.youtube.com/watch?v=wtc4OqEu43U
Oscar
When choosing to replace gears, choose machined Delrin gears, do not consider 3D printed or cast gears, as you will find the rough surface on those gears will cause you just as much noise.
  Oscar Train Controller

When choosing to replace gears, choose machined Delrin gears, do not consider 3D printed or cast gears, as you will find the rough surface on those gears will cause you just as much noise.
GoldenGirl

I agree GG. Must admit I've neglected delrin. I've been consumed with using nylon as per original that I've forgotten about alternatives but I may have a rethink as delrin would be better.

Regarding machining, there's a couple of issues for me.  For third party machining I put out a couple of feelers last year about getting 1.5mm bored replacement worms made but was told it was uneconomical for a one off or limited run. I assume the same would go for machining the helical and spur gears but since then I've been looking to tool up and go it alone and have been agonising over how to go about it and to what cost but it's an interest that's grown from a general interest in making stuff.

But the helical worm wheel/reduction spur gear combo has been a sticking point as I doubt they could be machined from one piece.  And if machined separately, I don't know how I'd attach them together securely with adhesive be they nylon or delrin.  3d printing is an attractive option to make that combo gear but I don't know if they'll still need machining to refine surfaces or how accurate the bore will be in size and centering.  Depends on the quality of the printer and as is typical in getting what you pay for, I go from looking at cheapies to chasing accuracy and high resolution at a few thousand dollars and start back at the bottom again.

Same goes for the lathe and mill plus accessories. I'm not in a position yet to buy all the gear I want and settling for the mini cheap everything will drive me nuts in frustration I'm sure. So although I agree with you, right now in the shorter term for the sake of prototyping a couple of modified gears I'm going to go down the printer path and see how that goes.  Plus the printer will get a workout making some other projects no doubt.
  GoldenGirl Junior Train Controller

When choosing to replace gears, choose machined Delrin gears, do not consider 3D printed or cast gears, as you will find the rough surface on those gears will cause you just as much noise.

I agree GG. Must admit I've neglected delrin. I've been consumed with using nylon as per original that I've forgotten about alternatives but I may have a rethink as delrin would be better.

Regarding machining, there's a couple of issues for me.  For third party machining I put out a couple of feelers last year about getting 1.5mm bored replacement worms made but was told it was uneconomical for a one off or limited run. I assume the same would go for machining the helical and spur gears but since then I've been looking to tool up and go it alone and have been agonising over how to go about it and to what cost but it's an interest that's grown from a general interest in making stuff.

But the helical worm wheel/reduction spur gear combo has been a sticking point as I doubt they could be machined from one piece.  And if machined separately, I don't know how I'd attach them together securely with adhesive be they nylon or delrin.  3d printing is an attractive option to make that combo gear but I don't know if they'll still need machining to refine surfaces or how accurate the bore will be in size and centering.  Depends on the quality of the printer and as is typical in getting what you pay for, I go from looking at cheapies to chasing accuracy and high resolution at a few thousand dollars and start back at the bottom again.

Same goes for the lathe and mill plus accessories. I'm not in a position yet to buy all the gear I want and settling for the mini cheap everything will drive me nuts in frustration I'm sure. So although I agree with you, right now in the shorter term for the sake of prototyping a couple of modified gears I'm going to go down the printer path and see how that goes.  Plus the printer will get a workout making some other projects no doubt.
Oscar
As far as I am aware, you cannot print Nylon or Delrin, so I do not see much point in trying. The best solution if you do not want to pay machining costs are the packaged gearsets from North Yard.
  Oscar Train Controller

I've no experience but the generic materials like PA and acetal or POM are printable from what I've read but have their own issues to print correctly on more expensive printers compared to the more common filaments. In that regard it might be a better option to outsource the job once I've drawn the gears. Still researching.  

I looked up Northyard a while back and didn't find what I need. Same as Northwest Short Line and RS components. Nothing matched the specs exactly. I did very briefly think about cutting the gear tower off and gutting that area to fit a NWSL or Highlevel Kits gear box but I'd probably have to drive the middle wheel.  The original layout does a great job of hiding the gears and motor whilst allowing a detailed cab layout and under boiler clearance, something I want to maintain.
  GoldenGirl Junior Train Controller

I've no experience but the generic materials like PA and acetal or POM are printable from what I've read but have their own issues to print correctly on more expensive printers compared to the more common filaments. In that regard it might be a better option to outsource the job once I've drawn the gears. Still researching.  

I looked up Northyard a while back and didn't find what I need. Same as Northwest Short Line and RS components. Nothing matched the specs exactly. I did very briefly think about cutting the gear tower off and gutting that area to fit a NWSL or Highlevel Kits gear box but I'd probably have to drive the middle wheel.  The original layout does a great job of hiding the gears and motor whilst allowing a detailed cab layout and under boiler clearance, something I want to maintain.
Oscar
We tried moulding gears in Acetal once. The die for the gears was produced using spark erosion, and the surface had lots of fine bumps in it, so the gears whined atrociously when assemble. 3D printing would be worse. The only way to get good gears is to machine them.

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