KATO GS-4 remotor project ? ? ?

[peteski]

Following along guys...

Yes, putting the flywheel on the worm shaft, and allowing the worm to still have its normal bearing play,
could let the flywheel vibrate and rattle around.  I had not thought about that.
But on the other hand, I am not so sure that little FEF motor's bearing was ever intended to carry
the weight of a flywheel, so I don't like that solution either.

There are experimental things you could try, like putting in a shim to lock that forward worm shaft bearing so
that it does NOT have any play in it, and put the flywheel on that shaft end.  Yeah, it might not work.  That's why it would be an experiment.  I'm betting that you just need to get it shimmed right and the worm would still engage fine with the driver gears, and the flywheel won't vibrate around.

The smallish GS-4 motor has the same diameter shaft and bearings as the standard Kato motors which have flywheels on them.  Why wouldn't it be able to support the smallish flywheels?  As designed, it has 2 flywheels (just like the larger Kato motor counterparts in diesel locos). That balances the load on the motor bearings. Also, if the flywheels are well-balanced, they do not generate vibrations (that is how a flywheel should behave anyways).

As far as placing the flywheel on the worm shaft, in this application, like Max mentioned earlier, this will not be an ideal solution (with a gear-reduction on the motor).  The ideal location for a flywheel woudl be on the motor shaft. With a gear-reduced coreless motor, even a small flywheel will be quite effective.

Going back to flywheels on worm-shafts, does anybody remember the original Kato Diesel: GP38-2?  The flywheels (2 per worm) were machined out of single piece of brass along with the worm.  That dual-flywheel/worm assembly was suspended on 2 somewhat loose bearings.  Yet that loco was one of the smoothest running Kato locos.  The flywheels were well-balanced.  I brought this up because I just happen to have one of those models on my workbench, and I was just admiring its construction.

[victor miranda]

the FEF has flywheels on the wormshaft also.
there is not a thing wrong with that.
The bearings are the important part, as flywheels get larger in diameter and weight
the more important the bearings become.

the GS4 does not have good bearings on the worm.
they would need to be replaced should you want to hang a flywheel off that shaft.

the GS4 has enough room for a small selection of good motors to fit.

at this point, all I have to add is that I am interested to see what comes next.

victor

[carlso]

Victor - I too am interested in what comes next.   

So, I have some more images. I hope I am not boring all of you guys but by doing this it forces me to check and double check my measurements and my plans. So here goes:

First on is the original KATO motor from my GS-4 :


Now for grins I placed an old Namiki that came out of my Key Challenger just to compare the two motors. I find the Namiki to be a larger diameter........


Here is the original KATO motor that is 11mm wide, so if that were a round motor it would have an 11mm diameter,right? You can see without the cradle it is actually pretty loose fitting........


Here is the Namiki just set into the motor cavity. The end of  the can is at the end of the flywheel area on right or rear of the chassis, the pencil is marking the gear tower location. I see quite enough room to put a gearhead onto the motor............


This one shows the small amount of milling that I am projecting to be necessary for the can/gearhead to fit into the motor cavity area. Basically remove the tabs or lugs that now hold the delrin motor cradle in the cavity.................


I think I have pretty much decided to not worry about any flywheel and just put in a 1016 or 1017 with a 4:1 gearhead. however, I am 74.7 years old and could most likely change my mind as soon as I post this comment.

Happy railroading and as "powersteamguy" says "have fun running steam".   

Thanks for putting up with me.

Carl

[victor miranda]

I love the write-up.

the 11 mm diameter is o-so-close to letting so many motors slide in there

have you considered removing all or part of the top frame halves?

I have a memory of looking at re-motoring and thinking they were the reason
for it being a tough fit.

I must have decided against carving at them or removing them...
 right now, I can't remember why.

victor
 

[peteski]

Removing weight from the rear of the loco will change its pulling ability (less weight on the traction-tire driver).  I suppose that whatever amount of the white-metal frame was removed can be replaced with lead (which will take up less room since it is more dense).

[superturbine]

You should to get rid of the upper frame half an Re-balance the mechanism.  I would suggest tungsten.

[carlso]

Thanks for the new coments and suggestions.

Victor, there you go and plant another seed into my pea brain. No, I did not even think about removing the top frame entirely. It doesn't do much but hold the motor and add weight. I guess that it probably supports the firebox end of the boiler shell as well but that would be no big deal to work around. As I mentioned before , parts are just not available for this loco, but yet the engine can still be found for sale brand new. I broke the drawbar and will need to fabricate one and will not attempt to use PB wire or any wire on the drawbar. I am going to drill and tap the two lower frame halves for .009 screws and hard wire power from engine back to tender for the decoder. Oh,oh, you know without all that upper frame the Loksound Select Micro might just fit in the boiler and all I would have to run to tender is wire for speaker and the power feed from engine. That would be cool as I am going to add firebox flicker as well as the normal lights.

Anyway, back to the topless version. I checked by laying the Namiki motor on top of the lower frame and the output shaft is only 1/8" or less lower than being straight and in line with the worm shaft. I can glue some real thin styrene strips onto the lower frame 1/2's to raise the motor a  tad and also accomplish isolating the motor from the lower frame. I can weigh the top frame and add a like amount of weight over the #3 driver ? Actually without the upper frame the engine looks much like one of Max's projects.

Food for thought,

Carl

[carlso]

Well, I have done it for sure now. I have a Maxon 1017 motor and 4:1 gearhead, no flywheel, being shipped soon. I have talked to NWSL and will be ordering a 1.0mm to a 1.5mm bushing to get the worm axle to match the output shaft of the gearhead. Dave also suggested some shaft couplings and driveline universals. I will order after I have a chance to measure the gearhead output shaft and also determine what length driveshaft I might need.

I can hardly wait to get started. One question however - will it be difficult to match the decoder chuffs to the driver speed, considering the 4:1 ratio ?

Carl

[mmagliaro]

Well, I have done it for sure now. I have a Maxon 1017 motor and 4:1 gearhead, no flywheel, being shipped soon. I have talked to NWSL and will be ordering a 1.0mm to a 1.5mm bushing to get the worm axle to match the output shaft of the gearhead. Dave also suggested some shaft couplings and driveline universals. I will order after I have a chance to measure the gearhead output shaft and also determine what length driveshaft I might need.

I can hardly wait to get started. One question however - will it be difficult to match the decoder chuffs to the driver speed, considering the 4:1 ratio ?

Carl

I assume the decoder uses back emf from the motor to estimate its speed.  Therefore, as long as you have some programming values that you can adjust on that chuff behavior, you ought to be able to make it work.  After all, the decoder folks have no way of knowing what kind of engine you are going to put the decoder into.  Forget the gearhead, and just imagine for a moment that you put that decoder into the engine and the chuffs were timed okay.  Then you put that same decoder into another engine that had a 4x higher gear ratio.  You have to still be able to adjust the chuff to match the drivers.   After all, you can make it work in a steam engine that has a 15:1, 36:1, 52:1, and so on
 and all of those are ratios found in commercial models.   It's got nothing to do with the gearhead.  It's just a matter of
matching the decoder to the total gear ratio between the motor and the drivers.

[peteski]

Not all decoders use BEMF for chuff sync.  I know that QSI does and I think ESU does also.  But Digitrax, Tsunami and MRC (all I can think of) do not.

QSI has couple of CVs dedicated to chuff sync. One is for driver diameter and the other for model's scale.  If you have a gearhead  motor you can just mathematically figure out the correct values to put in those CVs to get the proper sync.

[mmagliaro]

Not all decoders use BEMF for chuff sync.  I know that QSI does and I think ESU does also.  But Digitrax, Tsunami and MRC (all I can think of) do not.

QSI has couple of CVs dedicated to chuff sync. One is for driver diameter and the other for model's scale.  If you have a gearhead  motor you can just mathematically figure out the correct values to put in those CVs to get the proper sync.

But without some sort of feedback mechanism from the drivers, how can the chuffs ever actually be timed?   Knowing the driver diameter and scale are fine.  But how does the decoder know where the driver is in its rotation?   Either you need a mechanical scheme like a wiper on a partially insulated axle, or some other scheme to know how fast the motor or drivers are spinning, don't you?

[peteski]

But without some sort of feedback mechanism from the drivers, how can the chuffs ever actually be timed?   Knowing the driver diameter and scale are fine.  But how does the decoder know where the driver is in its rotation?   Either you need a mechanical scheme like a wiper on a partially insulated axle, or some other scheme to know how fast the motor or drivers are spinning, don't you?

Not needed - the BEMF circuitry is somehow used as a tachometer of the motor's RPMs.  I'm not sure exactly how it is done but it works really well.  I also don't know how they relate the scale and driver diameter to the motor rpm's (since each model has a different gear ratio).  That is why some experimenting is needed, but once set up, the chuffs will stay in good sync with the drivers (as far as the number of chuffs per driver revolution).

[mmagliaro]

Okay, but you said some makers do not use BEMF.  That's what I want to know.
How do they sync up the chuffs if they aren't using BEMF and don't have an axle wiper?

[peteski]

Okay, but you said some makers do not use BEMF.  That's what I want to know.
How do they sync up the chuffs if they aren't using BEMF and don't have an axle wiper?

Ah, now I get it. The ones that don't use BEMF all have the option to add a cam to the driver to trigger the chuffs. Even the ones that use BEMF have option to use a cam.  But using cams in N scale is rather cumbersome.

The cam will have lobes for each chuff.  A cam can be made from a printed circuit board and a contact wiper.

[mmagliaro]

Ah, okay.  Quite a chore, though.