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Frankenpannier VII - It lives, sort of.

richbrummitt

Entry posted by richbrummitt in Locomotives

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Back in the spring (installment 5) I had got the wheels turning again, albeit briefly. I since solved the problem of passing the pick ups through the footplate and onto the motor and had the engine on the track rather than a direct power supply for the first time since the body upgrade started.

 

The motor is retained in the lower visible part of the boiler, which is removable with the footplate. The tanks and smokebox cover over this. The worm mesh is separated every time the body is removed. This being the compromise for modelling the bottom of the boiler and the balancing pipe between the tanks. I contemplated several solutions and consulted the 2mm ZAG on the possibilities of passing track voltage from the chassis to the lower body section before realising the solution of phosphor bronze tangs sticking up vertically with suitable bends to bear upon some very thin double-sided copperclad sweated to the insides of the firebox forming the a contact pad. These tangs take up space either side of the worm - not yet used for anything else - and there is room on the pad to have the motor wires soldered on in the future.

 

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The pads have some temporary (thick) wires on to attach to the motor wiring until the final fix

 

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It was not working so well though, even with some weight added to aid pickup. I reasoned that either the ebay coreless motors are awful or something else was up with this previously operational chassis. It turns out it was a bit of both! I indulged in a Tramfabriek motor to prove the point on the motor and there was obviously more torque available. This was a strong step in the right direction and with some loctite holding the worm on the shaft in place of superglue the motor was turning the wheels or stalled. This chassis must have rather suffered at my hands during this body re-modeling since the movement was not as smooth as I recall. Particularly when going forwards the engine will not start smoothly, requiring extra voltage from the controller and then shooting off a little quickly. There is some noticeable gear or grinding noise, not much, but more so in the forward direction. I've tried a number of things:

 

  • Separating the wormwheel from the second stage reduction along the axis of the idler in case there was some interference with the teeth
  • Removing further material from the backhead
  • Additional mass (to try and aid pick up but it seemed only to make the stalls worse)
  • Clearing the gears, in particular the worm (the spur gears were done originally), of any burrs
  • Tweaking the worm mesh
  • Wiring the controller directly to the motor

 

It was getting closer but not good enough to avoid the stalling. The engine sat back in a drawer until I felt less grumpy about it. 

 

I again sought the help of friends for suggestions or advice. @queensquare suggested to give it a good wash in some cleaner (IPA) and if that didn't sort things then action should be what I feared: it was time to go backwards until the problem could be found. Remove the body and motor; get back to a rolling chassis. Check. Then: coupling rods off; secondary pick ups off; and if still all is not well then wheels out and start over. :swoon:

 

After a good clean the coupling rods and secondary pick ups are off. The former retained, the latter (now just bent and manky looking phosphor bronze wire) binned. 

 

It was rolling reasonably well after this brutality, but perhaps not quite perfectly. I have put it all back together for wiring the motor directly to the controller for another test. Unfortunately lack of materials halts progress now because the long lengths of wire I had used previously now seem inflexible enough to tell whether smooth operation has been achieved; the wire is influencing the engine on the track.  I've ordered some wire for Ogbourne and added some extra wire with many thin cores and the thinnest insulation I could find to the order in the hope it is extra flexible. 

 

 

Edited by richbrummitt

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Mike G

Rich

Does the chassis roll smoothly with no motor and the coupling rods on? If it does, then the gears are at fault. Before High level g/boxes turned up, anything with brass gears was treated to a toothpaste surprise. Some toothpaste mixed with a little motor oil, spread on all gears - not smoothered - and then connect it all up and let the motor run for 24 hrs. The toothpaste will smooth the edges of the gears so that they mesh easier. Obviously, a dunk in white spirit is needed to clean it all off. Just a thought...

 

Mike

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Mikkel
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I admire your stamina Richard . I wouldn't know where to start. Fingers crossed you will get there in the end. Sounds like you have qualified help :superman: 

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richbrummitt
On 24/10/2020 at 12:41, Mike G said:

Rich

Does the chassis roll smoothly with no motor and the coupling rods on? If it does, then the gears are at fault. Before High level g/boxes turned up, anything with brass gears was treated to a toothpaste surprise. Some toothpaste mixed with a little motor oil, spread on all gears - not smoothered - and then connect it all up and let the motor run for 24 hrs. The toothpaste will smooth the edges of the gears so that they mesh easier. Obviously, a dunk in white spirit is needed to clean it all off. Just a thought...

 

Mike


The chassis used to run, and well. It was the best of what I had made. 

 

16 minutes ago, Mikkel said:

I admire your stamina Richard . I wouldn't know where to start. Fingers crossed you will get there in the end. Sounds like you have qualified help :superman: 


Thanks Mikkel, It’s so frustrating but I will get there somehow I am determined. Then I will have the first off engine appropriate to period. 

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Simond

Yes, I think starting at “just wheels”, prove that it rolls perfectLy.

then rods, they too must allow it to roll perfectly.  
 

if you can, split the axles into two pairs, and prove each pair independently, then all three together should be fine, though it’ll highlight any quartering issues.

 

then gears, and finally, mesh the motor.  
 

you can buy very fine wire for wiring decoders, this is ideal for tests on the bench, as it is really thin and very flexible.  Alternatively, a rolling road is a worthwhile acquisition, if you’re planning to build more than a couple of locos.

 

hth

Simon

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Izzy
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Make sure the lay shaft with the wormwheel has a little bit of play so it spins easily. I have found this to often be the biggest cause of less than brilliant running. Either I’ve made the muff too tight a fit, or somewhere along the line bent the top of the chassis inwards to cause excess friction. The difference can be quite remarkable......

 

Izzy

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Ian Smith

Richard, I have found that locos often seem to run better in one direction. One thing that happens is a slight sideways movement of the gear wheel caused by friction with the worm, gear moving left in one direction and right in the other. Because of the need to shorten the muff, I rarely get a square end on the muff and have witnessed the “high spot” of the muff rubbing on the bearing in the frame. Might be worth looking to see if you are experiencing this in your chassis.

Ian

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richbrummitt

I'm not sure what I've got. The controller was upset when I went back to it. Oddly it quite happily worked for another engine I've been working on when the connector was cut off the wander leads and they were attached directly to some rail. It acted like there was a short but there is no short in the connector (or the pannier) that I could find. 

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