Great Southern Railway (Fictitious) - Signalling the changes...

[Skinnylinny]

OK< so the tender is now rebuilt, and actually square this time! 

So we're back to where I thought I was on Friday evening, only this time with coal rails! 

[jamespetts]

I approve of square, especially with coal rails. That does look good.

[Regularity]

2 hours ago, Skinnylinny said:

So we're back to where I thought I was on Friday evening, only this time with coal rails! 

If you think something isn’t right, it probably isn’t and it will only nag at you if you don’t go back and deal with it before you start adding other pieces. 
It is looking very good, those coal rails would have looked awful if the tender body wasn’t properly square.

[Skinnylinny]

Not much to report today, except... movement! The slight lumpiness of the running is due to the crankpins hitting the running plate, but I'm not going to shorten these until the chassis is painted and ready to be fitted for the last time. It's a bit growly but with weight blu-tacked on instead of the bodyshell it runs nice and smoothly. The plan is to fit as many pickups as I possibly can - the video shows the loco with 4-wheel pickup. The front drivers will soon gain pickups, and I intend to figure out how to add them to the tender as well.
 

Now I need to start cutting out the bottom of the boiler enough to let the gearbox through...

Edited May 7, 2020 by Skinnylinny

[Skinnylinny]

Well, that seemed simple enough, and the body seems to fit ok on the chassis. The gearbox and motor aren't too visible, and they'll be even better hidden once I fit the splashers. 

However, it doesn't run with the body on, and removing the body hasn't returned the chassis to running condition. I've put it down because I'm getting frustrated. Hopefully tomorrow, or maybe later this evening, will be a better day. That being said, she is definitely starting to look locomotive-shaped!



Pity about the somewhat pitted metalwork on the boiler, going to have to get some very thinned-down filler on that!

[Caley Jim]

2 hours ago, Skinnylinny said:

However, it doesn't run with the body on, and removing the body hasn't returned the chassis to running condition.......

What exactly do you mean by 'doesn't run'?  is there no movement at all, or is the motor buzzing indicating that something is jammed?  If the former, has a wire come adrift from either the motor or the chassis?  Has your battery died?  If the latter, has the motor got pushed down such that the worm is now too tight on the wormwheel?

 

It pays to be diagnostic about this situation, rather than just giving up in disgust!

 

Jim

[Skinnylinny]

I'll be diagnostic, don't worry! I tested the battery at the time with another loco, and it was fine. No buzzing from the motor, but a multimeter showed a good current path through each wheelset to the motor. I suspected it to be the gearing, especially because of the cut on the Branchlines gearbox which is very intolerant of any sideways movement whatsoever. 

I removed the wheels from one side (God bless Romford axles!) and undid the grub screw holding on the drive gear as I wanted to check whether the problem might have been coupling rod binding - I'd had to tweak the laminated rods and it looked like they might not have soldered properly up to the end. Unfortunately, in doing that... the head of the grub screw sheared off on one side. 

 

There's now not so much a slot as a raised D piece on the end of the grub screw. I've dropped an email to Branchlines, whose gearbox was supplied with the kit, to see if they either have spare grubs or can tell me what I need. 

It has not been a wasted evening though! I also found that the pickup wire that is provided with the kit is... not as springy as I'd like, and was making the chassis rather stiff; stiff enough that it wouldn't roll freely when pushed, even with the whitemetal bodyshell in place. I've been tweaking and adjusting and filing away bits of the bodyshell which were rubbing on wheels, and I now have a nice smooth chassis again. I'm going to look through my stash for some phosphor bronze strip, rather than the provided wire, and have another go at making pickups.

I did have a little fun while testing the chassis for free running though - got to have some fun every now and then!
 

 

[Edit: Forgot to add, when the pickups were fitted but the drive gear removed, the motor runs beautifully. I'll test the gear meshing once I'm able to reattach the gear to the axle properly.]

Edited May 7, 2020 by Skinnylinny

[Caley Jim]

Can you not just remove the grub screw, fit it in a pin vice with the (now not) slotted end projecting, hold that in a vice and re-cut the slot with a piercing saw or Exacto saw?  I've made grub screws out of off-cuts of 12 and 14BA screws that way.

 

Jim

[Dave John]

If all else fails I think wizard do replacement grub screws .

 

Might fit

 

https://www.wizardmodels.ltd/shop/locomotive/grubscrew/

[Steve Smith]

Quite clearly made of chocolate.  When this happened to me I carefully deepened the slot with a razor saw, then filed level to tidy up. 

 

Steve

[Regularity]

If the bore of the worm wheel us even slightly oversize, then tightening the grub screw will create a degree of eccentricity, which you will be able to identify as changes in nouse every revolution of the driving wheels.

Force fit worm wheels are better - if you are set up to mount them - but failing that, something which requires a degree of pushing is the best you can hope for. A lot of modellers file a small flat on the axle so that the grub screw can be tightened up against that without causing any eccentricity.

[Skinnylinny]

Wow,  many responses to wake up to! Thank you all.

 

9 hours ago, Caley Jim said:

Can you not just remove the grub screw, fit it in a pin vice with the (now not) slotted end projecting, hold that in a vice and re-cut the slot with a piercing saw or Exacto saw?  I've made grub screws out of off-cuts of 12 and 14BA screws that way.

 

Jim

 

9 hours ago, Steve Smith said:

Quite clearly made of chocolate.  When this happened to me I carefully deepened the slot with a razor saw, then filed level to tidy up. 

 

Steve

This definitely seems like an approach I can take. I'm still waiting for a reply from Branchlines, but I've nothing to lose by giving it a try! Thanks for the thought. While this seems obvious in hindsight, I'm very much a beginner at loco kits. Thank you especially to Jim for the idea of holding the screw in a pin vice.
 

9 hours ago, Dave John said:

If all else fails I think wizard do replacement grub screws .

 

Might fit

 

https://www.wizardmodels.ltd/shop/locomotive/grubscrew/

Unfortunately looking at the photo, the thread on those is rather coarser than the one use in the Branchlines gears, but noted for future use, thank you!
 

9 hours ago, Regularity said:

If the bore of the worm wheel us even slightly oversize, then tightening the grub screw will create a degree of eccentricity, which you will be able to identify as changes in nouse every revolution of the driving wheels.

Force fit worm wheels are better - if you are set up to mount them - but failing that, something which requires a degree of pushing is the best you can hope for. A lot of modellers file a small flat on the axle so that the grub screw can be tightened up against that without causing any eccentricity.

I have to admit the worm wheel didn't feel oversize; It slid onto the axle smoothly enough but there's no ability to "jiggle" it at all. The clearances in the Branchlines gearbox are very close though. I have to admit I don't understand how the axle flat would help - would the grub not still tend to push the gear to one side?

Anyway, before fitting the body, the chassis seemed to run well enough, but it was the sideplay of the wheels that seemed to cause the issue. Unlike Triang etc gears where the teeth are a straight cut, this worm wheel has a curved cut (I've not been able to figure out the name of this cut through Googling either!):

 

Thus, if there's any movement along the axle (at least, of the order 1/4mm), the gap between worm and wheel closes up and everything jams up solid. Hardly an ideal state of affairs! However, it must be said that after I got things nicely lined up the mechanism was silky-smooth. This is definitely one of my suspected culprits.

Edited May 8, 2020 by Skinnylinny

[Regularity]

57 minutes ago, Skinnylinny said:

I have to admit I don't understand how the axle flat would help - would the grub not still tend to push the gear to one side?

You tighten the screw, then release it slightly, so that it is enough to lock the wheel rotationally, but not to pull it off-centre.

 

A much better way is to drill a hole, which would also prevent sideways movement, but you would need to be very precise about it.

[Skinnylinny]

Ahhhhhhhh that makes sense, thank you! So with a pointed-tip grub screw, a V-shaped slot would be better than a flat?

[Regularity]

Which way is the vee going?

[Skinnylinny]

The vee slot going along the direction of the axle, to stop the rotary motion? I've just realised that would be rather difficult to file without filing along the whole length of the axle. I blame not being properly awake yet!

I had something like this in mind - perhaps a suitable cutting tool could be made for a Dremel to grind out a small V-shaped slot in the centre of the axle. Either that or a milling machine could produce a useful slot.

 

Edited May 8, 2020 by Skinnylinny

[TurboSnail]

If there's enough slop in the gear/axle interface that it causes an issue, can you slip something in the gap? I've done this before with thin paper - wrapped it round the axle and put the gear over the top. This also allowed the grubscrew something to bite into. Sounds like a horrible bodge but worked very well. Doesn't take away from the fact that the gear manufacturer should do better though!

[Skinnylinny]

In this case there's no trouble at all (as far as I can tell) with the fit of the gear on the axle. I'm away to make lunch and then the modelling shall recommence with cutting a new slot in the grub screw and seeing how we get on from there. 

[Regularity]

3 hours ago, Skinnylinny said:

The vee slot going along the direction of the axle, to stop the rotary motion? I've just realised that would be rather difficult to file without filing along the whole length of the axle. I blame not being properly awake yet!

I had something like this in mind - perhaps a suitable cutting tool could be made for a Dremel to grind out a small V-shaped slot in the centre of the axle. Either that or a milling machine could produce a useful slot.

 

You only need a short and shallow groove. If you had one going across the axle, it would locate very positively, but you would have to get it in the right place.

If you have access to a pillar drill, you could try drilling a hole into the axle for the grub screw. 

[Skinnylinny]

14 hours ago, Regularity said:

If the bore of the worm wheel us even slightly oversize, then tightening the grub screw will create a degree of eccentricity, which you will be able to identify as changes in nouse every revolution of the driving wheels.

Force fit worm wheels are better - if you are set up to mount them - but failing that, something which requires a degree of pushing is the best you can hope for. A lot of modellers file a small flat on the axle so that the grub screw can be tightened up against that without causing any eccentricity.

 

Ding ding ding! We have a winner! One culprit to the running was the pickups - I have since re-adjusted these (in fact, temporarily, two of them are rail-wipers) and that helped but I was then getting that noise variation, almost pulsing. I filed a flat in the axle and the loco is now running. Still not perfect, but a lot better, although that pulsing motor noise is still audible. And with the bodyshell on too (probably helped by carefully filing away to make sure there's nothing touching anything electrically live) she goes! Now that she'll run continuously, I can really focus on getting her to run properly smoothly. 

Thanks all for the advice!
 

 

[Caley Jim]

It's amazing what a bit of lubrication and simple running in will do. Put some oil on the moving parts, especially the gears, run it up against a stop and leave the power on. 

 

Jim

[Skinnylinny]

I've popped some tiny drops of oil on the chassis. I was planning on propping it on on blocks and clipping croc-clips to the pickups. At least it's not as loud as my neighbour upstairs, who seems to be doing some house renovation and is currently drilling into the stone wall!

[Caley Jim]

That would do just as well. I've clamped one upside down in the vice before now with the power clipped to the motor! 

 

Jim

[Skinnylinny]

All has been rather quiet on the modelling front over the last... goodness, two weeks. I've dug out some old HMRS carriage lettering sheets and had a go at some of the GSR carriage stock, making sure that I didn't use the same style of lettering as any stock that is likely to appear on the layout from another company. I have pinched LT&SR garter crests from the sheet, as well, on the basis hat they look much better than nothing, and they're small enough that I can't see them in enough detail to identify them without being about 6" from the models!



I think the red-shaded gold letters look rather good on the dark blue of the GSR livery, although blowing up he photo shows that part of the left axleguard has disappeared somewhere. I'll have to hide that with a footstep. I would like to get that window out of the horsebox, as it shows battle scars from my vain attempts to remove it. I also now see that I need to adjust the filling to the left, but I really don't want to mess up the window any more.

The saloon and a brake third have also gained some lettering, although I am not convinced by at least one compartment of the brake third. We'll see if it's noticeable after a week when I've forgotten about it...

[RedGemAlchemist]

17 minutes ago, Skinnylinny said:

Very nice horsebox, Linny. Love the colour.