Etched loco chassis

[Chris Higgs]

Season’s greetings to all,

 

I'm finally about to get my act together and start on one of these replacement chassis and have been reviewing all the thread and posts to get everything clear in my mind before starting to wave the iron about... (…possibly a last attempt at procrastination, but it really is the last excuse!)

 

I'm happy with all of the general principles of constructing these replacement chassis, but I do have 2 questions on the fitting of the wheel bearings:

1. I always thought it was normal practice to file the wheel bearing flush with the outside surface of the frame - I notice that this does not seem to have been done by people making these chassis kits - therefore is filing flush necessary?
2. When fitting Simpson Springs, I thought I'd seen a picture (somewhere online?) where the top half of the inside of the bearing has been filed away to allow the PB wire greater space to rest on the axle without interfering with the muff? Is this a good idea and can anyone think where I may have got this idea from?

Any suggestions and comments/observations appreciated

 

Cheers

 

1. In the end, you only need to make sure there is sufficient play for the wheels for normal operation. The frames are 7.5mm over their outer faces, and the wheel B/B is 8.51mm. So it is not necessary to file the bearings totally flat. But you can if you like.

 

2. Someone did it, but that does not make it a good idea. Combining this and point 1 would reduce the bearing surface to 0.25mm, which is too little. Taking a bit off the bearings (not the whole thickness) to make room for the springs may be beneficial, but shortening the muffs a touch is also an option.

 

Chris

[Nig H]

 

 

 

Season’s greetings to all,

 

I'm happy with all of the general principles of constructing these replacement chassis, but I do have 2 questions on the fitting of the wheel bearings:

• I always thought it was normal practice to file the wheel bearing flush with the outside surface of the frame - I notice that this does not seem to have been done by people making these chassis kits - therefore is filing flush necessary?
• When fitting Simpson Springs, I thought I'd seen a picture (somewhere online?) where the top half of the inside of the bearing has been filed away to allow the PB wire greater space to rest on the axle without interfering with the muff? Is this a good idea and can anyone think where I may have got this idea from?

Any suggestions and comments/observations appreciated

 

Cheers

 Hi Steve,

 

Filing the bearing flush gives you that little bit extra side play for the wheels - always useful and especially so if the frames are near scale distance apart. I always file the bearings flush.

 

I don't know if he originated the idea, but David Eveleigh files the top half of the inside of the bearing away to give more room for the spring. David certainly thinks its a good idea.

 

Nigel Hunt

Edited December 29, 2012 by Nig H

[SteveBedding]

Thanks Chris & Nigel for your prompt responses - no excuse for me now not to get cracking on!   Now that you remind me, I do remember it being a comment/picture from Dave E on filing the tops of the bearings but I still can't remember where I saw it

 

Thanks again

[Chris Higgs]

Thanks Chris & Nigel for your prompt responses - no excuse for me now not to get cracking on!   Now that you remind me, I do remember it being a comment/picture from Dave E on filing the tops of the bearings but I still can't remember where I saw it

 

Thanks again

 

I suggest you read this post from Geoff Jones on a way to thin the bearings to make space for the springs.

 

http://groups.yahoo.com/group/twomm/message/47713

 

Chris

[Valentin]

This is how I intend to attach the Association motor to the J94 replacement chassis (would be a better idea to use epoxy glue?)
 

 

I tried first to fit the motor to the bracket (scrap brass) using two screws but I ended up by damaging the thread so I chose to solder it:

 

 

I have to shorten the front motor axle first, using a piercing saw; any chance to damage to the motor?

 

From where can I get some good screwdrivers for 16 to 10 BA screws?

Edited December 30, 2012 by Valentin

[Chris Higgs]

This is how I intend to attach the Association motor to the J94 replacement chassis (would be a better idea to use epoxy glue?)

 

 

I tried first to fit the motor to the bracket (scrap brass) using two screws but I ended up by damaging the thread so I chose to solder it:

 

 

I have to shorten the front motor axle first, using a piercing saw; any chance to damage to the motor?

 

From where can I get some good screwdrivers for 16 to 10 BA screws?

 

Looks like it should work. You may want to omit the bearing that is attached in the gearbox next to the motor - it is superfluous if you are supporting the motor at its rear end as well. Three different bearings on one shaft tends to result in wear on one of the other of them.

 

A piercing saw is definitely not the ideal tool for cutting the shaft, a lot of people use a cutting wheel in a mini-drill. The easier the cut, the less stress on the axle and risk of damage to the motor.

 

I just use the cheap small screwdrivers sold in sets in model shops, and probably also in somewhere like Maplins (?).

 

Chris

[DavidLong]

A couple of points about motors. The motor in the Farish 03/04 locos is identical in dimensions to that sold by the 2mm Scale Association except that it is single-ended. If you are going to build a finescale chassis for one of these locos and have the whole loco rather than just the body then the motor from the GF chassis can be used in the conversion. It also saves putting unnecessary stress on the double ended version in removing one of the shafts.

If you require a shorter motor for a project and the 8x10 dimensions of the flat can are ok then it may be worth looking at this:

http://www.ebay.com/itm/Super-Mini-Size-Motorized-Chassis-TU-DEKI1-N-scale-/360509915299?_trksid=p2047675.m1850&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D11%26meid%3D4646158610354127405%26pid%3D100011%26prg%3D1005%26rk%3D1%26sd%3D200611639193%26

When the motor is stripped out you will find that it is only 11mm long compared to the Association/GF version length of 15mm. The 4mm may not seem much but in 2mm scale it can sometimes make a lot of difference. At current conversion rates, including postage, it works out at about £27. This is getting into Faulhaber/Maxon territory but as far as I am aware none of their motors are as short as this one. Should have mentioned that the single shaft is 1mm like the larger version. It has a short nylon worm and I'm no expert on these things but it may weIl be 64dp-ish or thereabouts! I haven't used motor yet but I have no reason to suppose that the performance or potential longevity would be any different to the 15mm version.

If anyone knows where these motors may be purchased separately and/or cheaper then it would be useful to know. 

 

Edit: If using the Farish motor you will need to remove the brass worm in order to fit the Association version. I bought the GWS pinion gear puller which does 1mm, 1.5mm and 2mm shafts. It makes short work of removing the worm. It's available from a number of outlets but you can see it here:

http://robotbirds.com/catalog/product_info.php?products_id=525

Edited January 4, 2013 by DavidLong

[SteveBedding]

 

Edit: I will add that the wheels were painted, cleaned, polished and blackened before the clock started; and that was quite a bit of work. However it is not specific to the replacement chassis.

 

Evening all,

 

I'm slowly making good progress on the chassis assembly - it went together very nicely and is now sitting waiting for the primer to dry.  I'll post some pictures when I sort out the camera...

 

Rich did a very credible 'Blue Peter' special (...here's one I prepared earlier...) with the wheels, but now I could do with some suggestions/pointers on who to prepare the wheels before putting to the frame.

• Do they need priming before painting black?
• Should the rims be blackened?
• How to fix the counter-weights (I'm assuming araldite on this one)?

Can people please offer their wisdom and experience on this aspect of the chassis building?

 

Thanks

[queensquare]

Evening all,

 

I'm slowly making good progress on the chassis assembly - it went together very nicely and is now sitting waiting for the primer to dry.  I'll post some pictures when I sort out the camera...

 

Rich did a very credible 'Blue Peter' special (...here's one I prepared earlier...) with the wheels, but now I could do with some suggestions/pointers on who to prepare the wheels before putting to the frame.

• Do they need priming before painting black?
• Should the rims be blackened?
• How to fix the counter-weights (I'm assuming araldite on this one)?

Can people please offer their wisdom and experience on this aspect of the chassis building?

 

Thanks

 

Hi Steve,

 

glad things are progressing well, I look forward to the loco running trials on Highbury/Tucking Mill!

 

To answer your three questions;

1. If I am being patient I do prime the wheels before painting them. I drill holes in a scrap of wood and sit the axles in that then make a mask from scrap card to sit over them to keep most of the treads free of paint although any overspray is easily cleaned off. That said I more often than not trial fit the wheels etc and find that having got the chassis running sweetly I'm reluctant to strip it down and resort to brush painting them (eventually!).

2. I don't tend to bother with blackening the rims although I know some do.

3. I use Araldite to fix the balance weights. 

 

Jerry

[SteveBedding]

Thanks Jerry for the prompt reply - I think I'm getting there slowly...

 

 

...just to prove that progress is being made   I'm working on a 57xx, 14/48xx, and 2251 chassis; either I'm learning / developing as each chassis progresses or I'm carrying the same errors across

 

I used tissue paper & Maskol to fill/cover the bearings when spraying and these have still to be fully cleaned up - the bearings have to be reamed out to 1.6mm and the springs have still to be fitted.  Following the comments so far in the thread, the bearings have been filed flat to the outside of the frame and the inside has been thinned down to 0.25mm to allow more space for the PB springs. I've aso ommited to fit the bearing at the motor end of the gearbox as it has been suggested that this can lead to wear in the motor.

 

I'm quite please on how they are progressing and I just hope that they run as well as they have gone together.

 

(I sort of hoped that the new camera would be easy to use and take nice clear shots - it looks like I've something else to lear how to use properly!)

[richbrummitt]

Evening all,

 

I'm slowly making good progress on the chassis assembly - it went together very nicely and is now sitting waiting for the primer to dry.  I'll post some pictures when I sort out the camera...

 

Rich did a very credible 'Blue Peter' special (...here's one I prepared earlier...) with the wheels, but now I could do with some suggestions/pointers on who to prepare the wheels before putting to the frame.

 

• Do they need priming before painting black?

• Should the rims be blackened?

• How to fix the counter-weights (I'm assuming araldite on this one)?

Can people please offer their wisdom and experience on this aspect of the chassis building?

 

Thanks

I'm still working on the body and getting mine together. It really only needs a drawbar now before it should run.

 

The black is primer applied from an aerosol with the wheels having their stub axles in a block of wood. The treads are cleaned in the lathe during the polishing and I blackened these as a test to see whether they are more resilient to tarnishing than the polished ones on the previous chassis built. I haven't thought about the balance weights yet. I didn't get any on my etch

[Chris Higgs]

Thanks Jerry for the prompt reply - I think I'm getting there slowly...

 

20130111-2mmChassis01-T.jpg

 

...just to prove that progress is being made   I'm working on a 57xx, 14/48xx, and 2251 chassis; either I'm learning / developing as each chassis progresses or I'm carrying the same errors across

 

I used tissue paper & Maskol to fill/cover the bearings when spraying and these have still to be fully cleaned up - the bearings have to be reamed out to 1.6mm and the springs have still to be fitted.  Following the comments so far in the thread, the bearings have been filed flat to the outside of the frame and the inside has been thinned down to 0.25mm to allow more space for the PB springs. I've aso ommited to fit the bearing at the motor end of the gearbox as it has been suggested that this can lead to wear in the motor.

 

I'm quite please on how they are progressing and I just hope that they run as well as they have gone together.

 

(I sort of hoped that the new camera would be easy to use and take nice clear shots - it looks like I've something else to lear how to use properly!)

 

I would certainly suggest that from here you build one of the chassis to completion before the other two, so that you do prove that you are not carrying across anything you later decide you would like to do differently.

 

The Pannier will look odd coupled to the Collett tender!

 

Chris

[SteveBedding]

The Pannier will look odd coupled to the Collett tender!

 

Chris

 

Oops...

 

... or I could claim it is the pannier shunting the tender....   

[Alex Duckworth]

Evening all,

 

I'm slowly making good progress on the chassis assembly - it went together very nicely and is now sitting waiting for the primer to dry.  I'll post some pictures when I sort out the camera...

 

Rich did a very credible 'Blue Peter' special (...here's one I prepared earlier...) with the wheels, but now I could do with some suggestions/pointers on who to prepare the wheels before putting to the frame.

• Do they need priming before painting black?
• Should the rims be blackened?
• How to fix the counter-weights (I'm assuming araldite on this one)?

Can people please offer their wisdom and experience on this aspect of the chassis building?

 

Thanks

 

   Hello Steve,

                     I usually prime the wheels, just a mist over with "Teroson" etch primer decanted into my airbrush and thinned with cellulose thinners. I don't blacken the rims, and I use an old Rotring circle drawing template to mask the rims, they have circles in 0.5mm increments, just push the wheel into the appropriate hole and spray. Also I've always used Devcon to fix my balance weights, I prefer it to Araldite.

 

Alex.

[richbrummitt]

Here she is light engine on Brafferton earlier today at St Albans.

 

 

The loco body cannot be fixed quite properly yet because of the clearance for the crankpin washers being an issue and I think that some more space is needed in the rear splashers - the 10.5mm drivers are a snug fit!

 

The brakes remain to be fitted and there are lots of details that still need adding/correcting on the body but the chassis itself seems to run okay 8)

[Valentin]

The motor is now fitted to my J94 chassis. After some consideration I have chosen to mount the motor to the chassis using the most simpler way (KIS is better), recommended in the instructions. And, to my surprise, my skills aren't so bad as the chassis actually run smoothly "ish" (more tracks and wheels cleaning is required)

 

 

 

At this point, my questions are:

• Is any easy way to paint in black only the visible parts of the chassis? Shall I use a primer?
• About the wheels, can I paint them black while they are fitted to the chassis? I really don't like the idea to remove them for blackening...

[richbrummitt]

My skills aren't so bad as the chassis actually run smoothly" (more tracks and wheels cleaning is required)

 

With well laid track and functional locomotives the cleanliness is the most important thing for good running. As you rightly point out this includes the wheels as well as the track.

At this point, my questions are:

 

• Is any easy way to paint in black only the visible parts of the chassis? Shall I use a primer?

• About the wheels, can I paint them black while they are fitted to the chassis? I really don't like the idea to remove them for blackening...

I would paint as much as you can reach with a brush. I didn't paint my first chassis because I was eager to see it working and wasn't sure it would. Since then I have always painted first because it is much easier to paint the individual parts before they are assembled.

[justin1985]

Great to see others making progress on their chassis. I've finally returned to my Jinty chassis, which seems to be running well, with the association can motor mounted via some nominal 1.5mm OD/1mm ID tube mounted inside the bearings, and an association 1mm ID worm substituted for the 1.5mm ID one supplied with the specified worm set (I think this means its 100DP rather than 64DP? Seems to work fine though).

 

I'm now adding the detail parts before I attempt to paint (while i painted behind the wheels before assembly, but most has worn off). Looking at the wheel balance weights on the etch, there are two sizes, small and large, but only four of the larger ones, and eight smaller ones. Looking at a few 1930s images online, it looks to me as if only one, large, balance weight was fitted to each side, on the central wheel only. Is this correct, or am I misinterpreting? What are the small ones for?

[Chris Higgs]

Great to see others making progress on their chassis. I've finally returned to my Jinty chassis, which seems to be running well, with the association can motor mounted via some nominal 1.5mm OD/1mm ID tube mounted inside the bearings, and an association 1mm ID worm substituted for the 1.5mm ID one supplied with the specified worm set (I think this means its 100DP rather than 64DP? Seems to work fine though).

 

I'm now adding the detail parts before I attempt to paint (while i painted behind the wheels before assembly, but most has worn off). Looking at the wheel balance weights on the etch, there are two sizes, small and large, but only four of the larger ones, and eight smaller ones. Looking at a few 1930s images online, it looks to me as if only one, large, balance weight was fitted to each side, on the central wheel only. Is this correct, or am I misinterpreting? What are the small ones for?

 

The smaller balance weights are for the other wheels. Balance weights did vary over the life of locomotives, and so it could be they were not fitted in the 1930s, but were later. There are a double set of everything for spares.

 

You can see a photo here of a Jinty with balance weights on the front and rear wheels:

 

http://www.flickr.com/photos/tatraskoda/5755795086/

 

Chris

Edited January 20, 2013 by Chris Higgs

[justin1985]

Thanks Chris! This is certainly one of those moments where my lack of understanding of a real steam loco is coming into play!

 

I was looking at the Wikimedia works photo  and a set of North London line 1930s photos on Flickr. It seems all the early photos are too blurred, or happen to have the wheels at a rotation making it impossible to see the smaller balances. Peering closer at the latter photo, I think they are there. I'll put them on the model now anyway!

[Chris Higgs]

Thanks Chris! This is certainly one of those moments where my lack of understanding of a real steam loco is coming into play!

 

I was looking at the Wikimedia works photo  and a set of North London line 1930s photos on Flickr. It seems all the early photos are too blurred, or happen to have the wheels at a rotation making it impossible to see the smaller balances. Peering closer at the latter photo, I think they are there. I'll put them on the model now anyway!

 

I had to look at a lot of photographs in regard to the balance weights for the various etched chassis. Often they are not shown on the works drawings, and as you say you need to find a good clear photo preferably side-on with the balance weights actually visible. For the GWR locos I had to go and measure the real thing. And then you discover they vary from period to period.

 

However for the Jinty they were on the works drawings, so I am pretty certain they are right, at least for an as-built loco.

 

Chris

[SteveBedding]

...with the association can motor mounted via some nominal 1.5mm OD/1mm ID tube mounted inside the bearings, and an association 1mm ID worm substituted for the 1.5mm ID one supplied with the specified worm set...

 

Hi Justin,

 

The method you describe for mounting the motor (particularly the floating end of the worm) sounds like quit a nice solution!  Can you expand on the 1mm ID tube - I'm guessing you mean a length of brass tube, and if so, are there any issues with the (mild steel I think) motor drive shaft in terms of wear and heat?

 

Do you have any pictures of this arrangement, and how you've mounted/supported the other end of the motor?

 

Cheers

 

Steve

Edited January 22, 2013 by SteveBedding

[justin1985]

The method you describe for mounting the motor (particularly the floating end of the worm) sounds like quit a nice solution!  Can you expand on the 1mm IF tube - I'm guessing you mean a length of brass tube, and if so, are there any issues with the (mild steel I think) motor drive shaft in terms of wear and heat?

 

Hi Steve,

 

I really doubt my example should be followed by anyone! The tube is from Eileens, and nominal 1.5mm OD and 1mm ID, brass. Its a very neat fit inside the frame bush, but a pretty loose fit on the nominal 1mm motor shaft. To mount the motor I cut some suitable wedges from plasticard, and with the motor held at the correct height by being pushed into the plastic worm, which was held on the other side by a 1mm drill bit through the other "bushed bush", epoxy'ed it in solid. 

 

However, the alignment of the motor can't have been that accurate by this method, because now the motor will barely run with a 1mm rod continuing through the worm into the second bush. But, with the motor held quite firmly, I suspect it will be OK without it? (presuming the epoxy holds with the heat of the motor?)

 

Attempting a bit of running in, I noticed a distinct "lollop" , and then noticed the smaller gear on the shaft with the worm gear was running quite eccentrically. Trying to extract the shaft to correct this resulted in nigh-on destroying the chassis. I've just about beaten it back into shape, but I suspect it will never be the same again And to top it all, the result of trying to correct the eccentrically mounted gear was only marginally successful! :-(

 

Time for attempt number two perhaps  

[Nigelcliffe]

The new metric worm/wheel sets should have both 1mm and 1.5mm bore worms supplied with them, so the problems of sleeving to different motor shafts should be reduced.  The specification I worked out with our Polish manufacturer included both bore sizes, and I expect the shop is sticking with that specification.

 

 

- Nigel

[Chris Higgs]

Hi Steve,

 

I really doubt my example should be followed by anyone! The tube is from Eileens, and nominal 1.5mm OD and 1mm ID, brass. Its a very neat fit inside the frame bush, but a pretty loose fit on the nominal 1mm motor shaft. To mount the motor I cut some suitable wedges from plasticard, and with the motor held at the correct height by being pushed into the plastic worm, which was held on the other side by a 1mm drill bit through the other "bushed bush", epoxy'ed it in solid. 

 

However, the alignment of the motor can't have been that accurate by this method, because now the motor will barely run with a 1mm rod continuing through the worm into the second bush. But, with the motor held quite firmly, I suspect it will be OK without it? (presuming the epoxy holds with the heat of the motor?)

 

I think the general experience coming out from various people is that is not a good idea to mount the motor shaft at three points i.e. in this case the motor itself, and the two bearings in the gearbox. So if mounting the motor securely, omit either one or the other of the gearbox bearings. If using both bearings, consider using something that just constrains the motor from rotating.

 

As to the problem with eccentric spur gears, it really pays to check everything at the point where it can more easily be corrected.

 

Chris

Edited January 22, 2013 by Chris Higgs