Video Archive         Recent Topics      
YMR logo

You are here:  Your Model Railway Club > More Practical Help > Members Projects > On Members Workbenches. > Nigel's Workbench 8 November 2013 To bottom of page
                 

 Moderated by: Spurno
Start New Topic Reply Printer Friendly

Nigel's Workbench 8 November 2013 - On Members Workbenches. - More Practical Help - Your Model Railway Club
AuthorPost
 Posted: Fri Nov 8th, 2013 03:49 pm
PMQuoteReply
link to this 1st post
BCDR
Moderator


Joined: Sat Oct 19th, 2013
Location: Reston, Virginia USA
Posts: 3139
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

I have a Bachmann Class 20 that I am converting to EM gauge. This is the newer, DCC ready model. Bit of a hybrid, the chassis was bought for another project; the body came from Bachmann as a spare. DCC sound has been fitted, but that’s another story (it might be DCC ready, DCC friendly it was not).


The wheel set arrived this week from Ultrascale Gears, and this should have been a simple 5 minute job between the other projects. Take the bogie cover plate off, remove the old wheels and axles, replace with the new set, put the bogie cover plate back on, and take another sip of tea. Oh if life was that simple. Bachmann have quietly remodeled the bogie frame with their latest model (and may have changed the position/design of the electrical pick-up), thus making this conversion more challenging than it should have been.


The first problem was the bogie frame. The new bogie has a separate molding for the brake rods and shoes that sit inside the frames, one on each side, and is glued at the bottom and ends. Quality control was apparently out for the day on these, the rods on one side of one bogie are quite visible below the frame, and the assembly was quite distorted when removed. There must have been a glue shortage that day as well. With these in place there is simply no room for an EM gauge wheel set. Looking at British Main Line Diesel Locomotives (Marsden and Fenn, OPC, 1988, page 69) as well as prototype photos on the web it seems that Bachmann have compromised on the design. The support bracket and rod is too low at the ends. The bottom rod should be just below the bottom of the axle box frame (as near as I can determine 1.5” or less) and then go behind the frames between the wheels. Bachmann have it a scale 4.5”-6.0” below the axle box with consequently lots of daylight showing. The inner brake shoes and supports are also badly positioned; more of them should be visible. There are 2 choices. The easy way out is to simply remove the brake frames them and bin them, and ignore the absence of brake work. The more interesting is to try and correct the manufacturing errors and position the brackets and rods nearer to the prototype, and, the point of all this, get those EM gauge wheels to fit.



The distorted rod.

The second problem was that the electrical pick-ups fouled the EM wheel hubs. EM wheels from Ultrascale have a large central axle hub to compensate for the increase in gauge. The pick-up wipers now foul this and stop the axle bearings from seating properly, and the bogie plate cover cannot be put back because the gear fouls the cover (those offending brake rods having been removed). There are apparently no issues with the previous bogie design, which I think had molded brake components. Again, there are 2 choices. Move the pick-up out of the way, which makes it visible, or modify the pick-up to accommodate the depth of the hub spacer.


As usual with most of my projects these days, not for the squeamish or faint of heart, as cutting, shutting and butchery is required, with the usual risk of having to get replacements parts because of measure once, cut twice.  These days I look thrice, measure twice and cut once. 


The following describes what I did:


1. The bogie brake work. I removed the brake assembly units by cutting through the glue joints and the central locating pin. The end lugs can be cut off if the glue is stubborn (they go anyway). Cutting through the rods gave 3 pieces per side – 2 ends and one middle piece. The top rods were removed from the end pieces. The length of the bottom rods was reduced so that they ended at the outside edge of the axle box bottom. Where the middle section of the original assembly had been pinned and glued on the underside of the  frame I made a channel using a square needle file so that when glued the bottom of the new middle piece was flush with the frame. I also bent the ends in slightly to show more brake shoe between the frames. The insides of the frames were reduced in thickness at the ends using a larger square needle file, the corresponding outside face of the brake pad was also reduced in thickness resulting in a half-lap joint with the inside of the frame. This reduction in thickness enables the brake rod to be glued to the inside bottom edge of the frame, ending at the slope of the axle box frame. Not visible from normal viewing angles. The lug on the brake block or frame (depending on how stubborn the glue was) was cut off. I’d recommend CAA for the putting the bits back on. Of course, the rods could just be cut out where the wheels go in situ, assuming it had been put on correctly in the first place (I did this first, all the bits fell off, which raises some questions about glue quality), but in my case this would have still left them too low and doesn't correct the design faux pas at the frame ends.



Brake rods on inside of frames prevent fitting of EM gauge wheel set.




Disassembled frame and brakes/rods. Distorted brake/rods on left





Frame modifications.





Brake rod modifications.
 
2. The pick-ups. A sharp tug down and to the side frees the lugs of the bogie assembly and enables it to be pulled out from the chassis. The screw holding each wiper onto the locating pips on the bogie chassis was removed and I took approximately 4.5mm off each end of the wiper using a pair of tin snips. I bent over the ends to make them flatter to the back of the wheel using a small pair of smooth pliers, and rounded the corners using a small needle file. I gave the contact surface a polish with # 600 wet and dry paper. I then reattached the wipers, bent them out to accommodate the increase in gauge and that was all it took. The back of Ultrascale diesel wheels is now solid, so no really precise measurements are required so long as the wipers are shorter than the axle spacer.
  
©Nigel C. Phillips 2013



____________________
©Nigel C. Phillips
Back To Top PMQuoteReply

 Posted: Fri Nov 8th, 2013 03:52 pm
PMQuoteReply
link to this 2nd post
Brossard
Member


Joined: Sat Jul 23rd, 2011
Location: Brossard, Quebec Canada
Posts: 2959
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

Nothing EVER seems to go as planned when doing things like this.  Every step becomes a problem that has to be solved.  Sometimes we get there, other times we have to have a rethink and start over, as I have been doing.

John



____________________
John

Back To Top PMQuoteReply

 Posted: Fri Nov 8th, 2013 04:14 pm
PMQuoteReply
link to this 3rd post
BCDR
Moderator


Joined: Sat Oct 19th, 2013
Location: Reston, Virginia USA
Posts: 3139
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

Hi John,
Photo's now included.
Nigel



____________________
©Nigel C. Phillips
Back To Top PMQuoteReply

 Posted: Fri Nov 8th, 2013 05:15 pm
PMQuoteReply
link to this 4th post
Brossard
Member


Joined: Sat Jul 23rd, 2011
Location: Brossard, Quebec Canada
Posts: 2959
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

Thanks for including the pictures.  I may get around to converting my 20 at some point.  A bit of curiosity, you seem to be using Ultrascale wheels a lot.  Do you think that the RTR wheels are wrong?

John



____________________
John

Back To Top PMQuoteReply

 Posted: Fri Nov 8th, 2013 06:32 pm
PMQuoteReply
link to this 5th post
BCDR
Moderator


Joined: Sat Oct 19th, 2013
Location: Reston, Virginia USA
Posts: 3139
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

Hi John,

RTR and Ultrascale have the same wheel diameter (and the same as the protoype).

Ultrascale are thinner (2.32mm vs 2.8mm) and have a smaller diameter over the flange (15.4mm vs 15.97mm). 

I don't have the run-out tools to determine profile.

Ultrascale have 2 holes on the disc, RTR none. Couldn't find any prototypes to compare. 

That difference in thickness is important (nearly 1mm for both wheels), it's a bit of tight even with the brake rods removed. I would hesitate trying to do this using the original wheels and a new axle, or converting to S4/P4.  

The alternative to removing the brake rods would to simply thin down the bogie frames, or to cut off the frames and move them out. I have no idea how much Bachmann compromised on the frame dimensions, it would be interesting to find out. The frame thickness is 3.4mm, corresponding to a 10" thickness in real life. I would have thought that was rather excessive. 

Nigel



____________________
©Nigel C. Phillips
Back To Top PMQuoteReply

 Posted: Fri Nov 8th, 2013 07:02 pm
PMQuoteReply
link to this 6th post
Brossard
Member


Joined: Sat Jul 23rd, 2011
Location: Brossard, Quebec Canada
Posts: 2959
Status: 
Offline

My photos:
view photos in Gallery
view photos as slides

Excellent points Nigel.  I just measured some coach wheels.  Bachmann are, as you found, 2.8mm wide at the tyre, Gibson are 2.16mm - quite a huge difference (2 holes in the disc as well).  EMGS spec is 2.28mm.  Bachmann's width is to cater for the Hornby and Peco generous point flangeways and to prevent wheels from falling into the chasm at the nose of the vee.  Finescale wheels don't do well on RTP points.

I think it's a question of empirical determinism, for EM at any rate.  For P4/S4 there's no question that fine wheels are needed.

John

 



____________________
John

Back To Top PMQuoteReply

This is topic ID = 11910     Current time is 04:48 pm  
You are here:  Your Model Railway Club > More Practical Help > Members Projects > On Members Workbenches. > Nigel's Workbench 8 November 2013
You can type a quick reply to this topic here. Click in the box below to begin.

Or to reply to an individual post, or to include images, attachments and formatted text,
click the Quote or Reply buttons on each post above.

To start a new topic in this forum, click the Start New Topic button below.
To start a new topic in a different forum, click the Forum Jump drop-down list below.
Start New Topic


Back to top of page

           
15 Most Recent Topics

Problems with this web site? Please contact the Webmaster.

All material submitted to this web site is the responsibility of the respective contributor. By submitting material to this web site you acknowledge that you accept full responsibility for the material submitted.
Unless stated otherwise, all the material displayed on this web site, including all text, photographs, drawings and other images, is copyright and the property of the respective contributor. Registered members are welcome to use it for their own personal non-commercial modelmaking purposes. It must not be reproduced or re-published elsewhere in any form, or used commercially, without first obtaining the owner's express permission.
The owner of this web site may edit, modify or remove any content at any time without giving notice or reason.    © 2008

                 

Recent Topics Back to top of page

Powered by UltraBB 1.15 Copyright © 2007-2011 by Jim Hale and Data 1 Systems. Page design copyright © 2008-2013 Martin Wynne. Photo gallery copyright © 2009 David Williams.