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Converting the Bachmann 3F to EM - Kit Bashing - More Practical Help - Your Model Railway Club
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 Posted: Fri Dec 5th, 2014 11:17 pm
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Brossard
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I've been itching to do this for some time.  I do like the idea of keeping the RTR mechanism when converting to EM.  However, if I were to add up what I spent, it would probably have been less than if I had gone for a replacement chassis.  I do like Brassmasters' engineering though.

So, what have got?

Well, there's the already excellent Bachmann 3F:




Then there's the marvellous Easi Chas kit:




Lovely looking etches for the loco and tender.  The Bachmann tender is a bit sparse underneath.  Brassmasters' claim that no soldering is required.

Finally, wheels:




This set was designed specifically for the Easi Chas.  There's a set from Gibson too, but what swayed me in favour of Ultrascale was the brass gear that is included.

You can learn more and see pictures here:

http://www.brassmasters.co.uk/3F_EasiChas.htm

Bachmann really threw a wrench in the works when they started using 2.17mm (???!!!) axles.

Let t'battle commence!

John



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 Posted: Sat Dec 6th, 2014 12:12 am
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Brossard
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Right, first stage is to dismantle the loco (and, as the instructions say, void the warranty):







I actually have been reading the instructions and, as recommended, I've been putting screws into baggies.

Correction, driver axles are 2mm dia - don't know where I got that strange number.

John



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 Posted: Sat Dec 6th, 2014 06:54 pm
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Brossard
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Yesterday, I got some of the main parts done.  This entailed quite a bit of bending with no requirement for solder (although I did reinforce some bends).




You can see the new mainframes in the center.  These are designed to slip over the old frames with a space between them.  The brass bearings slip into the hornguides and did require some light filing of the guides to remove the etch cusp.  The pin at the top of the guide will take a coil spring later.

There is also a new keeper which slips on the frames.  The whole is secured to the old frame with the existing screws.  I did ream the screw holes to get the screws to go in smoothly.

The instructions recommend a trial fit at this point to ensure the bearings slide smoothly:




The bearings need to slide into the cutout in the spring...they do.:doublethumb

John

 



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 Posted: Sat Dec 6th, 2014 08:33 pm
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Brossard
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The next job was to set up the drivers.  I decided to chemically blacken them (voiding the Ultrascale warranty) using Carr's fluid for steel and whitemetal.




I know Derek will be interested in this.  Crank pins are threaded and screw into the backs of the wheels.  The instructions recommend putting a very slight chamfer (break edge) on the axle ends and a chamfer on the inside of the wheels (using a 1/4" drill twirled betwixt finger and thumb).  This eases the axles insertion.  It was a fairly simple matter to push and twist to get the wheels on the axles.  The bearings and drive gear have to be installed before completing the axle.  For EM, it is recommended that a single washer be added to the front and rear wheels.  The crankpins have a 90 degree right hand lead (common to most locos, but should be checked).  Quartering was by eye and confirmed by squinting through the wheel to ensure that spokes were in line. 

The wheelsets rolled through my test point freely and looked square.  One fear with these plastic centered wheels, as Derek will attest, is that it is so easy to distort them.

John



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 Posted: Sat Dec 6th, 2014 09:23 pm
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Brossard
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Time to check that everything works together.  The springs were dropped onto their pins and wheelsets were installed (a fiddle to get everything lined up!).  A run over the test point confirmed all is good.  The drive gear was secured to the axle with Loctite 603 (I got mine from C&L - not cheap!).  I then put alligator clips on the motor contacts and applied power - whoo hoo!




This is all going too well. :roll:

John

 



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 Posted: Sun Dec 7th, 2014 12:05 am
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Brossard
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The kit gives you the option to re-use the Bachmann rods or to make up finer ones.  I chose the latter.




This shows the rods on the etch, you can have fluted or plain.  My model has plain rods but 3205 had fluted ones.  I should add that the kit comes with DVD containing the instructions with colour pictures and a section on the prototype.  There are numerous pictures of the loco in LMS and BR guise and 3205 is one of them.

So, I need fluted rods - my excuse anyway.

Rods are double thickness and soldered together.  A sharp toothpick aligns one end while some self locking tweezers hold the other.  I hold the rods with some angled tweezers while fluxing and allowing solder to wick between the rod halves.  Not too difficult.

There are boss overlays to be soldered on to thicken the rod bosses - a fiddle indeed.




This shows the rods complete. These are more prototypical in that the articulation actually works.  The rods are secured by soldering some 0.8mm (0.032") rod to the back of rod. (Sorry Derek, no rivets) To prevent solder wicking, I put oil on where the rod goes through.  The process is a bit fraught but all is well (surprisingly).  My first thought was to use a 16BA screw and nut - it would have been safer but the screw head is oversize.

Onwards and upwards.

John



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 Posted: Sun Dec 7th, 2014 12:41 am
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I'm loving this one, John.

Nice clear piccies, as well.  :thumbs

One thing that interests me though, is having the threaded part of the screw as part of the bearing set for the crank pins.

I worry that the threads will wear away, leaving the shank as a loose fit.

Has it ever been an issue?



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 Posted: Sun Dec 7th, 2014 01:03 am
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Glad you're liking this Max.

Threaded crank pins.  I haven't used them before but they seem to be widely used on these and Gibson wheels, although G are steel IIRC.  Even Markits now have a deluxe crankpin that is threaded.  My preference for Markits has been the plain pins that require the rod to be soldered in place.  In fact Markits pins can be used on Ultrascale and Gibson wheels if desired.

I'll show some pictures when I get there but the pins have a washer/spacer, bush which the rod boss fits over and nut.  The nut will get some threadlock Loctite when I'm happy.  I suppose one advantage of threaded pins is that the rods can be removed fairly easily if necessary.

I think to answer your question, the bush protects the threads from wear.

John



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 Posted: Sun Dec 7th, 2014 01:10 am
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Thanks, John.  I knew that you would have it in hand.  :cool:



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 Posted: Sun Dec 7th, 2014 02:21 pm
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Super stuff John,Great looking chassis kit and those wheels are excellent.
One thing I have learned with plastic wheels and threaded crankpins and something I will put into practice for the future.
When screwing the crankpins into the back of the wheels a tiny dab of glue to the last couple of threads in front of the screw head will make sure the pins stay fixed.
I have found that at least with the Gibson crankpin nuts when tightend they can unscrew the crankpins at the wheel back.
Looks like this baby is behaving on assembly John.
Derek.

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 Posted: Sun Dec 7th, 2014 04:30 pm
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Brossard
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Thanks for the tip on the crankpins Derek, I will do that.

John



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 Posted: Sun Dec 7th, 2014 11:48 pm
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Today, I fitted the balance weights to the wheels.

I also fit the coupling rods and found that the optimum hole is 1.5mm.  I had to tweak the quartering a bit but after some futzing and fiddling, it all came together.

In order to check out the running with rods installed, I wanted to remove the motor and worm gear.  Here, I came a cropper.  The one screw holding the worm gear cover is VERY tight and I stripped it.  I drilled it out and fortunately found a screw that will do in my spares box (never throw a screw away).

After confirming that the chassis runs smoothly, I trimmed off the pins and filed the ends down.

I put the chassis on my rolling road and applied power.  It runs very nicely indeed, quite happy. :cool:




I think the next job is to paint the frames and keeper.

One thing I'm chagrined about is, that now I've done this, I can't see any reason not to use Markits wheels, which aren't mentioned by Brassmasters' - modelling snobbishness I wonder?:hmm

John



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 Posted: Mon Dec 8th, 2014 10:33 am
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Well done John,Nice clean looking job.
I guess Markits get overlooked because of the axle diameter.Must confess though those ultra scale wheels do look good.Your chemical job has enhanced them as well.
Cheers,
Derek.

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 Posted: Mon Dec 8th, 2014 04:22 pm
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Brossard
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Hi Derek.  Yes, the chemical black does make a good job.  US wheels do look good, but I get nervous when quartering is held by a friction fit.

Although the Bachmann wheels had 2mm axles, the US wheels are 1/8" dia and just fit nicely in the Mazak cutouts (sized for the brass bearings).  As I say, no reason I can see for not using Markits.  I plan to get the 4F kit when it comes out in January and have a Markits 4F wheel set already - so we'll see.

John



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 Posted: Mon Dec 8th, 2014 07:37 pm
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This morning I soldered the ashpan to the keeper.  I also made wipers as recommended by the lads at Brassmasters':




I've always thought this method is kind of neat but, whenever I've tried a pigs' ear usually resulted.  The trick is to clamp the small screwdriver in a vice and use two hands to wrap the wire tightly around the shaft.  Use the pliers to help you pull the first coil tight.  Wind the wire as many times as you like but 4 is probably enough.  Note the coils are handed.  I use Rosin flux with 60/40 solder and my iron is set to 340C.

The wipers are soldered to a piece of PCB with a slot cut.

I have a large selection of various wires in brass, NS and PB.  It's not dear and I think it does pay to have these things to hand.

The frames and keeper were washed and have now been sprayed with grey primer.

John



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 Posted: Mon Dec 8th, 2014 09:28 pm
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With the loco parts drying in the paint shop, I turned my attention to the tender.




You can see the inside frames.  There are double thickness slots for the axles.  Suspension is CSB (Continuous Springy Beam).  The bearings are made by folding the NS to double thickness, making sure the holes line up.  I had to ream a couple of them where I slipped up.  A hole is made at the fold of the bearing for the steel wire to go through.  I soldered the edges of the bearings to make sure there was no gap for the very thin wire to slip through since I want the bearings to sit square.  You can just see small "ears" folded out from the frames.  The wire slides through holes in these and the brearings so that the three bearings are suspended on the wire.  When the wheels are installed, they will be free to move up and down in the slots.  Clever, n'est pas?

I didn't complete the wheels because I only want to do that once.  I will paint the frames next.

There seem to be parts to totally replace the tender deck and sides.  I'm not too offended by the Bachmann offering except for the brakes being molded to the sides :It's a no no.  I'll need to have a think.

John



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 Posted: Wed Dec 10th, 2014 10:50 pm
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I took the tender in hand and installed the wheels.  A bit of a fiddle to thread the spring wire through the bearings but not too difficult.




Next a trial fit of the body:




Brakes are next.

John



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 Posted: Thu Dec 11th, 2014 12:55 am
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Brossard
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I've put the brakes on:







The only real trial is to make sure the brakes don't touch the wheels, recognizing that they do move up and down.

John



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 Posted: Fri Dec 12th, 2014 11:24 pm
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Brossard
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Frustration reigns!  I put the frames, wheels and keeper in the loco today and gave it a run.  After a few revs, to my dismay it locked up.  In the course of trying to loosen things, a crankpin failed!

So, I see two issues:

1) Quartering drifted and

2) Threaded crankpins are by their nature weak since the threads are a stress raiser.

So, disassembled everything, removing the wheels from their axles, and then, removed all the crankpins.

I got out my trusty Romford crankpins.  The wheels needed reaming the Romford pins but when the hole is large enough the pins will self tap into the wheels.

Checking the rod bosses with the Romford pins, they are large, so I'll re-use the US bushes.

Next, I gave some thought to the wheels.  I mentioned earlier that I was skeptical about quartering being held by friction.

I thought I'd try something that has been discussed elsewhere - rolling the ends of the axles between two files, on the flat of one and the edge of another.  This puts a fine knurl on the axle.

I mounted the wheels on the axles, applying some Loctite 603 (sleeve retainer) to one side.  Loctite really needs to be between two metals but it expands in the absence of air so I should see some benefit - if I don't blow out the wheels.

For the other side I put the wheels on more or less normally and set the quartering - aligning spokes on either side.

All seems well.



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 Posted: Sat Dec 13th, 2014 01:01 am
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Thats a pain John.I agree that plain axles need knurling from my experience.I must confess I don't like those flimsy Gibson crankpin screws.Its all very well being scale size but some strength is needed as well.
Today I was getting in some lathe practice.Turning track gauges.Some with checkrail slots others with just Back to Back slots.Their gauge is spot on.
Best of luck with the next trial run.
Derek.

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