MDC/ROUNDHOUSE locomotive rebuilds

[modelsof1900]

Great modelling! Looks very good!

[cnrglen]

Thanks guys. I'm quite happy with how it turned out. I'm still learning the ins and outs of soldering.

I'm starting to concentrate on the pilot

I made a set of steps by cutting down (width-wise) a stair kit from evergreen styrene. I'm wondering if I should make a pilot deck like I did on the CP engine or should I just glue the steps directly to the pilot? I'm also wondering if I should glue the steps to the pilot or to the underside of the boiler walkway, since I will need to take the engine apart from time to time?

[Sumpter250]

I would guess that your primary "engine work", would be on the frame . . . . . my thought would be to fasten the ladders to the underside of the boiler walkways, as this would be the thing set aside while the work was going on, and there would be less risk of breaking the ladders off.

[cnrglen]

Thanks for the feedback. I've decided not to add the pilot deck material, it doesn't look like the prototype had it. I'll fit the steps between the walkway and the pilot. Right now this project has slowed down a bit due to some other projects making their way onto my plate but I will be plugging along all the same.

[cnrglen]

Well after finishing off several other project/distractions I'm back at these.
I few months ago I managed to find another MDC 4-6-0 with a working mechanism and intact side rods:

It looked pretty ugly but it ran surprisingly good on my test track. The previous owner put some improvements into it.

After taking off the boiler/cab I checked it out for differences, I found two things that were modified. One was to make the tender pickup through the drawbar. The original relied on the red wire from the motor to be threaded through the cab and attached to the tender underframe with a screw. This worked out well for me since I was no longer using the original tender and the wire/screw wouldn't work well.

The other Mod was adding simple wipers to the drivers for better pickup. This were just some stiff wire formed to run from the driver retainer plate screws to the rims of the front and rear drivers.

I decided to use the motor/ gear assembly and the drivers/siderods of the working engine for the swap. that way all the gears would remain the same and the rods wouldn't have to be removed from the drivers. Everything would continue to match.

I decided to keep the original frame though, since I had added the details to the front. But to make the drawbar from the other chassis work I had to drill out the original screw hole so that the insulating spacers would fit.

After that it was just a matter of re-assembling the mechanism and testing it.

I did have to modify the tender just a bit to accommodate the new drawbar pin as well as clean any electrical pickup surfaces such as wheels, truck and frame bolsters.

Perhaps the hardest part of the operation was something I hadn't planned on. Changing the tender' electrical pick up also meant that the screw and wire needed a relief routered out of the boiler casting's rear it took quite a bit of effort with both my drill press and dremel tool to remove enough material to prevent shorts.

[cnrglen]

Well I finished re-assembling the engine and testing it on my 3' dc test track. It runs quite well, a bit noisy due to the gears but it feels like it will out-pull many of todays engines due to it's weight and drive.


Now I can get back to the CNR 2-8-0. I figure I can use some of these improvements into that project as well.

[cnrglen]

Finally I can get back to working on the last of these engines (unless I find more)
About a month ago I gave the CPR 4-6-0 to a fellow modeller to see about adding a DCC decoder into it. He suggested to leave it as is because I had already painted and weather it as well as the fine gear mesh would make shimming the motor to isolate it impractical. I do, however plan to Decoder the 2-8-0 and started to look into the drivetrain over this past weekend.

This is the frame from the 4-6-0 that I got the drive out of.

this is the frame from the 2-8-0. The 4-6-0 is an older version, using screws to connect the main and side rods. The 2-8-0 is a newer version using plastic pins to do the same. You will also notice that the old frame has a slot for mounting the motor/compound gear assembly but the new frame only has a single hole.

The 2-8-0 that I bought was missing the motor/compound gear assembly but I managed to get the assembly out of the parts engine. However even though the gears are the same the mount is different. It appears as though it makes the gear ride too low, jamming the mechanism. But this might be a blessing in disguise as I have to add a styrene shim under the assembly anyway to isolate the motor for dcc.
I'll be checking with my DCC friend over the weekend and continue from there.

[BR60103]

As a non-DCC user talking,
Couldn't you isolate the second motor brush? I'm not sure about that configuration, but it should be possible without having to isolate the whole motor.

[cnrglen]

I'm not sure , David. I'll have to check that with my DCC guy.
However, I did manage to mount the motor/compound gear assembly tonight.

I used a piece of .03" or .7mm (for us Canadians) of styrene to shim the assembly up to the point where everything meshed smoothly and there was acceptable gear lash between the compound and drive gear.

I ran it carefully for a bit in both directions and didn't detect any binding.

to fully isolate the motor from the chassis I had to use a plastic Kadee coupler mounting screw to attach the compound gear mount to the frame. I hope that the plastic screw is up to the task in the long term.

[sailormatlac]

Glen, I didn't see the completed CPR 4-6-0. She's lovely and that tender of yours gave it a very CPR look. I'm looking forward for the 2-8-0.

Matt

[cnrglen]

Thanks Matt. I think this one will turn out better than the CPR engine, as I've learned a few thing since then.
I did talk to my DCC guy yesterday and he told me I'm on the right track this time and game me a few suggestions to complete it's conversion before the decoder goes in. He also said that he would take care of the hookups to the motor so I don't have to worry about the wires on the motor.
Today I started work on the drawbar.

I drilled the rear drawbar hole out so I could slide a 1/8" styrene rod through, which I reamed out to fit the drawbar screw.

I then made a spacer on the bottom on the frame from 1/4" styrene rod. My drawbar kit came with a bushing the fits the top.


Then I assembled the drawbar together. It's completely isolated from the frame. When it's time for Final assembly I'll use a dab of locktite on the nut to keep it from backing off.

One thing that was suggested from my DCC guy was the possibility of arcing from the brass wheels to the motor or motor mount. Since DCC runs at 12v+ to the chances of electrical arcing are greater than with DC.

So it was suggested that I use some varnish or something similar to paint the lower sides of the motor frame and the mount as insurance. I'll get to that next.

The last thing I did today was to ad the coupler cut bar in the front. When I give the engine to the installer I want the frame pretty much done and painted to I don't have to mess with it later when there's a decoder in there.

[cnrglen]

I finished off the chassis last night so it can go off to get a decoder installed.

I painted the frame, cylinders, yoke and drivers with flat black. I later cleaned off electrically important areas like the driver wheels with some Lacquer thinner. Like the other engines I used some Blacken-It on the rods.

I ended up using some testors semi-gloss clear on the sides on the motor and it's mount. It's a lacquer base so a bit tougher than enamel. The last thing I did before painting was to drill and tap a new screw hole in the frame between the cylinder casting and the yoke. this will be the second electrical pick up for the decoder.
Since I'm still using the open frame motor I have an older Digitrax decoder , a DH142 or a DZ123 that I will be using. Each has a 1.5 Amp rating with a 2 amp surge which should handle this application.

[sailormatlac]

Interesting work Glen. Do the DCD guy expect good performance from the original open frame motor? I have an old Prairie kit at one I never dared to complete and I'm curious to see if it could be OK not to remotor it.

Matt

[cnrglen]

I'm not sure about performance. I do know that the open frame motors in MDC steamers were fairly high quality in their day. They at least are 5 pole motors and not the ancient 3 poles that early brass engine might have. You do have to realize that they will have a higher current draw when starting, so you have to pick decoders with a higher amperage rating. They also might not crawl like the modern skewed motors do.

[sailormatlac]

I'm not sure about performance. I do know that the open frame motors in MDC steamers were fairly high quality in their day. They at least are 5 pole motors and not the ancient 3 poles that early brass engine might have. You do have to realize that they will have a higher current draw when starting, so you have to pick decoders with a higher amperage rating. They also might not crawl like the modern skewed motors do.

Thanks Glen. I also have MDC can motor. It seems to perform decently. It could be an option too.

Matt