A Baldwin DT6-6-2000 in HO – Test Print Part 11

In last week’s post, which you can find here, I shared with you the first images of the new HO Scale Baldwin DT6-6-2000.  I’ve now had some time to test it out and this week I’ll share with you some of the results.

As you may remember the new 3D printed shell fits on top of a Bowser chassis taken from an Alco C-630, as shown below.  The chassis is fairly standard and has two mounting holes at each end.  The shell fitted perfectly over the chassis once I’d poked the wires up inside, with the exception of the lugs at each end.  They were about 1/2 mm longer than expected, or rather the shell was 1/2 mm shorter than drawn.  This can happen and is called ‘shrinkage’.  When a 3D print, at least one printed in this material, comes out of the printer it’s heated to make all the support material liquefy and run off, then it’s left to cool.  This is a very precise system and shrinkage can occur if the timing of the heating and cooling is not spot on.  All the prints do it but the difference is normally negligible.  But, given the size of the print, 1/2mm shrinkage over the whole length is very acceptable, and I’ve adjusted the 3D model to allow for this.

The most disappointing thing was the locating hole for the connecting bolt.  If you remember I designed the shell to have a hexagonal hole to receive a nut that could be glued in place, as shown in the image below.  Sadly I didn’t allow enough tolerance; it’s too tight a fit for the nut.  For this particular shell I can file down the nut to make it fit, but for the actual shell that will be for sale I’ve made the hexagonal hole bigger.

The other hole close by is the off-center mount for the tiny motor that will power the Kadee uncoupler.  This was a tight fit but went in exactly as planned, although I’ve now added a little more tolerance.  I think the reason for the tight fit here was 3D print residue inside the hole, but it’s nearly impossible to get into the hole from inside the shell to clean it out so increasing the size was easier.

My cable loops also worked very well; using a pair of tweezers I was able to thread the wires through the loops which will keep them clear of the drive shafts.  I also fitted an LED which will be for the headlight; I used a yellow one just so it shows up in the photo.  The final one will be clear and emit a warm white light.

From the front the LED pokes though the 3D printed hole in the headlight and allows a lens to be placed in front if required.

The coupling didn’t fit perfectly the first time as I managed to get the hole for the Kadee in the wrong place; possibly I originally measured the wrong coupling? However, I was able to trim the coupling so it slid back a little further, and secured it with a screw.  It works well and is the right height.  I haven’t tried it yet with the motor to make it powered.

The cab interiors and horns were easily snipped off their sprew.  The tail on the bottom of the cab interiors allows them to be held with tweezers when fitting inside the shell.

The horns fitted right in, but having them loose allows for different horns to be fitted.  I’ll probably add different horns to the sprew, giving a choice

The cabs fitted perfectly as well; below you can see one cab fitted.  The recess for the cab light is just about visible where the other cab goes.  I haven’t tested these but as they’re so small I have no doubt they will fit.

With both cabs fitted you can see the backs of the cabs form the same width as the channel in the shell, allowing the chassis to fit in.

The crew are now visible through the window.  The N Scale version also has this, but in HO it will be much more visible.

Of course, test fitting is great, and I’m pleased I did it so I could fix the few issues that arose, but the real test is how does it run?  Last week I took the locomotive down to the workshop and ran it on a HO layout we’re currently building for a customer and it ran perfectly.  I managed to get a few quick videos.

For the test I simply fitted a basic DCC decoder without any setup and ran it.  This also has the 3D printed truck centers and gears so the trucks are rotated the right way for a DT6-6-2000.

The next stage now is for the brass to be drawn and etched and to test fit that, but with the 3D print issues resolved and the shrinkage accounted for on this scale, I think you’ll agree that this locomotive is very nearly ready to be made available.

A Baldwin DT6-6-2000 in HO – Test Print Part 10

It’s been two weeks since my last post but I’ve not been idle.  I finished the modeling for the HO Scale Baldwin DT6-6-2000 and sent the file off to be test printed at Shapeways.  And last Friday the 3D model arrived, so this week I’ll share with you some images of how it came out.

The test print was ordered in Shapeways’ Smooth Fine Detail plastic, which is an acrylic.  This is the material with the finest detail and allows for the highest accuracy with parts.  It’s the material I use for just about all my locomotive shells and parts.  3D prints always need to be cleaned when they arrive as they have residue on them from the print process.  I normally do this by soaking the parts in Goo Gone, but this time I used White Spirit.  The White Spirit I use has no other chemical in it that will affect the parts; it’s always worth checking before you use it to soak the 3D printed part.  After a 24-hour soak, followed by a wash off under the tap, all the parts turn white; this takes about half an hour.  I then leave them overnight and any remaining residue will turn into a white powder which can be brushed off. I use a brush in a Dremel tool; this is the same method I used on my O scale tenders which you can read about here.  The big difference between the O scale tenders and these models is the quality of the print.  Now that I can specify the orientation of the print I can ensure they are printed the right way up, which gives a smooth surface on top and down the sides.  If you’re wondering why I don’t use White Spirit to clean all my prints, it’s because of the fumes.  Indoors White Spirit lingers for days, Goo Gone doesn’t, but in this instance I didn’t have enough Goo Gone to hand for the size of the model.

The test print was for the whole kit; shell, truck centers, truck gears, crew and horns.

The truck gears come in a cage to keep the cost down and stop them from getting lost.

The two cab interiors with crew are attached to each other and the horns are attached to the linked piece.  These can easily be cut off.

I have to say I’m very pleased with the print. The top and roof are very smooth and the details are crisp.  Being an N Scale modeler it also seems massive!

I’m also very pleased that it’s so robust.  The N Scale version was designed almost on the minimal limit of material thickness to ensure it fitted over the donor chassis without making it wider than the real locomotive.  For the HO model, I left the thickness the same, meaning when it’s scaled up to HO the material is almost twice as thick making it much stronger.  The shell doesn’t flex when squeezed.  Given the weight of the chassis and the fact that the trainload will be conducted through the coupling, which is attached to the shell not the chassis, having a strong shell was important

Most of the detail was already on my N Scale version but it really pops out in HO.

Inside the shell, you can see the loops I printed into the shell roof for my wire runs.  Getting the wires into them will be tricky but worth it, as it’ll keep everything tidy and clear of the drive shafts and rotating truck towers.

The underside of the pilot is a little rougher, as this was the underside of the print, but you can clearly see the bolt hole for mounting the chassis, Kadee Coupling mount hole, and the off-center hole for the powered coupling motor.

The detail on the nose and pilot was again on the N scale version, but it has come out so well.  The modeled lever for operating the coupling often gets overlooked or broken on the N Scale version, but here it is clear and strong.

All the detail on the top is clear including the lifting eyes, radiators, exhausts, and riveted plates.

The chassis, as you may remember from my previous posts, had already had one of its trucks rotated by using the new 3D printed truck centers and gears.  Now both are done.

The right-hand truck was the first one done, but it hasn’t been cleaned in White Spirit or Goo Gone so it’s still opaque, as are the gears.

The left-hand truck is all white after cleaning but this has no effect on the running.  Note the printed gears and black original gears are positioned differently in each truck but again this has no effect on the running.  The holes for the gear spindles did need to be reamed out with a drill to allow the gears to spin.

The shell is now fixed onto the chassis and ready for a test run.  I only have a foot and a half of HO track at home so it’ll have to wait until I take it to the workshop tomorrow for a proper test, but I’ll get some video.

I still have the other parts to test fit such as the cabs and horns, but I’ll get that done this week.

The next task is to finish drawing the brass parts and get them ready for etching.  Once they come back, and assuming everything fits, the kit will be made available to buy followed by the various different versions of this great locomotive.

A Baldwin DT6-6-2000 in HO – Body Shell Part 9

Again this week’s post will be short as I haven’t had a great deal of time to work on any of the other current projects, but I did make some progress on the HO Baldwin DT-6-2000 body shell.

As this is a HO model, some of the details that were molded into the N scale body can now be made from brass, giving the larger model more detail.  For example on the front of the loco, under the marker lights, is a grab iron which is now made from brass.

The grab irons which run up the side of the main body have also been widened.  On the N scale model these were molded in, but when converted to brass, as shown below in a picture from a few weeks ago, I thought they looked too narrow.

I’ve now widened them and I think proportionally they look much better.  Also on the image below, you can see I’ve reduced the size of the windscreen wiper as it was a bit too chunky before, making it look out of scale.

The last big addition for this week is the cab lights; for this I’m going to use a tiny surface mount LED.  The LED itself only measures 0.9mm by 1.6mm and is 0.46mm thick.  Luckily DCC Concepts sell these pre-wired as shown below.

In the view below, which is a section through the cab, you can see the LED in the roof.  I’ve designed a recess for the LED to fit into, and a route for the wires to pass through, keeping them clear of everything else.

The route for the cables positions them in the center of the shell directly over the DCC decoder and circuit board.  The wires are also tiny so they and the LED can be glued into the recess to prevent them from moving.

Looking at the model for the HO scale, I keep finding little bits to re-design or change, but I think I’m now very close to ordering the first test print.  Having studied a lot of the real locomotives in photos, I realized that different railroads had different features which were quite prominent.  So as well as changing the shell to make it available as a Pennsylvania Railroad RT-624 I’ll also change it into a Trona Railway locomotive, for numbers 50 & 51, and maybe more if requested.  Also for the Pensy, it’ll be available with the phone antenna, and in the later version, without.

Now it’s back to the drawing board to get it finished.

A Baldwin DT6-6-2000 in HO – Body Shell Part 8

This week will be a short post as I haven’t had a great deal of time to work on any of the current projects, but I did make some progress on the HO Baldwin DT-6-2000 body shell.

The shell from the outside, as shown below, is complete, and this is mostly due to the fact it was already drawn for the N Scale version.  The work I’ve been concentrating on is inside the shell.

Inside the shell, as well as the chassis, are lots of wires and these are often forgotten about when it comes to planning an install of a DCC decoder into a locomotive.  This loco will have sound, lights, working couplings, and maybe a stay alive capacitor as well, which will create a lot more wires and take up space.  Fortunately, being a HO scale loco there’s a good amount of space inside, but the wires can still be messy.  It can be really frustrating to get everything fitted only to find the shell won’t push down that last 1mm because of the clump of wires in the way!  So I’ve created loops for the wires to pass through which should hold them all in the right place and keep them tidy.

In the image below I’ve taken a section through the 3D model and you can see the wires running from the headlights and coupling motor up inside the shell and along the underside.

Each nose section has two loops for the coupling motor wires.  These may prove tricky to feed through, but I think it’ll be worth it and will prevent the wires from being visible through the mesh grill. It’ll also keep them away from the truck towers.

The wires then pass through three, or four, if required, loops on the underside of the shell.  I’ve allowed for more wire in case more things are added, such as number board lights or speaker wires.  The black is the common wire with the reds powering a headlight and coupling motor each.

In the middle of the loco is the cab, and the cab interior will be the same part used for the N Scale version.  My drivers, Bert and Ernie, will also be used again, one for each side.  Normally you’d be able to see through the cab to the other side, but there’ll be a DCC decoder and circuit board in the way, as represented by the green block.

Having the crew and cab interior, I think, greatly improves the appearance of the loco. I may even put a cable path in to allow a surface-mounted LED to be fitted in the cab roof.  Several HO scale locos I’ve come across have cab lights that automatically come on when the loco is not moving.

The shell is now very close to being finished, and I will get a 3D printed test model soon. There’s just a few more details I want to add and some checks to make, but then I think it’ll be ready.  I still need to draw the brass etching tool so that it can be sent off to the etchers, and I may draw in a compartment for the speaker;  I’m planning on fitting a new ESU V5 Loksound Decoder; these come with a small but powerful speaker and having a location for it to fit into will again make things tidy and easy to build.  I’ll share the final 3D model with you when complete.

Replacement Atlas N Scale Motor Universal Connectors

Atlas make lots of railroad locomotives and rolling stock in a variety of scales, and I have several of them because of their quality and they enable me to use the chassis for other builds.  In particular, I use their C-628 and C-630 N Scale models as the donor chassis for my N Scale DT6-6-2000 and RT624 kits.  The chassis has been revised over the years to make improvements, but one version has an issue with the driveshaft coupling to the motor failing.  In this post I’ll share with you my fix.

Below are a pair of Monon C-628s; the rear one is actually a dummy using my 3D printed chassis kit.

The powered chassis is a standard design, used on many of Atlas’s N scale locos, with a central motor and flywheels.

The chassis is held together by the two screws near each end, and the fuel tank, which clips over both chassis halves.

Inside at each end is a driveshaft linking the flywheel and the worm gear, which drives the truck towers. These simply pull out.

The motor is clipped in a cradle which in turn is clipped into the chassis.

With the motor removed you can see inside the flywheel; there’s a plastic universal joint, and it’s cracked.

The universal joint is press-fitted over the axel and uses the friction to spin it with the flywheel.  Even when cracked it’ll spin so the loco will probably run okay on its own.  But as the load is increased, such as adding a train, the amount of force on the split universal is stronger than the friction, and the axel just spins.  So if your loco seems to run okay, but won’t pull very much, this is most likely why.

The universal joint is a plastic tube with two pegs which fit into the driveshaft.  The hole in the tube will be smaller than the axel to create the required tight fit but the constant pressure on this particular material causes it to crack.

Replacement universal joints are available from Atlas, but these have been known to fail as well.  So I’ve 3D modeled the part and printed it in Shapeways Smooth Fine Detail plastic because it’s both accurate and also hard-wearing

The new part is a direct replacement for the original.

If the old universal is cracked it should simply pull off leaving a clear axel inside the flywheel.

I fitted the new universal by placing it with a pair of tweezers but not pushing it on fully, just enough to hold it in place.  If it’s pushed at an angle it too may crack.

I then used a flat screwdriver, as to give even pressure, to push it on fully so the universal is all the way to the back of the flywheel.

And that’s it.  The loco is ready to be reassembled.

These are now available in packs of two and four using the links below:

2x Replacement Atlas N Scale Motor Universal Connectors

4x Replacement Atlas N Scale Motor Universal Connectors

This universal is used in many of Atlas’ diesel locomotives and will fit all.

I’m juggling an HO project as well as testing recent 3D printed replacement parts, but my focus is on returning to work on customer’s layouts where possible, so who knows what I’ll be sharing next week!

A Baldwin DT6-6-2000 in HO – Trucks Part 7

Two weeks ago I shared with you the first 3D test print for my new HO scale DT6-6-2000, you can find the post here.  As you may recall I had a few issues with the print, but this week the second test print arrived and the results are very good.

I reprinted the two truck center halves and the four gears as all had issues to be resolved.  The final kit will need four truck center halves and eight gears.

The gears came out even crisper this time, I assume because the axel section of the gear is now a part of the gear rather than held in place by 3D print residue.

The gears up close are very accurate, but there’s still some residue on the axel which will need cleaning off. To do this I simply wipe it off with paper towel. The holes for all the gears will also need cleaning out and for this I use a drill to ream each hole.  If it has 3D print residue in the hole it will cause the gear to bind and add drag to the motor.  If all the holes bind it may even jamb up the gears.

This time everything fitted as planned.  The clip covering the worm gear will need to be taken off, and the drive shaft removed, in order to fit it into the chassis.

The gears, as shown below, are simply positioned in place to check they are a good fit.  Before I tested them under power from the motor I did all the cleaning mentioned above, and lubricated all the axel holes with light oil, from inside and out.  Then, with the wheelsets removed, I checked that the sets of gears turned freely by running my finger along them.  With the wheelsets refitted the whole assembly was a little tougher to turn, but this was expected given there are 3 more gears than in the original configuration.  But once the driveshaft and worm gear was fitted I was able to turn the whole assembly by hand.

The test fit into the chassis was also good; below you can see the original truck on the left and the new one on the right now facing the right way for a DT6-6-2000 or RT-624.

The clip covering the worm gear holds the truck in place, and a pin in the underside of the chassis fits into a hole at the center of the truck, creating the pivot point.

The white of the truck center is barely visible through the truck side frames, but it can be painted, taking caution not to paint the axel holes.  With the chassis reassembled, albeit with one new and one old truck, I lubricated the gears using oil designed for plastic gears from LaBelle. You can find a post about these products here.

The final thing to do was test the new truck, so I connected a basic DC controller to the chassis (there is no DCC chip fitted yet) to see how well it runs.

In the video below you can see I ran the chassis at full throttle in one direction then threw it into the other.  Because of the two large flywheels, the direction change is not instant, but it’s still a heavy load on all the gears and they seem unaffected.  The chassis is in a foam holder because the first time I did this the sudden reverse toppled the chassis over!

The new truck ran very smoothly and the slow speed looks okay, but the real test will be when it’s on some tracks.  As I’m an N scale modeler I only have a short section of HO track at home, but later this week I’ll be able to test it on a layout.  The chassis has an 8 pin DCC socket so I can plug in a chip and see how slow I can make it crawl, but I feel confident that I’ve resolved the issue with rotating the trucks, so now it’s just a matter of finishing the shell.  I’m currently modeling the cab interior and I will share that with you when it’s finished and before we go to test print.