CNR D-1: Bring out the big guns

CNR D-1 and the air eraser
(Progress on the shells: Knocking down the ridges on one of the trailers)

As mentioned yesterday, I’ve decided to make some progress on the long-stalled CNR D-1 project.

CNR D1 - Grit blasting at Ryan's

A big stumbling block was how to deal with the ridges that are a characteristic of 3D Printed items. Such items are built up in layers and there’s often a ridge where the layers are bonded together. This stratification was very much an issue on the 3D Printed shell for D-1 and its two trailers.

Sanding and surface primer is the usual approach to addressing this problem, but there’s a lot of shell to cover here, and the sheer magnitude of the project made it easy for me to say, “Hmm… I wonder what’s on TV?” I needed a better answer. And that answer came in the form of a big red box fitted with cocktail-length rubber gloves…

Ryan and the air eraser
Ryan sets me up for a day of grit blasting

I visited my friend Ryan Mendell yesterday for an afternoon of hobby fun. (Stephen Gardiner, who designed the D-1, joined us too.) Ryan has been building patterns for resin casting and recently started his own hobby business, National Scale Car. He makes many of his masters using 3D Printing and was looking for a better way to deal with the ridges – and found the answer in the form of a grit blaster. I was curious about how effective it was, so I arranged a visit.

I worked on the three bodies for a couple of hours and I’m really happy with the results. The grit blaster (also known as an air eraser or media blaster) did a terrific job – especially in areas where it would be difficult to sand by hand, such as the recessed doors. In fact, I realized that if I focussed on those difficult areas, I could do the large flat sections of the shells with sanding sticks – or, even better, Ryan’s Tight Spot Sanders.

Ryan has a Paasche Air Eraser and a Blast Cabinet by Central Pneumatic (obtained from Harbor Freight). For the D1, I was shooting 220 aluminum oxide at 80 psi.

The before and after photos below show a definite improvement in the curved nose of the power unit:

CNR D-1 Texture - Before

CNR D-1 Texture After

The translucent nature of the 3D Print medium used makes it difficult to see the improvement, but running a thumbnail over the surface tells me the ridges are much less pronounced. I will finish sanding this shell using my Tight Spot Sanders then give it another application of Surface Primer and see how it looks. I expect this will be a “repeat as necessary until satisfied” operation, but I now have a strategy for tackling the project, which is the important thing.

Would I add a grit blaster to my workshop? Well, I do like tools, so the answer is “probably”. I don’t have the space right now – there are other things in the shop that must find their way to the curb – but I do have a suitable air compressor to power a blaster, and I’ve already thought of where I would hang the booth once I clear space for it. I would want to do something about muffling the noise of the air compressor, but a sound-insulated cabinet could take care of that.

Meantime, I envision another trip or two to Ryan’s before this project is finished. Thanks for the help, Ryan – the next beer is on me!

Tight Spot Sanders and Fret Saw Table

Here’s an awesome combination to add to any workshop:

Tight Spot Sanders and Fret Saw Table

I visited my friend Ryan Mendell yesterday. Ryan recently made the jump from hobbyist to hobby business owner by launching National Scale Car. His company’s focus is on rolling stock and detail parts for the HO craftsman kit / RPM market. (And yes, I’m talking to him about the potential for S scale kits and parts…)

But Ryan’s also a pattern-maker and he’s developed some cool tools to help him with pattern making and general model-building. He’ll offer some of these through his business – and his first tool is a small offering that’ll make a big difference:

Tight Spot Sanders - NSC

It’s the Tight Spot Sanders. As Ryan notes on the National Scale Car website…

Sanding in corners or between details can be difficult using sanding sticks with foam cores. Tight Spot Sanders are the answer. They allow one to apply enough pressure while sanding flat against a surface. Ideal for sanding inside corners or between rivet strips on a boxcar when plugging holes.

Made from laser-cut acrylic with a precision machined finger dimple that makes them easy to grip and propel. Sanders can also be propelled with the eraser end of a standard pencil or other such implement.

The Tight Spot Sanders are sold as a set of three, including two pieces of self-adhesive emery paper (180 and 320 grit). Definitely worth the $5.00. (While you’re on the National Scale Car website, be sure to snoop around at Ryan’s other offerings, too.)

In the lead photo, Ryan is demonstrating a Tight Spot sander and is supporting the model on a Fret-Saw Table from Lee Valley. Clamped in a vise, this is a terrific work surface for supporting odd-shaped objects – like a car body with braces in it, as shown. I’m definitely adding one of these to the shop next time I visit the Valley of Lee…

A drive train for D-1

CNR D-1 Drive Train

I’ve decided to tackle a few projects that have been stalled, to see if I can make some progress on them. The CNR D-1 passenger train set is an example – I last posted about this almost three years ago, and it’s been collecting dust since then. There are some issues to resolve, and other projects called…

Yesterday, I decided to solve one of those issues: The drive train. I was most of the way there: The motor and power truck – both donated from an S Helper Service SW1 – were installed. But I needed a drive shaft to connect them. I dug through my stash of Northwest Short Line driveline components and found a mostly suitable shaft, plus universal couplings.

I say “mostly suitable” because I had no drive shaft material that would fit the universal coupling at the gear tower end of the drive. Everything was too small.

Fortunately, I have a lathe and making a bushing is an ideal project for it. I had some brass tube that fits the universal coupling, so all I had to do was bore it to accept the drive shaft. I chucked the tube into the lathe and got to work…

Boring the bushing:
Boring the bushing.

Test-fitting the drive shaft:
Test fitting the shaft

Parting the bushing:
Parting the bushing

I cut a length of 2.0mm drive shaft, added the bushing and universal coupling at the gear tower end, added a universal ball at the motor end, and assembled the drive. Everything press-fits nicely – I experienced no slipping. (If I do in the future, I will add some Lock-Tite.)

The assembled drive

I tested the drive with a 9v battery, running it in both directions while wiggling the truck about and turning it to its extremes, and all runs smoothly and quietly. I was worried about the extreme angle of the drive shaft – but that turned out to be a non-issue. Progress has indeed been achieved!

The next step is tackling the texture of the 3D Printed body shells. I’m visiting a friend later today – we believe we have a solution for this. Stay tuned…

CNR D1 Texture (Before)

A new bench lamp (or two)

Mag light - close-up through lens

I hate getting old. I used to have terrific eyesight. These days, not so much.

But rather than try to ignore the inevitable, I’ve decided to throw money at it instead. A few years ago, I bought awesome reading glasses, which also get a regular workout at the hobby bench. (They’re even slim enough to fit inside safety glasses.)

Yesterday, I took another step, and purchased a magnifying bench lamp. There are many of these on the market, but I picked a nice one offered by Canadian-based tool specialist Lee Valley because I trust the company to source quality products that are designed for people who build things – whether it’s furniture or F-units, carving or cabooses.

Bench lamp - overview

The lamp does not have a brand name – but given that the box is clearly printed with the Lee Valley catalogue number I suspect they’ve sourced this directly from a manufacturer.

The lamp is catalogue number 17J30.30 – and here’s what Lee Valley has to say about it:

This is an excellent magnifying lamp. Its array has 56 LEDs with a color temperature akin to daylight (6500 kelvin), making it well suited for task lighting.
The 5″ 3-diopter optical-grade glass lens focuses at a comfortable distance (3″ to 9″) for detailed work. Its spring balance mechanisms are fully enclosed and the lamp has a maximum overall extension of 47″.

The lamp head is adjustable for viewing angle, has an integral flip-up lens dust cover and comes with a 2-1/2″ capacity table-mounting clamp. The LEDs are rated to last 50,000 hours, equivalent to 5 hours per day for 27 years. UL/CUL certified.

To let you mount the lamp in a dog hole, stainless-steel bushings with a 3/4″ or 20mm outside diameter are available separately.

I also purchased the 3/4″ bushing and installed the lamp in a dog hole on my work bench.

The 3-diopter really makes a difference. In the following photo, you can see identical bottles of Vallejo wash both inside the lens, and outside to the left:

Mag light - inside and outside the lens

I’m really pleased with this purchase. While I hope I don’t have to use it all the time, it will certainly help with those fiddly operations, such as reading mouse print on decals or painting figures. In fact, I actually bought two of these lamps and installed the second one on my desk in my home office, where I frequently paint war-game miniatures while waiting for clients to call me back.

Mag light - upstairs

I’m not yet ready for an optivisor – and maybe with these lights, I can put that off for a few more years. If you have a Lee Valley in your area, check out this lamp: They’ll have one on display, and I bet you’ll add one to your “must have” list.