Spray Painting Booth

  • A fairly basic setup for spraying models. The key component was a stove hood with a working exhaust fan and built-in light (tested before taking!)
  • A simple 3 sided structure holds the hood and it is supported on a rudimentary table at standing height for the user.
  • Air is supplied from a 9kg ex. bbq gas bottle. There are multiple YouTube sites showing how to do that safely and correctly.  The bottle is re-filled from my workshop compressor.

A simple bracket for an Iwata double acting air brush.

The hood was thoroughly cleaned to remove the old grease buildup. It has a protected fluoro light and a multi-speed fan that shifts a whack of air on the high speed setting.
I replaced the filter material with some obtained from a local auto spraying company. They gave me a small offcut.

An adaptor was cobbled together to carry the exhaust air outside the workshop. It has a self closing flap on the outside to keep unwanted visitors out. I also added and old flouro desk lamp to get a bit more light on the subject.

A nearby cupboard holds the necessary bits and pieces.

I use a technique described by Ian Dunn at a Modelling the Railways of NSW event.
The rolling stock or loco holder sits high enough so I can spray under it and it rotates to allow coverage of all surfaces. It can also accept track power so that the drive train of locos can be carefully sprayed while it is in motion (hence the elastic bands to keep the model in place).

Here is a mate’s Fleischman loco getting ready for the mechanism to be painted.

Speakers for DCC

SPEAKERS FOR DCC

This post combines new material with some hidden away in other posts. The photo below was of a common speaker such as those supplied with Loksound decoders. They are quite suitable for large body diesels and other larger models that have enough room.

This was the 25mm (1″) 4Ω  1.5Watt speaker and enclosure used for a 42 class diesel project. A silly but important point is make sure you solder the speaker wires to the speaker terminals before you seal it in place!

It is very important to make sure that the enclosure is fully SEALED around, and behind the speaker. The bigger the enclosure, the better but we are usually stymied by lack of space. See below for using Canopy Glue for sealing.

One of the best speakers I have used is the so-called “Sugar Cube” speaker. With even a small enclosure, they are remarkably compact combined with good sound quality. The ESU version is 12mm x 14mm and 5.5mm thick:

This is a sugar cube speaker with wires attached and ready to have an enclosure wrapped around. This enclosure is a little deeper than the depth of the speaker to improve the bass response.

I prepare some styrene strips equal to the height required and use a small machined metal block as an aid to assemble the pieces using a styrene cement.

The next photo shows one of the best TIPs that I have. If you are using super glue for assembling anything, use a small piece of teflon bearing material (or even thicker plastic) and drill a small depression into it. Put a drop of super glue in to the recess and it will last up to an hour or more without going off! It also helps when applying styrene cement. [PTFE teflon sheet can be purchased on eBay by searching for ptfe sheet]

To seal the speakers into their enclosure, I prefer to use “Canopy Glue” as it is sticky and remains in place, plus, it dries clear. As with the super glue, the best means of applying it is with a thin applicator such as a T Pin or a tooth pick:

THINK OUTSIDE THE SQUARE:

The speaker enclosure doesn’t have to be rectangular – consider a cylindrical one to fit inside the smokebox of a steam loco. I have fitted them to brass steam locos including 30 class, 36 class and whitemetal 32 class. Like this:

The curved part has been cut from a small section of plastic pipe which needs to be filed flat as in the previous photo. Two end plates have to be shaped to fit.

The benefit of the smokebox speaker is that the sound is coming from the correct part of the loco. The photos below show a 25mm speaker fitted to a custom housing in the tender of a 36 class brass loco. The sound was brilliant – but it was clearly radiating from the wrong end of the loco.

Fitting the cylindrical speaker can be difficult. In my brass 30 class (small) loco, the smokebox door was loose so I was able to remove it. For the larger 36 class boiler, I was able to insert the speaker from the firebox end of the boiler tube:

THERE ARE OTHER OPTIONS

This is an iPhone 4S speaker purchased from eBay. In this case I have split the speaker to see what was happening inside. As I understand it the chamber on the right is an acoustic cavity to improve the sound. The port where the sound exits is shown with a pink arrow, just below the speaker itself.

Here we have a 40 class diesel look-alike modified from a Kato RSD4/5 model. I like this model as it is well engineered and very smooth and powerful with 2 large flywheels. The tight space in the narrow hood filled with mechanism and weights meant I couldn’t easily fit a sugar-cube speaker but and iPhone 4S speaker sat nicely on top of the motor.
A close up shows the sound port on the RH end of the speaker.
Here is a sound file using an iPhone 4S speaker with an ESU V4 Loksound decoder programmed with an ALCO 12cyl 244 (FT) #73401 sound file. The loco sound volume is quite low and would be deafening if run at full volume.

I note that iPhone 4S speakers are currently (24/3/19) available on eBay from as little as $1.58 ea (+ GST) and with free postage.

For an even smaller loco, consider other iPhone speakers. The first 3 work but you would need to experiment.  The iPhone 5 speaker may be a good option for a small loco.

Solder directly to the contact springs.

iPhone 5 speaker showing the parts that can be removed.

If you have had any interesting success with speakers, I would be happy to post that on this blog (with acknowledgement). Rick

Servos for Points

Points /turnouts on my layout were initially operated manually using a wire-in-tube mechanism. There are currently 44 points on the layout and I started converting to servo control about half-way through.

The wire-in-tube (WIT) method I used worked very well and is shown to the right.
The mechanism is relatively easily fabricated and the cover is removable with one screw to allow easy adjustment of the point blades at the fascia.

It will handle a second wire to allow push/pull operation of 2 points in a crossover.
If there is any interest, contact me and I will add a section on the design and fabrication of the WIT method and the fascia mounted lever frames..

I changed to servo operation for the following reasons:

  • with this type of mechanical operation, control panels would not be able to operate the points (there are 4 mini panels on the layout).
  • the system selected allows precision adjustment of each point blade; variable speed of movement; position indication
  • servos can be installed from the top of a 50mm (+) foam layout
  • points can be controlled from a central position; a local panel; by a computer; as a route by changing many points at once and other options.
  • the system I use is based on the UK MERG model. Circuits vary from simple to complex.
  • Plus – I like working with electronics.

2019 UPDATE
(23/3/19)

I have had some of the servos become very noisy in operation which I believe may be due to their being relatively poor quality CLONES. This ARTICLE sheds some light on the differences between “counterfeit” and original MG90S servos.

I will report back on my findings.

The photo shows the basic setup. The servo is located to the side of the point/ turnout and connected to it with a short “L” shaped wire. I use 1.2mm steel wire running through a short guide tube. This connects to the servo arm via a “Quick Connector”. The servo cable exits under the layout. SEE PHOTO
The mounting slot in the foam is formed by drilling 12mm holes through 50mm foam to fit a micro servo … SEE DRILLING HOLES IN FOAM
The guide tube I use is a short piece of bicycle bowden cable outer – used for gear selection from memory. I just bought a metre or so length from the local bike shop.
The servos I use are Tower Pro SG90 style or my preference Micro 9g Metal Gear Servo.
Shown above is a “Micro 9g Metal Gear Servo For Futaba Hitec HS-55 GWS walkera RC HELICOPTER GA” as described on eBay.
Here is a LINK to the eBay site I used but check other sources for a possible better deal. The current cost is $4.87 (16 July 2016) with free postage to Australia. There are cheaper plastic gear models but I have found these ones to work more smoothly and to be much quieter. As you can see, they come with a variety of servo arms (aka servo horns) and any will work in this application.
To connect the servo to the point/ turnout a “Servo Quick Connect” (shown above) is very good. I bought a set of 20 for $4.12 !! ($3.83 in June 2017)
That’s a little over 20c each. They were sold as “Durable 2mm Aircraft Stopper Servo Connectors Connector with Screws – Set of 20” and one eBay supplier I used was at this LINK . These things are TINY. The Allen Key grubscrew is 3mm.
This what you get for about 20c (Aust). A beautiful piece of micro engineering.
I use any of the servo arms supplied. Select the second hole from the pivot point of the servo arm and drill a 2mm hole in there to take the servo quick-connect. The point needs to move less than 3mm (HO) and initially I went for maximum torque by using the first hole and that is what is shown in the very top photo of this post. That hole is too close to the hub of the servo arm and some fiddly trimming was needed. I discovered that there is no need to use it as there is plenty of torque when using the second hole as shown above.
Assembly order is shown for the quick-connect. It needs to be free to rotate in the servo arm and the nut is best secured using a tiny bit of thread locker. The grub screw allows positioning adjustment but the travel and end points need to be set by some electronics.
This servo is being retrofitted to a turnout on EPS foam. As the control wire to operate the point was already in place, an additionally longer access slot was needed to allow the servo to slide in under the actuating (control) wire to the throwbar. The brass foam “drill” can be seen on the right.
Shown above – 2 MERG boards in use on my layout. The left hand one controls the servos (8 of them) and the right hand one handles the switches controlling the servos operating the points. This system was devised by the MERG group in the UK – see their Website MERG.  The operating system uses a CAN bus (2 wires) to distribute control events around the layout in a manner similar to that used in modern motor vehicles. You still need a distribution bus for DCC (plus, in my case, sub buses for the yards etc) and a bus for 12V DC to operate points and the power the CBUS boards.
This is a MERG design for TESTING SERVOS with the left hand one designed only to test servos – in this case I use it to test new servos and to set them to their midpoint.
The right hand one is, in effect, a stand alone method of controlling one servo & its point with a switch. The 3 blue components are variable resistors used to control the speed of the servo and distance it moves Left & Right. I also use it for testing the servos.

MERG sells kits for the above 2 projects and they cost just £1.55ea  +postage from the UK for MERG members. Almost all of the more sophisticated CBUS kits are based on professionally manufactured Printed Circuit Board (PCBs) and usually kits of the necessary parts are available or you can buy the parts locally.

There are other alternatives:

The device shown to the right is a ” MegaPoints Controller” by a UK company and could be very good for those people not confident in building PCBs themselves. I have not used it or seen it in operation but it comes ready to connect to 12 servos and has 12 corresponding switch inputs. Here is their Website and here is a YouTube Demo There are 2 videos in sequence. Cost is said to be £50 in the UK.

I also notice that DCC Concepts have an “above board” system that looks interesting for someone not interested in a DIY approach – Cobalt SS.