Matthews’ Cowl Vents for Model Ships

Ships' cowl vents under construction

One of the most vexing parts to make for many large scale model ships is the classic “cowl vent”. The things defy verbal description, but you merely need to look at a picture to realize that a correctly shaped vent is a bear to make. In smaller scales, they can be made in solid, and are also readily available from model ship fittings suppliers. But the larger scale parts need to be hollow, and that’s the tough part.

Some will suggest that they can be made in the original fashion, fabricated up from bits of sheet material… but I have yet to see anyone make several good looking parts with such an approach. And while some prototype vents actually are built up in segments, many are hammered into smooth forms to hide the segmentation… and that’s more than I’m willing to do.

Then, even if you succeed in making a fair master part, the cored interior makes replication by resin casting techniques all the more difficult.

As an alternative to all this grief, I’m making my “3D printed” cowls available.

What is 3D Printing?

For those unfamiliar “rapid prototyping”, the process can be quite amazing… actually, I am familiar with it, and I still find it amazing. There exists a number of available process, but all start with a 3D CAD model of a part. The part model is then sliced into layers, which are “printed” one at a time on top of each other to build up a solid form. The printing process involves a laser tracing out the shape onto a thin layer of plastic. The laser’s energy sometimes solidifies a liquid polymer, or in other processes, fuses powdered plastic into a solid.

Moreover, several enterprising small companies make the process available to anyone submitting a model. The best one that I have found is Shapeways in the Netherlands, who have created an easy to use e-commerce site at http://www.shapeways.com/.

You can read about my experience with Shapeways and another 3D printer at this RC Groups posting.

Pat’s Cowl Vents

So I made a model in 3D CAD  of the classic ship’s cowl vent, and scaled it to several sizes. The models can be found at Shapeways by using this link to my “shop” there:
http://www.shapeways.com/shops/patmat

My vents might be best suited for modelers needing several large parts; the largest listed uses a 3/4″ (19mm) tube, with a 1-1/2″ (38mm) diameter cowl. The smaller vents might be a bit clunky due to the minimum wall thickness I needed to apply.  For smaller vents, commercially available cast parts should also be looked at. But you’re not likely to find anything like the larger parts I offer here.

Material

Shapeways offers a selection of materials (even sintered metal!). Feel free to select anything that looks good to you… but I recommend the “White Detail” plastic for best surface finish… “White Strong & Flexible” is lower cost, but may require a bit more hand finishing.

Since the material is laid down in layers, parts will have a stratified look on some surfaces. You will need to sand down and/or fill the surfaces to your own satisfaction.

Ordering

Shapeways handles the orders. You need to sign up on their site (easy), and order directly from them. They accept Paypal, and ship quickly; I’ve received parts in the USA within a week. Only one hitch: They have a US$25 minimum order. VAT will apply to European buyers.

Use the table below to select the size you need, then find that part at the Shapeways site.

Feedback

Let me know if you have any questions or feedback on the parts. Also note that I can scale the model to any desired size.

Matthews' Model Cowl Vent Dimensions

Dimensions Table

3D CAD Model

3D CAD Model

4 responses to “Matthews’ Cowl Vents for Model Ships

  1. David Hargreaves

    Read with great interest.
    I’ve heard somewhere another method for making cowl vents that uses electrolytic deposition of copper onto a cerrobend model cowl (which is later melted away in hot water). I’d like to know more of this if anyone can advise.

    Dave

    • Mike Snodgrass

      In an old issue of “Scale ship modeler” theres a small report of how someone made their cowls from a wooden plug, made a mold of silicone, then poured multiple wax molds of their cowl vent. Then they used a cooper electrolisys process at home and produced their cooper cowl vents. I know you can buy electrolisys kits from Micromark and im sure their avaiable from elsewhere as well. Dont remember the issue? Sorry.
      Mike

  2. John Parker

    Great work Patrick on applying new technology to the age-old problem of making model cowl vents. I was wondering what glue you would recommend (for example, to extend the down-tube) and whether spray putty or the like is needed to achieve a smooth finish for painting. I know of the method Dave refers, electroforming, which was more commonly seen in the early days, but can’t speak from personal experience of it.

    John.

  3. don cather

    I have made several large scale cowl vents using brass freeze plugs(auto parts stores) hammered to shape and then sanded and polished with rouge soldered to brass pipe, worked well!

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