What a Tool! Servo Templates for Dremel Rotary Tools

An illustrated tutorial along with free-to-download plan.

Published in

The New RC Soaring Digest

6 min readNov 2, 2021

Now that building season is here in the Northern Hemisphere, I dare say there will be a few of you needing to fit servos into foam wings. If you’ve had shop bought/RTF foamies in the past, they probably had nice neat servo pockets and cable runs already neatly moulded into the foam with the servos pre-fitted. If you’ve bought ARF type kits, they too probably had the servo pockets pre-cut though the veneered wing skins, nice and neat, ready for you to just drop a servo in and go fly.

But what if you are scratch building or perhaps you are modifying by adding ailerons or flaps to a vintage model? You can hack away with a craft knife and some pliers, it will work but its not ideal. You might try reaching for the rotary tool and free-handing it. Again, it will work, but unless you’re very good, its hard to get repeatable results.

Faced with the need to fit some servos to a scratch build I have underway (for another article to follow in RCSD) and wanting to make a neat job of it, I set about creating a simple, reusable template to use with my trusty Dremel. In the world of woodworking and carpentry, jigs and templates are frequently used to make repeatable cuts and enhance accuracy, the same ethos works for modelling!

With the Dremel in ‘router mode’ (I’m using the ‘cutting guide’ attachment that comes with the drywall cutting attachments — see link in Resources, below) wherein the ‘cutting guide’ becomes the equivalent of a woodworker’s router guide and depth is set from the same cutter guide. Now all that’s needed is some measurement and 10 minutes with some wood from the scrap box.

Making the initial cuts to the template, after the boundaries were glued to the base.

First pass, I’m not going the whole way through the 2mm ply.

Second pass, I make the full depth cut through, ensuing there’s something sacrificial underneath! Then neaten up the edges with a file or sandpaper.

Time for a Demo: Let’s Fit Some Wing Servos

Who doesn't love a demonstration!? Here’s my wing, in need of a couple of servos, a no-name 9g and a Hitec HS-81. I’ve marked the locations (I used a sharpie for clarity in the photos) with the tabs and cable locations included. The template is offered up, the window being where the material will be removed from.

Set the depth to match the servo plus the thickness of the sheet and any clearance you need; 30 seconds with the Dremel, the material is removed and you have a nice neat pocket.

Set for the servo’s depth **plus** the template thickness.

Next up, pockets for the tabs and the cable. Again, the template is your friend: line up the top edge of the template along the line of the tabs and route a few mm beyond each edge.

Cut servo tab pockets with the long top section.

Lastly, we can also use the template for cable management. Using the long top edge, we can cut a neat rebate (either shallow for a horizontal/flat cable, or deeper, for multiple / vertical cables). Where you need a junction or connection, you can set the depth a little deeper to create a pocket for the connectors.

Long top section can be used to cable runs, wing spars etc.

Make Your Own

You will need:

A flat sheet that will take a CA bond (I used some 2mm ply).
Some straight strip material (I used 1/4" x 1/8" spruce).
CA or other suitable glue (I used a high viscosity CA and a bit of kicker as needed).

Print the PDF template ‘actual size’ and trim off the top section, cutting to the inside of the long, isolated rectangle. You don’t need this bit, you can dispose of it.

Trim the long section, including the rectangle.

Next, carefully cut out the two large squares. We will be using both the two squares and the area they were removed from for measuring/locating stuff in a moment, so cut carefully and keep it all safe.

Carefully cut out the two inner squares.

Using the plan with the two squares removed, align the top of the plan with a long straight edge on the flat sheet. Mark the parallel, inner edge of the two cutouts on the sheet. Using the new marks, glue the 1/4" strip, ensuring it is straight and parallel to the sheet’s edge. You can use the plan again to confirm which side of the line the strip needs to be if unsure.

With the newly attached strip as a datum, three more strips, using the two squares as spacers to get the correct locations. The strips should be at right angles to the long top strip. Lastly, attach strips to close off the squares.

You should now have the basic template and be ready to cut out the central apertures.

I found it best to make two passes at cutting the apertures rather than trying to cut the whole depth in one go.

One More Thing

You may have noticed there’s a third square, unused on the template. Feel free to use as you wish! In my case, I cut part of the square out, to give me a right-angle template. I can use this for more ‘free hand’ cut outs, or for rebating servo covers for example.

Thanks very much for reading. If you have any questions or comments please add them as a Response to this article, below, and I will do my best to answer them.

Resources

All images by the author. Read the next article in this issue, return to the previous article in this issue or go to the table of contents. A PDF version of this article, or the entire issue, is available upon request.