Building an engine test stand

Tutorials > Building an engine test stand


Until 2016, when I built an airplane I installed the engine without running it first. Since I am in the habit of buying secondhand engines it occurred to me early in 2017 that it was high time I had an engine test stand. Many large ones are available but with limited storage space and (likely) limited usage I wanted something smaller.

While doing some research I came across a Fly RC magazine article from 2010 titled Build an Engine Test Stand and I knew it was the one for me. Firstly, it uses a Black and Decker Workmate as a base, and I already have one. Secondly, it uses a modular plate system which could mean a plate for each engine I test. I followed the design for the most part, with a couple of small changes.

Here are the plans:

Engine test stand - plans

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Tools and Materials

My stand is made from 3/4" plywood (with one exception) and is assembled with glue, screws and 1/4-20 hardware and reinforced with 1/4" dowels. Required tools are a drill and bits, screwdrivers, hammer or mallet, measuring tape, pencil, clamps, and a saw.

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I have some woodworking skill but I am no cabinetmaker and I made plenty of mistakes (and some changes). See the comments in italics.


I happened to have a piece of 3/4" plywood that was big enough for all the pieces. I decided to make three of the modular mounting plates. I don't know why the plans specify 6" x 8" mounting plates when the firewall is 6" x 9". Future plates will be 6" x 9".

Engine test stand - parts laid out on 3-4" plywood

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We have a decent wood shop, so I used table, mitre and band saws to cut the pieces. It could be done with a circular saw, a jigsaw (with a steady hand), or a hand saw (with patience and a VERY steady hand).

Here are the pieces. I forgot to take a picture before I started assembly - here you see the firewall glued to the base with the forward cleat and clamped to cure with the help of a couple of the mounting plates.

Parts cut - main firewall glued and braced

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I pre-drilled the mounting plates for their attachment to the firewall. I put the lower holes too close to the bottom of the plates because I forgot to take the height of the base into account, so I had to plug them and re-drill them higher up. Before doing that I clamped a mounting plate to the firewall and drilled the top holes.

Drilling the main firewall with a back plate

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Once the new holes were drilled through the mounting plates I marked and drilled them through the firewall, then attached the plate with 1/4-20 bolts, 1/4" fender washers and blind nuts.

Mounting plate #1 bolted to main firewall - front
Mounting plate #1 bolted to main firewall - back

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I decided I wanted spacers between the mounting plate and firewall to allow for routing of lines and wiring, and to provide space for hardware behind. I cut some to length from a 1" dowel and drilled them to 1/4".

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Spacers drilled
Mounting plate bolted on with spacers - 02

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The next job was to create slots for the braces. I should have done this before I started putting it together. I did what I could on the band saw (mostly straight cuts)...

Cutting the notches for the braces - band saw work done

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... then switched to a hand saw for the angled cuts.

Cutting the notches for the braces - hand saw work beginning

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Eventually I had the braces fitting the way I wanted, so they were glued and weighted to cure.

Port brace glued and weighted to cure

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I trust the glue I use (Lee Valley Cabinetmaker's Glue 2002 GF) but I wanted the extra security of dowels, so I marked the braces for drilling.

Port brace marked
Staboard brace fitted and marked

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When drilling through most wood (plywood included) I like to use brad point bits. To prevent tear-out in plywood I run the drill in reverse at low speed so the spurs on the bit can scribe the top layer cleanly.

Clean drilling in plywood*
Clean plywood holes

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2" lengths of 1/4" dowel were used. I like to taper the dowels for easy entry, and sand a flat spot on opposite edges to allow the glue to squeeze up. After the dowels were glued in place, I cut them flush. Then I trimmed off the ends of the braces. With the table saw. VERY carefully. More cuts that would have been better made before assembly.

Base complete

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Next, the spacer, which is attached to the underside of the base and is clamped in the Workmate to hold the stand in place. I had to make mine a little thicker than 3/4" because of the thickness of my Workmate table, so I cut some 1/4" plywood to shape and glued it to the spacer I'd already cut.

Spacer parts glued and clamped*
Spacer complete

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Spacer glued and weighted to cure.

Spacer glued to bottom of base

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And here's the stand clamped in the Workmate for the first time.

Stand clamped in Workmate - above

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Now for the cleats, which mount perpendicular to the spacer and act as a backup restraint. Cut 6" long as specified in the plan they didn't fit the widest opening of my Workmate, so I trimmed off 1/4".

Cleats too long
Remove 1/4" in from cleat
Cleat fits now

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Now screwed to the bottom of the spacer. Those are #10 2-1/2" screws that fasten the cleats all the way through the spacer and into the base.

Cleats attached

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Clamped in the Workmate again.

Cleats attached, stand clamped in Workmate

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I picked up some 1/4-20 socket head cap screws to replace the Robertson head bolts. They use a 3/16" hex bit.

1/4-20 x 2-1/2" SHCS
3/16" hex bit

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Stand clamped, mounting plate bolted.

Plate bolted to firewall - front
Plate bolted to firewall - top side

Last step - put some filler in the low spots and glue the standoffs to the firewall.

Standoffs glued to firewall

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I figure the mounting plates are going to get the bulk of the splatter, so those get coated with Helmsman Spare Urethane.

Spar urethane for mounting plates

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Three coats should do it. Two coats so far (then I have to do the back).

Mounting plates - second coat done

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I like this grey brush-on rust coat too, so the rest of the engine stand gets that.

Grey rust coat for test stand

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Getting there...

Putting the first coat on the test stand

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