Stainless Steel Cabinet Fillers for Over-the-Range Microwave

Problem

To save space, I replaced a 36-in wide range hood (see photo) by a cheap, 30-in wide stainless steel-colored over-the-range microwave (including exhaust). Hence, gaps would emerge on both sides of the microwave when it would be centered in the old space of the hood. I could not find fillers for sale anywhere to fill those gaps. Also I wanted them to be stainless steel to match the microwave.

Solution

I designed custom stainless steel fillers that match the microwave. I had them laser cut, manually bent, coated, and finally installed as described here.

• microwave
• laser-cut stainless steel sheets (x2) - see also this instructable
• dremel grinder + cutting discs
• acetone
• clear spray paint
• wood screws

Measure the required filler width, depth and height.

In my case I used Onshape for CAD, it can create the flat pattern for DXF export in seconds.

Sheet metal bending settings:

• material: 304-series stainless steel,
• thickness = 22 gauge (0.030in or 0.8mm); thick enough for the application,
• bend radius = 2mm,
• bend K Factor = 0.45,
• minimal gap = 0.5mm,
• corner relief type = Closed

Notes

Integrate plenty of 1/8in diameter (or so) mounting holes. I did not make not enough holes in hindsight.

Although both parts are mirror symmetric, I do not recommend ordering two copies of the same part because the same side (on both) may get some scratches due to handling in the laser cutting shop, and after bending, one of the two fillers may show that. Instead, first mirror the part in CAD and send a DXF of both the left AND right filler part.

It is pretty cheap nowadays to have parts laser cut. Especially stainless steel can be hard to cut.

In my case I used https://sendcutsend.com

Alternatively, there are other shops like https://www.oshcut.com.

Use a Dremel (or similar tool) with a 1 to 2in cutting disc to "score" (carve out) the bend lines before bending manually. Do not use an angle grinder with 4.5in discs (see photo) because those will add too much heat into the material, leading to ugly discoloration. Do not exceed scoring roughly half the sheet thickness to avoid structural weakening.

After scoring deep enough, you should be able to bend it manually, possibly laying it on the (preferably sharp) edge of a table.

This prevents corrosion. First degrease with acetone in a well vented area. Even stainless steel can show fingerprint "stains" (corrosion) from touching, depending on your sweat constituents.

Use pre-laser-cut holes for easy mounting.

Follow the microwave installation manual. The fillers should not be interfering with the microwave because the power and exhaust are usually on the top side of the microwave.