[Dougl]

I want to cut a semi circle out of the lower winglet spoiler to allow fitment over the OEM engine bars. BMW marks the cutout on the inside. What’s the best tool for doing this?

 

[Lee089]

Think Dremel would work.

 

[Dougl]

Think Dremel would work.

Grinder, cutter, or sander?

 

[mikeS]

@Dougl - My initial thought would be to use a fine tooth-hole saw. Lay the panel on a block of wood and align the outer edge of the hole saw and the semi-circle marking. Clean up the edge of the cut-out with some wet and dry sand paper.

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[Lee089]

Grinder, cutter, or sander?

Would start with the cutter for the big piece and then grind the edges.

 

[r0ckrat]

Drill a starter hole in the center, then a jeweler's saw with the teeth set to "catch" on the painted side. Cut close to but not on the line. Then sand or file to the line. This will give you both the greatest precision and cleanest cuts. The type of plastic is something that will soften/melt with the use of power tools if you are not extremely careful.

 

[mikeS]

Whatever the method the key consideration is to go slow - low-speed setting otherwise high-speed will melt the plastic.


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[Lee089]

And always…..absolutely always….a cold beer next to you 🍺

 

[mikeS]

Oh, also, when you want to clean up the cutout edge, try using a deburring tool and then wet and dry sandpaper to finish.

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[fireman]

If you have a Dremel (rotary cutter), you could do use that, but be careful because it is easy to overdo and remove too much material.

I used a Coping Saw on trimming thin plastic, as recent as yesterday. Cheap and effective. Clean-up sharp edges with a fresh box knife blade or a round file.
The higher the teeth count blade, the finer the cut, the tighter the turn can be. I do have a Dremel with a bunch of attachments, and it was useful in cleaning-up plastic parts, but I used a coping saw instead to cut the OEM BMW mudguard.
IRWIN Tools ProTouch Coping Saw (2014400), Blue & Yellow - - Amazon.com

 

[Panzermann]

@Dougl - My initial thought would be to use a fine tooth-hole saw. Lay the panel on a block of wood and align the outer edge of the hole saw and the semi-circle marking. Clean up the edge of the cut-out with some wet and dry sand paper.
View attachment 119052

If you used this method, you would want to screw the part to the wood using some self tapping screws around the periphery of the waste piece.

 

[mikeS]

If you used this method, you would want to screw the part to the wood using some self tapping screws around the periphery of the waste piece.

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[Dougl]

Imunna try a diamond hole saw. Can’ find fine easily and my standard coarse is, well, too coarse. Thanks!

 

[Panzermann]

You could always do it like the shop would - a pair of curved snips. Rough enough is good enough. 😄

 

[degeorgis130]

You could always do it like the shop would - a pair of curved snips. Rough enough is good enough. 😄

I think they are known as "Aviation shears". They come in straight cut, left cut, right cut models.

 

[Dougl]

I think they are known as "Aviation shears". They come in straight cut, left cut, right cut models. View attachment 119062

Have those. Loathe to take it to rigid plastic.

 

[Dougl]

You could always do it like the shop would - a pair of curved snips. Rough enough is good enough. 😄

Already butchered one set of these.

 

[sturgeon]

You could always do it like the shop would - a pair of curved snips. Rough enough is good enough. 😄

Or if you're in a hurry, chainsaw.

 

[Panzermann]

You could engage the Cookie Monster …

 

[mikeS]

Better still

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