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Good techniques for cutting in the middle of aluminum panel

DavidP2020

Well Known Member
I need to make a couple cuts inside of a skin or floor panel for things like NACA vents and an access panel. I recently did a trial on a scrap sheet with a new metal blade in a jigsaw and it resulted in mangled scrap.

I need a technique that is controllable (don't want to replace a skin that is permanently installed), can be done on the airplane (not the bench), and makes a cut that can result in a very neat edge along a specific line. I recognize a couple methods may need to be paired for the final product.

What are your good techniques for cutting in the middle of an aluminum panel?
 
Carefully mark your area to cut. Use a drill bit to drill holes in the corners, make sure the outside edge of the holes are on your cut lines. Now use a dremel tool with a cutoff disc to cut the lines between the holes. This will make large amounts of aluminum dust, which is not friendly to electronics, so it would be a good idea to have someone hold a vacuum cleaner nozzle at the dremel while you are cutting.

Pro-tip: cut just barely inside the lines and use a handfile for final fit.
 
Drill holes with unibit and then use Dremel with cutoff wheel.
Clean up with scotchbright wheel.

Boomer
 
Marking fluid and a scribe make for precise cut lines.

As others have said, drill a starter hole and use a dremel tool or a nibbler. Work slowly up to the lines with files and/or scotchbrite pads/discs.
 
cutting

Jigsaw works well if material is 0.063 or thicker. Use masking tape around edges to avoid scrapping the alum. This is what I do for instrument panel.

Circular holes can use a centre punch or circular hole cutter.

Otherwise I use unibit in corners of a square hole. Nibbler around the edge and then file and sandpaper smooth.

Dremel tools works well also for some applications.
 
Several people have suggested using a Dremel tool with a cutoff wheel and I agree. HOWEVER; Please use caution and NEVER have the cutoff wheel in line with your face. These wheels have no tolerance to side loads and unless you are very experienced with them, they will fracture and send shrapnel into your face.
If a minimum kerf is not required, use a fiberglass reinforced wheel.

It also goes without saying, ALWAYS wear safety glasses!
 
Marking fluid and a scribe make for precise cut lines.

As others have said, drill a starter hole and use a dremel tool or a nibbler. Work slowly up to the lines with files and/or scotchbrite pads/discs.

Can you elaborate on the marking fluid and scribe? Thanks!
 
Several people have suggested using a Dremel tool with a cutoff wheel and I agree. HOWEVER; Please use caution and NEVER have the cutoff wheel in line with your face. These wheels have no tolerance to side loads and unless you are very experienced with them, they will fracture and send shrapnel into your face.
If a minimum kerf is not required, use a fiberglass reinforced wheel.

It also goes without saying, ALWAYS wear safety glasses!

Good tip - I'll definitely try to avoid the shrapnel!
 
I often use a nibbler and file for jobs like this. Drill holes in the corners, nibble up close to the line, file smooth.
 
A manual nibbler works well, but it is slow and gives you wrist ache. Super controllable though.

Rotozip bits are good in a Dremel but you need a firm hand and cut with the rotation - cut down hand. Practise on scrap and you will understand.

Digitize and water jet cut :rolleyes:
 
A cheap nibbler from harbor freight is around $30 and works well for .032 or less. It throws out little aluminum "fingernail clippings" like crazy though, so be aware. It's also hard to get a perfectly straight line unless you clamp an angle or something on the work piece to use as a jig and run the business end of the nibbler against it. If I'm trying to free-hand it, I will stay well inside the line then creep up on it with a hand file after.

For a one off, I sometimes will drill the corners then make the straight cuts with an abrasive disk in a dremmel or 90 degree dotco.

As others have said, those little dremmel discs are great, but if you side load them at all they will come apart in spectacular fashion. the bigger discs for a dotco are more durable, but I still wouldn't use one without safety glasses and trying to keep my face away from the plane of rotation.

For the big holes in my instrument panel, I drilled about a million holes close together, then just played connect the dots with a cutoff disc and sanded down to the lines with a flapper disc in my dotco.
 
Embarrassed, not

Well when I saw the title of this thread, I thought I would be embarrassed at my crude methods as compared to the "experts". After reading this thread, I am not so embarrassed, you all are doing the same crude way as me! (connect the dots, Darwinism with Dremel...)
 
I’m with Stu on the jigsaw. If the part is flat enough to temporarily bond a piece of 1/8”/1/4” MDF to the saw side with say 3M 77 you can do an amazing job with a step drill and a fine tooth jigsaw even on thin material by laying the cutout on the MDF and cutting through both.
 
Making new holes

I bought the Bad Dog Biter nibbler at Sun-n Fun and it’s my go to for cutting holes. Nibble up close to your cut line and finish with a file. Cuts very clean and doesn’t distort the edges. It does discharge sharp little crescent moon shaped chips. Love the dremel, but for the places I don’t want the dust from the cutoff wheel I go with the nibbler.

Don Broussard
RV9 Rebuild in Progress
57 Pacer
 
Router

I have tried using a router (actually the electrical box cut-out tool for drywall). Wears out the router bit rather fast and also produces "dust". Definitely recommend clamping or gluing on a guide instead of doing it freehand.

In most cases, however, I've used my hand-nibbler and a lot of patience -- builds muscle :)
Google "HT-204 Nibbling Tool"

Finn
 
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Agree with most of the posters.
You can do a lot with a unibit, nibbler, and files.
Slow? Yup, but you will be done faster than drawing it up on CAD and getting it laser/waterjet/milled.
I wear a glove on the hand nibbler hand and take breaks.

I find this for many build tasks. A hacksaw and file gets the job done faster than getting fancy.
 
Several people have suggested using a Dremel tool with a cutoff wheel and I agree. HOWEVER; Please use caution and NEVER have the cutoff wheel in line with your face. These wheels have no tolerance to side loads and unless you are very experienced with them, they will fracture and send shrapnel into your face.
If a minimum kerf is not required, use a fiberglass reinforced wheel.

It also goes without saying, ALWAYS wear safety glasses!

I use big safety GOGGLES when dremeling for this reason. When those little wheels break, shrapnel goes everywhere and can go around corners! Pieces can easily fly under the rim of safety glasses and up into your eyeballs.
 
Several people have suggested using a Dremel tool with a cutoff wheel and I agree. HOWEVER; Please use caution and NEVER have the cutoff wheel in line with your face. These wheels have no tolerance to side loads and unless you are very experienced with them, they will fracture and send shrapnel into your face.
If a minimum kerf is not required, use a fiberglass reinforced wheel.

It also goes without saying, ALWAYS wear safety glasses!
Having spent 15 years as a welder in a fab shop, anyone entering the shop HAD to wear safety glasses with side guards ( they were provided). Anyone cutting or grinding would wear a full face shield. Even at that, I had several stainless steel slivers removed from my eyeballs over the years. We had specialists close by. You don't want this to happen in your garage.
face sh.JPG
 
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Face shield

Having spent 15 years as a welder in a fab shop, anyone entering the shop HAD to wear safety glasses with side guards ( they were provided). Anyone cutting or grinding would wear a full face shield. Even at that, I had several stainless steel slivers removed from my eyeballs over the years. We has specialists close by. You don't want this to happen in your garage.
View attachment 36773

I have a face shield on my belt sander grinder. I have to remove it from the machine, (and put it on) before I can use the machine.
 
Real Safety Glasses go all the way to your face!

I use big safety GOGGLES when dremeling for this reason. When those little wheels break, shrapnel goes everywhere and can go around corners! Pieces can easily fly under the rim of safety glasses and up into your eyeballs.

I guess I should have been more clear. In my opinion, safety glasses that don't go all the way to your face are NOT safety glasses.
 
If the hole is big enough you can use a razor saw after drilling the corners and avoid all the issues with the dremel or nibbler. A little bit of boelube is good to use. Also works for cutting off tabs or anywhere you need a straight line cut and have enough room.
 
Router with Template

I have really good luck with a router, but I start by making a template out of plastic or wood for the router to follow. - Jason

7C447E8B-C17D-41AA-B619-8E9EE0E88825.jpg

80DD57D8-523D-4CE1-B683-139AD867A1CA.jpg
 
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