cutting into skins
 

What are some methods for cutting rectungular holes, or other odd-shaped holes, into a skin, or other piece of sheet metal? I suspect a jig-saw would probably rip it to shreds.

Phil,
I use a cutoff wheel in a Dremel. Drill a hole at each corner to give a radius first. Practice on scrap. These wheels won't take ANY side loads. Once you get it down, they're a easy to master. WEAR EYE PROTECTION!

Hi Phil:

For making the rectangular cutouts on my instrument panel (stock Van's 0.063) I used a jigsaw with no problems whatsoever. Just be sure to use a high tpi (teeth per inch) metal cutting blade.

For thinner material I like to use my Dremel tool with a cutoff wheel. I've also used a cut-off wheel in my pneumatic cut-off tool for making some cuts. Regardless of what you use you're going to end up doing a lot of filing to final shape.

For smaller rectangular holes (like the baggage bulkhead cutout for my ELT remote) I like to use #30 bits in the corners of the rectangle. Then I will use a uni-bit to remove as many large holes in the center of the cutout as possible. Next I use a Dremel cutting bit (similar to this one) to remove the remainder, then file and scotch-brite.

Hope that helps,

A few days ago, I cut in a hole to accept a Gretz pitot mast. First, I used a Unibit to remove most of the material from the hole. That was followed by more material removal using a small cutoff disk fitted to a Dremel-like pneumatic pencil grinder and finally edge finished using a small rotary file fitted to the same tool. I pretty much use the same technique for cutting in all odd-shaped holes.

cutoff wheel
 

Will a cutoff wheel work in my die-grinder? I've never used one before... is there a particular size/shape/type that I should get. Then do I use it basically like a circular saw?
I'm thinking right now about hte holes in my leading edges for my duckworks lights.

You can use a die grinder. Use the larger cutoff wheel that Van supplies for cutting the canopy. Just make sure that the wheel is designed for the speed of the die grinder. WEAR EYE PROTECTION!

I've used both a Dremel and a die-grinder with their respective cut-off wheels for this kind of job, and unless the hole is really small, I prefer the die grinder. As Mel said, the Dremel cut-off wheels are very fragile when it comes to side loading - I've busted bunches of them. Larger cut-off disks are generally better reinforced. But fit the size of the tool to the size of the job.

Paul

Dremel +
 

As others have noted, the Dremel works great. I have a metal cut off wheel with abrasive edge that I now use for cut off use. No worry of the disk coming apart.

The metal disk is thinner and will allow you to get closer to the line. It also cuts much smoother and will reduce your filing time.

There are at least two types of cutoff wheels available for the Dremel. The thinnest ones are indeed very fragile and grenade with little provocation. There is another fiber-reinforced disk that is much more durable and the kerf is only a little larger. But these disks can tolerate more abuse and are much more practical to use. Both are used with the same mandrel.

And has been stated---Wear Eye Protection!

I've found this little Dremel attachment to be very handy for cleaning up the edges after the initial cutting.



It can do some serious damage if it gets loose, so practice on some scrap first.

Dave

roto zip
 

I've found that by far the best holes are made using a roto zip tool. You can get one at harbor freight for about $20. Make a template from wood and clamp it to the back of the metal. This will guide the roto zip. The template should be female, i.e. it will have the same hole cutout that you want to cutout, preventing the bit from wandering into material you don't want to cut. I used this for my NACA ducts and a completely clean and finished cut is done with a single pass. No risk from freehanding.

In general, what can a Dremel do that a pneumatic die-grinder can't do? I have a small die-grinder that I got for about 20 bucks. A dremel costs about $80CAD. Is it worth getting one? Can't I just use dremel bits in my die-grinder with exactly the same effect (being careful of the RPM of course).

The pencil grinder can do everything a Dremel can do. Having both varieties, I prefer the pencil grinder. About the physical size of a Corona cigar, it uses air for power. It is much slimmer than a Dremel in which you are actually holding its motor. As such, a pneumatic pencil grinder is easier to manipulate, particularily useful in accessing very narrrow recesses. Having said that, a while back I purchased this really great deal at Sams.
http://www.vansairforce.com/communit...ead.php?t=6577
What I particularly like about this Dremel-like tool is that you can change it many accessories very fast without the need of a wrench. You merely depress a button near the collet to lock the spindle for accessory insertion or removal.

I don't own a Dremel either. I do have a small Sioux pneumatic die grinder. Avery and others (McMaster-Carr, for example) sell the cutoff wheels and arbors to fit die grinders. I used mine to cut Duckworks landing light holes in the wing, then used the same blade to cut the plexi lenses to size. Quick, easy. Very controllable.

Oh yeah: Wear Eye Protection!

My dremel will be buried with me, when i go, along with my pneumatic squeezer.
I cant think of two tools that have made otherwise difficult tasks a piece of cake.

Its not only the cuting of the initial hole. the sanding drum attachments etc. make hole cutting and edge finishing in skins childs play.
I appreciate the die grinders have more horsepower, but for accuracy, and detail work, I think you cant beat the dremel. Ive got a Li-ion rechargeable one. Its great.

Cheers
Richard
Sydney, AUS

I hardly ever use my dremel tool on the RV
 

I have a regular variable speed "corded" dremel. I've used it very little on the RV project. Not real sure why. I think it's because it's noisy and it usually throws all the dust right in your face. More times than not for me I just can't hold it in a position that will allow me to see what I'm doing and not get sandblasted in the face. Maybe I need some schooling.

I prefer to drill the corners with a unibit and then use a nibbler.
The nibbler reminds me of the old Pac Man game. If you don't have one, get one. Usually they are less than $20.
[IMG][/IMG]

See how it works here:
http://www.mytoolstore.com/klein/76011b.html


The nibbler made this defroster cutout easy:



Mark

I cut out my landing & taxi lights, custom access panels, and instrument panel, all using the standard 3" diameter cutoff wheels as sold by Avery
(http://www.averytools.com/cart/p-408-cutoff-wheels.aspx), driven by my 18v battery drill or die grinder. Works fine, as long as done very carefully. Earlier work done with the die grinder. Later work done with the battery drill. Other suggestions listed here sound good, too. I'd use the larger 3" wheels on larger holes, and smaller Dremel wheels on smaller holes.

Examples:

http://www.meyette.us/WingsMar03.htm

http://www.meyette.us/AccessPanels.htm

http://www.meyette.us/avionicsJan06.htm#jan29

brian

I did all the way up to the finish kit with a die grinder, nibbler and file. Recently got a Dremel and wish I'd had it all along. It's a lot quieter than a die grinder/compresser and easier to handle (less torque/weight). It's also cool to be able to go to Depot and get all the neat little tips for it. And you should definitely wear glasses and also try to keep your face out of line with the cutter. Don't ask me how I know this.

Mark,

Thanks for the excellent tip. Personally, having never considered nor used a hand nibbler...sometimes you just know instinctively a real tool winner when you see one. I'll be picking up my copy real soon. Thanks again.

More than one way to skin a cat
 

My tool of choice is a body saw.

Talk about a knife through butter!

Nibbler for me to...
 

I used my nibbler on my panel and for my wing skin light. It works great. The panel was a little thick but for fine cuts it was the right tool. I also used a jigsaw with a fine blade on the panel for the ruff cuts.

Kent

nibbler work
 

Hey, that is some nice, clean work, Mark!
brian

You just cost me 20 bucks. Yet another tool I need
:D

To me, the pencil die-grinder is just a Pnematic dremel tool.... takes all the same attachments.

What kind of file
 

What kind of round file did you use to smooth the corners for the duckworks light cutout?

For cutting out holes in aluminum sheet one option I used was a router.

It had to be a situation where I could clamp thing properly but a small router (laminate trimmer type) with a carbide blade does great work on thin aluminum sheet. For straight lines if you can clamp a piece of bar or angle stock as a guide the laminate trimmer blade will cut a great straight line.

I've even made templates from thin plywood or masonite sheet to cut other shapes.

I read once that this was the basic technique used to cut the window openings in the Lockheed Constellation.

As with other methods eye protection is mandatory. Use the goggle type eye protectors as the chips really fly and will find there ways behind any type of safety glasses that are not enclosed on the side.

It won't work in a lot of situations but where it will it produces a nice an edge as if you CNC milled it. Which, come to think of it, you did, the C being your noggin.

get an assortment
 

I suggest that you go to a hardware store and pick up a few round files with different radii, and use the one that most closely matches the final radius you want, so, for the landing light cutouts, a file with a fairly large radius.

Another tool not mentioned that is great for cutting aluminum sheet in some situations is a coping saw with a diamond blade - cuts fast and with great control.
Bill Brooks
Ottawa, Canada
RV-6A finishing kit

Your local Hobby Shop...
 

...should have a House of Balsa cut off wheel. It's kerf is the same as the fragile Dremel wheels and the 2 inch diameter makes it easier to use - less need to tilt your Dremel tool body to clear the surrounding surface. It's also pretty close to indestructible.



http://www3.towerhobbies.com/cgi-bin...?&I=LXM409&P=0

AFAIK Dremel does not make a large diameter cut off disk...

If you're not doing the cutting on the airframe, a mill works quite well...