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  #11  
Old 03-12-2018, 10:49 AM
az_gila's Avatar
az_gila az_gila is offline
 
Join Date: Jan 2005
Location: 57AZ - NW Tucson area
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Exclamation

If the hole doesn't have to be a perfect circle, make the biggest hole you can and enlarge it with a sander in your die grinder.



Works pretty well if you can mark the circle first with a Sharpie -



I've been doing this to create 2 inch holes for air ducting in my -10 bulkhead after fuselage assembly.

It's safer than the circle cutter and can be done free hand without a drill press.
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Last edited by az_gila : 03-12-2018 at 11:04 AM.
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  #12  
Old 03-12-2018, 10:59 AM
Pixair Pixair is offline
 
Join Date: Jul 2017
Location: Napa Valley
Posts: 12
Default 1.5" hole in alum sheet

The Rotacut annular cutters by Hougen are great for thin sheet stock.
Cutter goes on mandrel/arbor and will fit in 1/2" chuck.
Much cleaner hole than hole saw, great if you need precision hole.
Clamping in drill press or mill is essential for that size cutter.
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  #13  
Old 03-12-2018, 11:14 AM
rv7charlie rv7charlie is offline
 
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Location: Pocahontas MS
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Yep, I've cut quite a few holes using flycutters. Including holes for additional instruments in completed panels in flying a/c.

The cautions are legit; be careful. But as strange as it may sound, there are situations where controlling one can be easier with a variable speed hand drill than in a drill press. You need to turn these slowly, and be able to disengage from the work instantly if the tool grabs the work. With a drill press, you can't stop the tool quickly, you're limited in how slow you can turn it, and if it 'grabs' the work, you can't disengage unless the work is held perfectly all around on the table. With a quality variable speed drill, you can run the tool so slowly that you watch the blade move around the circle it's cutting. If it grabs the work, simply release the trigger. You still need to secure the work, of course.

It takes a bit longer, but is actually more controllable; at least in my experience.

To the OP, do practice on scrap. If you need perfect holes, get some shaft stock the same diameter as the center drill. Drill the center hole in the work with a slightly smaller bit, so you get an interference fit on the shaft stock. Use the shaft stock to replace the drill bit in the cutter. This will give much tighter tolerances on the final hole (the flutes on the center drill bit tend to wallow out the guide hole as you cut, otherwise).

Charlie
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  #14  
Old 03-12-2018, 11:25 AM
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maniago maniago is offline
 
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I didnt catch what thickness of material youre holing out, but that makes a difference on what method you choose. For thin stuff up to .032 and onsie-twosie holes, I just go old school with drilling holes around the periphery and perfecting it with a half round file. I have three steam gauges with tight spacing in a sub panel and I've remade that sub three times now (changes along the way), all old school filing and very sweet fitting. It does work.
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Last edited by maniago : 03-12-2018 at 11:29 AM.
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  #15  
Old 03-12-2018, 11:27 AM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
Posts: 3,525
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For that size hole, I use one of the Lenox annular hole saws. I've cut many holes with them. My drill press goes down to 500 rpm and I use that.

I use some plywood under the part, and pre-drill the center of the hole in the part and in the plywood to 1/4". Then I use a 1/4" pilot (really a bolt with the head and threads cut off) instead of the normal drill. This helps give a good hole.

If necessary, I use a drum sander to finish off the circumference of the holes.

All very easy and quick and quite reliable - safe, too. And the local hardware store carries the hole saws, so I can do the job soon after I find that I need to.

Dave
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  #16  
Old 03-12-2018, 11:43 AM
gasman gasman is offline
 
Join Date: Mar 2007
Location: Sonoma County
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Quote:
Originally Posted by rv7charlie View Post
Yep, I've cut quite a few holes using flycutters. Including holes for additional instruments in completed panels in flying a/c.

The cautions are legit; be careful. But as strange as it may sound, there are situations where controlling one can be easier with a variable speed hand drill than in a drill press. You need to turn these slowly, and be able to disengage from the work instantly if the tool grabs the work. With a drill press, you can't stop the tool quickly, you're limited in how slow you can turn it, and if it 'grabs' the work, you can't disengage unless the work is held perfectly all around on the table. With a quality variable speed drill, you can run the tool so slowly that you watch the blade move around the circle it's cutting. If it grabs the work, simply release the trigger. You still need to secure the work, of course.

It takes a bit longer, but is actually more controllable; at least in my experience.

To the OP, do practice on scrap. If you need perfect holes, get some shaft stock the same diameter as the center drill. Drill the center hole in the work with a slightly smaller bit, so you get an interference fit on the shaft stock. Use the shaft stock to replace the drill bit in the cutter. This will give much tighter tolerances on the final hole (the flutes on the center drill bit tend to wallow out the guide hole as you cut, otherwise).

Charlie
All very good information..... I did exactly this process when I needed to cut a 1.5 inch hole in my rear baffle for heat muff air. Used a battery drill motor and a 90 deg. adapter. Place the cutting tool so the taper is on the inside and will taper cut the scrap.... it will then leave a nice square edge on the hole. Start off so slow that you see the cutting tip just etch the surface. As you see the line appear, you can tilt the drill to keep the bit in continues contact. You will be pleased at how easy it is to do.

The fly cutter can be purchased at any hardware store.

BTW.... the 1.5 scat to the heat muff did provide a very good flow of air and temperature of the air was greatly increased.
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  #17  
Old 03-12-2018, 12:04 PM
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bkervaski bkervaski is offline
 
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Thanks all, great information. Love VAF!
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  #18  
Old 03-12-2018, 12:25 PM
bill v bill v is offline
 
Join Date: Mar 2011
Location: zeeland michigan
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Default hole saw

I have used a hole saw to drill out a plug from 3/4 plywood and then bolted this plug to the part (firewall) and then this plug is the guide with the center drill bit removed from the hole saw also had a piece of plywood on the backside held on by the same bolt holding the guide plug
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  #19  
Old 03-12-2018, 03:09 PM
Ethanol1 Ethanol1 is offline
 
Join Date: Oct 2007
Location: MN
Posts: 34
Default Harbor Freight

Harbor freight has a knock out punch set.
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  #20  
Old 03-12-2018, 05:43 PM
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plehrke plehrke is offline
 
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Location: Defiance, MO
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Canít beat a set of Greenlee punches. Pricey but work great. A&P in hangar a couple over has almost every size. Way better than flycutter and safer.
https://www.greenleestore.com/collec...dard-knockouts
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