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Deburing advice

A

atalla

Well Known Member
Hi all Im working on my practice pieces and have been reading a lot about deburing no more than 10% of the thickness of the work piece. I'm using a 3 flute deburing tool from Aircraft Spruce. With my drill press set at max 3050rpm i was getting a fair amount flashing on the backside on my #30 holes through my angle. I debured as lightly as i could due to the sharpness of the new tool but i noticed two things

1- The round hole no matter what i tried was turning the chamfer into a rounded triangle due to the three flutes.
I have a 6 flute which will cut down on chattering but am unsure of the angle and don't want to chance it. Is a single flute (round hole ) cutter in these sizes avail?
Iv seen the drill mounted spring loaded debur tools that do both sides at once but there pricy, only work with one size, and I haven't heard anyone here raving about them.

2- To pass the finger nail test 3 and sometimes 4 turns of the tool were needed which worried me due to the 10% rule. heres the angle with what i think are over debuted
Notice the chattering.....

I also want to ask all about a switching to a reamer. Cost? benefits? RPM ?

Thoughts? Pics of a perfect marginal and scrapped hole?
 
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Deburring

Don't over think.
Thick parts will have more burrs no matter how you drill but reamers will produce less.
I call those holes over deburred. Probably ok on a thick piece but too much for a skin. Two spins with very light pressure, more on a thick part with bigger burrs. Too much pressure will make it chatter. You can barely see the chamfered edge when done.
The standard three flute is fine for deburring the gazillion holes in your plane. Some use scotch brite and just scrub the surface. You're just removing any burrs on the edge of the hole.

Yes, IMHO, you can and probably should invest in a set of single flute but more for countersinking.

Reamers are great. Cost about $9 each. Perfect round holes with almost no burrs but extra work. Speed is the same. I usually drill one or two steps small and use the reamer for final hole. #40, #30, #19, #12 and maybe 3/16", 1/4" and 3/8" will cover most jobs.
 
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I run my drill press very slowly; will yours go slower? Recommended RPM for aluminum is under 1000 I believe. Your post got me wondering about the actual math, and I've found varying numbers, but 5500 is way above any of them. Also, I like to deburr thicker items like that either on the scotchbrite wheel or with a dremel and sanding drum. Makes super-quick work of it, and since those parts generally get primed, no worries about scuffing them up.

The deburring tool will work much better on the skins where much less pressure is needed.

Chris
 
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I deburred everything with a hand tool. I found it impossible not to apply too much pressure with a drill press.
 
NO drill press for deburring! as mentioned before use the hand deburring tool. One or two light turns should be enough. Do NOT debur if there are no burrs, not every hole needs to be done. Over doing this operation will cause a lot more damage then not doing anything at all. All you are trying to do is to get rid of anything that will keep the two parts from nesting snuggly together.
Lightly run your finger over the surface. If it feels smooth, leave it alone. Be careful with your fingers if you have office hands, cuts can result.
 
Here's how I'd deburr those holes:

1. Make a light pass down the length of the angle with a flat mill file, a fine one. That'll take off anything that sticks above the surface.

2. With the correct size reamer in a chuck, I run the reamer down into the holes by hand, turning it a half or full turn. That cleans out the hole. Note that although I leave the chuck on the drill for this, I don't connect the drill to the air hose. This is strictly by hand. The only reason for the chuck is to get some mechanical leverage on the reamer.

3. Check with fingers and repeat as needed.

This goes VERY fast and doesn't hurt the holes.

Dave
 
wirejock said:
Reamers are great. Cost about $9 each. Perfect round holes with almost no burrs but extra work. Speed is the same. I usually drill one or two steps small and use the reamer for final hole. #40, #30, #19, #12 and maybe 3/16", 1/4" and 3/8" will cover most jobs.
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Awesome Thanks

YellowJacket RV9 said:
I run my drill press very slowly; will yours go slower? Recommended RPM for aluminum is under 1000 I believe. Your post got me wondering about the actual math, and I've found varying numbers, but 5500 is way above any of them.

Chris
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I was under the impression min 3600 rpm for alu as per the sioux drill 6000 for acrylics and plastic ?

rv7charlie said:
https://www.google.com/webhp?sourceid=chrome-instant&ion=1&espv=2&ie=UTF-8#q=120+degree+single+flute+deburr+tool

helps with the chatter marks. What are you using to run the deburr tool? Hand powered, or drill?

On the subject of excessive burrs, are you using backing material behind the stock? Sharp drill bits? Dull bit &/or no backing will cause the bit to push a chunk of metal out of the way instead of cutting it away at the end of the hole.

Charlie
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Hand use only, i used an oak backing while drilling using the drill press.
 
I was referring to drill press RPM. I have no idea what my air drill runs at, I'm sure it's closer to what you refer to. For thicker pieces like the one you show, I prefer the drill press. Sorry for the confusion!

Chris
 
YellowJacket RV9 said:
I was referring to drill press RPM. I have no idea what my air drill runs at, I'm sure it's closer to what you refer to. For thicker pieces like the one you show, I prefer the drill press. Sorry for the confusion!

Chris
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Hey Chris sorry, I'm new here, Why would you run a drill press slower than a drill if their running the same bit through the same material ?
I would always use a drill press if I could; its always square, and a wood backer is often used.
Thought?
 
That's a great question, and I honestly couldn't give the right answer. I'm just so used to drilling skins with the air drill and thicker pieces with the drill press, which naturally runs much slower. I guess with the same bits, the drill press would work just fine at much higher rpms, if it would go that fast. I'm sure somebody smarter than me will be along shortly.

Chris
 
Yes I would love it if someone smarter than me could chime in on this,
My sheet metal kit from Snap-on(ATI) includes sioux 3x+2700RPM drill, but most ppl here have the 3600rpm drill from Browns. one has to think Why would ATI (Snap-on) an OEM tool Supplier sell a kit with a drill which turns too slowly for ALU?

My drill press has speed setting which include 570,900,1390,2050,3050 (error corrected on initial post)
 
For optimum drill speeds, google 'machinist drill speed tables'. Cutting speed is typically given in feet per minute, but tables are easy to find that show optimum rpm for each material and drill size. (Bet you'll be shocked at optimum rpm for a 1/8" bit in aluminum.)

But... drilling aluminum isn't rocket surgery, and drill speed really isn't that critical. Lots of guys have used old nicad powered cordless drills to build an entire RV, and they typically run at <1500 rpm. A dull bit, or a bit that's got aluminum stuck to the cutting edge will make a nasty lip (burr) on both the entry and exit. It's not that hard to get aluminum stuck to the cutting edge when drilling 6061.

For me, the 'best' available burr removal tool is a really sharp 135 degree drill bit that's significantly larger than the hole (3/8-1/2" for a 1/8" hole), but they are inconvenient to use because there isn't a convenient handle. I think 150 degrees would be even better, but I don't have a source. The problem, at least for me, is that sharper angled (120, 100, 82, etc degree) deburr tools are more prone to removing material from the edges of the hole itself (like in the picture in the 1st post) instead of the burr, which is curled up on the surface.

Somebody mentioned sliding a file along the surface. I guess you can get away with that on 6061 (angle stock), but I'd think 2024 alclad sheet would get nasty scratches, and lose the alclad everywhere the file touches.

Charlie
 
rv7charlie said:
For optimum drill speeds, google 'machinist drill speed tables'. Cutting speed is typically given in feet per minute, but tables are easy to find that show optimum rpm for each material and drill size. (Bet you'll be shocked at optimum rpm for a 1/8" bit in aluminum.)

But... drilling aluminum isn't rocket surgery, and drill speed really isn't that critical. Lots of guys have used old nicad powered cordless drills to build an entire RV, and they typically run at <1500 rpm. A dull bit, or a bit that's got aluminum stuck to the cutting edge will make a nasty lip (burr) on both the entry and exit. It's not that hard to get aluminum stuck to the cutting edge when drilling 6061.

For me, the 'best' available burr removal tool is a really sharp 135 degree drill bit that's significantly larger than the hole (3/8-1/2" for a 1/8" hole), but they are inconvenient to use because there isn't a convenient handle. I think 150 degrees would be even better, but I don't have a source. The problem, at least for me, is that sharper angled (120, 100, 82, etc degree) deburr tools are more prone to removing material from the edges of the hole itself (like in the picture in the 1st post) instead of the burr, which is curled up on the surface.

Somebody mentioned sliding a file along the surface. I guess you can get away with that on 6061 (angle stock), but I'd think 2024 alclad sheet would get nasty scratches, and lose the alclad everywhere the file touches.

Charlie
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This seams to be working well. the debur tool is 100' and so sharp it chamfers the hole before removing the flashing from drilling. The extremely large drill bit removes the burr without touching the hole. Awesome!
so now, how are you guys dealing with areas like this?
 
If you're careful, even a fresh (sharp) Exacto knife, razor utility knife tip or even a really sharp narrow blade chisel can shave off the burr without doing damage to the skin.
 
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