Inside Surface Deburring

[Brian Jackson]

Quick question:
When drilling through square tubing, is it customary to deburr the inside edge of the holes? And if so, what tool/method would one use to reach that inside edge? If left burred on the inside, are stresses distributed non-uniformly as a result? I ask because I'm drilling my keel tube currently and wondering if I need to invest in a different style of deburring tool to reach the inside edges of the holes (assuming such a tool exists.

Thanks,
Brian Jackson

[LGoodhind]

There's a deburing tool you can use to reach inside a hole and trim the backside- here (http://www.aircraftspruce.com/catalog/topages/deburringtool.php) is a pointer to Aircraft Spruce's catalog entry for one but you can find them from Enco and others as well.

[Brian Jackson]

There's a deburing tool you can use to reach inside a hole and trim the backside- here (http://www.aircraftspruce.com/catalog/topages/deburringtool.php) is a pointer to Aircraft Spruce's catalog entry for one but you can find them from Enco and others as well.
Thanks Larry. Already have one: see last photo here (http://www.gyrobuilder.com/qb/drilling2.htm). I can angle the blade in a coordinated rotation and catch part of the inside edge that way, but didn't know if there was a better, more precise tool to use. Where's those endoscopic (butt hole) cameras when you need them :D

Cheers,
Brian Jackson

[LGoodhind]

The machinist's way

In my department at the University, we have a splendid machine shop (I often use it), and we have Jim and Otto, both splendid machinists. They know every trick of the trade. Suppose I could hand the drawings to Otto, and have him make six Dirods. He would use precision methods, and make six of every part, all alike. In final assembly, he could pick up any part and use it in any of the Dirods. All machines would fit together with high accuracy, with no adjustments needed.

Your Way

Totally different. You may never have built anything this complicated. You learn as you go along. Most of your screw holes are well located, but some are a little off. Also, wood for the base is not an ideally workable material. In making a hole for a wood screw, it can be a bit off; that tilts a bearing post sideways, and makes the shaft out of alignment. That's when you somewhat enlarge the hole in the plexiglas, make the adjustment, and go ahead to the next job. When done your generator will work as well as one Otto would make.

from Electrostatics, A.D.Moore

I certainly hope that using a deburing tool is sufficient. =)

[Rotornut]

Hey Larry Good to see You Post. Will you make it down for Bensen Days 2005??
Hope so. MJ :)

[Harry_S.]

IMO, I don't believe, in a thru bolt application, inside burrs should cause any concern. If sharp drill bits are used and reamed to size, burring should be minimal at best.

If you were to install inside anchor nuts, then all burring should be removed.


Cheers :)

[Brian Jackson]

IMO, I don't believe, in a thru bolt application, inside burrs should cause any concern. If sharp drill bits are used and reamed to size, burring should be minimal at best.

If you were to install inside anchor nuts, then all burring should be removed.


Cheers :)
Fortunately there are no interior anchor nuts used on a GyroBee to my knowledge. I understand burrs to be most detrimental for stresses when compressed. That makes sense because the compression and subsquent stresses would be unevenly distributed to the surrounding material.

Again, I'm still learning so everyone's input is of great value.

With respect,
Brian Jackson

[WesTech]

Here's the tool you need. It's called a "cogsdill reverse deburr" tool. Do a search on ebaymotors and you can see what they look like and probably get one for next to nothing. Get the one for the size of hole your drilling...It has a little spring loaded blade on it that sticks out and as the drill turns, the bur is shaved off and as you push the blade will collapse and will be pushed through to the inside where now you pull, (all the time while turning with your drill) and it will debur the inside of your material for you, and then simply pull it out, the blade again (spring loaded) collapse's into the shaft. Sounds complicated but they aren't and they work great!!!

[mceagle]

IMO, I don't believe, in a thru bolt application, inside burrs should cause any concern. If sharp drill bits are used and reamed to size, burring should be minimal at best.
Cheers :)
I would agree with Harry on this one. Inside burrs should be of no concern whatsoever. Burrs can only cause a problem when they are lodged under the head or the nut washer on a bolt. As Harry said, good sharp bits cause minimal burring anyhow.