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Drill bit depth stops damaging skin?

bmellis11

Well Known Member
Sponsor
I just tried out these depth stops for drilling holes for the Vans control surface practice kit.

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They were recommended in one of the EAA videos as a way to help prevent elongating the hole.

When the depth stop hits the aluminum surface it scuffs it up a bit.

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You can also see it in the bottom of the dimples.

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Here is a photo of other dimples where I didn't use the depth stop for comparison.

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Is anyone else using these and have a recommendation on how to minimize damage to the skin?

Also, do my dimples look ok?
 
Try moving the stop farther up the bit. Practice with it. The stop should not be spinning when it hits the surface. It's a stop, more than a depth gage when you don't want to scuff the surface.
 
Turf the stops!

The holes without using the depth stop look better, so there's your answer! Another technique is to extend a finger from the drill motor to help steady it and also to stop it from punching through suddenly. You should also be able to sense when it's about to break through and ease up the pressure a bit.

I think the dimples look good, try inserting a rivet to prove that they are flush.
 
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i use a piece of fuel hose cut to length so it is 1/8'' short of the end of the bit. for me it works way better.
 
don't use them unless there is something behind

43 years of structures experience speaking, and I don't use them at all unless I have something behind I could hit. The stop device itself isn't always the culprit of what you are seeing, but more so the shavings trapped between it and your aluminum skin. The Alclad coating is soft as butter and looks nasty, though you aren't likely damaging the 2024-T3 parent alloy. If I have worries of the chuck hitting, I often spin on a wrap of masking tape way up the shank JIC. As others mentioned, triangulating with your fingers will help as well.
 
you might look at cleco boots, small plastic piece that goes over a cleco and prevents marring the surface.

Keith Rhea
RV7
 
After I lost the grub screws on my drill stops, I just wound some electrical tape tightly onto the bit and it serves the same purpose but doesn’t scratch. Use different colors to define different drill sizes, so you can always grab the right one at a glance.
Tom.
RV-7
 
Paul's comment bears repeating:

"You should also be able to sense when it's about to break through and ease up the pressure a bit."

Cutting metal operates partially in cutting and partially in tearing or breaking when the cutting tool pressure is greater than the strength of the metal remaining to be cut.

cutting, by in large, will be "accurate" tearing will not.

FWIW
 
43 years of structures experience speaking, and I don't use them at all unless I have something behind I could hit. The stop device itself isn't always the culprit of what you are seeing, but more so the shavings trapped between it and your aluminum skin. The Alclad coating is soft as butter and looks nasty, though you aren't likely damaging the 2024-T3 parent alloy. If I have worries of the chuck hitting, I often spin on a wrap of masking tape way up the shank JIC. As others mentioned, triangulating with your fingers will help as well.

+1

Paul's comment bears repeating:

"You should also be able to sense when it's about to break through and ease up the pressure a bit."

FWIW

+1 Except just match drilling is pretty light already.

Also, unless the swarf is getting trapped, you could use a dot of milk carton plastic, or felt cabinet door stops, but the above solutions are more practical. ;)
Just adapt your technique ??

Does this dress make my *** look . . . . Your dimples look fine.
 
One more thing to keep in mind, is that a bit will eventually get dull. Learn to feel when the edge is starting to dull and change bits at that point. If you have the time, it's worth learning to hand sharpen the dull ones, but realize that a package of #30 jobber length bits from a good source is only about 10-20$, depending on coatings and point angle. A quality bit, using correct techniques and speeds, should last you several hundred holes.
 
For the match drilling I've found reamers to be awesome, along with extending the fingers of the non-drill hand to prop up and not drive the drill in.
 
Drill stops

I found a few places where you really want to use the stop.
There are holes going into the spar where you do not want to hit the spar cap. Probably lots of other spots I can't remember. A little scratch on the skin is negligible compared to hitting something expensive.
Drilling rivet heads. I keep two bits #40 & #30 with preset stops so I can't drill past the head and hit the hole edge. Pull the bit out of the drill, flip, snap the head off.
 
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