Best Drill Bit For Gummy Aluminum?

The shooting club I belong to uses aluminum clips to hold cardboard target backers to wooden target frames. The clips are made from soft
aluminum roll flashing, and are held to the frames by a pair of aluminum nails. Over time, the frames & clips get shot up, and we have to keep building new frames & making more clips. I've made some jigs to help mass produce the clips. Part of the process is to drill a stack of the blanks to make holes for the nails. The jig I made has two 3/32" steel drill bushings for this purpose.
The problem is the drilling. Roll flashing is typical soft aluminum, and wants to stick to the drill & stick to itself. It also wants to fuse together rather than cut. I'd like to just be able to zip through a stack of 10 or more blanks, but if I'm in the least bit impatient, I end up welding the stack together at the holes. I also end up with stringy chips stuck in the drill flutes. To minimize mess, I'm doing this dry, with no cutting lube. It slows things down considerably if I have to keep peeling chips out of the drill flutes, and pry all the blanks apart at the end of the drilling process.
I started with some fast twist bits from McMaster Carr, on the theory that they would pull the chips out better. They have a bright finish, and I'm not convinced that they are any better than normal drill bits.
Rumor has it that black oxide finished will help prevent the chips sticking to the drill bit. I'm wondering if there is anything else special I should look for. Split points might be helpful, but I'm not sure anyone bothers for drill bits this small.
Ideas or suggestions would be appreciated. I don't mind spending a few bucks on fancy drill bits if it will speed up the process considerably.
Thanks!
Doug White
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One cheap and easy thing to try is spraying the drill bits with a moly-disulfide spray. One of the top coatings used in very fancy multi-coated tools, specifically to prevent chips from sticking or welding to the tool, is straight moly disulfide.
Since this is not a high-temperature application, any hardware spray would be worth a try, including the ones that combine moly with Teflon. You might try spraying it around the spots on the aluminum sheets where you're going to drill, too. It may help keep them from sticking.
Good luck.
--
Ed Huntress



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Normal drills work fine. Use diesel as a lube and make certain the drill is sharp. Steve

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You might want to try the wood bits with the spurs or regrind a regular bit with the same configuration. http://www.rockler.com/product.cfm?page 613
And I REALLY like a punch for such things. $55 for punch, $80 for the kit. I keep two of them in the lab with different punch sets loaded http://www.mcmaster.com/#3461a22/=5lr067 http://www.mcmaster.com/#3461a11/=5lr0pp
Doug White wrote:

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Doug, it would probably be a lot faster to punch those holes with something like a Roper-Whitney bench-top punch. You can buy a Chinalloy version for about $30. It should be able to handle four sheets at a time.
LLoyd
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"Lloyd E. Sponenburgh" <lloydspinsidemindspring.com> wrote in

I have a Roper Whitney punch, and drilling is a LOT faster because I can set up a much thicker stack and the drill bushings make locating the holes effortless. Even with prying them apart, drilling is a win. The goal is also to provide the Club with idiot proof tooling so I don't have to do this in the future. The drill jig is something anyone with an electric drill can use.
I found that McMaster Carr has split point parabolic drills in 3/32". I can get them bright, black oxide or TiN. I suspect they will work better than the plain point fast twist drills I have now. I found one source that says black oxide is no good for aluminum, so I will probably try TiN. I can try coating the drill with a spritz of lube as Ed Huntress suggested. That will help keep the mess under control.
Doug White
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The nice thing about the moly is that it dries. No mess. And it wipes off easily.
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I have a couple of options to try, but they are both greases that may be a bit messier than what you suggest. I have a tube of mil spec moly grease for torquing AR-15 barrel nuts, as well as some really high moly content assembly grease. The tube of mil spec stuff will last a dozen life times, and is cheaper, so if I go the moly route, I may start with that. Is there a specific moly spray that you would recommend that dries?
Doug White
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Sorry, but I don't have a recommendation. I haven't had the industrial stuff for a couple of decades, but it was great stuff.
There are several manufacturers. Here's one, for example:
http://www.thomasnet.com/catalognavigator.html?cidY7157&cov=NA&what=moly+disulfide+spray&headingD960409&searchpos=3&cnurl=http%3A%2F%2Fantiseize.thomasnet.com%2FCategory%2Fmoly-spray-trade-dry-film-lubricant&prodpos=1&searchpos=3
You probably can find one at any good hardware store, although the ones I've been are diluted with graphite or Teflon. Still, I don't think that would be a problem drilling soft aluminum.
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<snip>

McMaster Carr has Dow Molykote L-0501, but it isn't clear if it actually has much moly in it. Molykote 321 sounds perfect, and McMaster carries that as well as Dri-Slide, which is a similar product. Dri-Slide is rated at twice the pressure of Molykote 321, and they also have a marine grade spray that is rated three times higher than Dri-Slide (at about the same price). I think a can of spray moly sounds like a good thing to have around in general. I'm always buying something from McMaster, so I'll toss in a can with the next order & give it a try.
Doug White.
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Doug, get some stick wax/lube it will help with the chips.
http://www.emisupply.com/catalog/walter-alucut-metal-cutting-lubricant-105oz-stick-p-2307.html?utm_source=googprod&utm_term=WAL-53B303
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Thanks. I've got some for my bandsaw, I'll give it a try. At least it isn't as messy as a liquid lube.
Doug White
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wrote:

Black oxide is good for ferous metals, aluminum likes to to stick to it. go with the TiN. Also avoid coatings with Al in them, AlTiN or TiAlN.
Thank You, Randy
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On Sat, 30 Jan 2010 20:55:34 +0000, Doug White wrote:

Just nail through the @#$% metal?
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Roofers nail aluminum flashing all day with aluminum nails and it certainly didn't take jigs, tooling, or much training to get even the newest hires doing this. Art
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They are nailing small clips to the edge of a 1x3, and without the holes, they make a mess of it. Don't ask me how, I don't know. I need to make this completely idiot proof so I don't have to deal with it in the future.
Doug White
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On Sun, 31 Jan 2010 00:43:05 +0000, Doug White wrote:

It seems to me (sitting here in my armchair, yards from my shop) that it may be easier to make a jig to pre-punch the holes. I.e. hold the part, locate the holes, let you pre-bash a nail or equivalent through them to get 'em started.
I could see getting fancy and making something that punches all necessary holes with one stroke of a lever, or something as crude as a few holes in some angle, through which you run a nail and bash away.
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Tim Wescott wrote:

If the aluminum is thin enough, you could modify a three hole paper punch.
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The clips are small, only 2 1/2" tall, bent in an L shape. One side of the L gets nailed to the sides of the frames, and the other is spaced forward to hold the cardboard.
I've already built the drilling jig after hand punching several hundred clips, and trust me, drilling is faster. I suppose I could have made a gang punch using Roper Whitney punches & dies, but I've already invested more time in this than I'd like. The drilling works OK, but if I can spend an extra $1 on a TiN split point drill bit to make it better, that would be money well spent. If a spritz of spray moly lube allows me to drill 16 at once cleanly vs 8 or 10, that is a huge win.
Doug White
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I'm using 14 mil thick roll flashing. I think I would still be stuck doing only a couple at a time, vs 10 with a drill. A Roper Whitney punch can handle 4 or 5 at once, but not 10. With the right drill & lube, I'm hoping to get up to a dozen or more at once.
Doug White
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