Geoff Heap
Joined: 12 Jan 2006
Posts: 266
Location: Lindenwold, New Jersey
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 Posted: Thu Jul 01, 2010 1:34 pm Post subject: Holes in aluminum sheet metal |
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Some general advice on hole drilling reaming and deburring
Put a piece of .025 in a vice with a piece of 2 x 4 to back it up and drill in with a ½” drill, or the biggest you have. You’ll get a nice triangular hole.
2 suggestions for you to get better holes.
1. Drill undersize and use a reamer.
2. Use a #1 center drill for your A4 rivet holes then open up with the #30 reamer (.128)
A #1 center drill has a .04 pilot and so will pick up a center punch mark much better than a 1/8 drill point. The body size of the center drill is .125. it's all I use.
The reamers don’t cost a lot considering they can open up a few thousand holes and the center drills are cheap. Buy HSS only. They are the cheapest and will cut aluminum almost forever.
Below is an old post of mine on deburring. Hope I helped…..Geoff
First we need to get rid of the mindset that hole deburring is an unimportant distraction. It is an operation in itself. Think about
how many holes you will debur in your building process. Using the wrong tool will add countless hours to the process over the life of the project. Please buy the right tool and avoid being cheap. I've seen this question so many times over the years and someone always says to use a drillbit. Sorry guys this only works sometimes, usually with small diameter holes. No machinist would ever do this. The rotating blade is very good at this job. The most common brand name at MSCDIRECT.COM is the VARGUS. There are other brands, plus, I think SEARS sells something like it. One MSC debur set is from VARGUS (msc ORDER # 00424523). One handle and about a dozen blades for $3.92. One blade will almost last forever in aluminum. Add in a few steel parts and this set will build a couple of aircraft. This tool is great for holes about 3/8 dia. or larger. However, if the burr is thick and raised as a result of a dull drill, the resulting debur will be ugly.(same for using a drillbit). A smooth
file should be used first to get rid of the raised part of the burr. Then the deburring tool can take the sharp corner off the hole nicely. I'm Building a CH701 so my holes are mainly 1/8" and 5/32". For these sizes the drill bit approach can work fairly well but only if the original hole was made with a sharp drill which will produce a very small burr. However you can do a better and I think, quicker job with a small countersink tool in a pin vise/chuck holder(you still need the file if the burr is heavy). It looks exactly like the rotating blade tool holder but instead of "snap in/snap out" as with the rotating blade, it will hold anything round just like a drill chuck does. MSC sells Part # 06491906 (5/16 dia. capacity) for $21.72.(I spent a while looking up these part numbers). Now all you need is a small countersink to use in the pin vise. There are millions of them out there. Try MSC PART # 60316650. It is 90 degrees, 5/16" dia. with 1/4" shank (MSC Part # 60316655 $12.69). Now here's the important part. This tool and all coutersinks have 3 or more flutes. This gives stability and is the reason why a 2 flute drillbit cannot debur well. I have all these tools and use them constantly. If you don't buy them now you probably will later. The parts I list here total about $37 + shipping. You can find them cheaper and possibly locally at SEARS. Don't baulk at the cost. I have a rivet squeezer that I paid a bundle for and only needed it for less than a hundred rivets. The deburring tools I use ALL the time. I hope this helps put this problem to rest. It's a recuring question from new builders. Regards to the group....Geoff Heap.
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