Cutting Aluminum Question

[JohnW]

Need to cut some 1-1/4" holes 1/8" thick box store aluminum flat stock. I have forstner bits and spade bits. Anyone know if this will damage the bits or have suggestions of which one to use. Only need to drill four holes.

 

[Mike Davis]

Buy a cheap Forster or be prepared to sharpen afterward.

I would not not use a spade bit, could be dangerous.

A hole saw saw would be the best, but that is not what you asked.

Be sure to clamp well three or four clamps if possible, back up the plate with plywood, run the drill press on lowest speed.

 

[Raymond]

John, you may end up destroying either of those bits by using them on a metal, a soft metal to be exact but still - you are attempting to drill metal with wood drilling bits. It would be cheaper to buy or borrow a bi-metal hole saw. Which I happen to have.

If you would like to link up - PM me and we can go from there. I live in the Derita area of Charlotte.

 

[AllanD]

Another option is a step drill. Not cheap but if you think you will be using in the future they can replace a lot of drill sizes.

http://www.irwin.com/tools/drill-bits/titanium-fractional-hole-enlarging

 

[Gofor]

If you end up with a lot of aluminum galled on the bits, submerge the tips in sodium hydroxide (Draino crystals dissolved in water is one option) which will dissolve the aluminum but not damage the steel. It won't sharpen them if dulled, but will get rid of the aluminum mess. Use eye protection. Sodium hydroxide can permanently blind you very quickly.

To prevent galling, lower speed and a lot of cooling/lubricant will work better than high speed in aluminum. That goes for both metal and wood bits.

Go

 

[Joe Scharle]

Carbide tipped hole-saw in a drill press. Spray the work with PAM frequently. Clamp the work to the table and wear long sleeves, gloves and safety glasses.
I'm no expert on this, but this is the technique I've used a few times with good success.

 

[chris_goris]

You could also make a wooden template with all 4 of your holes drilled in it and use a carbide top bearing mounted cutter (3/8 or larger diameter I would use) and a router to finish the holes. By finish, I mean predrill a center hole in your aluminum with a standard drill bit (probably about 1/2 diameter) that the router bit will fit into. Clamp your wooden template on top of your aluminum and work in a ever widening circular pass until your bearing hits the inside wall. This should result in nice clean, smooth holes.

 

[allisnut]

Larsen storm doors from Lowes come with a 3/4" spade bit for drilling the lockset holes, which works OK. For 1-1/4" holes I would prefer using a drill press with the material clamped and backed up by wood. Like the other said, a hole saw would be better.

 

[VTHokie]

If you happen to use sodium hydroxide (see Mark's post) to dissolve the aluminum from the bits, be sure to also wear rubber gloves and protective clothing in addition to the eye protection. Sodium hydroxide is a caustic base and will cause severe chemical burns upon direct contact with skin (not instantaneously but close enough that you want to immediately flush with plenty of water if an exposure occurs). Good luck!

 

[nn4jw]

I agree with using a carbide hole saw for this task.

I'm sure there are all kinds of substitutes that people use instead of actual aluminum cutting fluid but this is what I use for drilling and cutting on my horizontal metal bandsaw:

You can get if from Amazon if not locally.

https://www.amazon.com/gp/product/B0000DD2EX/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

 

[Gilley23]

You don't need anything fancy, just use a regular holesaw. Low to medium speed, medium pressure, steady water to keep it cool.
Don't use a spade bit, don't use a forstner bit, don't use a step bit.

 

[garymuto]

I've used hole saws in the past. I always used oil but water might be an interesting alternative. Using a slow speed and oild I uave not had galling problems

 

[AllanD]

Funny coincidence but Jody's latest Welding Tips and Tricks video shows him drilling holes in aluminum plate.
http://www.weldingtipsandtricks.com/aluminum-tote-tray.html

 

[Gilley23]

I've used hole saws in the past. I always used oil but water might be an interesting alternative. Using a slow speed and oild I uave not had galling problems

The oil is just used for keeping the saw and stock from overheating. Aluminum isn't going to rust so water will work great. Shoot, I've cut 1/4" steel plate with a sawzall and water....high speed and low pressure with a high tooth count works like a dream as long as it stays cool.

 

[Gofor]

Water with a little bit of dawn dish soap lubricates well. We use that to keep the sawzalls cutting well when removing people from car wrecks. I am told that Dawn is more of a soap than a detergent, and so lubricates better. I do know it worked well when we used it to cut a large hole in the side of an aluminum passenger bus during one of out training exercises.

Go

 

[JohnW]

Thanks for replies. I know a hole saw is the right tool for job but I don't own a set and was trying to come up with a way to drill 2 or 4 holes without buying/borrowing a hole saw kit. Thanks for the offer Raymond. I would have taken you up on it if it was a critical thing but I'm just making backer plates for adding some flush mounted rod holders on a fiberglass boat, so pretty and real accurate is not important.

I ended up using my adjustable circle hole cutter. I use it cutting out guitar sound holes and such. It has a hardened steel blade and with a little machine oil, cut the aluminum fairly well. Not like butter but a little more like frozen butter. Holes came out very nice and the tool was not damaged other than needing sharpening.

Also don't have a metal blade for my handsaws so I made straight cuts on my RAS using an old carbide tipped blade installed backwards. I had heard of this tip before. I will report that it worked but...I turned it around to cut "normal" and that worked better.

 

[GeorgeM]

My suggestion would be a chassis punch in the size hole you need. It is very easy and safe to use. I punched more holes that I care to count with them over a 35 year aviation career. You can find them in about any size you would every need.

Have a Blessed day.