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Cutting 3.25" Hole in Aluminum

Texasbowhunter

Aluminum
Joined
Oct 11, 2019
I'm in need of some guidance without breaking the bank...I'm trying to decide on how the most accurate way for me to cut a 3.25 dia. hole in apiece of 1/2" thick aluminum would be with a floor mounted drill press which has a MT2 spindle...The hole I'm shooting for needs to be clean without any ugly in the cut walls...accuracy doesn't have to be precise since the part that will go into the hole I can adjust for tight fit in my Lathe...I have several hole saws of various sizes but I fear that the quality of the hole would be sub standard as far as the wall finish...My chuck on the drill will only go to 1/2" I believe however it may stretch to 5/8" I just have not pushed this limit...
I have tossed around a carbide china hole saw set up specifically for the dia. hole but am concerned it may not be deep enough to cut thru the 1/2" plate aluminum
My hole saws are the older style where you have a arbor and attach the hole saw of desired size and lock down the locking nut...They spin and not very accurately at all...
Fly cutter???
Thoughts???
Paul
 
Everything depends on the tools you have to work with.Since you mentioned a lathe, I would drill with a 3 1/8" hole saw in the drill press then bore to final size in the lathe. If you have a mill then you can bore to final size with it. If it won"t fit on the lathe and you don"t have a mill, since it is aluminum, you could cobble together a treepanning cutter for the drill press.
 
Or set it up and bore it out using the lathe. I don’t think the drill press is gonna get it done.
Rob F. Beat me
 
Like curve bits, opening saws throw directly into your drill and will slice through slight measure sheet metals like aluminum and steel. Utilize a piece of compressed wood as a patron for the opening saw's pilot bit and to secure your work surface.
 
All these 'bore it in a lathe' comments ASSUME the part will fit in a lathe....not a great assumption.

If your drill press is especially good, you could try an annular cutter.
 
Paul,
Send the job out to someone that has the tools or acquire the tools yourself. Anything else endangers you, the tools you are abusing and the work.
This has crossed my mind
However I would like the learning experience of seeing if I can muster up something before I send out...
 
All these 'bore it in a lathe' comments ASSUME the part will fit in a lathe....not a great assumption.

If your drill press is especially good, you could try an annular cutter.
The part will fit on the lathe now that I'm visualizing more ways of loading it on a lathe
 
A fly cutter seems reasonable from what I looked at last night before I went to bed
I have never used a fly cutter
Are you supposed to provide a hole first then gradually increase the cutter of the fly up to size increasing the hole dia. slowly while feeding?

The first and foremost is safety
But if I can rig something up on the cross slide that would hold this odd triangular shaped material in place and that is providing I can rig something up with my limited visualization I might be able to make the cut with the use of the lathe

Ill try and come up with some ideas hopefully watching the YouTube videos and getting the brain working...
Or
A fly cutter in the Drill press? would be an option as well
I like the thoughts of using the lathe better though
paul
 
Do you own a router?

If so, one way would be to drill with a 3-1/8" hole saw and then use a flush trim bit in the router with a guide ring precisely bored to size in the lathe. A 1/16" cut in aluminum is well within the capability of a carbide router bit.

Also make a stepped plug to center the guide ring on the sawed hole.

Many woodworkers have used a router on aluminum to trim against a template so this is far from a radical idea. Use WD-40 for lube.

FYI: A fly cutter in a drill press is a terrifying thing. Without controlled feed as in a mill the chance of snagging the bit are high and the results won't be pretty.
 
Do you own a router?

If so, one way would be to drill with a 3-1/8" hole saw and then use a flush trim bit in the router with a guide ring precisely bored to size in the lathe. A 1/16" cut in aluminum is well within the capability of a carbide router bit.

Also make a stepped plug to center the guide ring on the sawed hole.

Many woodworkers have used a router on aluminum to trim against a template so this is far from a radical idea. Use WD-40 for lube.

FYI: A fly cutter in a drill press is a terrifying thing. Without controlled feed as in a mill the chance of snagging the bit are high and the results won't be pretty.
An Idea I had not given any thought on but a Very Good Idea...
You got me thinking in another direction Thanks
Paul
 
I agree.... a flycutter in a DP is not gonna fly. Well, it will fly....

The annular cutter runs slower and is a balanced cut....that's why it might work.


But nothing beats a lathe for an easy, good cut....assuming it's a circle you want.
 
Unfortunately the piece of aluminum wont chuck up in the lathe chuck
Its a large piece shaped like a triangle 11.5 x 12.5
I might be able to rig something up on the cross slide which what ever I do there will be weighed out having a local shop cut it for me...
 
If you are thinking of using a hardware store FLYCUTTER be aware. MANY of these things will not stay set. No matter how well you tighten the set screw securing the cross arm, vibration will work things loose.
Of all the tools in any shop the inexpensive FLYCUTTER may be the most dangerious!
 
One old-school way is to center punch the location. Use a compass or a trammel to draw/scribe the finished size and another circle to draw the drill holes. Then drill -drill- drill till you can knock out the slug. then finish to +- .003 or so with a round-sided flat file.

Very likely any drill press fly cutter will be a turkey shoot and not as good as by hand.
 








 
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