How can I make a big hole in a plate that is 1 inch think (Alum) without using a hole saw. I used a hole saw and it almost broke my bridgport. I hate those things. The hole is over 2.5 inches.
Big Holes
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Or, if you have a rotary table but are too lazy to use it (like I am you can free-hand the circle with a 1/4" end mill like this (You'll want one with more than 3/4 cutting edge), then afterwards you can remove the remaining material with a boring head/bar. Just draw out the circle on your 1" alum plate, and "route" out the circle as close to the line as possible, then make several final boring bar cuts to your final size:
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I use hole saws to cut large holes pretty frequently. The main problem I have encountered is build up of chips, which causes the saw to either not cut or fetch up. To counter this problem, I drill a hole (say 1/2" dia.)in a location so that it's outer periphery is tangent to the outer periphery of the hole saw kerf. This gives the chips somewhere to go.
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<font face="Verdana, Arial" size="2">Originally posted by x39:
I use hole saws to cut large holes pretty frequently. The main problem I have encountered is build up of chips, which causes the saw to either not cut or fetch up. To counter this problem, I drill a hole (say 1/2" dia.)in a location so that it's outer periphery is tangent to the outer periphery of the hole saw kerf. This gives the chips somewhere to go.</font>
Good idea... In fact, I would suggest cutting several holes maybe 1" apart along the circle.
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A boring head will do the trick, 2.5 inch is a small hole, when you get to 5-10" holes you can still use a boring head with the bar out the side in a 4" boring head.
on a 2.500 inch hole I use a 2" boring head with a tool out the side thats shaped like a rounded threading tool, run it at 3000-4000 rpm and .0015"-.004" feed, it will leave a great surface finish.
it works.
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It's late here and cold so no going out into the workshop for pics of hole saws.
Probably the trouble you are having with cutting alloy and going deep is jamming.
I have the same problem and have got by this by grinding odd opposite teth aay to give a deeper gullet in places.
It pays to not be too neat about it and stagger the cuts.
A couple of deep cuts up the side with a thin slitting grinding wheel will also help to clear chips out.
The problem with hole saws is that they are made for material thinner than the depth of the teeth, increase the depth and you can a longer bite before clearing chips.
Coolant/ lube is a must, WD40 or similar [ see recent post ] works well.
Sir John.
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I don't have a rotary table or that is what I would have done. The hole saw just takes way to long and shakes may table and head when I put any real presure on it.
I used a boring head to clean the hole up after so it does not need to be a good hole.
I think next time I will try the single point in the boring head and see how that goes. Thanks for the info.
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I agree with you on the holes saws, pieces of crap imo, maybe i'm just buying the wrong ones (starrett) but they are so uneven it sets whole mill rockin & rollin. great for spruce lumber. last time i did a largish (4") hole in AL, I used the boring head after a 1.25" S&D drill with a carbide insert and cranked the speed up - for a one of it didn't take that long.
[This message has been edited by Mcgyver (edited 11-23-2005).]located in Toronto Ontario
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Using holesaws in thick material. Some things that will help, most have already been mentioned.
Drill a 1/4" hole all the way through your workpiece where the pilot bit would hit. Remove the pilot bit from the hole saw and replace it with a piece of 1/4" rod. Make sure the rod gets some lube.
Drill holes around the edge of the hole for chip clearance.
Grind out teeth on the holesaw for chip clearance.
Cut halfway through then flip the workpiece over.
I think one guy had some information on his website about truing holesaws up, somehow. I have forgotten all of that info.
Use cutting lube.
Yet, there may be better ways than a holesaw.
Brian
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