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Advice on annular cutter for 3" hole please

I don't think you know what a Weldon adapter is.
People come here to give and receive help.
You seem to be picking the fly shIt out of the pepper.
If you have a Rotobroach holder great.
If you need to modify a Weldon holder to make it work,
also great. Looking for a problem with people trying to
contribute, not so great there fella.

-D
I know exactly what a Weldon adapter is. What I said was, since the OP had said he had an annular cutter and the Weldon adaptor "for it", I took that to mean exactly what it turns out he was trying to describe. Was the term Weldon adapter used incorrectly yes, you are absolutely correct. I just don't get why you feel the need to insult people, when correcting them. There's a big difference between being a hard ass, and being an asshole.
 
Back to the original question, I'd feel perfectly comfortable using the HSS Hougan cutter. Made many holes with them, but have no experience with their Copperhead line. We always used the standard HSS, and the German made Milwaukee's.
 
Dust of the old rotary table to put the hole in. You would have been done before you read all the comments!!!

Even simpler (although not as proper): layout/scribe a 3" line on the plate with a scriber in the spindle (or a compass). Pop some holes around the circumference (such as a 5/8 or 3/4" hole). follow up with a 1/2 or so endmill to chew around the line. Does not have to be perfectly round. just close to the line.

Follow with the boring bar you were going to use to clean it up.

Personally i think the 3" hougen drill would be fine. I would use HSS not carbide.
 
I know exactly what a Weldon adapter is.

The guy already said he has the proper R8/annular cutter adapter, so why not just use the purpose built holder he already has?
Again, why are you asking stupid questions on the internet.
If he has an adapter that fits
or I suggest using an end mill holder
or he already has what he needs for the hole saw,
Why do you care so much to interrogate why I was
making the suggestion that I was?
It is zero consequence to you.
Waiting for you to put me on ignore and go watch
some Taylor Swift videos.

-D
 
Even simpler (although not as proper): layout/scribe a 3" line on the plate with a scriber in the spindle (or a compass). Pop some holes around the circumference (such as a 5/8 or 3/4" hole). follow up with a 1/2 or so endmill to chew around the line. Does not have to be perfectly round. just close to the line.

Follow with the boring bar you were going to use to clean it up.

Personally i think the 3" hougen drill would be fine. I would use HSS not carbide.
That would be one way to do it. I suppose I could just torch it out too. About a month ago I torched out a 32" circle out of plate using a bolt in the center and a wire attached to the torch. It worked OK, but was thinking there would be easier and cleaner ways to cut this 3" hole.

A lot of good ideas here. Thanks for yours.
 
They make jigsaw blades that fit into a full size reciprocating saw. AKA sawsall. Worked okay in 3mm plate I would not want to try in 3/4" thick stuff.
Bill D
 
I have a job coming up which, among other things, involves cutting a 3.250" hole in a 3/4" plate of 1018. I plan to cut the hole on a Bridgeport using an annular cutter. I have an R8 to 3/4" weldon adapter for it. But I'm not sure which cutter to buy, since I don't have anything near a 3" size hole cutter. I plan to finish the hole with a boring bar.
I wouldn’t bat an eye to use a quality (like DeWalt or Milwaukee) 3” hole saw to do that. However there are some tricks to make that work . . .
I've done the hole saw hack route for a big hole once. I only drilled one relief hole, but on the second big hole, all the teeth sheared off the hole saw in the partially cut hole. Not fun to get the sheared off teeth out of the partially cut hole. As I recall, I think that was also in 3/4" thick steel. The hole saw was a Milwaukee bi-metal. I've heard of people successfully using hole saws to cut thick steel, but it didn't work for me. What was I doing wrong? Was it that I didn't have enough relief holes?

Don’t bother with relief holes, coolant or oil. None really work right for this operation.

One of two ways of chip removal will make this work: either hold the tip of a short air gun right near the hole saw while cutting, or hold the end of crevice tool on a shop vac right against the hole saw body while cutting. There are slots in the side of the hole saw that will allow the air to flow either in or out of the hole saw body and that airflow, with either method outlined, will keep the chips out of the cut. I prefer the shop vac method as it doesn’t blast chips all over.

A 3” saw will pull hard but a 3/4 hp drill press will do the job. Can’t imagine a BP can’t do it.
 
Again, why are you asking stupid questions on the internet.
If he has an adapter that fits
or I suggest using an end mill holder
or he already has what he needs for the hole saw,
Why do you care so much to interrogate why I was
making the suggestion that I was?
It is zero consequence to you.
Waiting for you to put me on ignore and go watch
some Taylor Swift videos.

-D
Your wait is over, douchebag.
 
I know exactly what a Weldon adapter is. What I said was, since the OP had said he had an annular cutter and the Weldon adaptor "for it", I took that to mean exactly what it turns out he was trying to describe. Was the term Weldon adapter used incorrectly yes, you are absolutely correct. I just don't get why you feel the need to insult people, when correcting them. There's a big difference between being a hard ass, and being an asshole.
Problem is those two flats at 90° annular cutter connection is known as a 3/4 Weldon.
Its not a side lock end mill holder that machinists know as a Weldon holder, but it shares the same name.
 
Thanks to all for your comments. Unless I've missed it, so far I've not seen any comments that someone has cut a 3" hole with an annular cutter on a Bridgeport. But I've read lots of warnings in this thread that it may not work, so I don't believe I'll try it.

Smaller annular cutters do cut very nicely on a BP and don't make it growl like larger drills do, but, as many point out, 3" is a big hole.

I try the hole saw route again. Thanks especially for all the advice on how to cut holes with a hole saw.
I have done 64mm in 3/4" stainless on a Bridgport, lock quill and table and feed with the knee, carbide cutter in one of those cheap R8 annular cutter adapters, in back gear fairly slow. Was ridiculously easy.

I don't see how 3" would be a problem.

Yes if you jamb the cutter it could be bad, a step pulley head would be better as you could slacken the belt so it would slip if you did jamb it up.
 
I’ve been able to drive similar size HSS with a Bport by grinding off a few teeth and running dead slow. Not the fastest, but worked. Take out the set screw if you still have one in your quil.
 
Late to the thread. I bought an adapter from McMaster-Carr for annular bits, with a 3/4 straight shank. I use it in Millrite Mill. It is the section with the annular bits.
Ben
I just made my own adapter for annular bits. I did not have the right size stock on hand so I used an old 2" trailer hitch ball I had lying around. It was just the right size and worked perfectly.
 
I did the ring of holes and clean up with a milling cutter technique suggested by dandrummerman21 to do 4" and 8" holes in 3/4" plate. Worked a treat. Put a sacrificial piece of ex-kitchen cabinet chipboard on the rotary table, set the quill stops to ensure the table was safe and had at it. Pleasantly surprised how relatively quick the job was.

I've used hole saws and annular cutters successfully on smaller holes and thinner material, up to 2" or so in up to 1/2" material, but for these bigger ones I wanted a technique I knew would work. Holesaw for your 3" holes is well up in "Hmmm, maybe if really I had to." territory for me. A place I avoid unless there is no other option.

Clive
 
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Btw, a couple people have mentioned having the hole plasma cut, slightly undersized, then finish it up myself. That would be the way to do it, but the customer already has the blank made and wants me to machine some various holes, some threading, a through slot, and a blind slot. I could take it back to someone to plasma cut the 3" hole, but consensus here seems to be that a 3" hole is pretty doable with a hole saw. So I plan to give that a try.
why not spend less then the 300 bucks and have someone helical interpolate it on a CNC. I know guys who would do this quick for $50 for 5 minutes of hand programming on the machine.
if the part is small enough, chuck it in a lathe.
 
I love these carbide tipped annular cutters, the largest I have is 2-3/4", I just chuck them up in a 3/4" R8 collet. 3/4" thick cold rolled is totally possible if you use coolant are careful about clearing the chips. The tool will slip in the collet if you get too aggressive.
 








 
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