using an expanding auger to make big holes

[Spindle]

Hi

I fear that unless you can control the feed rate of the bit you are not going to succeed. Just pressing on and taking aggressive cuts is destroying the centering of the bit or the area of cut is preventing efficient engagement of the cutting edge. In my opinion, a bit as large as this needs to be used in a pillar drill.

I'm sorry a router is not an option for you as it is probably the best tool for the job in this case.

Regards Mick

 

[Phil Pascoe]

I suspect a near 3" hole would cause many pillar drills to stall. As I said before, I've never used one of these bits successfully - or come to that, seen anyone else do so either. I presume it must be possible, the things are still made and sold.

 

[adrian]

I have a pillar drill and no objections to using it, but there's the problem of finding a cutter (other than a set of six hole saws). As I noted earlier, several years ago I cut some large circles using a fly cutter: http://www.leevalley.com/US/wood/page.aspx?p=32275&cat=1,180,42316

This device caused the chuck to fall off of the drill's arbor. I think the lateral forces from the unbalanced bit, with all that weight in one point, worked the chuck loose. After that the chuck fell off all the time until I learned about a trick involving the freezer. So I'm reluctant to use such a cutter again (and I returned the one I had used).

I would imagine that a 3" hole cut be cut with a pillar drill as long as the feed rate was kept slow. Of course, with a hole saw it should be no problem at all.

Note that when I just press on I'm not taking aggressive cuts, but actually fairly light ones. The bit seems to want to take aggressive cuts all on its own, and again I'm not sure if that's because the lead screw has a fast feed rate or if it's because I'm tipping the bit.

 

[Phil Pascoe]

Even forstners that size might stall a smaller pillar drill, a hole saw shouldn't. Afaik expansive bits are designed for hand use, so the pitch of the lead screw is too fast to use under power. How accurately sized do your holes have to be?

 

[adrian]

Holes cannot be undersized and I'd say they shouldn't be more than 3mm oversized.

I wasn't aware you could even get a 100 mm forstner...but there they are. I guess somebody's drill must be able to run these things. But it seems like for through holes the hole saw is going to be a much better option...cheaper and easier to use.

 

[Ian down london way]

I've a device like this:
http://www.longchengtools.com/Adjustabl ... Cutter.htm

the pillar drill and wood need to be very stable, but the size of the hole didn't cause a problem when I last used it. You do have to take it slowly, both in terms of rotation speed, and downward movement. the drill in the middle controls, it doesn't grip. I think the benefit is that it's not cutting all the wood way, just cutting a circle.

 

[adrian]

You don't indicate which of the two styles of cutter you have. The site shows a "wheel and circle cutter", which looks very similar to the item I tried from Lee Valley that worked my chuck loose. But also shown is an "adjustable circle hole cutter" which is a balanced device with two cutters instead of one. I wonder how you adjust the two cutters to the same position.

 

[Phil Pascoe]

I wondered how accurately the holes had to be sized because if you haven't many to cut, you might have got away with one of those cheap multi hole cutters. They are carp but may have got you out of a jam.

 

[Ian down london way]

I'e actually got both the wheel and circle cutter and the adjustable circle hole cutter. The latter is not so robust (the cutters are much thinner) and not so accurately adjustable. I've used the former quite well, but I set the speed of the pillar drill as low as it can go. I hadn't had any problems with the drill chuck being worked loose. Maybe I was lucky. I think I may only have used it on soft woods (making wheels).

Where abouts are you Adrian, your profile doesn't say.