Bottoming out bit in Drill Press?

I was perusing my latest FWW this morning, flipping through an article on the benefits of a drill press. In that article, they make the statement--I don't have it in front of me, so I'm paraphrasing--that when you put in a drill bit in, you should be sure to make sure it isn't just being grabbed by just two of the three jaws and to make sure that the bit isn't bottomed out in the chuck. The first point is pretty obvious, but the second one was a new one on me, and they didn't explain.

Frankly, I'm not sure I pay that much attention to whether its bottomed out or not, my goal is usually inserting it such that the jaws will clamp down on a good portion of the straight shank of the bit. But I'm curious since I've never heard this advice before... Why would inserting a bit all the way and bottoming it out be bad? And if it is bad for a DP, would bottoming out bits in a router be bad too, 'cos I know I do that...

You should never bottom out a router bit for safety reasons. Most bits taper out just a little at the beginning of the cutter head so when you bottom out the bit you could only be getting the bit tight in a small area and not on the full length of the shaft. Not sure about the reason for the drill press unless it is doing the same thing only in reverse.

If you don't bottom out the drill in the drill press it will slip & you will lose your depth setting and drill shallow. Would like to know what FWW the story was in.

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Originally Posted by Roger Bullock

You should never bottom out a router bit for safety reasons. Most bits taper out just a little at the beginning of the cutter head so when you bottom out the bit you could only be getting the bit tight in a small area and not on the full length of the shaft. Not sure about the reason for the drill press unless it is doing the same thing only in reverse.

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That seems like really odd design. What is the purpose of that? I think I'll take a set of calipers to my bits tonight.

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Originally Posted by pat warner

If you don't bottom out the drill in the drill press it will slip & you will lose your depth setting and drill shallow. Would like to know what FWW the story was in.

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Was this month's FWW--story was about the benefits of a drill press. Pic was a guy with a small, older benchtop DP.

OK. Here's the reason.
When you bottom out the bit, (router or drill) the chuck faces are still moving inward when you tighten it. With the bit pressing against the bottom of the chuck, there is a chance it will not tighten completely, causing a loose bit in the chuck. Leave 1/8" or so for clearance.

The reason why you don't bottom out router bits is that the dag blasted things tend to get jammed in the chuck when you do. I've got a rubber washer in the bottom of mine from a mix pack of faucet o-rings. I'd not seen any taper in my bits. But then, I've got cheap bits? *shrugs*

Far as bottoming out drillbits. I ALWAYS bottom mine out, unless I need to squeak some extra depth out of the bit. But like Pat said, if it does manage to slip while you're pressing down, you loose your depth gauge. And it certainly is possible for it to slip deeper into the chuck without it stopping spinning. Deceptive lil suckers.

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Originally Posted by Eric DeSilva

That seems like really odd design. What is the purpose of that? I think I'll take a set of calipers to my bits tonight.

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Squaring it off would be another step that costs money. There was a brand that was doing it, I forget who. If it was a big deal to the end users it would have caught on. I leave an 'o' ring on the shaft of all my router bits, problem solved.

A sharp angle at the cutter/shaft junction of a router bit would be more likely to crack than the filleted juncture. I would avoid any bits built like this.

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When you bottom out the bit, (router or drill) the chuck faces are still moving inward when you tighten it.

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I'm thinking that when the jaws of my drill press chuck are tightening, that they are moving out instead of in.

I don't think that I have ever "knowingly" bottomed out a drill in my DP chuck before tightening. As long as it's gripping the shank well, there has not been a problem.

In fact, if you have drill bits with a stepped shank, (sometimes bigger than 3/8 or 1/2") you will not be able to bottom it out, unless you use the stepped shank as the reference against the jaws themselves.

The reason for not bottoming a router bit is the collet pulls the bit down when you tighten it and if it is bottomed it cannot be pulled down. Drill press chuck is completely different in how it works.

FWIW I do not bottom my bits in my drill press.

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Originally Posted by Myk Rian

OK. Here's the reason.
When you bottom out the bit, (router or drill) the chuck faces are still moving inward when you tighten it. With the bit pressing against the bottom of the chuck, there is a chance it will not tighten completely, causing a loose bit in the chuck. Leave 1/8" or so for clearance.

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Myk has the correct answer. Watch what the chuck jaws do as you tighten them around the bit. They try to move up into the chuck. If the bit is centered in the jaws and the jaws are properly tightened the bit will not slip in a good chuck. Bit slippage in a cheap chuck may reflect as to why the chuck was less costly....it may also be less quality.

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Originally Posted by Will Overton

I leave an 'o' ring on the shaft of all my router bits, problem solved.

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Actually, come to think of it, so do I. Guess I'm not bottoming them out after all.

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Originally Posted by Keith Westfall

I'm thinking that when the jaws of my drill press chuck are tightening, that they are moving out instead of in.

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I agree. So I think I'm still looking for an answer...

Given that the action of the jaws moving out would pull the bit away from the bottom, I'm not sure you could bottom one out even if you tried. I think my reality is that when I hold the bit for insertion (other than stepped shanks), I'm holding it so that the fluting on the bit starts more or less where the jaws end. On that basis, I'm probably not bottoming them out anyway.

Just seemed like a strange statement that was made as a self-evident pronouncement that I can't figure out. I hate that.

I called Jacobs this morning to see if I could get a straight answer on the practice.

I asked 3 Questions

Practice of bottoming Drills; to do, or no to do. Jacobs official position?

Short shank cutters, Shoulder contact/load on nose of jaws, Safe practice as far as Jacobs is concerned?

Country of origin of Jacob's precision keyless chucks?

Answer to one and 2 was Jacobs had no official position. Second that the jaws are coming out of the chuck body at a 15 deg angel when tightened. Thus sending a drill bottomed or otherwise out toward the work. No matter what, a bottomed drill will not be exerting full force on the ceiling of the chuck. Mike said he could see no adverse outcome to either method of loading a Jacobs chuck provided proper feed rate and RPM were abided by. Also Jaw contact with shouldered cutter (countersinks, etc) posed no problem provided impact type drilling was avoided and proper feed rate and RPM were abided by.

JKT 130 country of origin? Well first let me say that fit and finish are immaculate. TIR with the chuck on a late model 15" Buffalo Drill Press (<.0005 TIR on nose of JT33 arbor) presented just a shave under .002". Impressions were absolutely favorable. The caveat? No published country of origin, no stamp on the body, no print in or on the box. Verdict per Jacobs was different dependent on who you spoke with. Spain or Taiwan. Considering mine had an inspection stamp of obvious Asian origin; I suspect Taiwan. Asked why would one pay 240 bucks for an Asian chuck when you could get the German counterpart for a few dollars more? Just so you know; the Keyed Ball Bearing Super Chucks are going off shore too And soon!

I called Albrecht a year or so ago and asked same questions. Granted it was a year ago, but I remember coming away with "Do bottom drill out. And do not make shoulder contact of short shank tool on jaws."

Jon

Thinking on it, the drill chuck does push out. Thanks for straightening me out.
I do know that a router bit is pulled in when tightened. That will cause problems.

If a drill bit works out, or into the chuck, either it wasn't tightened enough, or the chuck is defective.