I have been working with 4 x 4’s to make candle vessels for my wife’s business. The first round I did with a 3” steel forstner bit and used treated lumber on a 1/3 HP drill press. It worked ok, but the treated had too many cracks down the grain so it wouldn’t work.
I took my brother in law’s (former furniture builder) advice and got cedar 4 x 4’s. I cut them 3 1/2″ long to match their true dimensions and then took a 1/2” off on side with the hole going into the 3 ” side.
I’m now using a carbide tipped 3″ forstner bit in a 3/4 HP drill press at 250 rpm and no matter what I do it chips away about an 1/8″ and the just stops. The motor is still going and the belts aren’t slipping.
I thought it was my bit which is why I got a new carbide one but it’s doing the same thing as the one I used on treated lumber for the first group I did.
Any advice on what is causing this and how to work around it?
Replies
I'm a little confused. Can you clarify a few things about your problem?
Is the bit not spinning?
Is the bit clogged?
Is the bit spinning but not cutting?
Is the quill not going down?
Is the hole tearing out at the entrance?
The bit stops spinning, but motor and belts are still going as if the bit is still spinning.
I sharpened my original all steel bit thinking it was just dull but it did the same thing. So I replaced that bit with a carbide bit and it did the same thing on the very first try.
It isn’t clogged because it doesn’t get further than about an 1/8” deep.
Does the chuck keep spinning, and if so How are you tightening the chuck, are you using a chuck key or by hand?
We have it narrowed down except for Ben's question. Is the chuck spinning and the bit not turning in the chuck? If so that is a check key issue. Tighten from each hole position to assure a good grip.
This is not a self-feed bit, right? With a controlled feed (by you) there is no reason for the bit to jam to a stop that I can think of. If the bit is dull, it may stop cutting but, to stop the bit requires quite a bit of force.
If the bit and the chuck are stopping, remove clean and re-seat the arbor. We'll have to wait for the answer on the chuck-still-spinning question to go further.
The chuck stops along with the bit.
Chuck key
It’s a brand new carbide bit so not thinking its a sharping issue.
Neither bit I’ve used is self feed. Standard forstner bits.
The chuck is on a Morse taper shaft. It's not seated right, so the quill is slipping. Better machines will have an adjustment to fix the issue. Cheaper machines dont. Check your manual to see what it says about quill adjustments.
John_C2 bringing us home with the wrapup haha. the only other thing I can think of is the pully somehow sheared off the indexing on the shaft, and is only still spinning the shaft with some friction but not torque. That's a long shot though, it's gotta be the loose chuck
It’s a shop fox w1668 and I see from the manual it does have that adjustment. What makes you think based on the description that is the most likely cause of the issue?
The bit in the chuck; the chuck on the morse taper; the belts on the pulley wheels .... these are all friction-fit with no cogging or other complex drive mechanism to jam. In fact, they work by jamming.
If the motor energy is still produced, the pulley wheels are turning .... but the drill bit ain't then one or more of those friction drive faces is slipping. You can go through the procedures to ensure all of those friction drive faces are as they should be: clean and tighten belts and pulleys; properly fit and clean the morse taper interface; make sure that the drill bit is properly chucked into the chuck.
You already know that the chuck and drill bit are stationary while the motor is going. Check that the belts are't slipping on the pulley wheels. If not it must be the .....
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That's a large bit you're using. It'll need slow speed and a light pressure to cut whilst not demanding a lot of energy/second and it's transfer from motor to bit cutting face through the drive train. The more energy/second you put through the arrangement, the more likely something will give in the drive train.
If the bit has even a very slight wobble in the workpiece, one part of the rotation will have more drag than other parts. That effect will increase as you drill deeper. In addition, such a slight wobble is likely to be caused by an ill-fitting morse taper. That's the most likely friction interface to give, then, as the wobble momentarily increases the drag and the demand from the drive train.
Lataxe
This is a common problem with woodturning, where larger forstner bits are used to hog out waste.
Probably the issue is not clearing the waste. This jams the larger bits.
The best thing to do is to drill a smaller hole first, then the larger one. It requires you to use a jig to line up the workpiece but works every time.
Rob_SS is right about sneaking up on the 3" hole. By starting with a smaller hole first. But instead of relying on a jig to line up the workpiece when making the final 3" hole, just start with a 3" hole about 1 /8" deep, then go with the smaller bits to your target depth, then take the 3" bit down to your target depth. This way wood: bit friction is less and you don't need a positioning jig.
You could run the large bit long enough to get a registration rim and then swap to a smaller bit and drill a 5 or 6 hole ring inside of the rim. This will reduce the strain on the large bit when you swap back.
So I adjusted the quill screw to make sure it was right as well as the motor location to keep the belt tight. Then I used a 2” and 1 1/2” bit which ate through it no problem. However, when I went back to the 3” to finish it out it still wanted to stall more than I think it should.
As I mentioned previously, even a slight wobble with such a large bit will see the force necessary to get it through the greater amount of cutting that the wobble will demand put a great albeit momentary strain on the drive train. The rim of such a big cutter is farther out from the axis so the resistant force of the wood to being cut is much greater than with a smaller bit.
Unless the large forstner bit is one of those very high price German ones or similar, it's likely that it isn't absolutely perfect; it will have a slight wobble in all likelihood. It might not be very obvious but if it's there it'll momentarily amplify the cutting force or, rather, the resistance to it at the bit's rim, at least once every revolution.
Unless the drill press is a super-engineered high price thing made for engineers rather than woodworkers, it's likely that the chuck will have a slight wobble. Same problem and effect.
Even slower drill speed and very light pressure is perhaps the only way to prevent a stall. Once the bit has stalled, it needs an even greater amount of initial energy to start up again if still in the cut. And, as you've found, the energy is likely to be transferred somewhere else where it can release so your drill bit slips in the chuck or the chuck slips in the morse taper or the drive belt slips over the pulleys.
Worse case is nothing slips but the motor stalls and overheats to the point of melting copper windings!
Lataxe
How about use the 2" bit to hog out most of the waste and then finish the 3" bore with a router and a template?
...or use 2" candles. ;-)
If you can't turn the speed down lower, try turning it up. Keep your workpiece clamped to the table, and hands free. Faster us generally not the way to go with large bits, but if you've tried everything else, give it a shot.
I just got the same machine as the OP (Shop Fox W1668) and have been testing it out with some new -- albeit, inexpensive -- Forstner bits from Irwin.
Putting the 1-1/2" bit into some 3/4" birch ply scrap is stalling the bit.
There's no detectable slipping on the belts, but the bit, chuck, and tapered shaft have all stalled. I checked the quill setting but on this machine, the manual states the quill adjustment "prevents the quill from rotating during drilling and sanding procedures, and if adjusted incorrectly, the quill may have lash or bind." I have no binding when going through the range.
This is my first drill press so I'm sure my technique is poor, but it feels like very little pressure is causing it to stall. I'm running the bit at 980 RPM. I'm not sure if it's a fair comparison but my cordless DeWalt doesn't have any problems getting through the plywood with the 1-1/2" bit.
Edit: Ok, I feel kinda silly now. The nut that secures the pulley was loose. I assumed it would be tight from the factory but it wasn't. I snugged it up and all is well.
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