What am I doing wrong with drill-press?

[David Brimm]

Hi guys I need some of your collective wisdom applied to a bit of a problem I'm having here.

I have a Grizzly G7946 1/2 HP 110V floor radial drill press that I use amongst other things for drilling counter-bored 1.5" / .75" holes in wood stock from each side of small (4-6" tall, 2-4" wide) square stock for game calls and other projects and I'm having some problems drilling the larger hole. In most woods I manage just fine but in some harder woods (Purpleheart, Osage Orange, etc) the forstner bit is binding up and stalling the motor at the lightest cut. I'm drilling these into the end-grain and I know that makes it harder but again like I said it works great with the exception of some denser woods. My bits are sharp as sharp can be and I get the same result with generic HSS ones, my Colt Maxicut ones and my Rockler Carbide tipped ones.

So my question is what do you think my problem is here and what do you think a solution might be? Is it simply that my Grizzly doesn't have the power to drive these bits through this dense wood? Should I upgrade to a more powerful drill press? If so which one?

Thanks in advance!

[John Coloccia]

Is the motor stalling or are belts slipping?

[David Brimm]

Hi John, it's the motor that's stalling.. belts are tight and in good shape and don't slip.

[Myk Rian]

Bad motor is my guess. Not the first Grizzly to have one.

[David Brimm]

Bad motor is my guess. Not the first Grizzly to have one.

You think the motor might be bad Myk not just underpowered? It seems to work great for every other use than these large bits and seems to have a good amount of power but again just not enough for these woods and these large bits? I'm having a hard time understanding how the motor might be bad in this case?

[Kirk Poore]

You say your motor is 110V. Could it be dual voltage (120/240v)? If so, I'd check the wires and make sure it's not actually wired for 240V, despite the plug on the cord.

If not that:

Do your bits stick in wood drilled from the side grain, not just end grain?

Is the chuck on straight? Put a dial indicator on the side of the forstner shaft and see what kind of runout you have.


Kirk

[David Brimm]

You say your motor is 110V. Could it be dual voltage (120/240v)? If so, I'd check the wires and make sure it's not actually wired for 240V, despite the plug on the cord.

If not that:

Do your bits stick in wood drilled from the side grain, not just end grain?

Is the chuck on straight? Put a dial indicator on the side of the forstner shaft and see what kind of runout you have.


Kirk

Just came back in from the shop: the motor is 110v only, 1/2 HP, I haven't drilled any wood so far that stalled it in the side grain, only these few woods/end grain/large bit combination. I don't have a dial indicator but the chuck seems to be on straight and there is no appreciable run-out that can be felt or seen.

[Myk Rian]

You think the motor might be bad Myk not just underpowered?
Typically, a drill press requires 1/3 to 1/2 hp. If yours can't turn a 1 1/2" bit, there must be something wrong with it.

[pat warner]

Drilling down the end grain only? Be specific about holding the work, size of drill and how deep you're drilling.

[David Brimm]

Drilling down the end grain only? Be specific about holding the work, size of drill and how deep you're drilling.

Here's an example of a piece I'm making today that I was having this problem with.

I take a 2"x2"x5" (grain running long ways) piece of Purpleheart and place it in my drill press vise which is clamped firmly to my table. After marking my center I drill down into the piece (end grain) 2" using a .75" forstner bit, I never have problems with this operation. I flip the piece around in the vise and then drill down into it (end grain) 3" with a 1.5" forstner bit from the other side until the holes meet, this is the operation that causes the bit to bind and stall the motor with very little provocation. It doesn't matter which side I do first the 1.5" bit binds and stalls.

Today I did 5-6 pieces as above but using Ash and hard Maple with not a single problem. Then I do the same in a piece of Purpleheart and it literally binds/stalls every 2-3 seconds while trying to drill the larger hole. I could be totally wrong but it seems as though there just isn't enough power in the drill press to drive that large bit through the end grain on these super hard/dense woods.

[randy boughton]

No expert but I would think that the purplehart is shrinking after the cutter head and rubbing on the side of the forster bit causing drag.

[Carl Civitella]

Hi, it could be your speed, try slower on the denser woods like purpleheart. I make game calls and used purpleheart, but i drill on the lathe about 400 rpm. Before i invest in a new press i would put that money into a good 4 jaw chuck and a drill chuck. Search Goggle on info for drilling on lathe. Good luck. Carl

[johnny means]

+1 on the drill speed. I can drill these types of holes with an old hand drill, so obviously HP is not the issue.

[John Coloccia]

Even the large Delta is only a 3/4HP motor. 1/2HP is enough to drill some serious holes. I'll jump on the bandwagon and say to slow down the press...like down to 300 or 400 RPM if you can. What's bothering me, though, is you say it's stalling every few seconds. That's almost sounding like a chip clearing issue. When it stalls and you yank it out, does it pull a big wad of chips up with it? Maybe you just need to feed slower and periodically lift out of the hole to let it clear.

[David Brimm]

Thanks for all the suggestions guys.. I'm running on the second slowest speed (800'ish) but I'll slow it down to 550 and see if that helps.

It's definitely not a chip clearing issue John as it's not even able to cut any chips out before catching. If I can't find a solution and get it working I'll have to take the camera out to the shop and take a video of it so you guys can see exactly what's happening.

Thanks!

[rob huley]

Sometimes when my forstner bits stick and squeal a bit, i hold a nugget of beeswax to the outside of the bit while it turns, just putting on a bit to give some lubrication. As long as you don't think it would affect your finishing process of the inside, and it might, this has really helped my forstners do their thing.

[Van Huskey]

I hope you find the answer, those medium sized Maxi Cuts (haven't used the Rocklers) should be flying through that end grain.

[pat warner]

" I could be totally wrong but it seems as though there just isn't enough power in the drill press to drive that large bit through the end grain on these super hard/dense woods."
***********************************************

No kid gloves:
Your Forstner is dead.
Speed should be 250 absolute max, slower if possible. (Power ok for sharp tools fed at a reasonable rate at a reasonably slow RPM.)
Whence in wood, the Forstner traps its chip and stalls. It (chip) has to back vacuumed out every 1/16 - 1/8" of cut depth.
Your vise is not deep enough to hold the work nor will it keep it from pivoting.
A work piece has 12 degrees of freedom, you have control of up/down, maybe L/R & in/out but none of the works' 3 rotational axes are in your control. The work tilits and jams the cutter. That big dead drill requires a lot of force to cut. As such your quill forces are high. And high enough to move the work; it's jamming the drill.
You need a near perfect material prep, a setup that confines the work in/out, l/r and up/down.
And at least 2 of its rotational axies must be under your control.
A 3 or 4 fluted counterbore is a much better tool here, one that will track a pilot hole.
And of course, the gold standard for such rigor: An expensive HSS brad point.
Not what you wanted to hear, I'm sure, but I'm not surprised you're having trouble.

[David Cefai]

The problem could be due to the capacitor starting to fail. Should this be the case then the problem will gradually get worse.

You could try replacing the capacitor. At worst you'll be out a couple of dollars.

[David Brimm]

" I could be totally wrong but it seems as though there just isn't enough power in the drill press to drive that large bit through the end grain on these super hard/dense woods."
***********************************************

No kid gloves:
Your Forstner is dead.
Speed should be 250 absolute max, slower if possible. (Power ok for sharp tools fed at a reasonable rate at a reasonably slow RPM.)
Whence in wood, the Forstner traps its chip and stalls. It (chip) has to back vacuumed out every 1/16 - 1/8" of cut depth.
Your vise is not deep enough to hold the work nor will it keep it from pivoting.
A work piece has 12 degrees of freedom, you have control of up/down, maybe L/R & in/out but none of the works' 3 rotational axes are in your control. The work tilits and jams the cutter. That big dead drill requires a lot of force to cut. As such your quill forces are high. And high enough to move the work; it's jamming the drill.
You need a near perfect material prep, a setup that confines the work in/out, l/r and up/down.
And at least 2 of its rotational axies must be under your control.
A 3 or 4 fluted counterbore is a much better tool here, one that will track a pilot hole.
And of course, the gold standard for such rigor: An expensive HSS brad point.
Not what you wanted to hear, I'm sure, but I'm not surprised you're having trouble.

Thanks Pat, at first I wasn't quite sure about your post because my piece seems to be rock solidly clamped in the vise and I can't detect even the slightest bit of movement on any rotational axis. I stopped and thought about it for a bit though and then did a quick test and I think you may be on to something. This type of drill press has very long arms and so the head and table stick out quite a ways from the column and when I bore into one of these harder woods I'm seeing a little bit of flex in the arms which then in turn obviously pushes the piece askew on the rotational axis and I think that might be what's causing the binding. I'm going to move things all the way as close to the column as possible and see if that reduces the flex and binding. Thanks!

I would love to be using a counterbore but haven't found one that is sized right to do the job in this case and I've been hesitant to have a custom one made. I do have some nice brad points so maybe I'll give that a try.

Thanks again..

[David Brimm]

Just a quick update here, Pat was right and my problem was movement on the rotational axis. It was exactly as I suspected and mentioned above after he got me thinking about it. Being stuck out that far the arm was flexing just enough to bind the bits under the quill pressure of the larger bit. Moved the arm and head in to right next to the column and she's cutting easy as pie.

Thanks guys!