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I bought the 3" individual Forstner bit from Rockler to drill some recesses in hardwood for hockey puck displays.

I adjusted the belts on my 16 1/2" Delta drill press down to 250 rpm. The workpiece is held against the fence and a stop block. When I start drilling the bit doesn't really cut, it freezes and the spindle stops turning.

Have I got a problem with the drill press? Or is the bit just not good enough quality?

The DP is new to me but came to me well used. It's worked fine otherwise with smaller diam bits in both HW and SW.
 

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The belt is slipping. I'm not sure if the tension lever is doing anything. On low RPM there seems to be a lot of tension to take up between the center and rear (motor) pulley and that's the one that is slipping. Would I normally see the pulley move when moving the tension lever? I guess another possibility is the belt is just old and slack.
 

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Hard to say without seeing how the tensioning lever works. But generally, yes, the motor/pulley should shift visibly when the tensioning mechanism is tightened/loosened.

Look for a way to adjust the mechanism, it may be out of whack. Another possibility is that at some point the belt was replaced with one not quite the right size, i.e. it's just a little too long.
 

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I believe everyone else has pretty much hit the nail on the head. It's pretty obvious that the belt slipping is the problem. This could be, the belt is worn, the belt is the wrong size, the tensioning mechanism is not getting the belt tight enough. On my drill press, the tensioning mechanism has a "spring" that should keep it tight enough, but I always have to help it a little and it fortunately has a lock bolt that holds it in place to keep it tight. The spring isn't strong enough by itself.
 

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I agree, something is probably slipping, either the belt or the chuck.

When that is taken care of, I would consider starting with a smaller diameter bit, and working up to the final finished size. I was drilling into Bubinga end grain with a 2 1/8" Forstner bit. It would hardly drill it (brand new bit). I tried starting with a 3/4" bit and working up to the final size and had no trouble at all. It was well worth the extra time. Since I had the piece clamped to the drill press table, there was no additional set-up. Each bit remained centered.
 

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Whenever I need to drill a large hole with a forstner bit, I clamp the piece securely in place and drill in steps. First I drill a 1' hole, then a 1.5" hole, then a 2" hole, etc. until I get up to the size desired.

Drilling a 3" hole without going through the steps puts a lot of stress on your drill, especially if you are drilling a very hard wood. I have used my technique to drill a 3" hole into Padauk (a very hard wood).

One more thing - sometimes, I start with the largest bit just to help position the piece before clamping. Then I will only scratch the surface with that bit to know exactly where the hole will eventually be.
 

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It's possible that your bit needs sharpening. I bought a set from Rockler and they weren't very sharp, but after a little work with a small needle file, they cut much better. In the future I may get small diamond hones to make them even sharper.
 

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If you are going to replace your belt, look into the link-belt system. Hard to go wrong with them for sizing, and your machine will run with less vibration.

If your spindle stops, it is the drill press problem, not the bit.
 
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