How to test a used Drill Press?

[mbeach]

What do I need to look for when buying a used drill press to make sure it is working ok...

How do I test and make sure it is a straight hole with no wobble?

How do i test for accuracy?

Anything else i should look for?

Thanks

Michael

 

[Mike Davis]

There are two places the drill could be off.

1) the chuck could be worn or set badly


2) the shaft could be bent or the bearings worn

Chucks can be replaced fairly easily and cost as much as you want to pay. Decent one is $30 to $50 and a great one could be $250.

So, the main thing to check is the shaft. I have to assume you don't have a Brown&Sharp or Starrett dial gauge. So, to check for bearing play, crank the quill up and down and look for movement side to side, then with the quill all the way down try to move it with your hand. It should feel rock solid, no play. Let the quill back up and turn on the drill on with the slowest setting or pulley combination. Watch the chuck turn and see if you can see any wobble or movement. Set a block of wood on the table and slowly slide it toward the chuck till it is just barely touching. It should make a smooth swishing noise. If it makes a clicking or modulating noise then the chuck or shaft is not concentric.

To determine which one you would have to remove the chuck and repeat with just the shaft. If the shaft runs true then it is the chuck.

If the rest of the drill looks good and works as expected then the chuck can be replaced.

If you do have a dial gauge then you can set it up to measure the amount of non-concentricity in the shaft or chuck.

 

[CarvedTones]

Quick and easy first test would be to take a scrap of hard half round (or something with a similar curve and flat back) and try to drill a couple of holes just off center on top of the curved part with a dull drill bit. It will want to skate off to the side, but a good drill won't let it; it will burn and pound its way in. Don't treat it like this after it's yours, though. :rolf:

Passing that means you need to look harder, but a substantial number will not pass this test.

 

[Mike Davis]

Good way to break a bit.

 

[CarvedTones]

I probably should have put some kind of size with it; I didn't mean a really small bit. Something substantial enough to take its bending or breaking out of the equation. And maybe "dull" is taking it a bit (NPI ) too far. But a really sharp new bit can fool you as to how well a drill will track given some resistance.

 

[DaveD]

Take a piece of straight rod about 1/4" in diameter and about 6" long and chuck it up. Run the drill press at slow speed. You will be able to easily see if the rod is wobbling. If it is, the snout that the chuck is on is probably bent. Bent snouts happen by trying to use a drill press for something its isn't designed for (they are designed to drill holes) like running a sanding drum on it or trying to use it to cut a slot sideways in something. Drill presses typically aren't made to handle side loading of the cutter.

I'm not sure what any new run of the mill drill press has for chuck runout specs.

Any testing you do with actual drill bits requires that you use a good drill bit. How do you know its point is ground on center or that the drill itself is manufactured off center by several thousandths?

I can really tell how crappy new drill bits are when I chuck them up in my lathe tailstock and run them against a pilot hole drilled with a spotting/centering drill or a drill countersink. Even a 1/2" drill bit will 'tweak' over to try to follow the starting pilot hole (which is in the correct position).

 

[CarvedTones]

It sounds like you two are against any testing of resistance to side loading. I agree that side loading as a matter of course is not what they are built for, but I also think it should have some decent resistance to going astray. The only way I know how to tell if it does is test. My lousy DP will spin a bit or rod fine with no resistance, but good luck getting it to drill a straight hole through a rosewood plane handle.

 

[Mike Davis]

That's why i say rack it down and give it a good shake by hand. If you can feel it move it won't drill straight.

Try it on yours and tell us if you can feel movement in the quill.

 

[Dudelive]

That's why i say rack it down and give it a good shake by hand. If you can feel it move it won't drill straight.

Try it on yours and tell us if you can feel movement in the quill.

+1

If it is run all the way down and moved left and right then forward and backward...listen for the sound it makes. It (in a perfect world) should make no sound at all and the only movement to be measured with a dial indicator.

Back to your question, it really depends on what you are paying for it and the brand name of the item. Better brand name tools are made better and last lots longer hence which is why they cost more unfortunately, you actually pay for quality.

Keep us posted on your purchase.