Drill Press Runout

[Tom Watson]

I used to have a cheap Delta floor model drill press but it took up more floor space than it was worth.

So, I bought a cheap Delta bench top drill press to replace it.

It's a 1/4 horse, made in Taiwan, with a No-Name chuck, and it was made in 1990.

For most of its life it lived with a jig table on it that was for drilling Euro-hinge holes. It was accurate enough for that and gave good service.

Now I want to do some drilling that needs to be a bit more accurately done.

I chucked up a new 25/64" twist bit and squared the table up to it, using a Starrett 3" Engineer's Square that I use for setup work.

Then I checked the concentricity of the No-Name chuck, using a Starrett Dial Indicator and Magnetic Base.

It started out at .003 and the best that I could get out of it was .002, by smacking things around a little bit.

Then I set the Dial Indicator up to check the runout on the bit. I set the tip to run on the plain part of the shaft, just above where the flutes started, about 1" down from the jaws of the No-Name chuck.

The best I could get out of it was .003.

Question: Is it worth buying a piece of drill rod to set this Cheap Thing up, or can I assume (or live with) the accuracy of the drill bit's shaft? (Assumption: Said drill rod is < $15.00)

Question 2: Can I reasonably expect accuracy greater than .002 out of this Cheap Thing - or am I dreaming? (I might already be in tall cotton and just don't know it)

Caveat: No way I'm buying a good chuck for this Cheap Thing. That would be even crazier than most things that I do.

Caveat 2: The holes that I want to drill will be made with a #44 bit and will only be 1" deep, into mild pine.

Caveat 3: I don't want to dismount the No-Name chuck on this Cheap Thing - for that way madness lies.

Tia (not Carrere - sigh...)

Tom Watson

[Frank Arthur]

Runout of .003 is no problem for a drill press. It should have no effect using your #44 drill in pine.

You are not dealing with a high precision boring machine. Relax. Your drill is fine and will probably last another hundred years (if you don't keep smacking it around). Frank

[Teamcasa]

"Tom Watson" snip

snip

A drill is normally as straight as a drill rod.

On that DP, your good.

.003" in pine? Trust this, no one will ever know.

Dave

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[Jim Wilson]

Tom Watson wrote (in part)...

The 0.002" you got is probably only temporary. Drill a few holes and check it again to see if the improvement "sticks."

Secondly, 0.003" TIR is not horribly awful for a drill press. But where did you measure? The outside of the chuck is not a good location. If you can get your indicator on the taper that the chuck fits on, that's better. Best is to remove the chuck adapter and check the spindle taper directly.

If you have a threaded chuck, then you might not be able to isolate the spindle error from the chuck error. But since you'll not replace the chuck, anyway, there's really no need to isolate them.

FWIW, the spindle TIR is usually pretty low; under 0.001" is to be expected. But once you insert the taper adapter, mount the chuck, and chuck a rod, anything in the neighborhood of 0.003" or under is fine.

That was the most important test you can do, and 0.003" is reasonable for a drill press. You can check up near the chuck jaws to see your minimum runout. If it's significantly worse as the distance from the chuck increases, you may have a dirty or bent taper adapter, or it could be the chuck.

Not if you have a good quality drill bit. If you *really* want a piece of drill rod, I'll send you one. I've got far more worth than the postage could possibly be from reading your stories here on the wreck.

Not really...

No, you're not dreaming, either. Better accuracy is possible; it's just not worth the trouble (or expense). Drilling is simply not a precision operation. Trying to make it one is futile.

There's the rub.

The grain in pine will deflect a #44 bit far more than 0.003", especially over such a deep hole (over 11 times the diameter!). Here's some of what will be working against you: Pine has a huge variation in hardness between growth rings. The hole is small enough to fit between rings. The bit is slender enough to be deflected by hard parts of the grain. The twist-drill design has an angled cutting edge, which aids in the deflection.

You can improve your accuracy far more with technique than you could possibly by futzing with the machine. Use the finest grain stock you can. Use the highest RPM your drill press can deliver. Use the sharpest drill with the bluntest point angle (at least 135 degrees) you can find. Use a pecking cycle: drill no more than four times the bit diameter before withdrawing the drill to clear the flutes of chips (I'd go no more than

1/4" per peck).

If you really need to maximize accuracy, you have to use a different type of bit. Your best bet might be a coring bit.

You ain't drilling pinewood derby blanks are ya? :-)

Jim

[Tom Watson]

Thanks for the replies.

I'll live with it as it is.

As to Jim Wilson's inquiry:

"You ain't drilling pinewood derby blanks are ya? :-)"

Yah, You Betcha!

(watson - who never saw any need to question the accuracy of the thing when it was about money - but, The PineyWood Derby? - that's several orders of magnitude more important.)

Tom Watson - WoodDorker

tjwatson1ATcomcastDOTnet (real email)

[Jim Wilson]

Thought I'd seen that problem before!

Here's another tip: Cut the dadoes in your blanks, and then drill the holes. Either the saw or the router will do, whichever is easier for you to get a 1/16" cutter into. If that's a toss-up for you, the saw is the better option.

The biggest problem with the kit blanks is that the dadoes are not often parallel to each other nor perpendicular to the sides. But the dadoes really help guide the drill. So, dado 1/16" first, then drill

0.089".

Jim

[bridgerfafc]

.....snip......

.....snip.....

remember, that good chuck can be transferred to the good drill press when you get it.

you *are* planning to get a good drill press someday, arent you?

[Tom Watson]

I have a kit left over from last year and one that I bought for this year.

Neither of the blanks are square in section.

One of the blanks is quartersawn. (hooray!)

None of the grooves are square to the blanks.

The placement of the existing grooves does not allow for the maximum possible wheelbase.

Both blanks are slightly longer than the allowed 7".

Out of eight wheels there are only two with the same mold numbers.

All of the wheels are out of round.

All of the axles/nails are uniformly non-uniform.

Our pack rules do not allow us to use other than the blanks, wheels and nails that come with the kits but we are apparently allowed to bring the wheels into round, although the treads have to stay flat. We don't get involved with district level stuff, so I don't have to worry about conforming to other than the pack's standards.

We figure on squaring up the quartersawn blank and planing off the grooves. We'll set the axle holes with the drill press, drilling them at the points that will allow the car to have the maximum wheelbase.

We'll take the snags off the nails, relieve a portion that will be within the wheel hub, so as to remove most of the contact area, true them up a bit and polish.

We'll make two cars. I'll take the lesser blank and my son will take the quartersawn. I think that if I do a step on mine and have him replicate it on his he'll learn a good deal.

I was going to use the bandsaw to rough out the blanks but I'm afraid to let my eight year old use it and don't want to do what he can't do, so we'll rough out with a coping saw.

I'm not so scared of him using the drill press, which will do a lot of the work, so he should be able to do most of that work on his own, with me doing the setups.

He's going to design the body, sand it by hand, paint it and decorate it.

I've got a spray booth but don't have a mask that will fit him, so it looks to be a brushed finish.

I hope that the boy comes out of this with a basic understanding of the physics of potential energy and friction. I hope he begins to develop a sense of orderly work habits. I hope he gets a little more comfortable with the tools than he already is.

And I hope that he has big big fun!

We're going decal shopping this weekend. I'm pretty sure that this will be the most important element of the car to him.

Tom Watson - WoodDorker

tjwatson1ATcomcastDOTnet (real email)

[Tom Watson]

Nah. I don't even really like drill presses.

Tom Watson - WoodDorker

tjwatson1ATcomcastDOTnet (real email)

[someone]

I'd suggest sending him out to the driveway with a few colors of rattle can, an exacto knife, and roll of wide masking tape. He can make pin stripes, flames, or pretty much whatever design he wants with a little creative masking. Good time to teach him about the importance of a good coat of primer and a final coat of paste wax too.

(My cars never won, but they always looked the fastest. ;-))