Drill Press runout question

[Joker11]

I have a craftsman drill press. It was the biggest one they have. It is a floor standing unit.

The chuck is put on simply by pressure on a conical shaft.

This dang thing seems to have a lot of runout. I am the original owner.

It doesn't start drilling a round hole. More like an octogon.

Is there anyway to improve this?

[76GMC1500]

Drill bits don't make round holes. You've got to use a reamer for a round hole. If the bit is walking use center punches and split-point bits.

[shortfuse]

Sometimes dirt or debris can get on the cone, causing the bit to get off-center. I got a new Rigid DP and when I ran it the first time, the bit had a tiny bit of runout. I pulled the cone and there was a tiny bit of debris on it. I wiped it squeaky clean, checked the hole it went in for any other crud, pressed it back in place, and the runout was then almost imperceptable. It's surprising how little crud it takes to create significant runout.

[Joker11]

i will clean it then. I think there is play between the moving shaft and the outer housing tho.

[rlitman]

Originally Posted by 76GMC1500

Drill bits don't make round holes. You've got to use a reamer for a round hole. If the bit is walking use center punches and split-point bits.

A reamer, or a boring tool.
A single point cutter will always follow a circular path. A reamer will too, for other reasons.

A two lipped cutter will naturally make a hole that is triangularly biased. You can do things to help with this issue though. Using a backing material, plus adjustments of the rake angle specifically to match the material you are cutting, will minimize (but not eliminate) this issue.

What is happening, is that one cutting face will get stuck in the material, and the bit will pivot and twist around the corner of that edge, allowing the other cutting edge to sweep out a chip. Then that edge will get stuck, and it will now pivot on that corner.
The bit will rock and twist through the cut, roughly creating a shape called a reuleaux triangle.
If you read this, it may help your understanding:
http://en.wikipedia.org/wiki/Reuleaux_triangle
"The Reuleaux triangle is a constant width curve based on an equilateral triangle. All points on a side are equidistant from the opposite vertex."
Only if when both cutting lips are actually working together, do you get a circle. There are other shapes, that have constant width, which are not circles.

Originally Posted by shortfuse

Sometimes dirt or debris can get on the cone, causing the bit to get off-center. I got a new Rigid DP and when I ran it the first time, the bit had a tiny bit of runout. I pulled the cone and there was a tiny bit of debris on it. I wiped it squeaky clean, checked the hole it went in for any other crud, pressed it back in place, and the runout was then almost imperceptable. It's surprising how little crud it takes to create significant runout.

You're delusional. A piece of crud in the taper that was large enough to create runout visible on a dial indicator in the thousandths, would be plenty to prevent the taper from seating completely, and the chuck would just fall out on it's own.

[Bluewelders]

Just chuck up a piece of drill rod and measure runout with a dial indicator,while turning it by hand.
If you get a bad reading,take the chuck off and check the mounting tapers runout.
You may have a bad chuck,bad bearings,or any number of things.
Drill presses and drill bits will never be a precision way to bore a hole,but it sounds like yours is unusually off.

[OPUS FERRO]

rlitman - Thanx for the Releaux link. I have always wondered about the math of
the pentagonal bottom of a partial hole.

Miller Killer - To improve your concentricity: punch, drill a pilot hole with a single
point drill that is minutely larger than the web of the desired hole size. Opus

[forhire]

Measure your drill points and make sure the center is in the center. I've had new drills that were off center. Always measure new drills. A refund or replacement of a defective drill doesn't mean much when the bad drill boogers a part.

[WyoRoy]

Take the time to chuck up a section of drill rod and use an indicator to check for runout, both on the chuck and with the chuck and drill rod removed, your arbor/quill. I believe you'll find your simple answer...scrap the cheap chuck that came with the drill press. I wish I had done it years prior to the time I finally became perplexed enough to do it on my Harbor Freight drill press purchased back in the mid-'80s. Before you think Harbor Freight (hah...cheesy crap!!!) realize that Sears was selling the same drill press as one of their Craftsman lineup at the time (may still, check your casting #s and slide over to a nearby HF outlet and check) with a slightly different shroud and their funky safety/key switch. When the chuck no longer "grabbed" drills sufficiently, I deemed it was time to replace. The replacement was a Jacobs Super Chuck in size 16N, slightly larger diameter rating...5/8" instead of 1/2" I believe. The drill press had from day one never really drilled well due to runout. As with most folks, I figured it was Harbor Freight quality coming back to bite me...it wasn't. The drill press no longer serves as my primary drill press, but the runout is gone and the Jacobs Super Chuck, with it's hardened jaws, holds even the hardened bits well. Replaced every chuck in the shop with eBay Jacobs Super chucks...mill (2), Jet lathe (2), Royersford drill press (2)...up to a 20N, South Bend (0)...shares the smaller chuck from the Jet lathe, Harbor Freight (1). All were replaced with used Super Chucks...auction photos provide a fairly clear indication of condition...if not, don't bid on that one. All that I have purchased with that in mind have been in good to great condition. Buy new, if you want the absolute assurance of a quality chunk of steel, but realize new will oftentimes cost as much or more than the machine you will be refurbishing the chuck with.

I hope you find your runout without having to get a new or used/quality chuck, but don't be overly surprised if that isn't the case. Dollar point rules on the sales of the smaller homeowner drill presses and the chuck is generally the first/easiest dollar savings for the manufacturer. It helps that most consider that a new chuck "ought" to be able to do its job right out of the box. Best of luck!

EDIT: Albrecht chucks, German manufacture, are another alternative. Sadly, they never seem to go for much off full retail used on eBay.

LAST EDIT (?): You sound as if you may need a bit of handholding in regards to your drill press's quill/arbor size. Come back with a photo and some measurements and one of us should be able to line you out correctly. Not absolutely sure of what method you have at present as there and several to choose from. Yours may even have an intergal taper to the quill...harder to buy replacements for, but not impossible. Generally, you will need to know the JT, jacobs taper, of the chuck mount and the MT, Morse taper, of the quill mount and replace with the proper arbor...if you haven't one already.

[shortfuse]

Originally Posted by rlitman

A reamer, or a boring tool.

...

You're delusional. A piece of crud in the taper that was large enough to create runout visible on a dial indicator in the thousandths, would be plenty to prevent the taper from seating completely, and the chuck would just fall out on it's own.

Wow, flamed right off the bat. I merely posted a suggestion that might be a very simple fix to the poster's problem. After all, contributions are the backbone of a forum. A simple reply without the sarcasm would have been better.

Delusional or not, it worked for me

[rlitman]

Originally Posted by shortfuse

Wow, flamed right off the bat. I merely posted a suggestion that might be a very simple fix to the poster's problem. After all, contributions are the backbone of a forum. A simple reply without the sarcasm would have been better.

Delusional or not, it worked for me

Hi welcome to the internet. You must be new here.
But in all seriousness, I apologize if you took offence.

I really don't know how many thousands of times I have seated a Morse taper (or how many hundreds of times I have seated a Jacobs taper), but I've never had one seat snugly and then seen any significant runout after that (or at least, any runout that couldn't be attributed to the jaws themselves or the spindle). Every instance I had trouble with a taper seating tightly were either related to dirt, overuse of grease, or a raised burr. But that's not to say it is impossible.

[Kaos]

Originally Posted by Joker11

I have a craftsman drill press. It was the biggest one they have. It is a floor standing unit.

The chuck is put on simply by pressure on a conical shaft.

This dang thing seems to have a lot of runout. I am the original owner.

It doesn't start drilling a round hole. More like an octogon.

Is there anyway to improve this?

I recently bought a large Craftsman drill press used. Never thought to check the runout with a straight rod before the purchase. It was about like you described, lots of noticeable runout.
I took it apart and checked the bearings, they were ok. A friend suggested that someone may have hit the chuck with a hammer and damaged the taper where it is pressed on. I took the chuck off and he put the shaft on his metal lathe and straightened the taper taking out almost all of the wobble.

[WyoRoy]

Originally Posted by Kaos

I took the chuck off and he put the shaft on his metal lathe and straightened the taper taking out almost all of the wobble.

By cutting the shaft or just whacking the bejezus out of the shaft with a hammer and then checking for trueness?

[MarkBall2]

You need a mill instead of that drill press. that solves several problems.

[Kaos]

Originally Posted by WyoRoy

By cutting the shaft or just whacking the bejezus out of the shaft with a hammer and then checking for trueness?

Not sure if I understand the question but I did not hit with a hammer, it was suggested that the previous owner hit it with a hammer and knocked it out of trueness because the bearing were still good. Something had to have bent the taper or shaft for it to have some much runout. Maybe I didn't explain that well enough.
The problem was corrected by putting it in a lathe and basically recutting the taper.

[shortfuse]

Originally Posted by rlitman

Hi welcome to the internet. You must be new here.
But in all seriousness, I apologize if you took offence.

I really don't know how many thousands of times I have seated a Morse taper (or how many hundreds of times I have seated a Jacobs taper), but I've never had one seat snugly and then seen any significant runout after that (or at least, any runout that couldn't be attributed to the jaws themselves or the spindle). Every instance I had trouble with a taper seating tightly were either related to dirt, overuse of grease, or a raised burr. But that's not to say it is impossible.

Check my posts here, only about 4-5, yep, new to this forum but not new to the internet.

Apology noted, thanks.

I always try the simplest fix first, then if that doesn't work, go from there

[Sandy]

I always try and run as slow as practical and cut a curl when possible rather than chips. Some bits just won't allow that to happen but when I can that's what I shoot for. Especially once you get deep enough for the flutes to have sides to run against, then bear down a little and get a curl going. There's a feel to getting a good cut going. I've got a couple of bigger bits that I just plain don't have enough horses to do that with. Annular cutters is the way to go. Not so cheap to get set up with tho.

[jakeru]

1. Using a dial indicator on a magnetic base set on the drill press table, measure runout on a chucked precision steel dowel. If it's too much, say > .008" right below the chuck, proceed to the next step. If not too much, rejoice. Maybe measure runout of steel dowel further down (like 3"-6" away from the chuck) , to see if the chuck is not chucking things straight (maybe causing a wobble)

2. Measure runout on the chuck body, just above the jaws. Not on the part that moves. If runout is too little, chuck jaws are bad. They can be replaced to rebuild your chuck (if it's a decent chuck like a jacobs), or the chuck can be replaced. If runout of chuck body is bad proceed to next step

3. Remove chuck from taper, and measure runout on the taper. If taper runout is good, wipe taper clean, wipe female part in chuck clean, coat with some prussian blue (I just color with a sharpie in a pinch) and rub the chuck tight against the taper. Remove, check to see that die rubbed off evenly. If not rubbed off evenly, figure out where it is interfering, and why, and fix it (maybe a burr needs filing off, or maybe something is bent?) If chuck is mounted evenly across the taper, the taper has no runout, but chuck body does, replace the chuck. If the taper has runout well, maybe you'll need a new drill press part. Check with sears to see if replacement part is available.

I'm not sure if I'd recommend wacking with a hammer, seems like a good way to damage the bearings. If there is play in the bearings, maybe change them too to fix it while you're at it. IME, you can sometimes get a small amount of movement by hammering, but don't reasonably expect to get more (without risking damaging your bearings, etc) than the slop between the chuck and the taper (or perhaps the slop between the chuck jaws and chuck body, or something like that...)

PS - I had a drill press that due to worn jaws, had runout of about .012". It was noticeable with the naked eye, and took out medium sized bits (damaged the tips) drilling into steel. didn't drill well. I replaced the chuck (cheaper than buying new jaws and easier than rebuilding) which reduced the runout down to about .003" or so, drills *much* better now.

[MarkBall2]

Hector, bring the shaft/chuck out this Sunday after church. I'll chuck it up in the lathe & we can see if that's the problem.

Personally I think there is some dirt or something easily fixed in the quill. Shouldn't be too hard to fix if that's it.

[WyoRoy]

Originally Posted by Kaos

Not sure if I understand the question but I did not hit with a hammer, it was suggested that the previous owner hit it with a hammer and knocked it out of trueness because the bearing were still good. Something had to have bent the taper or shaft for it to have some much runout. Maybe I didn't explain that well enough.
The problem was corrected by putting it in a lathe and basically recutting the taper.

As most say anymore, not a problem. I was asking because machining the taper seemed to me to be a last ditch effort. Unless there is enough meat left on the quill/taper to machine, I would have guessed that recutting the taper would have resulted in either too short a taper or too small a diameter taper to mate up with.

As far as the hammer and wailing the bejezus out of material, I wholeheartedly agree with you! I've a "friend" that is always looking for me to chuck bent die grinder burrs in my lathe and true them up because he has a friend that, "Does it all the time." So far, I've been able to put him off with using that friend's lathe. Lack of experience on my part has me leery about subjecting my lathe's headstock bearings to that sort of abuse. I've always figured that those re-trued burrs just weren't worth the cost of saving...especially on the typical "friend" discount payment plan...not in my lifetime.

[76GMC1500]

You always want to machine both tapers on the same lathe that way the taper matches. If the taper doesn't fit well enough you can use lapping compound to lap the tapers together. I work with much larger tapers for boat propellers (10" diameter, the shaft not the prop) and use Prussian Blue to check the fit and a barrel grinder to adjust. It's an awful job.

[OPUS FERRO]

Techs vs Technique

"It doesn't start drilling a round hole. More like an octagon".

rlitman answered the cutting face profile, and taper seating questions.
He gets big points for technique, and professional curiosity.

Failure Analysis, require you start at the beginning.

Miller Killer doesn't tell us anything about: what, how, on what, or
completion of his operation.

Looking at the hardware:

This is a cheap drill press, with a cheap drill chuck.

No mention is made of the quality of the drill bits being used.

M-K's original question emotes inexperience. "It doesn't start . . .

M-K "Is there anyway to improve this?

The answer is yes, and it is really simple, have someone show you how
to set up your drill, how to drill a hole, and critique your tool choice.

When you are operating with inferior tools, good results can only occur if
you have technique. Technique is command and result of the tools you
are using, regardless of their quality. Because you understand them.

Techs, I rely upon you everyday in my profession, but you have
hi-jacked the answer to M-K problem.

You went to the most complex solution first; the concentricity, or the
grind of the spindle taper.

The general consensus is brain surgery, when the problem is a hangnail.

For decades machine tools have had shifting manufacturing origins,
regardless of when or where in the world the the tool was built, the one
thing of superior quality was always the spindle taper. Everything else
can be junk, but not the taper!

All of M-K's questions are normal machine tool occurrences that any
journeyman could easily remedy, but must be observed.

Human Factors far exceed mechanical failure.

Miller Killer - reach out to your local network for a knowledgeable person
that can observe your operation in person.

Opus

[WyoRoy]

Opus, I agree with you in general. I even agree with you that both the drill press and the chuck are, in your word(s) "cheap". I somewhat agree (more or less wholeheartedly, but with one glaring difference) that a quality end product can be had using experience, skill and "cheap" tools or tooling. The glaring example would (in this case) be the drill chuck. While spindle tapers are manufactured on an exact measurement (since the days when the Morse company decided to develop a standard) the quality/design of any drill chuck is NOT. Until you, or any other, can convince me that, (in this case using a rough example) a round bit (drill) held in a square hole ("cheap: drill chuck) has the ability to produce (as manufactured) a perendicular, round, well-placed hole, I'll remain ever so slightly in disagreement. I am very open to being convinced. Heck, even with a full-blown, dynamite, killer, world class, expensive drill chuck mounted on a jig borer and top of the line drill bits the results are in no way guaranteed...it is why there are reamers out there (isn't it?).