Drill Press Accuracy (Lack Off...).

[Nogoingback]

I think 0.025" of waggle is lots! After more than 2 decades of use, maybe it deserves a make-over.
There is not a lot else that can move anywhere sideways except the middle of bearings relative to their outside races.
Take it apart. Go after the bearings.
Then also start getting picky about the chuck condition. If the chuck is spinning without any bad run-out, but the drill rod it is holding does have run-out, the chuck jaws may need some help - or just replace it with a nice keyless type.

At this point I've pretty much decided that a bearing replacement is in it's future. As far as the chuck goes, I've already replaced it with a good
one. The chuck that came with this DP wasn't worth the steel it was made from.

This one is a Jacobs Precision Chuck: sort of their version of an Albrecht I think. Chinese made, but with a guaranteed TIR of .0016
or better. I believe it since every time I've put an indicator on it it's barely twitched the needle. It has been an excellent chuck.

 

[RJSakowski]

In my experience, play in the DP spindle or quill doesn't contribute to drill wander, A small amount of play can actually reduce any wander. This is because the center punch mark may not be exactly in line with the spindle axis and the play will allow the tip of the drill to find the center. Clickspring did a recent video where he made a bow drill and in spite of movement on the upper end was able to drill some consistent holes using home made drills.

The question that I would ask is this: are the holes always drifting in the same direction? If so, you may have a table that is tilted. It doesn't take much of an angle to cause the drill to wander. If a lot of force is used in the drilling process, you may be experiencing deflection of the table. Not locking the table can also cause deflection.

Since you apparently have the problem with multiple drills, it should rule out improperly sharpened drills. I very seldom will clamp drill press work to the table but prefer to allow some movement of the work. If I need to clamp the work, there is the mill/drill or the CNC mill.

 

[Nogoingback]

You have two sources of play. 1, between the quill, and the drill press body. And 2, between the spindle, and the quill. Tackling each are different. Try to measure each before deciding on a method to tackle a fix.

Are you centerpunching holes before attempting to drill? that can make a big difference in any drills ability to start a hole where you want it.

If there's play between the quill and the housing, there isn't much to be done about it I think. I've adjusted the setscrew on the side
to minimize play, but that's about all there is. That pretty much leaves bearings as my only option if I understand correctly.

Yes, I center punch before drilling, and am very careful to line up the drill with the center punch "divot".

 

[Nogoingback]

In my experience, play in the DP spindle or quill doesn't contribute to drill wander, A small amount of play can actually reduce any wander. This is because the center punch mark may not be exactly in line with the spindle axis and the play will allow the tip of the drill to find the center. Clickspring did a recent video where he made a bow drill and in spite of movement on the upper end was able to drill some consistent holes using home made drills.

The question that I would ask is this: are the holes always drifting in the same direction? If so, you may have a table that is tilted. It doesn't take much of an angle to cause the drill to wander. If a lot of force is used in the drilling process, you may be experiencing deflection of the table. Not locking the table can also cause deflection.

Since you apparently have the problem with multiple drills, it should rule out improperly sharpened drills. I very seldom will clamp drill press work to the table but prefer to allow some movement of the work. If I need to clamp the work, there is the mill/drill or the CNC mill.

I've already checked table alignment and corrected tilt. The last time I checked it (fairly recently) it was square. I also set my table
so that it's centered under the drill bit so that I won't put pressure off center and cause it to tilt while drilling.

Unfortunately, I don't own a mill, and because of budget and space limitations, it probably isn't in the cards for the foreseeable future.

 

[gerritv]

Pin prick, centre punch, spot drill then a pilot drill, then your final drill. If you try to run a 3//8 drill through in one go from a centre punch mark it will move one you, and go worse from there. The pilot drill should be of a size that lets the final drill engage with the tip touching anything. The larger the drill, the blunter it is at the tip.
I just built a 17x17x6" gantry cnc mill/router using a drill press. Everything lined up through multiple layers of metal (which were drilled separately). My drill press spindle bearings are ok, but the cartridge shifts in the casting. To mediate that I drill with minimal extension of the quill.

What RJ mentioned about table tilt is also vital to get rid of, shims are your friend for that.

 

[Nogoingback]

When I need to be accurate, I always center punch and spot drill. For anything but small holes, I also use some sort of pilot. I also
raise the table as much as I can to minimize quill extension. When I indicated the spindle today, I tried deflecting it with the quill
all the way up, and then with it extended to a distance that's probably typical for drilling. With it all the way up, I got about .020
of play and with it extended I got about .025. That suggests to me that my quill isn't too bad and the bearings are the majority of the
problem.
As I responded to RJ, I keep an eye on tilt in the table and adjust to square.

It seems that I've pretty much decided to change the bearings. It certainly won't hurt anything and bearings aren't too expensive.
After 25+ years of service, I don't have any heart burn about doing some work on this thing. I've given some thought to
selling it and finding a good Clausing or Powermatic to replace it, but around here decent machines like that go for $800 - $1000.00,
which isn't in the budget right now.

 

[pdentrem]

I added a couple brass set screws on two sides, 90 degrees apart to locate the bottom bearing in the housing. There is a couple photos somewhere on this site.
Pierre

 

[rust rescue]

Center punch and then start hole with a center drill until you get a good taper. Proceed with drilling. Drills dead on every time.

 

[NortonDommi]

It almost always wanders off

Yes, I center punch before drilling, and am very careful to line up the drill with the centre punch "divot".

It was here on the site that someone mentioned years ago about knocking the top off the centre punch mark for accuracy, use a riffler or buzz with a flexi-disk on a small angle grinder. I remember being told about this decades ago but had gotten lazy. Yes it does make a difference. The raised ridge around the punch mark WILL cause the drill bit to track to one side and once started on a trajectory it will continue on that line.
Like RJSakowski I also like to start a pilot with the work free to move but I always have the work against a stop, this allows the bit to find and centre on the mark. I like to start with a centre drill and follow with the intended bit unless I feel a need to step drill a pilot hole then I use a bit the width of the web of the larger bit.
With that lovely chuck upgrading the spindle and quill bearings would be a good way to go.

 

[Nogoingback]

I added a couple brass set screws on two sides, 90 degrees apart to locate the bottom bearing in the housing. There is a couple photos somewhere on this site.
Pierre

Was that needed to compensate for loosness of the bearings in the housing?