Drill chamfer not centered?

two_chips · Dec 6, 2020

New to machining and this forum.

I have a grizzly G0759 mill with a DRO and have found it pretty difficult to get a good chamfer centered on a drill hole.

I'll drill a hole, and not move the bed at all, only swap from the drill bit to a chamfer bit. When I cut the chamfer, it'll be quite a bit off center, which is really annoying.

I also ran into this issue when I was drilling a 82* counter sink.

Any ideas/suggestions on what might be going wrong?

Thanks.

BoxcarPete · Dec 6, 2020

Are you sure your hole is where you drilled it?

Drills wander on the start if you just jam it into the material. Using a spot drill or center drill will help put the hole under the spindle.

That said, your equipment doesn't inspire too much confidence, and in fact would be better left unmentioned since hobby grade machinery isn't to be discussed here.

howieranger · Dec 6, 2020

First off it would be good idea to read the machinery discussion guidelines in the stickies. First thing to check is if the table is moving in X or Y. Second if the head is out of tram and your drill is not the same length as the countersink they will not hit the workpiece because in the same point it looks like the whole head on this machine moves up and down to feed because there is no quill feed.

D Nelson · Dec 6, 2020

You can’t make chicken salad out of chicken shit
Don

Sent from my iPhone using Tapatalk Pro

EmGo · Dec 7, 2020

D Nelson said:
You can’t make chicken salad out of chicken shit

But you can countersink holes with a Black and Decker hand drill and have them come out okay. I wonder what "quite a bit" means in the original post ?

From the description given, I'd go with head out of square plus different length tools, but that's just a guess from the feeble amount of info given.

eKretz · Dec 7, 2020

I don't know the cause, (like EG said, too many unknown variables involved) but I would certainly agree that it's very annoying.

Mtndew · Dec 7, 2020

two_chips said:
Any ideas/suggestions on what might be going wrong?

Yeah, you didn't just buy a piece of shit hobby "machine" you bought the cheapest piece of shit out there.
That's where you went wrong.

michiganbuck · Dec 7, 2020

on a mill, the tram can be off and so a different length cutting tool can spot off the first or DRO location. A handheld drill held chamfer tool can be quicker. A floating holder can sometimes make a better chamfer.

A poorly sharpened drill can start off-center.

Be sur your quill travel and your head tram are the same. or use the one you know is straight square to the table/part.

jscpm · Dec 7, 2020

You always cut the countersink BEFORE you drill the hole. Not the other way around.

DDoug · Dec 7, 2020

Machine in question:
7" x 27" 1 HP Mill/Drill with Stand and DRO at Grizzly.com

EmGo · Dec 7, 2020

digger doug said:
Machine in question:
7" x 27" 1 HP Mill/Drill with Stand and DRO at Grizzly.com

I'm sure, but it doesn't matter. You can do this with a hand tool. He's fucking up a basic process, the machine is not responsible.

HuFlungDung · Dec 7, 2020

two_chips said:
New to machining and this forum.

I have a grizzly G0759 mill with a DRO and have found it pretty difficult to get a good chamfer centered on a drill hole.

I'll drill a hole, and not move the bed at all, only swap from the drill bit to a chamfer bit. When I cut the chamfer, it'll be quite a bit off center, which is really annoying.

I also ran into this issue when I was drilling a 82* counter sink.

Any ideas/suggestions on what might be going wrong?

Thanks.

Welcome to the world of intricate details that matter (aka "machining"). Tramming the spindle to the table certainly sounds like the best advice. Murphy's laws are strong in machining, any detail that you don't attend to, will work against you 99% of the time. While using a hand drill to chamfer with is a workaround, having the spindle out of tram is a fundamental error that needs to be corrected. This error affects edge finding, circularity of holes, uneven tool entry (like starting on a sloped surface).

JS · Dec 7, 2020

Mike1974 · Dec 7, 2020

EmanuelGoldstein said:
I'm sure, but it doesn't matter. You can do this with a hand tool. He's fucking up a basic process, the machine is not responsible.

Not necessarily. If the spindle is loose, and he is running a harbor freight drill (man I have seen some bad grinds in my day from the chinesium drills), and the drill is walking all over, assuming the part and table are clamped, then the center/spot/chamfer comes down it is more likely to be right at the spindle, of which the hole may not be.

Mike1974 · Dec 7, 2020

A random thought, the OP, obviosuly didn't read the forum 'rules', but he did say what machine and what he did and asked for help. Immdeiately gets his head chewed off, no wonder people don't want to learn machining...

michiganbuck · Dec 7, 2020

Very often a slower handheld drill motor with a chamfer cutter or an abrasive point wheel can make quick work of beveling holes.

Faster die grinders or drill motors can chatter.

Abrasive points are not good for aluminum because they load up with aluminum.

eKretz · Dec 7, 2020

I'm guessing he didn't initially start the drill on location with the spindle centerline. Didn't use a spotting drill or similar to keep the hole on location at the beginning. It could be head out of alignment with the travel too though. Can that even be adjusted on that dinky thing?

Regarding the Chinesium: I try to concentrate on advice about the machining process rather than the machine, but sometimes the machine is the problem...

Also, no offense to the O.P. but this guy's problem is beginner stuff. Many here don't want to babysit someone who hasn't even read enough to try to do things the right way. I don't mind usually, but it can get on my nerves occasionally too. Remember this is supposed to be the "professional's" site. What I really like is letting my brain chew on the tougher, puzzle-type conundrum-y questions. I think a lot of the guys here are the same.

L Vanice · Dec 7, 2020

Weldon makes a line of piloted countersink bits that work very well in the holes for which they are designed.

https://www.travers.com/zero-flute-...High Speed Steel and Solid Carbide|20-40|C:45

If the job is simply breaking the edge of a drilled hole, a hand deburring tool is probably quicker than using a countersink bit in a milling machine. I have a multi-tooth countersink bit stuck in the end of a wood file handle that I have been using for decades. I also have commercial versions, with two or three-flute bits in plastic handles. Then there are all those Shaviv and Noga deburring tools with their Swiss army multi-do-any-job interchangeable tips. They really do work well for many different jobs.

https://www.travers.com/zero-flute-...High Speed Steel and Solid Carbide|20-40|C:45

https://www.mscdirect.com/product/details/41031774

Larry

ignator · Dec 7, 2020

Looks like the column is held to the base with 4 cap screws, should be adjustable:

Scottl · Dec 7, 2020

two_chips said:
I have a grizzly G0759 mill ...

I think we've identified the problem.

Something is sloppy and shifting position under cutting forces.

Other possibility if you don't center drill first is that the drill bit is "walking" and flexing off-center while the more rigid countersink cuts in line with the spindle.

Drill chamfer not centered?

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