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Drilling on an extreme angled surface

darcus

Plastic
Joined
May 24, 2014
Location
Birmingham, UK
Hi

I am wondering if there is a quick and precise way of drilling on a sloped surface.

We manufacture hex nuts. We have some customers asking for nuts that have a through-hole drilled across two flats.

In essence we are drilling onto an EN36 steel surface sloped at 30 degrees to the vertical.
C Drill Nut.jpg

The drill diameter is 2.5mm

The drill depth is 10.5mm

I am wondering if I should make some sort of drill guide for this. Or perhaps I should come down with flat bottomed end mill, to produce a flat on either side of the hole, then drill it?

Some sort of solid carbide drill should do the job as it will need to be a 5D type, so 12.5mm length.

I need to be able to do this in a repeatable manner, for about 1000 pieces without breaking too many drills because they're about £20 each.

Any help would be appreciated.
 

Booze Daily

Titanium
Joined
Sep 18, 2015
Location
Ohio
I do a job like that a couple times a year. I use a flat bottom endmill the same size as the thru hole to start a flat surface, then the same size ballmill to give the drill point something to follow.

I used to break drills randomly until I added the ballmill. 303 stainless, .062 holes.
I had to eff around with my peck depth so the drill wouldn't break on the exit side.
 

Finegrain

Diamond
Joined
Sep 6, 2007
Location
Seattle, Washington

DDoug

Diamond
Joined
Oct 18, 2005
Location
NW Pa
Looks like this fixture only goes across the flats. OP wants to drill through one corner, a much harder thing.

I've done this before, made a drill guide. It was still touchy. If I were to do it again I would probably use an endmill to make a flat, then drill.

Regards.

Mike

No, you make the drill bushing bottom to fit, and adjust the location accordingly.
 

michiganbuck

Diamond
Joined
Jun 28, 2012
Location
Mt Clemens, Michigan 48035
You might make a bushing jig the angles and fits close to the part angle
and perhaps try a drill with an end mill point grind.

No, I have never tried this.

the drill with having a thinner web so not being as strong as an end mill, but with having an Od circular land so to position better to hole and bushing center.

and yes a special point would be an extra cost.

it is not uncommon that a Parabolic drill has a thicker web.
 

memphisjed

Stainless
Joined
Jan 21, 2019
Location
Memphis
naichi drill. Dyed in the sweat of mermaids- but that is the type of hole they do. no guide bushing, no tool change.
 

Limy Sami

Diamond
Joined
Jan 7, 2007
Location
Norfolk, UK
You use something like this Safety Wire Nut & Bolt Jig Kit - Imperial

FWIW I shudder to thing how many 000's I've done over the years using such jigs, ....just take it very gently when starting the hole, sorta let the drill lips cut their way in first - oh and it's hard on drills, so buy plenty and don't bother with anything fancy dancy.

FWIW 2 - Once you've dialled yourself in, it'll take you longer to change the part than drill the hole.
 

DDoug

Diamond
Joined
Oct 18, 2005
Location
NW Pa
You use something like this Safety Wire Nut & Bolt Jig Kit - Imperial

FWIW I shudder to thing how many 000's I've done over the years using such jigs, ....just take it very gently when starting the hole, sorta let the drill lips cut their way in first - oh and it's hard on drills, so buy plenty and don't bother with anything fancy dancy.

FWIW 2 - Once you've dialled yourself in, it'll take you longer to change the part than drill the hole.

Cheaper is better eh ?
 

DDoug

Diamond
Joined
Oct 18, 2005
Location
NW Pa
Within reason?? very much so Doug (ordinary general decent'' HSS jobbers will do fine) it's the last sort of job on earth I'd use carbide drills for.

I was referring to the fixture, not the drills.

Your is "quick and dirty" and the linked I show is more versatile, and has a replaceable standard drill bushing for much longer life.
 

TeachMePlease

Diamond
Joined
Feb 11, 2014
Location
FL
Within reason?? very much so Doug (ordinary general decent'' HSS jobbers will do fine) it's the last sort of job on earth I'd use carbide drills for.


He says they manufacture them. To me that says they're already setup in a CNC machine (guessing). Adding 2 operations with a spot and a drill that are done in a CNC controlled, precise, repeatable manner, adding a few seconds to a part inside the machine seems more efficient and likely cheaper than a 2nd op with a homemade or store bought jig on a drill press. But maybe that's just me. Given a good machine, and coolant through the tool, or at least some high pressure coolant, I'd wager you could get through 1000 of these on 1, maybe 2 drills. The drills are about $120 each. How much time did you save over breaking 6x $20 drills and the handling time to do 1000 of them on a drill press or knee mill?

I could be way off here, but those're my thoughts.
 

Limy Sami

Diamond
Joined
Jan 7, 2007
Location
Norfolk, UK
He says they manufacture them. To me that says they're already setup in a CNC machine (guessing). Adding 2 operations with a spot and a drill that are done in a CNC controlled, precise, repeatable manner, adding a few seconds to a part inside the machine seems more efficient and likely cheaper than a 2nd op with a homemade or store bought jig on a drill press. But maybe that's just me. Given a good machine, and coolant through the tool, or at least some high pressure coolant, I'd wager you could get through 1000 of these on 1, maybe 2 drills. The drills are about $120 each. How much time did you save over breaking 6x $20 drills and the handling time to do 1000 of them on a drill press or knee mill?

I could be way off here, but those're my thoughts.

Good thoughts Glasshopper me ole china, it really comes down to process requirements.
 

gustafson

Diamond
Joined
Sep 4, 2002
Location
People's Republic
I think I go with the fixture, maybe not the one you buy but you could make one pretty fast to hold 'x' number in a vise. The real problem with CNC is opening the GD door. 2 vises 10 per vise and you are making these with a 50 cent drill

Yes if I was doing one or two I would spot it with a carbide endmill and drill with a regular drill
 

barbter

Banned
Joined
Oct 27, 2007
Location
UK
Previous place we used to make a crapton of these.
Had a drill jig that had a ground/angled bush so the drill would start in the bush pass through the part and exit through into the base bush. The jigs were a UK supplier for wire locking nuts - can't remember the name now as it was 2000/2005.
The biggest problem was deburr - round oil stone in a windy touched on the entry and exit used to suffice, but took a steady hand.
For the lower qty's/specials, we used to make from round bar on the millturns - this way we could mill a wider flat and start/drill the hole deep enough but it would be blind, then mill the hex, then re-pass the drill through the hole to deburr.
This would leave a lovely sharp hole with no burr, so it would just take a second with a scraper to deburr.
Carbide drills so a nice straight hole but always a PITA feature that always takes a little more time or throws a little more problems (deburr) than most give thought to.
 

crickets

Hot Rolled
Joined
Jul 3, 2021
I do a job like that a couple times a year. I use a flat bottom endmill the same size as the thru hole to start a flat surface, then the same size ballmill to give the drill point something to follow.

I used to break drills randomly until I added the ballmill. 303 stainless, .062 holes.
I had to eff around with my peck depth so the drill wouldn't break on the exit side.

Can one go straight to ball end mill ?
 

Booze Daily

Titanium
Joined
Sep 18, 2015
Location
Ohio
Maybe if you want to feed slow enough. I don’t like the side pressure that comes from the angled wall.

Maybe I’ll try next time.
 

Overland

Cast Iron
Joined
Nov 19, 2017
With a regular drill in a drill bushing, your initial contact on the job will be right on the corner of the drill, with lots of side forces. To me, that's really hard on the drill, even in a drill bushing.
A short stubby endmill will resist these forces much better, designed for side forces. Once a flat surface is created, the drill will be fine.
Used to drill oil holes in cranks, always at an angle to the crankpin bearing surface. Would start with a drill at 90 degrees to journal, shallow depth, then oil hole drill at an angle, but "square" to the 118 degree faces of initial hole. These were 5/32" drills going 3" plus from one crank pin to the next. Always with a drill bushing.
Good luck.
Bob
 








 
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