please, how would you cut this blind hole ?

deadlykitten · Mar 25, 2017

hello

after seeing some posts, i thought to ask you about your opinion to deliver this :

milimeters : o26.50 [ +0.13 ] x 182 [ +3 ] in normal steel, on lathe

hole is checked with :
... go caliber o26.50[±0.003] x 190
... no go caliber o26.63[±0.003] x short

inches : o1.0433 [ +0.0051 ] x 7.1654 [ +0.1181 ]
hole is checked with :
... go caliber o1.0433 [±0.00011] x 7.4803
... no go caliber o1.0484 [±0.00011] x short

many parts, so to do not worry about custom tools

surface rugozity does not matter ...

bottom shape may be drill

once per year i craft those parts

thank you

SpeedsandFeeds · Mar 25, 2017

Drill snd then use a flatbottom drill to clean up the bottom of the hole.

WABOOM · Mar 25, 2017

The operation you describe is like... the easiest thing in machining. Can I come and work for you? You'll be impressed!

michiganbuck · Mar 25, 2017

SpeedsandFeeds said:
Drill snd then use a flatbottom drill to clean up the bottom of the hole.

Most of us just snub off a drill end on a bench grinder to a hand held square, gash face to almost center (or to center.) and follow into the drilled hole. Gash one flute to enter for a very smooth flat bottom and even a little depth cutting to make exact size.

deadlykitten · Mar 25, 2017

hello guys

thank you for replies so far

i think i made a mistake : by "bottom shape may be drill" i mean that the bottom can have an angle of 120...140degress, so it is not required to be flat

sorry

my english, my bad !

Drill and then use a flatbottom drill to clean up the bottom of the hole

hy SpeedsandFeeds

drills alone can not deliver stable setup

Can I come and work for you? You'll be impressed!

hy WABOOM

you are welcome any time

WABOOM · Mar 25, 2017

It would basically be this easy on fanuc. Check math for tolerance values specs. I'm American.

(1.122 inch diam. 135° COBALT DRILL, LONG)

G30 UO. W0.
G97 S175 M3
M8
T0101
G0 G54
Z.1
X0.
G83 Z-7.16 R0.1 Q4. F0.004
G80
G0 Z1.0
X8. M9
G30 U0. W0.

CarbideBob · Mar 25, 2017

Just for inch guys,
This is a 1.12 inch hole 7 inches deep with a .005 tolerance so it's over 6:1 L/D.
Just for giggles assume the OP wants a trusted process control limit on the batch within 50% of the tolerance as any good machinist would shoot for.......
Bob

litlerob1 · Mar 25, 2017

Drill 1-3/32 " run 1" solid carbide bar for finish. Not sure if "normal steel" is better than abnormal steel, but the biggest challenge will be chip evacuation. Thru coolant would be the best route IMO.

R

Ox · Mar 25, 2017

CarbideBob said:
Just for inch guys,
This is a 1.12 inch hole 7 inches deep with a .005 tolerance so it's over 6:1 L/D.
Just for giggles assume the OP wants a trusted process control limit on the batch within 50% of the tolerance as any good machinist would shoot for.......
Bob

I ass-u-me that the opp already knows how to run it, as he says that he runs it every year.

I also ass-u-me that he is baiting us in - since he seems to know how to doo every other question posed on the board. It would seem hard to imagine that he needs help here...

But - I don't see why anyone would need more than a 28.5 spade drill for the app.

---------------------------

Think Snow Eh!
Ox

deadlykitten · Mar 26, 2017

Drill 1-3/32 " run 1" solid carbide bar for finish

hy litlerob, there are a lot of vibrations when the knife goes that deep

in original post i typed 8 instead of 6; sorry

i have updated post#1 with dimensions in inches, but i am not sure about the number of digits that i should have used ....

I ass-u-me that ... I don't see why anyone would need more than a 28.5 spade drill for the app

if i may : hy ass-u-me

the go caliber does not fit after the drill, because the hole is long

it feets sometimes, when the insert is new, but not all new inserts deliver a good hole

is a 7D hole that is checked with a caliber as long as the hole

if you drill a o10x2D hole, with a o10h7 short drill, than a go caliber o10[±0.003] x [>2D] may enter untill the bottom
if you drill a o10x4D hole, with a o10h7 long drill ( + pilot hole, etc ), than a go caliber o10[±0.003] x [>4D] may not enter untill the bottom

kindly !

litlerob1 · Mar 26, 2017

deadlykitten said:
hy litlerob, there are a lot of vibrations when the knife goes that deep

in original post i typed 8 instead of 6; sorry

i have updated post#1 with dimensions in inches, but i am not sure about the number of digits that i should have used ....

if i may : hy ass-u-me the go caliber does not fit after the drill, because the hole is long it feets sometimes, when the insert is new, but not all new inserts deliver a good hole

is a 7D hole that is checked with a caliber as long as the hole

if you drill a o10x2D hole, with a o10h7 short drill, than a go caliber o10[±0.003] x [>2D] may enter untill the bottom
if you drill a o10x4D hole, with a o10h7 long drill ( + pilot hole, etc ), than a go caliber o10[±0.003] x [>4D] may not enter untill the bottom

kindly !

Not sure what you're getting at here, this is a really basic operation. That can be done a few different ways, especially with the allowance of a drill point. The easiest and simplest way will be to drill it to size. Don't change drills out if they are both cutting to size just do it in one shot. If you need to get the spade drill going you only need enough of a spot, center, stub length drill whatever to get it started. I have no idea what your tooling availability, machine capacity, or financial restraints are, but you can get a .75 diameter bar from Sandvick that will run 10:1 all day $$$$$

R

Milland · Mar 26, 2017

I don't know what Mr. Kitten has for equipment, but I'd like to do that job with a short carbide drill to establish a pilot, then gun drill the balance with a well designed (replaceable pads and insert) gun drill with 70 bar or so through coolant. Should be a doddle...

Edit: Or just a regular carbide-tipped gun drill that can be reground a number of times. Should last quite a while, get two so you always have a sharp one.

I don't think I'd want to bore this hole, too slow and dealing with chips is annoying.

deadlykitten · Mar 26, 2017

but you can get a .75 diameter bar from Sandvick that will run 10:1

hy litlerob

i will check again tomorrow for such a tool; last time i checked i did not look at Sandvick

... well designed (replaceable pads and insert) gun drill

hy Milland

yup, something like that ... so far i used integral tools, but lately i also started thinking of replaceble inserts, etc

Or just a regular carbide-tipped gun drill that can be reground a number of times

this is also a good idea, however such tools arround here are not so common

I don't think I'd want to bore this hole, too slow and dealing with chips is annoying

so far i could not avoid this operation

the go_caliber is as long as the hole, so if i only drill, than the caliber wont fit, because the drill is long and it vibrates; kindly !

Mr. Kitten

kitten is not suposed to be a Mr

deadly is more than enough

Milland · Mar 26, 2017

I've seen their pointy little claws, adding "deadly" to "kitten" is redundant. If I got the "Mr" wrong I apologize, sometimes it's tough to get honorifics correct on the internet.

You can order carbide-tipped gun drills from a variety of sources around the world, with a short, relatively large diameter like you're dealing with they shouldn't be too expensive or hard to get. The short pilot drill means you won't need fancy fixturing to make it work, except for the through coolant adapter/pump if you don't already have one at hand.

Should be repeatable, accurate, straight and on axis, reasonably fast, and no worries about chip evacuation. Just be sure to give the vendor enough information so they can make the tip geometry correct, which means materials you're cutting, hardness, etc. Maybe get them to specify the correct pilot drill grind, or have them supply it.

deadlykitten · Mar 27, 2017

You can order carbide-tipped gun drills from a variety of sources around the world

hy Milland

i look a while ago for such tools at the vendors arround here that i know, but they did not provide such tools

i will look again ... kindly !

I've seen their pointy little claws, adding "deadly" to "kitten" is redundant

not all cats / kitties with pointy little claws are also "deadly"

i am deadly, i have claws, but i dont use them

i believe in non intrusive methods and i mean no harm

Milland · Mar 27, 2017

This company makes gun drills at least as large as you need, this is their pricing page. It's not clear where they transition from solid carbide to carbide tipped, you'd need to email them with your application data and the diameter/length required to get a proper estimate for two (or whatever number) pcs.

Prices - Standard Single Flute Gun Drill - Sterling Gun Drills

deadlykitten · Mar 27, 2017

thank you again

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