7xd plus recommendations (big drills)

Hey guys what kind of drills are you using for 2.25 holes up to maybe 2.75 in diameter. Using 100% sandvik 880s right now but they are capped at 5xd. We do lots of deep drilling say 15 inches long at various sizes sometimes up to 20 inches long. Using 880s on crazy extensions but need to peck and it takes forever.

Hopefully looking for a drill that is maybe adjustable and can possibly hold sandvik inserts. Also looking for ones where you could drill half and half and when they meet up it doesn't destroy the inserts.

Thanks so much. Doing this on a lathe mostly.

asticx said:

Hey guys what kind of drills are you using for 2.25 holes up to maybe 2.75 in diameter. Using 100% sandvik 880s right now but they are capped at 5xd. We do lots of deep drilling say 15 inches long at various sizes sometimes up to 20 inches long. Using 880s on crazy extensions but need to peck and it takes forever.

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Need to peck ? Are you pushing them hard enough ? I have never pecked an insert drill, well, never since I figured out you can get a chip trapped between the bottom and the insert and there goes your insert. There goes the body, if you aren't on top of it. Pretty sure it was my Sandvik salesman who said, "Do NOT peck these drills ! Just do a short dwell if you have to clear the chips."

If you are pecking now and it's really slow, I used to use spade drills with replaceable blades. They were slower than insert drills but much more forgiving. Had some that had to be 18" long, and they worked well.

Doing this on a lathe mostly.

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Me too. 316 stainless 12 - 15" deep. It was awful. Had to run at night because the neighbors all complained about the noise. They were okay in regular steel and good in aluminum, tho.

Got some insert drills at auction, ran 3" holes in 8620 about 5" deep very fast, but took a bunch of horsepower - like 40 or more. I could only do a few at a time between letting the 125 amp breaker cool off. If you can push the inserts hard and keep the coolant pressure up to get the chips out, they work awesome.

But the spade drills are a lot less scary Cheap to try, too.

Indexable Drills

They work $$$$$$

asticx said:

Hey guys what kind of drills are you using for 2.25 holes up to maybe 2.75 in diameter. Using 100% sandvik 880s right now but they are capped at 5xd. We do lots of deep drilling say 15 inches long at various sizes sometimes up to 20 inches long. Using 880s on crazy extensions but need to peck and it takes forever.

Hopefully looking for a drill that is maybe adjustable and can possibly hold sandvik inserts. Also looking for ones where you could drill half and half and when they meet up it doesn't destroy the inserts.

Thanks so much. Doing this on a lathe mostly.

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1) as length to dia ratio increases you often have to slow sfpm or rpm to avoid chatter vibration squealing. so often spade drill with hss or cobalt is better which can take more vibration without chipping or breaking apart as easy
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2) hp requirements can easily be higher than machine can apply or the part and fixture can take the cutting forces involved. i often use a pilot hole. feeds are often below recommended max settings to get reasonable tool life. often find with pilot hole i can increase feeds and without pilot hole feeds often are so much slower as its faster to put a pilot hole in first
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3) without through spindle coolant often need to peck at slow rapids to let chips out and cool drill tip with coolant. many a drill tip i have seen break through other side throwing sparks as the drill tip was dry or no coolant reaching it. i have had to slow rpm to avoid burning drill tip up if i wanted to peck less. usually the in small fine print they mention reducing sfpm with longer drills and they may or may not mention a further reduction if not using through spindle coolant. often they say not to peck as they only recommend through spindle coolant. if you dont have through spindle coolant it can effect rpm and feed and use of peck by easily 50%
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4) the worst to drill is drilling ductile iron with hard spots of slag deep in casting. often need to slow rpm and feed so if it hits a hard spot you got more time to hear squealing dull drill tip and stop. if its sudden dull you can loose drill tip and melt it deep in hole in a few seconds too quick for operator to react. after drilling hundreds of big deep holes you soon learn what works better with reasonable tool life and success rate at finishing the hole drilling. dont under estimate hp needed. you can easily overload machine and have it stop from overload. i have had part move in fixture too from too much cutting forces.
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calculate hp needed. embarrassing to order $1000. drill then have to tell boss you cannot use it at rpm and feed cause machine dont have the hp to run it that fast. big drills in carbide can need 20 to 100 hp. obvious a problem if you dont have the hp or cannot hold the part to resist tons of cutting pressure. rough calculation take cubic inches removed per minute and if 1018 steel figure a hp needed per cubic inch. SS needs 200 to 300% more hp. aluminum less.

asticx said:

Hey guys what kind of drills are you using for 2.25 holes up to maybe 2.75 in diameter. Using 100% sandvik 880s right now but they are capped at 5xd. We do lots of deep drilling say 15 inches long at various sizes sometimes up to 20 inches long. Using 880s on crazy extensions but need to peck and it takes forever.

Hopefully looking for a drill that is maybe adjustable and can possibly hold sandvik inserts. Also looking for ones where you could drill half and half and when they meet up it doesn't destroy the inserts.

Thanks so much. Doing this on a lathe mostly.

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There are not a lot of options at that diameter after 5D - that's the limit for indexables regardless of brand. The 880 inserts are captive, no chance of using them in anything else. The kennametal drills that rob posted do work but they are not fast like modern indexables. They are much more comparable to spade drills in terms of penetration rate. Also they work best on blind holes - breaking through can be a bit uncomfortable with those...

In your situation I would probably just go spade drills for when the 880's are not long enough. I have had good luck drilling up to about 30 inches deep with those kinds of sizes - pretty good finish and runout, just needs a good strong flow of coolant. My go to are these from YG1. They have a better selection of bodies for quite a lot less cost than Allied. Don't know why they don't seem to show them on the YG1 website though...

you can get spade drill insert tip in carbide too. but when drill long and vibrating i have had carbide break apart and not even finish one hole.
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long length drills often have to use hss or cobalt cause of the vibration

gregormarwick said:

The kennametal drills that rob posted do work but they are not fast like modern indexables. They are much more comparable to spade drills in terms of penetration rate. Also they work best on blind holes - breaking through can be a bit uncomfortable with those...

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It's uncomfortable when the ceiling falls in too, the first time we ran them we had to drill 2.125" 8x deep from both sides almost 40" and in the middle on the second side that's what it seemed was happening, obviously this was not on small machine but it felt like we were opening amine shaft. It did not fail, but yeah it's a little un-nerving with 4k with of tool in the hole. We did that about 25 times in succession without failing. The first 4-5x diameter ran easy and fast like an indexable, but after that probably half, then on breakthrough a quarter of that. The inserts are staggered so break a chip on each revolution BUT we are also using a chip blaster so 1000 psi.

R

Komet Centron KOMET of America - Solid Drilling

Allied & Kennametsl have similar tools as well.

Spade drills are too slow. They have the length but take forever.

Only pecking with 880s after the flutes are completely in the part.

Shop Supply Guru said:

Komet Centron KOMET of America - Solid Drilling

Allied & Kennametsl have similar tools as well.

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I've heard good things about these. May try

litlerob1 said:

Indexable Drills

They work $$$$$$

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We have one to try at shop will see how it goes.

gregormarwick said:

There are not a lot of options at that diameter after 5D - that's the limit for indexables regardless of brand. The 880 inserts are captive, no chance of using them in anything else. The kennametal drills that rob posted do work but they are not fast like modern indexables. They are much more comparable to spade drills in terms of penetration rate. Also they work best on blind holes - breaking through can be a bit uncomfortable with those...

In your situation I would probably just go spade drills for when the 880's are not long enough. I have had good luck drilling up to about 30 inches deep with those kinds of sizes - pretty good finish and runout, just needs a good strong flow of coolant. My go to are these from YG1. They have a better selection of bodies for quite a lot less cost than Allied. Don't know why they don't seem to show them on the YG1 website though...

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The 880s work fine with extensions and pecking up to 7/8 x d but like I said slow going. Doing pecks usually after 5xd and the time really jumps.

If you're OK with customs, you can stretch the standard indexable design past the 5xD threshold. I've seen some drills in our custom shop with carbide guide pads for lengths over 5xD. They may also alter the point geometry as well, for better stability at these longer lengths. (Just a hunch - I know we've modified the point geometry before for specific drilling tasks.)

Seco's SD600 series drills would be a decent option as well. These are very similar to the Kennametal drills linked-to above. The Seco version has guide pads as well for stability - I would hope they would keep the drills stable on brrak-thru.
SD62 Modular Drill System - YouTube

Need to peck ? Are you pushing them hard enough ? I have never pecked an insert drill, well, never since I figured out you can get a chip trapped between the bottom and the insert and there goes your insert.

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hy SeaMoss if needed, i peck by feeding the tool out not in rapid, but in feed : G01, not G00

i also push drills as deep as possible without pecking; if flutes are inside the hole, and chips can not evacutate, than i peck

There goes the body

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somewhere arround is a place where i fix bended drills, or drill with nose broken ... back as new

... so i worry no more about holder costs

Just do a short dwell if you have to clear the chips

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i encountered cases where dwell did not clear the chips ...

i dont dwell, but retreat in feed; for example :

common code :
... cut Z-
... dwell
... rapid / feed out

alternative code :
... cut Z-
... cut Z+ for 0.3
... rapid / feed out
...... the difference is :
......... feed is slow enough for the tool to get in the in-position and stay there for a while
......... also, gentle retreat wont break the insert, and, more important, will create a bit of clerance
......... rapid is done after the clearance position, thus cutting edge is not agresivelly taken out from the hole, even if a full rotation occured

kindly!

I've seen some drills in our custom shop with carbide guide pads

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hy Jashley please, can you share a photo with this tool ? or at least, please, can you describe where are the guide pads and if there is a concetricity condition with nose insert ?

if this pads are on the insert, than it may be ok if they are on the holder, and insert positioning has radial errors, than pads must be on a lower diameter, or just left as they are, and they will get wear during cutting ... kindly !

Have you looked into gun drilling?

http://a_viktor.tripod.com/PeterThesisWriter.pdf

Ran into this article some time ago. Great information on hole making

litlerob1 said:

It did not fail, but yeah it's a little un-nerving with 4k with of tool in the hole. We did that about 25 times in succession without failing.

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Ouch ! Can i ask a question ? Did you come out on top with risking 4 thou (plus spares) worth of index drills every time you pushed go, or would you have been better off either

1) spade drill, slower but cost WAY less

or

2) bht, ejector drill, or whatever the word is for the next size up of gundrilling ? Or maybe even job it out to a deep-hole drilling place ? Do you guys still have deep-hole drilling places ? When I did long shafts with a hole through them, it was way cheaper to have one of those guys do it ...

Kennametal's KSEM Plus system. You will get the penetration rate of the 880 drill, going up to 10X dia

KSEM PLUS™ Modular Drill System

some big drill bits are over $1000. and you can easily be drilling into a $10,000. part
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cost to benefit ratio on feeds and speeds should be done. many a time trying to save 10 minutes or less ended up costing many hours and many $1000.'s of rework, remaking part, etc.
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if you collect data over the years often the data says going slower is faster by the end of the year. just saying i have seen drills go in seconds that are too close to their max limits. what i would call no extra safety factor

JMC said:

Kennametal's KSEM Plus system. You will get the penetration rate of the 880 drill, going up to 10X dia

KSEM PLUS™ Modular Drill System

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I like the look of those......................looks like the closest thing to a winner here...............................