small dia drill bit with replaceable tips

[alan speyrer]

thinking about trying a small diameter drill bit with a replaceable tip for drilling on my cnc lathe, drill diameter is 8.4mm, have to drill some 1045 steel, drill depth is 3.25". i dont have thru coolant, all i have is flood coolant. any suggestions??
currently im just drill with a standard cobalt parabolic flute drill bit, these bits usually last about 75 to 100 parts. im drilling at 650rpm, .005ipr feed.

 

[guythatbrews]

Doubt if you'll have much luck without higher pressure through coolant. Your speed and feed seem reasonable. I assume you are pecking.

SFM is a better way to pose the question than RPM.

 

[hanermo]

As was said.
It´s 8.x mm D to about 80 mm depth, about 10:1 ratio.
1045 is okay, but you are dealing with a lot of extra heat due to rubbing on the very long drill and needing to extract all the chips.

Are you pressed for cycle time aka speed, for tool duration, or for accuracy ?

IF it´s feasible, you might maybe consider pre-drilling about 6-6.5 mm on sections of maybe 3xD of the drill, around 20 mm in depth for say 6.5 mm D of drilll, 3/4" deep or so.
Then jank the drill all the way out -- it clears the chips, cools the drill.
You can now swap to the final drill.
And you have 3/4 less final material to remove and 300-500% more extra space behind the drill tip for the chips.
And the final drill is not heated and binding and the bore is much much cooler.
Because a 6 mm drill in the 8 mm bore does not pack the chips in, and does not rub, hardly at all, as it has space behind the cutting area.

I remember that deep-drilling stainless for 6.00 mm target accuracy on 800 mm bores, my times and heat went to less than half with occasional pre-drilling to clear the bore, cool the drill, and evacuate the chips.

And on most machines its a few secs to just evacuate the bore letting the chips come out.

Your drills last 100 parts which sounds about right, and 650 rpm / 8.3 mm D sounds about right.
The occasional pre-drill in the deeper 1/2-1/3 sections might double your tool life, and it might halve your parts temp when they are done.
But of course it probably costs another 30-60 secs per part, and this might or not matter.

 

[EmGo]

thinking about trying a small diameter drill bit with a replaceable tip for drilling on my cnc lathe, drill diameter is 8.4mm, have to drill some 1045 steel, drill depth is 3.25". i dont have thru coolant, all i have is flood coolant. any suggestions??
currently im just drill with a standard cobalt parabolic flute drill bit, these bits usually last about 75 to 100 parts. im drilling at 650rpm, .005ipr feed.

I'd be wiling to put up $.25 that you won't get any better than the p-flutes unless you go to something exotic, like gun drilling. For deep holes those were the best thing I found.

 

[Ox]

thinking about trying a small diameter drill bit with a replaceable tip for drilling on my cnc lathe, drill diameter is 8.4mm, have to drill some 1045 steel, drill depth is 3.25". i dont have thru coolant, all i have is flood coolant. any suggestions??
currently im just drill with a standard cobalt parabolic flute drill bit, these bits usually last about 75 to 100 parts. im drilling at 650rpm, .005ipr feed.

IDK about replaceable tips on that small of drills?
They may be available, but how good they work or last is another story.
Meaning - the "body" will likely wear out after a few tips?

You can add HP coolant easily if your volume justifies it.

You can buy a coolant inducer toolholder for not a lot.
That should have a port that connects to coolant 180* from the tool change arm.
An bag filter and an extra pump and a spare M code - or an M code that you can borrow or piggy back on for a while (chip conveyor? Air blast?) and you are in business.

Then get a Titex A6685TFP8.4 or similar drill and things will go a LOT quicker!
I have a 5.5mm drill here and it will go that deep, so you may be able to back down one tool length to a shorter tool.


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Think Snow Eh!
Ox

 

[BT Fabrication]

need to change something, drilling 1045 isnt bad, might need to only drill 2x diameter then retract, heat is the enemy, and only retracting is the only way to cool it.
should be able to easily get 300+ holes per bit in that.
reccomended from like Norsemen is about 70-80sfm, at 75 is 866rpm and feed rec about .004 to .010

id be feeding it a bit harder and retracting it.
you are currently about 56sfm

 

[alan speyrer]

I’m using a McMaster carr parabolic flute cobalt 8.4mm drill, cost 12 dollars each. Maybe I should try another brand, that might be better?
Currently I spot drill, then drill with the 8.4mm drill to .850” deep, then retract and drill .200” then retract and drill .200” etc,to a depth of 3.20”.
I do this job every month, 500 parts per month.

 

[DarrenwChuck9]

thinking about trying a small diameter drill bit with a replaceable tip for drilling on my cnc lathe, drill diameter is 8.4mm, have to drill some 1045 steel, drill depth is 3.25". i dont have thru coolant, all i have is flood coolant. any suggestions??
currently im just drill with a standard cobalt parabolic flute drill bit, these bits usually last about 75 to 100 parts. im drilling at 650rpm, .005ipr feed.

What is retrofitting in CNC?

 

[Ox]

IDK about replaceable tips on that small of drills?
They may be available, but how good they work or last is another story.
Meaning - the "body" will likely wear out after a few tips?

You can add HP coolant easily if your volume justifies it.

You can buy a coolant inducer toolholder for not a lot.
That should have a port that connects to coolant 180* from the tool change arm.
An bag filter and an extra pump and a spare M code - or an M code that you can borrow or piggy back on for a while (chip conveyor? Air blast?) and you are in business.

Then get a Titex A6685TFP8.4 or similar drill and things will go a LOT quicker!
I have a 5.5mm drill here and it will go that deep, so you may be able to back down one tool length to a shorter tool.


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Think Snow Eh!
Ox

Just re-read first post, and see that it is a lathe.

I don't understand not having TTC on a lathe. Doo you not have flood on the turret at all, or just not an enclosed holder?


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Think Snow Eh!
Ox

 

[Philabuster]

I’m using a McMaster carr parabolic flute cobalt 8.4mm drill, cost 12 dollars each. Maybe I should try another brand, that might be better?
Currently I spot drill, then drill with the 8.4mm drill to .850” deep, then retract and drill .200” then retract and drill .200” etc,to a depth of 3.20”.
I do this job every month, 500 parts per month.

Replaceable tip drills that small are fragile and expensive when you wipe out the body.

It currently costs you 16 cents in tooling to drill each part ($12 per 75 holes) with a reliable process. Bump up the price per part by $0.16 to offset the cost of the drill bits and move on.

 

[EmGo]

I don't understand not having TTC on a lathe. Doo you not have flood on the turret at all, or just not an enclosed holder?

I've never seen a 5/16" drill bit with thru-coolant, not sure how they'd do that ?

I think he's just screwed, doing 10x diameter .... Unless you go to gun drilling, parabolic flute is the best I've found for deep holes. He's not saying whether he is resharpening the drills, you can get several sharpenings before the web gets so thick that it's a problem. I played with raycon point some, can't hurt to try.

Or the other way is, look into gun drilling. It's expensive to do on your own but at one time in a universe far far away, places would do it for you for pretty cheap. I never had any success with those pseudo-gundrill things that were supposed to work on a regular lathe, they were just mickeymouse crap that should have been advertised inside matchbook covers.

At .330" diameter and 3.25" deep, it's just going to be unpleasant. Name of the game.

Maybe buy in bigger lots to see if you can get a better price ? Or find the actual manufacturer instead of going through McMaster ? They probably get a better deal than you will tho.

Or buy a Walter tool grinder and make your own

edit: Just looked. If you want to try some Chinese ones, they run about $5 here in small quantities. Not sure if that would be good or bad - our experience with custom tools is, the accuracy is good but the hss is less wonderful, so longevity is not as good. Add shipping and I'm not sure you'd save much but anyhow, them's the numbers.

 

[lumley32]

I've never seen a 5/16" drill bit with thru-coolant, not sure how they'd do that ?

the short answer is witchcraft!

but I have used 1mm TSC drills, they weren't even any more expensive than normal carbide.

 

[EmGo]

the short answer is witchcraft!

but I have used 1mm TSC drills, they weren't even any more expensive than normal carbide.

Oh yeah, carbide ! You guys from the ritzy side of the railroad tracks

Do you s'pose it'd hold up in his lathe tho ? It's not only not a hardinge, it's almost one of them not supposed to be mentioned here.

And how do they get the holes in them tiny things ? I thought carbide drills were ground from blanks but must not be, with those tiny passages ?

Where's that damn Bob ?

 

[BT Fabrication]

Replaceable tip drills that small are fragile and expensive when you wipe out the body.

It currently costs you 16 cents in tooling to drill each part ($12 per 75 holes) with a reliable process. Bump up the price per part by $0.16 to offset the cost of the drill bits and move on.

that being there is only one hole per part. could be more.

 

[Philabuster]

that being there is only one hole per part. could be more.

He said this is a lathe job.

 

[lumley32]

And how do they get the holes in them tiny things ? I thought carbide drills were ground from blanks but must not be, with those tiny passages ?

my understanding is they put 2 bits of wire twisted in a double helix in the mold before sintering then just pull them out of the black after, then you just have to align them to the flutes when they are ground.

 

[Ox]

I've never seen a 5/16" drill bit with thru-coolant, not sure how they'd do that ?

I think he's just screwed, doing 10x diameter .... Unless you go to gun drilling, parabolic flute is the best I've found for deep holes. He's not saying whether he is resharpening the drills, you can get several sharpenings before the web gets so thick that it's a problem. I played with raycon point some, can't hurt to try.

Or the other way is, look into gun drilling. It's expensive to do on your own but at one time in a universe far far away, places would do it for you for pretty cheap. I never had any success with those pseudo-gundrill things that were supposed to work on a regular lathe, they were just mickeymouse crap that should have been advertised inside matchbook covers.

At .330" diameter and 3.25" deep, it's just going to be unpleasant. Name of the game.

Maybe buy in bigger lots to see if you can get a better price ? Or find the actual manufacturer instead of going through McMaster ? They probably get a better deal than you will tho.

Or buy a Walter tool grinder and make your own

edit: Just looked. If you want to try some Chinese ones, they run about $5 here in small quantities. Not sure if that would be good or bad - our experience with custom tools is, the accuracy is good but the hss is less wonderful, so longevity is not as good. Add shipping and I'm not sure you'd save much but anyhow, them's the numbers.

The Titex drills that I listed above are coolant through solid carbide, and boy doo they work!

I don't recall the exact times, but I had a job that I was trying to run with basic parabolics in 310SS @ 5mm, and they would sit there and "pop, pop, pop" as the bar tried to untwist them. I'm sure that it would win before long.

It cost $250 to try the carbide, but Titex said to run it this fast and it would last that long.

I did, and it did! And it didn't "pop" anymore.
First time I ever seen recommended S/F ever last more than a cpl of parts!
Tool lasted exactly as long as they said that it would, which I think was around 250 parts.
So the perishables were $1/part.

The HSS drills weren't working very good at all, and the new tools took a 3.5 minute hole into 30 seconds maybe?
It seems like those were prox the numbers.

I had HP coolant, but on a 5mm tool it was more like a wet tip than chip flushing pressure, but that was all that was needed I guess.

I started the hole in a certain way, and I did break a cpl of tools over the job, but for the most part - I got my tool life out of them. They are resharpenable as well I am purty sure.

I am sure that I ran them in a floating holder. (it's been some years now)

So I would think that an 8.4mm tool will have coolant at the tip with even 30psi, and any machinist worth his pay should be able to devise a means to git pressure to the back of a tool in a lathe if it is needed.


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Think Snow Eh!
Ox

 

[alan speyrer]

i do sharpen the drills on my lisle drill grinder, once or twice, then just toss them in the trash. honestly, i thought i would get more comments about different brands of prarbolic flute drills, i may try a different brand or just keep going the way im doing it, the lathe is drilling these holes fine, im always thinking of ways to do drilling and other operations faster and better on my milltronics cnc lathe.

 

[Ox]

Well Titex and Ghuring are your main parabolic drills.
They look the same (Germany)and they look different than anyone else's.
Reportedly b/c they are ran on the same make grinders, but that really doesn't make sense to me, but that's what they say...

I have had better luck with Titex, but many folks like Ghuring too, so ...

("Walter" / Titex these days)


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Think Snow Eh!
Ox

 

[EmGo]

The Titex drills that I listed above are coolant through solid carbide, and boy doo they work!

I don't recall the exact times, but I had a job that I was trying to run with basic parabolics in 310SS @ 5mm, and they would sit there and "pop, pop, pop" as the bar tried to untwist them. I'm sure that it would win before long.

It cost $250 to try the carbide, but Titex said to run it this fast and it would last that long.

I did, and it did! And it didn't "pop" anymore.
First time I ever seen recommended S/F ever last more than a cpl of parts!
Tool lasted exactly as long as they said that it would, which I think was around 250 parts.
So the perishables were $1/part.

The HSS drills weren't working very good at all, and the new tools took a 3.5 minute hole into 30 seconds maybe?
It seems like those were prox the numbers.

That's cool to know ... I tried carbide a couple times with bleh-so-so results, but with 4140 and 8620. 8620 especially makes grunchy little chips that clog up flutes, so the p-flute worked well and the carbide ... snapped

Looks like I should have more of an open mind

OP, I know you can get more than two sharpenings, but those have kind of weird touchy points. You might save money by saving them up instead of throwing them away, then having a sharpening place do 100 at a time or something. Somebody with a good sharpener, like a Winslow.

You don't get as much life out of them as conventional drills because the web gets thicker fast but still, two sharpenings ? Pretty sure you could cut your tool costs in half pretty easy !