drill out broken drill bit use big or small drill

DMF_TomB · Dec 3, 2016

had a .129 hss drill broke about 1.5" deep into cast iron (casting weighs 1 ton). so i start with 1/8 carbide endmill but end up using 3/16 carbide endmill to drill it out
.
get about .25 deep with each 3/16 endmill til the broke drill pieces jam and end mill breaks. so i get about 1.2 deep using 5 each 3/16 end mills after 4 hours (ran out of end mills). i put in request to ok bigger hole and or screw plug hole
.
programmer says wasting time and money on end mills. just drill out with .453 carbide drill and will end up putting 1/2-20 screw plug in to plug hole and drill it out as programmed. i was concerned .453 carbide drill if broken is really expensive $200 to $300 and 3/16 endmills about $15 each
.
so .453 drill does drill out another .25 depth right through broke .129 hss drill literally in 5 minutes, of course .453 drill tip badly damage and needs resharpening
.
i go to tool crib and had gotten .201 die drills made for drilling hard metal, carbide tipped straight flute with rake and clearance made for hard steel and these cost about $15 each too. i show these to programmer and explain better for drilling hard metal. but programmer mad i wasted money buying from tool crib. i really thought $60 in small die drills better than risking $300 big carbide drill. so far between die drills and 3/16 end mills i had about $160 into drilling out the broke drill bit
.
so was programmer right using big carbide drill and drill out in 10 minutes or use many smaller end mills or drill bits and take over 4 hours ? seems like he was correct. not my first choice to use .453 expensive carbide drill made for soft cast iron to drill out a .129 broken hss drill bit 1.5" deep.
.
learn something new every day. programmer not always correct but in this case seems like he had the better solution. anybody else drill out broke hss drills bits ? you use small or big diameter drill ? programmer said big carbide drill can better take little broken drill bit pieces moving and getting jammed in hole without breaking. sure tip badly damaged and need resharpening but big .453 drill did not break

Jashley73 · Dec 3, 2016

4 hours with the machine tied up could be $400 lost overhead, at $100 and hour. Likely your big machines are calculated with a much higher overhead than $100/hour too...

His idea makes sense. The .453 drill's web is likely thicker than the puny little drill you were trying to extract, so it's going to be a lot stiffer.

I think he won this one...

DMF_TomB · Dec 3, 2016

Jashley73 said:
4 hours with the machine tied up could be $400 lost overhead, at $100 and hour. Likely your big machines are calculated with a much higher overhead than $100/hour too...

His idea makes sense. The .453 drill's web is likely thicker than the puny little drill you were trying to extract, so it's going to be a lot stiffer.

I think he won this one...

.
.
programmer not always right but in this instance his way of using a bigger dia drill was better than my way and certainly faster. i learned to listen and try what he says. often he is correct. like i said i learn something new everyday even after 36 years machining

HuFlungDung · Dec 3, 2016

I'd recommend using ball nose endmills for this sort of salvage operation. Once you get a hemispherical depression milled in the top of the broken drill, that helps keep the tool centered as it makes further progress. The large radius of the ball nose is not so easily chipped elsewhere. I think you cannot effectively drill non-stop of course, as the chip clearing ability of a ball nose is maybe only .01" per peck, so that's what to do.

Winterfalke · Dec 3, 2016

Ugh, in my experience, removing a broken anything, bigger is always better. You need a portable tap burner.

DMF_TomB · Dec 3, 2016

Winterfalke said:
Ugh, in my experience, removing a broken anything, bigger is always better. You need a portable tap burner.

.
we got a tap burner but only 3/16 biggest rods. not easily portable or fast last time i used it took over 4 hours to get a 1/2 drill out in hole 8" deep

DMF_TomB · Dec 3, 2016

HuFlungDung said:
I'd recommend using ball nose endmills for this sort of salvage operation. Once you get a hemispherical depression milled in the top of the broken drill, that helps keep the tool centered as it makes further progress. The large radius of the ball nose is not so easily chipped elsewhere. I think you cannot effectively drill non-stop of course, as the chip clearing ability of a ball nose is maybe only .01" per peck, so that's what to do.

.
i always used carbide spade drills working at other places
.
carbide spade drill - Google Search
.
the short solid straight flute type made and sold for drilling out broke taps. programmer seems to have not used before. he wanted me to use big carbide drill i always have in tool magazine on cnc machine and not anything not normally used
.
sure it dulled the .453 carbide drill tip badly but looks like maybe only 0.1" length needed to resharpen

mrmetalchip · Dec 3, 2016

I think the ball nose approach has merit. I will have to try that. Just food for thought but when this happens at my shop AND we have the option to screw in or weld in a plug I prefer to use an Annular cutter. The hole through the center needs to be bigger than your broken drill but at least this way is straight forward and quick.

Sent from my SM-N920V using Tapatalk

Vancbiker · Dec 3, 2016

IMO you are fortunate that the parts you are making allow repair processes like doing an O/S threaded plug. IME many customers will not buy a part that is not to print and the piece is scrapped if a broken tool is not able to be removed and the part machined per print. I've seen a fair number of $5k -$15k forgings, Ti investment castings, and other big chunks of material sent to the bin.

mrmetalchip · Dec 3, 2016

MSC Industrial Supply Co.

Sent from my SM-N920V using Tapatalk

DMF_TomB · Dec 3, 2016

mrmetalchip said:
I think the ball nose approach has merit. I will have to try that. Just food for thought but when this happens at my shop AND we have the option to screw in or weld in a plug I prefer to use an Annular cutter. The hole through the center needs to be bigger than your broken drill but at least this way is straight forward and quick.

Sent from my SM-N920V using Tapatalk

.
sure annular cutter or hole saw if it can be a through hole but this was solid 12" thick

DMF_TomB · Dec 3, 2016

Vancbiker said:
IMO you are fortunate that the parts you are making allow repair processes like doing an O/S threaded plug. IME many customers will not buy a part that is not to print and the piece is scrapped if a broken tool is not able to be removed and the part machined per print. I've seen a fair number of $5k -$15k forgings, Ti investment castings, and other big chunks of material sent to the bin.

.
.
depends on what part is and what it does in a machine of course. most castings in the $1000 to $10,000 range
.
screw plugs i have seen often on castings over 90 years old. not like it is a new and unproven thing. above my pay grade to decide. i tell them problem and they tell me if ok to screw plug. sometime plug is welded. again decision is made by engineers not by cnc operator
.
machine parts are covered under machine warranty. never heard ever of problem with screw plug. company 150 years old. they would know what works long term

adama · Dec 3, 2016

^ Think there’s a bit of a difference between plugging a over sized hole in a machine casting compared to a forged titanium landing gear leg too.

G00 Proto · Dec 3, 2016

I occasionally have to remove broken tools from injection molds (where plugging can be accepted). By far the best way I have found is to circle mill around the OD with the smallest end mill that I can get around the broken tool. In other words, in your case I would have drawn a .130 circle around the broken tool, and ramped down with a 1/8" or 3/16" em to the depth I figure it is broken off. Then a little rap with a punch and the whole column break off, broken tool and all. Turn a plug, ream the hole and press or thread it in. Drilling or machining HSS has always just put more broken tools in the same hole. An annular cutter would do the same thing... if I had one of each size.

Jashley73 · Dec 4, 2016

I feel like I've removed way more bolts & taps than I should have in only 10 years. Now, the first question that I ask myself and the boss... "Can I just toss this part and start over?" Meaning, is it worth the time to dig out the broken item, or is it quicker/cheaper to just start over?

Since you're talking about a big part, the answer is going to be a "No", so at this point, you just have to grit your teeth, and start over...

One thing that I've learned, is that even once your carbide drill/endmill breaks, it will still cut... As in, once you've broken the entire end off, and it looks like a jagged prison-shank, it will still cut. It's still a piece of hard carbide, cutting something that's made of softer steel. It's still harder than the bolt/tap, it will still cut. It just takes more pressure...

I certainly wouldn't recommend using a piece of broken carbide as best practice, but it's why I hang onto broken endmills - just for removing broken steel tools.

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

I would never recommend using a spade-drill however for removing broken taps & fasteners. I've seen too many of them get lodged in the hole, once the broken fastener moves, or the spade drill hits a casting void, or whatever else... About 2 years ago I was using a spade drill in a lathe, and it lodged the drill into the hole so bad, that it actually spun the drill-body in the lathe's toolholder. That is, despite being clamped with (3) set-screws, it still spun the drill-body... The part, drill, and toolholder-block were all scrap.

Suffice it to say, there's no way I'd trust these tools to remove broken fasteners on big large castings. If you got one of those drills stuck in the part, you're all the way back to square-1, but with potentially more damage than what you started with...

DMF_TomB · Dec 4, 2016

Jashley73 said:
I feel like I've removed way more bolts & taps than I should have in only 10 years. Now, the first question that I ask myself and the boss... "Can I just toss this part and start over?" Meaning, is it worth the time to dig out the broken item, or is it quicker/cheaper to just start over?

Since you're talking about a big part, the answer is going to be a "No", so at this point, you just have to grit your teeth, and start over...

One thing that I've learned, is that even once your carbide drill/endmill breaks, it will still cut... As in, once you've broken the entire end off, and it looks like a jagged prison-shank, it will still cut. It's still a piece of hard carbide, cutting something that's made of softer steel. It's still harder than the bolt/tap, it will still cut. It just takes more pressure...

I certainly wouldn't recommend using a piece of broken carbide as best practice, but it's why I hang onto broken endmills - just for removing broken steel tools.

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

I would never recommend using a spade-drill however for removing broken taps & fasteners. I've seen too many of them get lodged in the hole, once the broken fastener moves, or the spade drill hits a casting void, or whatever else... About 2 years ago I was using a spade drill in a lathe, and it lodged the drill into the hole so bad, that it actually spun the drill-body in the lathe's toolholder. That is, despite being clamped with (3) set-screws, it still spun the drill-body... The part, drill, and toolholder-block were all scrap.

Suffice it to say, there's no way I'd trust these tools to remove broken fasteners on big large castings. If you got one of those drills stuck in the part, you're all the way back to square-1, but with potentially more damage than what you started with...

.
.
there are 2 very different distinct types of spade drills one is insert type used to make big holes other is more like a solid 120 degree point endmill
.
spade drill carbide
Google
.
made for drilling out broke taps and sold as such in catalogs and i have used over 36 years
.
different shops got different ways. current shop never heard of spade drill or die drill specifically made for drilling hard metal. like i said they just recommend using big carbide drill normally used for soft cast iron and already in tool magazine. sure it dulls drill but they says drill rarely breaks it just drills out broke hss drill in like 5 minutes. cost reasonable low and quicker to drill
.
i quietly listened to advice given and although i did not agree i tried my current shops best recommendation on drilling out broke hss drill. seems like my way was not the better way and the programmers advice was actually the better way. even an old timer can learn from a younger programmer. he is maybe 40 so not exactly a kid. experienced enough to know some better ways than me. i learned often better to listen to advice and try different methods. sometimes they are better ways

huskermcdoogle · Dec 4, 2016

I used to arc gouge broken drill bodies and carbide of of .8" holes about 3" deep. Was nasty slow work, and after welding it back up you would always ruin another drill tip going back through it. Since, we have given up on that proceedure. At $300/hour for the machine plus labor, you can cut the whole section out, drill carbide and all, weld back up and be up and running in 20minutes. No broken tips, taps or anything after the fact. Worst part is removing oxidation layer in the hole after cutting it out. Die grinder with burr bit, then small wire wheel, and you are good to go. Overall, I don't care how you do it, but you have to make sure there is least amount of risk to the parts and you have an design engineering approved repair. Then you can labor over the cost of fixing the part. The cost of some tools is usually going to be far cheaper than scrapping the casting or weldment.

machtool · Dec 5, 2016

DMF_TomB said:
had a .129 hss drill broke about 1.5" deep into cast iron (casting weighs 1 ton). so i start with 1/8 carbide endmill but end up using 3/16 carbide endmill to drill it out
.
get about .25 deep with each 3/16 endmill til the broke drill pieces jam and end mill breaks. so i get about 1.2 deep using 5 each 3/16 end mills after 4 hours (ran out of end mills). i put in request to ok bigger hole and or screw plug hole
.
programmer says wasting time and money on end mills. just drill out with .453 carbide drill and will end up putting 1/2-20 screw plug in to plug hole and drill it out as programmed. i was concerned .453 carbide drill if broken is really expensive $200 to $300 and 3/16 endmills about $15 each
.
so .453 drill does drill out another .25 depth right through broke .129 hss drill literally in 5 minutes, of course .453 drill tip badly damage and needs resharpening
.
i go to tool crib and had gotten .201 die drills made for drilling hard metal, carbide tipped straight flute with rake and clearance made for hard steel and these cost about $15 each too. i show these to programmer and explain better for drilling hard metal. but programmer mad i wasted money buying from tool crib. i really thought $60 in small die drills better than risking $300 big carbide drill. so far between die drills and 3/16 end mills i had about $160 into drilling out the broke drill bit
.
so was programmer right using big carbide drill and drill out in 10 minutes or use many smaller end mills or drill bits and take over 4 hours ? seems like he was correct. not my first choice to use .453 expensive carbide drill made for soft cast iron to drill out a .129 broken hss drill bit 1.5" deep.
.
learn something new every day. programmer not always correct but in this case seems like he had the better solution. anybody else drill out broke hss drills bits ? you use small or big diameter drill ? programmer said big carbide drill can better take little broken drill bit pieces moving and getting jammed in hole without breaking. sure tip badly damaged and need resharpening but big .453 drill did not break

What a Cluster Fuck, Are Gleason Gear stuck in the 60's.

Operator / large bridge mill can fuck about for half a day. Don't you have only 3 of those machines available? Good thing you were only wasting 3 /16" endmills @ $15 bucks each. Don't count the half shift the machine was down for.

I'd enter that in Bold for your Excel Spreadsheet. 0.129" Bad Drills.

Mike1974 · Dec 5, 2016

Jashley73 said:
I feel like I've removed way more bolts & taps than I should have in only 10 years. Now, the first question that I ask myself and the boss... "Can I just toss this part and start over?" Meaning, is it worth the time to dig out the broken item, or is it quicker/cheaper to just start over?

Since you're talking about a big part, the answer is going to be a "No", so at this point, you just have to grit your teeth, and start over...

I would never recommend using a spade-drill however for removing broken taps & fasteners. I've seen too many of them get lodged in the hole, once the broken fastener moves, or the spade drill hits a casting void, or whatever else... About 2 years ago I was using a spade drill in a lathe, and it lodged the drill into the hole so bad, that it actually spun the drill-body in the lathe's toolholder. That is, despite being clamped with (3) set-screws, it still spun the drill-body... The part, drill, and toolholder-block were all scrap.

th...

Obviously doesn't apply in Toms case with A HUGE CASTING, but I like the throw away method if possible.

Like someone else mentioned, at least you have the option to repair a broken drill/tap... well maybe, sometimes that is a double edged sword. :ack2:

I suppose I would rather fix a big casting rather than wheeling my box to the door after I told the boss I scrapped a 10-20k casting. Neither sounds good though.

I hate the aerospace work where they think everything is critical. I had a non-flight part that had a little tiny ding (that would be covered in assembly) and it was rejected. Seriously, it was a couple thou deep with an indicator, and maybe .06 long/wide.

DMF_TomB · Dec 5, 2016

machtool said:
Operator / large bridge mill can fuck about for half a day. Don't you have only 3 of those machines available? Good thing you were only wasting 3 /16" endmills @ $15 bucks each. Don't count the half shift the machine was down for.

I'd enter that in Bold for your Excel Spreadsheet. 0.129" Bad Drills.

.
.
obviously i did not think it would take over 1/2 day to remove a .129 drill that is 1.5" deep. i have done plenty of shallow holes only 1/2" deep and have taken less than 1/2 hour to remove a broke drill or tap
.
part has been made well over 60 times. nothing wrong with feeds and speeds. sometimes casting has slag or hard spot in casting. a small dia tool will break where often a bigger tool will go through it.
.
as a matter a fact i did refer to excel file on feeds and speeds did record the drill breaking and did reduce feed from F2.5 to F2.2
.
programmer was correct faster to use big carbide drill already in tool magazine to remove the .129 drill broke 1.5" deep into part. i am not very experienced removing broke tools that deep into castings. i have removed dozens that were only 1/2" deep over many decades. like i said i still learn something new every day.

drill out broken drill bit use big or small drill

Diamond

Titanium

Diamond

Diamond

Stainless

Diamond

Diamond

Plastic

Diamond

Plastic

Diamond

Diamond

Diamond

Hot Rolled

Titanium

Diamond

Stainless

Diamond

Diamond

Diamond

Similar threads