Saw this from my local monthly machinist catalog sometime back. similar to the methods some of the ppl proposed, punch / drill/ and scrap out.
broken tap extractor
broken tap extractor
Broken 1/4" tap in through hole
- Thread starter PT Doc
- Start date
Thanks for the offer. I'm going to try a carbide end mill. What size and style end mill would you recommend. Since I don't have a mill, would using the 1/4-20 screw with a thru hole as a bushing in my drill press work ok to provide some rigidity the setup? Thanks
Tap extractor trick:
Make sure the fingers are retracted as much as possible. Then, use the extractor with a cordless variable-speed impact tool. Slowly squeeze the trigger and keep squeezing harder until things start to move. The two work together like a charm.
Although, as Kevin pointed out, sometimes when a tap breaks it shatters and jams. Then, removal becomes more difficult.
Make sure the fingers are retracted as much as possible. Then, use the extractor with a cordless variable-speed impact tool. Slowly squeeze the trigger and keep squeezing harder until things start to move. The two work together like a charm.
Although, as Kevin pointed out, sometimes when a tap breaks it shatters and jams. Then, removal becomes more difficult.
What type of carbide end mill should I get to try the chew up the rest of the broken tap.? I would try using a drilled thru 1/4-20 screw as a bushing/guide. I don't have a mill, only my 16 speed drill press. Based on your carbide end mill recommendation, what speed would you recommend?
I think 1 flute might be a bit packed with my attempts and breaking up the remaining pieces so I'm not sure it's worth getting the Walton extractor and extra fingers.
Thanks
I think 1 flute might be a bit packed with my attempts and breaking up the remaining pieces so I'm not sure it's worth getting the Walton extractor and extra fingers.
Thanks
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given the size of the "carbide end mill" you will use....
and the spindle runout on drill presses
and that the tap is broken at an angle
and that tap drill size is 13/64" 0.203
you're looking at a 3/16" cutter MAX, think that'll take side load?
send it out.....way cheaper
Thanks for the opinion. Pooo.
I thought that maybe the thru hole in a 1/4 screw would make this a more viable setup. Risk reward ratio.....I might give it a go still though.
Kevin54
MEMBER EMERITUS
First off....is it a four flute or two flute tap?
You need a carbide end mill, 4 flute, run it just as fast as you can. Then slowly, just a few thousandths at a time come down on the tap. DO NOT touch the carbide end mill to anything first, or you'll break the corners off. Set the stop on your drill press just so the endmill is a tad above the broken tap. Then adjust the stop a few thousandths at a time so you don't come down too hard on the tap.
And I'll tell you this now, forget the coolant. Carbide against HSS is going to cook the snot out of both of them no matter what. Coolant just throws a shock to the hot metal.
And chances are that you will break a flute off of the endmill, maybe two, maybe all four. As long as it doesn't snap the endmill in half or snaps off in the tap, keep on going. I've taken thousands out with dull endmills. I keep dull ones just for that reason.
Don't take a torch to a Vee Block. That is just ludicrous. Sorry Kevinweg, but you don't want oxy/acet on precision tools.
PT.....the offer still stands, if you can't get it, I'll get it out for you.
You need a carbide end mill, 4 flute, run it just as fast as you can. Then slowly, just a few thousandths at a time come down on the tap. DO NOT touch the carbide end mill to anything first, or you'll break the corners off. Set the stop on your drill press just so the endmill is a tad above the broken tap. Then adjust the stop a few thousandths at a time so you don't come down too hard on the tap.
And I'll tell you this now, forget the coolant. Carbide against HSS is going to cook the snot out of both of them no matter what. Coolant just throws a shock to the hot metal.
And chances are that you will break a flute off of the endmill, maybe two, maybe all four. As long as it doesn't snap the endmill in half or snaps off in the tap, keep on going. I've taken thousands out with dull endmills. I keep dull ones just for that reason.
Don't take a torch to a Vee Block. That is just ludicrous. Sorry Kevinweg, but you don't want oxy/acet on precision tools.
PT.....the offer still stands, if you can't get it, I'll get it out for you.
Bondo
Well-known member
Ayuh,.... Exactly,.... with an "0" cuttin' tip,....
rlitman
Well-known member
BS. That's the safest procedure to remove a broken tap from a rifle barrel when drilling and tapping for a mount goes wrong.
Your way can make the hole deeper. The torch will not.
Kevin54
MEMBER EMERITUS
Explain to me how a through hole is going to become deeper, and if the block is tool steel and not yet hardened, by torching that area, will make it hard. Then how are you going to finish tapping it.
I'm taking it that you haven't worked with tool steel much.
There is a big difference between a rifle barrel and tool steel for a hardened toolZeke
Well-known member
Jody did a video this week on this very subject:
dr_clyde
Well-known member
I've always puddled up a little mound on it with the TIG and then welded a short piece of 1/4" rod on it like a lever. A quick shot of kroil and work it free. Takes a bit more effort if its shattered, but still doable. Never had any that I couldn't get out this way.
Kevin54
MEMBER EMERITUS
See...that's the difference between a machinist and a mechanic. It's fine to weld on something like a broken stud on an engine block, but if you have precision machinist equipment, applying heat, whether through a torch, or through a welder can warp the tool. When it comes to machinist tools, you want them as close to precision as possible.
If one weld splatter got on the end of a Vee Block like the OP has, and the block was heated up beyond being able to hold it in your hand, it has been compromised. A precision Vee block has to be precise setting on the bottom or setting on the end withing .001 at least. Ideally you want squareness and parallelism withing no more than .0005 and preferably .0002
Fretters
Well-known member
What's it actually stuck in? That link you posted earlier in the thread just lead to a page with loads of random stuff on it for me.
Zeke
Well-known member
Kevin, I guess the OP has to decide how any procedure is going to affect the tool. Jody take a very conservative approach to the task certainly not using an oxy torch. But his theory on compromising the material used to make the tap and the subsequent hardening process bears consideration, don't you think?
The v block looks like this.
http://www.ebay.com/itm/Starrett-57...7?pt=BI_Tool_Work_Holding&hash=item2a33872273
It is indeed accurate to about .0003.
http://www.ebay.com/itm/Starrett-57...7?pt=BI_Tool_Work_Holding&hash=item2a33872273
It is indeed accurate to about .0003.
PugetDude
ALLIANCE MEMBER
If it is a Starret V-Block that is certified to within .0003, Maybe a diamond dentist drill or diamond burr, work it down really slowly until the tap is just a shell... I agree with Kevin54, NO HEAT!
Steinmetz
Well-known member
Arc welding or heating machinist tools with an oxyacetylene torch? What an obscenity.
Success at last!!!!!
I decided to just pound the snot out of the rest of the tap. Initially after the break the tap seemed really hard but towards the end it seemed to morph more and not break into pieces.
Now, knowing that this is a hardened v block, if I wanted to clean up the threads, what type of tap would I use?
Thank you very much to everyone for your help. The BFH in the end sorted be out. Now what to do with the deformed punches....
I decided to just pound the snot out of the rest of the tap. Initially after the break the tap seemed really hard but towards the end it seemed to morph more and not break into pieces.
Now, knowing that this is a hardened v block, if I wanted to clean up the threads, what type of tap would I use?
Thank you very much to everyone for your help. The BFH in the end sorted be out. Now what to do with the deformed punches....
Kevin54
MEMBER EMERITUS
What is the problem with the threads in the first place? I'm assuming that you are just NOW becoming a machinist...correct? One other thing you don't want to to is "pound the snot" out of something that is highly precision. All of our equipment like that, we had to have them calibrated periodically to make sure they were square and parallel within specs.
If a bolt goes into the threaded holes, then you are fine. If anything get a small wire brush on a drill and clean the threads that way.
And always remember.....A HSS tap, going into a hardened tool is a recipe for trouble as you have found out.
Kevin54
MEMBER EMERITUS
Zeke.....I watched the video. Thats fine for a part like stainless, or any part, but not for a precision tool that has already been machined, hardened, and precision ground. It's hard to explain to someone that is not a toolmaker, or a machinist that has to make highly precision parts day in and day out. It is actually a completely different world.
Just like in your business as a finish carpenter, you have to have precision miters, but they may be able to have a tolerance of 1/32" because no house is square and there is a lot of other variables. In the machining world, especially today, most parts have to be within.005-.015 depending on the part. In the toolmakers world, we are allowed 10% of that to work with. A lot of the tools made, we are allowed +/-.001 and sometimes we are only allowed .0005 to work with. So in the case of, lets say that Vee Block for instance. If we were making a tool, and we had to use a vee block standing on end, and the piece we are making has to be within .0005.......the Vee Block is only good to .0003. Now we only have .0002 to play with depending on which side the Vee Block may be off, if in fact it is off. The .0003 is just the allowable tolerance.
When we drill and ream, or drill and bore holes, we have to use gage pins to check the holes. All of our pins are .0002 undersize. A .250 pin will not fit in a .250 hole, so we use undersize pins so they will slip fit. One person dropped a pin and got caught grinding a nick off of it, and got a verbal warning. You drop it and chip it, you turned it in and ordered a new one.
So if the OP was removing the tap from say the upper portion/flange of the Vee Block, and he pounded the snot out of it, chances are that block may be slightly warped. Not saying it is, but there is a good chance.
that's why machinist tools are so damn expensive. With most, it's not the making of the tool, but it's the grinding process and inspection process that takes time and drives the cost up. Plus with any tool, you have to go and have the equipment to be able to check the products.
That's what I make a piss poor carpenter. I get too frustrated. I'm used to perfectly flat, square, or round. I can fathom machining metal because I can keep very close tolerances. I can do it in my sleep as I've done it practically my whole life. But when it comes to wood, a board may have a twist, a knot right where you cut, or maybe it's cut a 1/16" off. To a carpenter it's fine, to me, it goes against everything I have ever done and screws with my mind.
I can look at a metal part and tell you it .005 off before I ever mic it to see. Because that is what I know. Give me a stack of lumber and I get nervous. I can get by, but I get too **** about it, then end up frustrated.
So I know that when someone says they are going to pound on a precision tool, something is going to go wrong somewhere. Pounding the snot out of something is something going wrong. I've trained quite a few people to be good machinist when they come from the assembly floor. They thought I was an *** for being hard on them until they finally "got it".
Thanks again for the help.
Just to clarify, initiate ally I was being gentle with a small hammer. Last night, I used the same hammer with a little more force.
I took the v block to the surface plate and height gage and it showed the same .00025 at all surfaces. Being gentle is the key.
Just to clarify, initiate ally I was being gentle with a small hammer. Last night, I used the same hammer with a little more force.
I took the v block to the surface plate and height gage and it showed the same .00025 at all surfaces. Being gentle is the key.
Fretters
Well-known member
Why were you originally trying to clean up the threads anyhow, just out of curiosity?
Farmall450
Well-known member
This machinist made v block is a pair. One larger and one smaller. The larger has three clamping positions and the smaller has 2. They look identical and measure out identical but the smaller one does not have holes that are fully threaded through the top flange. So I found that weird and inconsistent between the 2 and in the end broke the tap. It's not like I need to have the thru holes since there is one clamp that goes on the larger block. The machinist must have had a reason for not tapping all the way thru but I don't get it.
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Fretters
Well-known member
It's always the inconsequential little niggles which bite you, ain't it. That's why I'm a great believer in walking away from something which is prefectly sound and functional these days, rather than trying to correct that niggling little quirk. It gets you without fail if you don't.
That's why I'm a great believer in walking away from something which is prefectly sound and functional these days, rather than trying to correct that niggling little quirk. It gets you without fail if you don't. It's always the inconsequential little niggles which bite you, ain't it.
I agree. This was a very good lesson since I was thinking to myself that if the tap broke it would be a pain. But in this situation, I am not likely to use these holes so if the hole was really FUBAR, then the functionality would not be compromised. But in the end, it is good to figure things out ahead of time, ask questions first on forums like this, THEN make a move. The machinist that made these might be rolling over in his grave but...
Kevin54
MEMBER EMERITUS
PT....are you a machinist, or training to be a machinist, or just a home hobbyist?
There is no tap to clean up those threads. Unless it isn't that hard. But I am going to assume it is. You would have to have it annealed then run a tap through and then have it hardened again. I think you are just going to have to live with it the way it is.
I can hold a .001 tolerance but when its down to a micron or even a half thousandths I hand it off to a tool and die maker. I have made stuff and heated it up only a few degrees and when it cools off its out of tolerance and that is just frustrating. Usually the tight tolerance parts I see aren't +/- they are one or the other so you have even less wiggle room.
rlitman
Well-known member
Explain to me how a through hole is going to become deeper, and if the block is tool steel and not yet hardened, by torching that area, will make it hard. Then how are you going to finish tapping it.
I'm taking it that you haven't worked with tool steel much.
I must have missed the through hole part. But i take it you're not too familiar with an oxy-acetylene torch.
The idea is that the block has so much thermal mass compared to the tap, and that the tap is not well thermally connected to the block, so that by the time the tap is completely burned out, the block is still cool enough to hold.
With a small part like this, you could sit it in a dish of water to help with the fact that is is relatively light (how do you think it would be kept cool if edm'd out?).
Although this is one situation that I would try a tap extractor first.
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Home hobbyist. Just like to tinker with all things metal. I do thank you for your help with this issue.
Kevin54
MEMBER EMERITUS
No problem. That's what Garage Journal is all about....people helping people. We may not all agree at times, but in the end, things get resolved, and everyone goes to bed happy
If you ever need machining help, you can always ask me, AP is a fantastic machinist, and there are many others on here. So ask away when you feel a need, and you'll always get an answer, and many answers.
BTW....what sort of things do you tinker around and make? Any pics to post?
619DioFan
Well-known member
No problem. That's what Garage Journal is all about....people helping people. We may not all agree at times, but in the end, things get resolved, and everyone goes to bed happy
If you ever need machining help, you can always ask me, AP is a fantastic machinist, and there are many others on here. So ask away when you feel a need, and you'll always get an answer, and many answers.
BTW....what sort of things do you tinker around and make? Any pics to post?
I've been wanting to ultimately wanting to get into knifemaking. I'm making a table that will flip my 2x72 belt grinder. It's powered by a 3phase baldor motor with vfd. I need to make a versatile work rest that will work in vertical and horizontal. I'm just so jammed up for space and time that things seem to have stalled. If I move to a new place, a home shop would have a mill and lathe. No ladies or dogs allowed.
Kevin54
MEMBER EMERITUS
Maybe you want to get in contact with this member by PM http://www.garagejournal.com/forum/showthread.php?t=200204&highlight=knife+making
This member made a heat treat oven http://www.garagejournal.com/forum/showthread.php?t=237184&highlight=knife+making
Post a thread in Free Parking or in the Fab Forum about Knife making. There are a few on here that does it.