I got all 4 holes drilled & partially tapped through the jig. The tap was getting tight so I didn't push my luck until I got all 4 holes tapped as deep as I felt comfortable with.

I removed the fixture & started working on getting the tap all the way through @ the front receiver ring. No problem, I went about 1/2 turn @ a time & got the tap to go all the way through both holes.

I figured the front ring would be the hardest heat treat so I thought the rear bridge would be a piece of cake.

WRONG!

I started on the front hole in the bridge & I didn't get far until the tap snapped off!

To add insult to injury, the threads seemed to be plenty deep enough to start with as I was able to screw down the rear screw through the rear base. It looks like I should have quit while I was ahead!

I tried to turn out the stub W/a pair of needle nose pliers. Of course all I accomplished was to break off the stub.

So, what's the SOP when this happens?

This is a large ring M98 action. There is about 1/8" of tap sticking through the rear bridge into the bolt race.

SEE LAST POST FOR HAPPY ENDING

You might try a very small easyout and see if it will grab the tap.

good luck!

If it's a plain carbon tap you can try driving it through. I do all my drilling and tapping in a milling machine so if something like that were to happen, which occasionally it does, I am already aligned on the hole and can surgically remove the offending beast with a 3/32 carbide end mill. I drill a hole and then immediately tap it before moving to the next hole.

If you brought it here, I would set it up in the mill and do the same. Driving broken taps from threaded holes isn't high on my list of cool things to do. I don't like the damage that is likely to ensue.

quote:

Originally posted by Westpac:
If it's a plain carbon tap you can try driving it through. I drill and thread in a milling machine so if something like that were to happen I am already aligned on the hole and can surgically remove the offending beast with a 3/32 carbide end mill.

If you brought it here, I would set it up in the mill and do the same. Driving broken taps from threaded holes isn't high on my list of cool things to do. I don't like the damage that is likely to ensue.

I was thinking of trying to shatter the piece that is sticking through the bridge. hoping that it would possibly break through the flutes making it a bit more likely to get the broken piece/pieces out of the hole & salvage it.

The tap seems to have been a bit out of spec as the holes that the tap only went part way through will allow a 6-48 screw to thread all the way through W/O getting tight.

Damn, I should have tried the screws in the holes after I removed the fixture BEFORE I went @ them W/the tap.

Things were going so well. I got the barrel out W/O too much dificulty. (1st time doing this) I got the stripper clip hump ground down most of the way on my belt sander (another 1st) & was able to true it up within a few/1000s W/a mill file.

I was going to put the finishing touches on the rear bridge mount base alignment after I tapped the holes by mounting the rear scope base & truing it up W/some Dykem & a straight edge.

quote:

Originally posted by DanM:
You might try a very small easyout and see if it will grab the tap.

good luck!

This is a 6-48 tap, not much to grab onto.

quote:

Originally posted by wildcat junkie:

quote:

Originally posted by Westpac:
If it's a plain carbon tap you can try driving it through. I drill and thread in a milling machine so if something like that were to happen I am already aligned on the hole and can surgically remove the offending beast with a 3/32 carbide end mill.

If you brought it here, I would set it up in the mill and do the same. Driving broken taps from threaded holes isn't high on my list of cool things to do. I don't like the damage that is likely to ensue.

I was thinking of trying to shatter the piece that is sticking through the bridge. hoping that it would possibly break through the flutes making it a bit more likely to get the broken piece/pieces out of the hole & salvage it.

The tap seems to have been a bit out of spec as the holes that the tap only went part way through will allow a 6-48 screw to thread all the way through W/O getting tight.

Damn, I should have tried the screws in the holes after I removed the fixture BEFORE I went @ them W/the tap.

Things were going so well. I got the barrel out W/O too much dificulty. (1st time doing this) I got the stripper clip hump ground down most of the way on my belt sander (another 1st) & was able to true it up within a few/1000s W/a mill file.

I was going to put the finishing touches on the rear bridge mount base alignment after I tapped the holes by mounting the rear scope base & truing it up W/some Dykem & a straight edge.

You might take it to a machine shop and see if they can cut it out with a small carbide endmill. Take out the core and the flutes will follow.

quote:

Originally posted by Westpac:

quote:

Originally posted by wildcat junkie:

quote:

Originally posted by Westpac:
If it's a plain carbon tap you can try driving it through. I drill and thread in a milling machine so if something like that were to happen I am already aligned on the hole and can surgically remove the offending beast with a 3/32 carbide end mill.

If you brought it here, I would set it up in the mill and do the same. Driving broken taps from threaded holes isn't high on my list of cool things to do. I don't like the damage that is likely to ensue.

I was thinking of trying to shatter the piece that is sticking through the bridge. hoping that it would possibly break through the flutes making it a bit more likely to get the broken piece/pieces out of the hole & salvage it.

The tap seems to have been a bit out of spec as the holes that the tap only went part way through will allow a 6-48 screw to thread all the way through W/O getting tight.

Damn, I should have tried the screws in the holes after I removed the fixture BEFORE I went @ them W/the tap.

Things were going so well. I got the barrel out W/O too much dificulty. (1st time doing this) I got the stripper clip hump ground down most of the way on my belt sander (another 1st) & was able to true it up within a few/1000s W/a mill file.

I was going to put the finishing touches on the rear bridge mount base alignment after I tapped the holes by mounting the rear scope base & truing it up W/some Dykem & a straight edge.

You might take it to a machine shop and see if they can cut it out with a small carbide endmill. Take out the core and the flutes will follow.

That sounds like a good plan.

What about hitting it from the side through the bolt guide slot?

If I break it off in pieces from the sides I might get lucky.

Do you think that would do any harm before trying the machine shop routine.

I'm not shure I can find anyone W/a small enough carbide endmill up here on the Tundra.

Only if you drive the broken tap out and/or
all your screw holes are pretty loose and you can't get the screws to tighten, drill them out with a 8-40 tap drill (don't remember the number size offhand, maybe a #28 and you don't actually have to re-drill them) and retap them 8-40. USE LOTS OF TAPPING FLUID. Brownells sells a cutter that will bore you bases out for the larger 8-40 screw heads. Better that way, especially if your shooting a real big-bore. 8-40's don't tend to shoot loose ar shear as easily as a 6-48. DO use a sight jig to do the tapping, in and out. That way you won't put radial pressure on the tap and break it. Two fluted taps are a good way to go.

You can try it. I'm all about getting it done with the least amount of damage. I have seen some pretty buggered up holes come through the shop that required going up a size. If the person doing the job would have stopped to seek professional help from the "git go", it would have saved them some aggravation and possibly some much needed change. Good luck!

A dental burr in a dremel works pretty well, but fortunately I've never had to do it on something so small.

As mentioned, if this is a carbon steel you may be able to break it up with a punch. If it is HSS don't even bother trying.

Then next time you break a small tap or easy out and there is a small stub projecting, first thing to do is put a torch on the stub and anneal it! make a shield with some sheet metal and drill a hole in it, then hold the torch flame horizontal and heat it up to cherry red and let it cool. I'd suggest doing it 2 times for luck. When it files easily, file it flat, center punch and redrill.

quote:

Originally posted by Mark:
A dental burr in a dremel works pretty well, but fortunately I've never had to do it on something so small.

As mentioned, if this is a carbon steel you may be able to break it up with a punch. If it is HSS don't even bother trying.

Then next time you break a small tap or easy out and there is a small stub projecting, first thing to do is put a torch on the stub and anneal it! make a shield with some sheet metal and drill a hole in it, then hold the torch flame horizontal and heat it up to cherry red and let it cool. I'd suggest doing it 2 times for luck. When it files easily, file it flat, center punch and redrill.

How about using this in the drill press?

http://www.widgetsupply.com/pa...de-cylinder-1/D-AM04

If worst comes to worst find a shop with a EDM and get it burned out....I am not an FFL holder so I can't help you or I would have you mail it to me and I would burn it out for free.

They make tap extractors, brownells sell them.
Don

Don,
I have not had any luck with tap extractors or most EZ outs. Maybe I'm a klutz. I'm like Malm, I have done many with a carbide endmill. EDM is a great alternative. If I were you I would quit now and seek professional help.
Butch

A method for removing carbon steel taps recommended by several of the older gunsmithing manuals is to:

Put a drop or two of nitric acid on the tap remainder (in the hole). Let it sit a few seconds, then pour it out into the sink and rinse with cold water. Supposedly this makes the tap remainder very hard...hard enough it will shatter when struck a sharp blow with a hammer and punch.

I haven't had to do that for about 40 years or so, but the last time I tried it, it worked fine for me.

quote:

Originally posted by butchlambert:
Don,
I have not had any luck with tap extractors or most EZ outs. Maybe I'm a klutz. I'm like Malm, I have done many with a carbide endmill. EDM is a great alternative. If I were you I would quit now and seek professional help.
Butch

Me too Butch.

From what I remember, the nitric acid serves to erode the steel at the tap-hole interface, allowing the tap extractor to work. Supposedly.
Regards, Joe

A lot of good advice & alternatives here.

There is a stub sticking up so I think I will do the anealing route W/my small welding tip & a heat sheild, file down the stub, use my fixture, bushing & drill bit to locate hole center & use a carbide drill end carbide cutter to cut out the center of the tap.

I ordered 3 ea. 5/64" & 3/32" cutters like this. I bought 6 because the price of 6 is about the same as the priority mail shipping & these are lightly used cutters. (from the electronics industry)



Would this be better than the carbide drill end cutter? I can get 3/32" diameter cut W/3/8" flute on a 1/8 shank, 1 1/2" overall length.


Only problem is, I have to order $25 worth of product. Anyone need some endmills to split the order" They are just under $6 ea.

If you don't have a mill and a rigid setup you are wasting your time. Pay a professional! I have a pretty nice machine shop, but I think I know my limitations. I have used a lot of guys on this board to do what I am not comfortable doing. My ego is not that large that I won't use the expertise of the experts to save myself heartache and money.
Butch

quote:

Originally posted by butchlambert:
If you don't have a mill and a rigid setup you are wasting your time. Pay a professional! I have a pretty nice machine shop, but I think I know my limitations. I have used a lot of guys on this board to do what I am not comfortable doing. My ego is not that large that I won't use the expertise of the experts to save myself heartache and money.
Butch

It's not "ego" or "paying a professional" that is the issue here. It is learning how to make the best use of what I have on hand. I want to be able to address this situation myself. I am a retired skilled tradesman W/above average aptitude & have a very good grasp on what is required thanks to the advice given on this thread.

I do have "rigid setup" W/my drill press vice & the drill fixture.

I do not have a "mill" but I can use the mechanical properties of the drill fixture to locate the piece within a acceptable tolerances of a few 1/1000s".

Chuck up the drill bit W/the bushing in the drill fixture W/the receiver in it, clamp down the vice, remove the drill bit & replace it W/the endmill. Once the drill press vice is clamped down the fixture will be located plenty close enough for this job I thonk. After all, it was close enough to drill the holes in the 1st place, right?

Once the work is secured & the tool located I see no mechanical difference between an endmill turning in the drill press & one turning in a "mill" for machining in a fixed position such as cutting out the center of the tap.

Perhaps you could give me some advice that would be helpful such as to what RPM to run the 3/32" end mill?

BTW: Here is what I have.

I use carbide drills to clear out broken taps, but I work real hard to not break them in the first place. Machine tool distributors offer various broken tap kits and extractors, but I've found the carbide drills work best for me.

Did you use a tap wrench supported at the end by your drill press chuck or milling machine? Tapping any small holes without doing this is asking for trouble. The one I use has a sleeve that I chuck into a 1/2" collet and I use the DRO to make sure I'm exactly in the same place I drilled. I also don't use taps more than a dozen times or so. I can feel whether or not its cutting right and I NEVER push it...at least not any more . And for tapping fluid I use AMZOIL gear lube mixed with Rapid Tap fluid. Most people cringe a little when I tell them I charge $25 for the first hole and $10 a hole for each additional hole, but there's a lot more to it than most people think.

Now that I see the pictures you have a bigger problem than a broken tap. That rear bridge is neither straight nor square and unless you're planning on milling custom bases I see scope mounting problems in the future.

quote:

Originally posted by Toomany Tools:


Did you use a tap wrench supported at the end by your drill press chuck or milling machine? Tapping any small holes without doing this is asking for trouble. The one I use has a sleeve that I chuck into a 1/2" collet and I use the DRO to make sure I'm exactly in the same place I drilled.

The fixture I have is the Wheeler & it does have bushings for both the drill bit and another for the tap. I used a small tap handle as I felt that a better "feel" would out-weigh the perfect alignment in the drill press.

I made the mistake of taking the receiver out of the fixture after the holes were partially tapped to
finish" the tapping operation. However, I think it was too much TQ rather than side load that broke the tap.

I think the tap was dull as I had to coax it from the gitgo. I could not feel the tap cutting as I shoiuld have, but attributed it to hard steel although the drill bit had no trouble cutting through quite easily. The 1 remaining hole @ the rear of the bridge was tapped plenty deep enough W/O the "finish" tap as the screw ran right down to the head W/O resistance.

quote:

Originally posted by Toomany Tools:
Now that I see the pictures you have a bigger problem than a broken tap. That rear bridge is neither straight nor square and unless you're planning on milling custom bases I see scope mounting problems in the future.

No the top of the bridge is not flat YET & the rear view is @ an angle so it looks like one side is much thicker @ the guide slot. I am going to "spot in" the base W/inletting black & laocate it true to the front base. That was to be accomplisehed after the rear base was able to be screwed down. The base is still high on the front & left side.

Fact is, I had to true up the rear bridge on a commercial 98 VZ500 action just the other day W/a mill file using the same process.

This roughed in bridge, bad as it may seem, is better than the VZ500 was when I started on it.

Look thru http://www.mcmaster.com/# and get a center cutting carbide endmill. Use the knee of the mill to run the endmill into the broken tap. I find that the knee works better than using the quill. Part of my daily job involves removing broken taps from stainless tooling. Without a tap burner this has worked best for me. Also I would hunt down a Mill or send it out before using a drill press. Buy some new taps while you are at it.

quote:

Originally posted by J.D.Steele:


I hesitantly offer one caveat about your choice of actions for your project. I've used several forms of these Yugo intermediate-length actions and I really like them, but have found that some of them have a somewhat off-center rear bridge hump. The scope mount holes are centered OK but they appear to be off-center because there's a big bulge in the rear bridge hump, usually on the left sloping side. I simply use a large mill file to even-up the sloped sides of the bridge hump since the off-center bulge appears to be extra metal that had been left by some fault in the shaping process. A simple fix for a problem that should never have occurred in an otherwise-OK action.
Regards, Joe

After reading the above post on another thread, I checked on the VZ500 action & indeed found that the rear bridge was high on the bolt release side by @ least .010", maybe a bit more.

I did as J.D.Steele did, took a mill file, & W/the use of a straight edge & inletting black, trued the rear base W/the front.

Here is the contact pattern of the rear base on the bridge after I filed the left side of the bridge. (the base is mounted in a reversed position to allow for the scope being mounted)




In one of my 1st posts on this thread I wrote that the rear bridge OF THAT PARTICULAR RECEIVER merely had the stripper clip hump ground/filed off & that the contour would be spotted in by hand.

Is this the "easy way"? No, but I have sent an action away to a reputable, highly esteemed gunsmith & had to true up the rear bridge after it was "machined". Place the bases on the action, spot them in for full contact along the edges & check both straight & on the diagonal W/a straight edge. Folow this up W/a feeler gauge under the rear standard Leupold ring & any mis-alignment can be detected.

It ain't he "easy way", but it works & if you have the time & are limited in funds it is a good way to DIY.

quote:

Originally posted by J_Zola:
Look thru http://www.mcmaster.com/# and get a center cutting carbide endmill. Use the knee of the mill to run the endmill into the broken tap. I find that the knee works better than using the quill. Part of my daily job involves removing broken taps from stainless tooling. Without a tap burner this has worked best for me. Also I would hunt down a Mill or send it out before using a drill press. Buy some new taps while you are at it.

OK, I went to the site & could not find a "center cutting endmill"

Is that the same as "square end" & just what is the "using the knee" of the mill?

Things sure changed in the hr. between photos. Did you do all that work in an hr?
Butch

quote:

Originally posted by butchlambert:
Things sure changed in the hr. between photos. Did you do all that work in an hr?
Butch

If by work, you mean the pictures, then yes.

I did the VZ500 action pictured in the latest post about a week ago. The 98K receiver 1st pictured was roughed in W/an upright belt sander & mill file earlier to day just before I broke the tap.

I had so much success W/the "German Mill" (mill file) trueing up the "factory" rear bridge on the VZ500, I decided to go the grind then hand spotting job on the rear bridge or the 98K from the git-go since I have yet to get a "machined" rear bridge that was absolutly true anyway.

There is still enough material on the 98K bridge to true up. I am pretty good W/a mill file having built several muzzle loaders "from the block". A mill file is slow (if you want to be accurate) but it might surprize many how damned accurate they can be.

Once I get both screws in the rear base, I will be able to get some inletting black contact spots on the bridge & bring the base into true & square.

Once a flat surface is attained, it takes several strokes to remove .001" of materaial.

quote:

Originally posted by butchlambert:
Things sure changed in the hr. between photos. Did you do all that work in an hr?
Butch

Butch, you have PM

Look at this part number 8835A64. The knee moves the table up and down. The quill is the spindle.

Now what? Here's what a pro would do to a buggered up hole



Thanks Malm!

OK, to clear up some confusion.

Here is a picture of a VZ500 ACTION that I trued up by hand spotting the rear base & draw filing the rear bridge. This action is ready for scope mounting. The flats where the rear base is making contact are true & square W/the front base.




This is the 98K RECEIVER that has the broken tap in the front hole of the rear bridge. As you can see, the crown of the rear bridge is a bit rounded front to rear. This is a moot point as this portion of the rear bridge will not contact the base anyway & the rear bridge is still "high" so material will be removed. The bases will contact the rear bridge on the flats adjacent to the crown.




Here is a picture of both the VZ500 ACTION & the 98K RECEIVER.


On the 98K RECEIVER, the flat to the right of the bridge crown is flat & appears to be true to the front base. The flat to the left (bolt release side) of the bridge crown is flat & appears to be a bit high @ the front.

I can not verify the truness of either flat to the front base W/O spotting them in, but they are FLAT. Once I bring the left side down in plane W/the right side & make full contact @ the edge of the base when the base is screwed down, I can then check for elevation & plane W/the front base. It will take me about 15-20 minutes, maybe 1/2 hour to do this once I get the tap out so that I can snug down the base screws W/inletting black on the base edges.

When the inletting black shows contact on the crown of the bridge (high spots) I will remove material so that there is no contact between the base & the bridge @ the crown.

quote:

Originally posted by J_Zola:
Look at this part number 8835A64. The knee moves the table up and down. The quill is the spindle.

That's what I was thinking on the "knee", but I was not sure.

So what is a center cutting endmill?

quote:

Originally posted by PWS:
Now what? Here's what a pro would do to a buggered up hole



Thanks Malm!

Am I missing something here?

PWS, is there a before photo of your receiver?
What did Mr. Malm do to help you.

I sure would like to see a photo if you have the time................

Thanks.........burgie

I have broken off a few taps when setting up for scope mounts over the years and always managed to get them out with a small hardened pin punch by shattering the remaining stub of the tap. never failed yet and does not damage the threaded hole.

WOW!!! No comment coming from me. Professional, I think not, not even close

The best way to get it out is to find a place with small EDM machine. They will "spark" it out for you without any further damage. Where I come from, every bigger tool making shop has one just for similar cases.

quote:

Originally posted by Burgie:
PWS, is there a before photo of your receiver?
What did Mr. Malm do to help you.

I sure would like to see a photo if you have the time................

Thanks.........burgie

Sorry, I didn't take a "before" photo. When I sent the reciever to Malm, it had two receiver sight holes in front of the bolt stop, one in the right place but with buggered threads and the other, eggshaped, about 1/8" lower and to the right of where it should have been.

Dumbazz me tried to freehand D&T it for a receiver sight using a cheapass Wheeler D&T kit. So much for saving time and money...

Malm TIGed in the holes and recontoured the rear bridge.

quote:

Originally posted by wildcat junkie:I started on the front hole in the bridge & I didn't get far until the tap snapped off!
I tried to turn out the stub W/a pair of needle nose pliers. Of course all I accomplished was to break off the stub.

So, what's the SOP when this happens?

The is a variety of EDM people call a "tap burner" that will burn it out. Look for a local machine shop, they'll know where to find the closest one.