Broken drill bit in tie block

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lamanoditrento
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Broken drill bit in tie block

Post by lamanoditrento » Mon Jun 11, 2018 3:56 pm

Boy, my current build is giving me no end of grief. I am making a new bridge after the first one split under string tension along the lamination while stringing up. I noticed however that one of the 18 holes on the new bridge hadn't gone all the way through the tie block. Using a eggbeater style had drill I have broken the 1.5mm drill bit in the hole and in the attempt to remove it with plyers, the end has broken off flush with the back edge of the bridge.

Any ideas about how to remove the bit now without making a mess of the bridge would be welcome:
Brokendrillbit.jpg
Brokendrillbit.jpg (53.02 KiB) Viewed 594 times
Apologies for the bad photo - but you can just make out the drill bit

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kiwigeo
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Re: Broken drill bit in tie block

Post by kiwigeo » Mon Jun 11, 2018 4:09 pm

The only idea Ive got - get a bit of stiff fencing wire and bend over a few mm of the end. Poke the bent over end into the saddle/tie block valley and push the drill bit out the back of the tie block enough to grasp it with the pliers.

You mentioned the previous bridge failing under tension. Id be interested to see pics of the bridge.
Martin

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Steve.Toscano
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Re: Broken drill bit in tie block

Post by Steve.Toscano » Tue Jun 12, 2018 12:13 am

Does the hole go through to the otherside? If so as Martin mentioned push it through with some wire or a nail from the saddle side.
Otherwise maybe you could drill a temporary hole from the saddle side at an angle over the top of the saddle slot to meet up with the end of your drill bit then push it through.
Afterwards carefully filling the new temporary hole.

OR
You could route a bevel across the back of the tie block, careful not to hit your drill bit with the router/dremel but go very close to it. This should allow you to get needle nose pliers in to remove the drill bit - ensure to pull straight and twist obviously. After removal tidy up with the router/dremel.
See below what i mean with the bevel. I do this on all mine now anyway, looks good, with the added bonus of weight removal. Sorry i dont have a better photo showing it at the moment.
2017-04-02 20.13.31.jpg
Braz RW Bridge glue up
I do this with a ball ended dremel bit upside down in a make shift table and a fence.

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Trevor Gore
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Re: Broken drill bit in tie block

Post by Trevor Gore » Tue Jun 12, 2018 12:14 am

IF you managed to drill right through before it snapped AND you have a drill press...

...set up the bridge in a drill vise so that any hole aligns co-axially with the chuck. Put the busted part of the drill in the chuck, upside down. Using the drill stump as a drift, press the broken piece of drill through its hole from the butt side. (Don't switch the drill on!) When it meets the saddle ramp, snap off the piece you can see with a pair of needle nose pliers. (Twist sideways rather than up). One repeat and you should have it all pushed through and a clear hole.

If you didn't drill right through, you should be so close as makes little difference. Try the same trick and hope you don't get too much splintering as you break through.

Good luck!

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lamanoditrento
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Re: Broken drill bit in tie block

Post by lamanoditrento » Tue Jun 12, 2018 7:43 am

Thanks everyone, I will give these a go. It is funny how when you're a bit downbeat your problem solving skills can go out the window. I think having to remove the 1st bridge, mucking up the finish a bit removing it and then struggling with broken bit knocked my resilience. I really appreciate replies and the collective wisdom here
kiwigeo wrote:
Mon Jun 11, 2018 4:09 pm
You mentioned the previous bridge failing under tension. Id be interested to see pics of the bridge.
Here ya go - the original was only a 6-hole and made pretty much per Trevor's method. Lamination was rosewood/cf/tassy oak/cf/rosewood with epoxy
Strings still attached.jpg
Strings still attached.jpg (115.52 KiB) Viewed 529 times
Strings removed.jpg
Strings removed.jpg (108.33 KiB) Viewed 529 times
Bridge removed.jpg
Bridge removed.jpg (128.22 KiB) Viewed 529 times

simso
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Re: Broken drill bit in tie block

Post by simso » Tue Jun 12, 2018 6:20 pm

Ouch, so disheartening for sure.

Many times, I walk away and come back to it the next day, as our mental aspect becomes very fogged when frustrated.

Steve
Steve
Master of nothing,

Do your own repairs - http://www.mirwa.com.au/How_to_Series.html

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Mark McLean
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Re: Broken drill bit in tie block

Post by Mark McLean » Tue Jun 12, 2018 10:33 pm

I do love the look of that bridge. And 18-hole is a great design for tying the strings quickly and neatly, and so much neater than tying them around the tie-block. Your triplets of holes are a lot neater than my last effort at that. I am sure you will get there in the end.

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