Removing stripped 2mm allen bolt

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martakz's picture
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Hello All,

On my bike I use avid arch rival brakes. Anyhow, I needed to remove a small bolt on the side, a 2mm bolt.

But the damn head has been rounded off! The 2mm allen key wont grip...

Anytips to remove it?

-Cutting a slot wont help as this would destroy the brake arms, as the bolt is flush

Anything?

Thanks

T

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2 mm bolt removal

You say the bolt is flush, do you mean that it is a flatheaded bolt?

If it isn't, then you could grip it with a small needle nose vise-grips, and then rotate it loose.

If it is a flat head, you might be doomed. You could drill it out, then drill and tap a new threaded hole.

eeun's picture
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easy-out

A machine shop, and possibly a bike shop that does repairs, should have something called an easy-out. You may be able to buy one, too, though it's a bit of an expense for just one job.

They drill a hole into the head of the allen bolt, and the easy-out is screwed into that hole. It's reverse-threaded, so the tighter the easy-out goes into the hole, the closer it gets to releasing and unscrewing the stuck allen bolt.

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martakz's picture
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The head is flush to the brac

The head is flush to the bracket, ie there is no bolt protruding. I'm not sure if an easy out would work...this bolt is tiny! Its about 2.5mm diameter. Also the bolt is only about 4mm deep, so I doupt I could easily find a replacement.

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martakz's picture
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The bolt has no head. Its ju

The bolt has no head. Its just a thread...

Its in the right arm of this pic:

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rael9's picture
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Set screw?

You mean it's a set screw like these?:

If so, an easy out will work if you find a small enough one. I know they are made, I'm not sure how available they are over there though...

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martakz's picture
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Yup :) Its definatly a set s

Yup Smile Its definatly a set screw exactly like the pic...though one of the smaller ones.

I need to find an easy out...

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how about drilling

can you drill it out? other than that, needle nose pliers and a lot of WD-40 to work it loose

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martakz's picture
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I will probally drill it out.

I will probally drill it out...but will have to find a bolt slightly larger than the drill bit, so it taps a new thread.

I cant find any place in england that sells them...

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jt
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Try a tiny centerpunch . . .

. . . and a hammer! Evil Block Company

Mechanics don't like to use easy outs/extractors etc. on hardened bolts (like set screws, IIRC) because when they break off inside the drilled hole (VERY difficult to make one of those in hardened steel to begin with, btw) you're REALLY SOL.

If you're not going to be wearing safety goggles: READ NO FURTHER!

Hit (tap gently in your case) something pointy and hardened, like a punch, with a hammer that is NOT hardened, ball peen = OK, but a carpenter's claw hammer or my framing hammer = DUMB IDEA! An upholsterer's tack hammer might make a very good choice for something this small. You want to apply force downward/tangential to the center near the edge of the screw.

A chisel/punch applied to the edge of the rounded out allen socket might be a good alternative if the size and clearance is workable.

I think I have a deburer (or a countersink?) for metal work that has edges that might work well in reverse on my hammer drill, you might look for one of those if you have a variable speed hammer drill that works in reverse (NOT a rotary hammer!).

Now that you've got me thinking about it, did you say it's a threaded hole in an aluminum caliper arm? Make sure the threads on that side are right handed, the only good reason I can think of for that allen socket to be rounded off is that it's been forced the wrong direction!

jt

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edit: back to make an overly long post longer: If you find out that it's reverse threaded, try a standard drill bit on it in reverse. If it actually is a set screw and not a socket headed pivot bolt or some such (which actually sounds more likely . . . hrmmm?) . . . you only need to break it loose and you should be able to turn it out easily

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martakz's picture
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I think the factory screwed i

I think the factory screwed it in too much and stripped the head.

The bolt is threaded in the standard direction into an aluminium arm.

It holds a centeral axcel in place (how do you spell axcell...mind block..). The axcel holds the brake pad pivots in place. The whole linkage and arch keep the brake pads parrelel with the rim at all times, to get maximum breaking power.

I found some screw extractors. They are not like easy outs. You drill a deeper hole. Insert the extractor which is just smaller at the tip. You them rotage the extractor backwards and hopefully remove the bolt. I'm going to try it later...

Anyway to tell if the set screws are actually hardened? If they are hardened...i'm surprised the heads strip so easily.

Thanks

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jt
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That'd do it!

martakz wrote:

I think the factory screwed it in too much and stripped the head.

That'd be forcing it in the wrong direction in my book!

"An overtorqued bolt is already half broken!" unknown

You should have seen the first Delta 14" bandsaw I got. Some yoyo on the assembly line must have had trouble getting the drive pulley onto the keyed motor shaft. That thing vibrated like a paint shaker compared to the 10" Craftsman three wheeler I'd "upgraded" from for a big plastic cutting job. I finally figured out the problem at about midnight of the day it arrived. The Dork had pounded the freakin' pulley on BACKWARDS! and it was on there so tight I couldn't get it off to realign the saw because a gear puller would have destroyed it!

I took care of it . . . Evil Block Company loooong story . . . whatever . . .

Delta took it right back when the job was done and sent an upgraded model as the replacement when they picked up that heap of scrap metal some factory idiot had turned mine into with a mallet!

Get yourself a free replacement, that aluminum arm is overtorqued too, probably in the same direction as the braking force it applies*, good luck!

jt

* see quotation above!

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Dr. Webster's picture
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You can get easy-outs at Sear

You can get easy-outs at Sears for pretty cheap. I bought my dad a set last Father's Day for $20.

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Re: I will probally drill it out.

martakz wrote:

I cant find any place in england that sells them...

Have you tried Machine Mart, or your local Snap-On distributor? Normally if they can't source it it doesn't exist.

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martakz's picture
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Thanks blackstealth...i'll ch

Thanks blackstealth...i'll check them out, though I doupt any are local.

Avid tech replyed and said I should "Use a left-handed drill bit of a smaller size than the screw -this should back out the screw"

Eh?? Left handed drill bit??!?! :S

Thx

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jt
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Roto-Zip bits?

Check out the bits for Roto-Zip and Spira-Cut type mini routers, the plunge type bit designed to hold material down is reverse twist. The points on mine look like they'd do the job, but I don't know if they're available in a small enough size.

I usually wind up making my own tools for doing off the wall crap like this . . . Evil Block Company . . . maybe that approach will work for you. Find a torx bit to file down, I'd go for sharpened flutes with a reverse twist and put a sharp conical profile on the edge of the tip so it'll bite into the remains of that ^%^%@^%#@^%# (rounded out) allen socket as pressure and torque are applied. I'd use safety glasses AND a face shield, with the bit chucked into my my DeWalt hammer drill so the hammer action would help to break the set-screw loose as it's rotated.

If you want to try for a little more sophistication, file each flute so you also get a recessed center point/inverted conical profile. That way the deepest part of your tool is on the edge, just slightly inside the overall base of the outside (pointy tipped) cone. It'd look sort of like a "W"profile, but really more like a cap "M" in a font that has a slight angle to the straight strokes of the letterform.

I'd anneal the bit before filing, heat with a torch until it's bright red and let it cool slowly to remove the hardening . Do the same, but quench it in water to re-harden it for use after achieving the desired profile.

. . . then I'd lose it just before the next time I needed it again.

jt =8-/

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martakz's picture
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I'm getting the damn thing if

I'm getting the damn thing if I have to weld the allen key to the bolt...

Thanks for the reply JT. I'm going to call in a few favours owned at the tech departement. Maybe i'll be allowed to play with the new laser CNC machine while I'm there...I want to engrave the top of my lappy...

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jt
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CAREFUL!

If it were in a steel casting or part it would be fine, but find out if you'll be likely to weaken the aluminum part by the heat and expansion of the set screw during/just after welding. What kind of welding?

If you do a gas weld with the arm set up clamped so that most of it is under water in a pan/tub, you might get away with it, dunno where you'd attach the clamp to do it with rod or wire on that thing.

Nopro, on the replies, I just LOVE figuring out workarounds for this kinda crap! * see footnote

jt =8-D

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* To get that backwards pulley off my Bandsaw's main shaft (I boobooed in the statement above) I ended up making an opposed wedge pair out of some cast steel alignment wedges (angled washers for structural iron work) to fit between the main bearing and the aluminum pulley and then using an I-Beam pipe hanger clamp to apply the sideways force. It finally came off after about 15 minutes work once I'd figured it out and made up the tooling. A gear puller would have torn the rim right off its hub if I'd tried to use one, that's how tightly that pulley had been pounded on there.

I actually found a bar of key stock at Home Depot at 1 AM after being told they didn't carry it. I was cutting plastic Saturday morning for a Monday Night deadline. I'd run out and bought the dang thing Thursday for a Friday delibery to "save Time!" HAR!(tm) . . . well . . . it actually DID save me time overall, HEH! Wink

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martakz's picture
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Brazing should not damage the

Brazing should not damage the aluminium...its only around 1000C. The allen keys support themselves in the bolt. So all I would have to do is heat the area and feed the golden solder in...

Either that or laser it out! Well maybe not, but I did find some screw extractors...

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martakz's picture
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Also, aluminium expands at a

Also, aluminium expands at a greater rate and to a larger size than steel. Thats why one should freeze a stuck steal seatpost in an aluminium frame.

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Drill

Drill it, and then get an "easy out" from your local hardware store.

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