The Stovebolt Site Forums The Shop Area General Truck Talk Machinists Alert -- Advice needed for a broken set bolt/screw

Help me, Obi Wans!

I am trying to remove the safety brake drum from the worm gear of a Braden LU-4 winch and someone previously snapped off the set screw/bolt. We successfully drilled down through the center of the screw, and we've even burned up several drill bits attempting to anneal the wall of the screw to get it to loosen. Nothing doing yet. It's been soaking (at times with a little heat) in penetrating oil for two weeks now. We've tried two different easy outs (and love taps with a small hammer). We've twisted one easy out and I don't want to snap the other.

Any tricks? Hints? Helpful advice? This little screw does not want to come out. And I would really like to not ruin the safety brake drum as it is a pricey item.

I'm no machinist. But at least I haven't snapped the easy out ... yet ...

Thanks,
John

My favorite and most successful broken screw removal method is using the TIG welder.
Weld a little blob on top of whatever is left and grab that with vice grips. If a hard to get spot use a nut or bolt welded to it.

If you want to bring it by I'll give it a try.

Grigg

What diameter setscrew are we dealing with? Is there enough room in the hub to tap a larger thread, like going from 1/4" to 5/16", etc.? I'd find a solid carbide drill bit the size of the major diameter of the screw, and take all the threads out. Then I'd tap the hub for the next larger thread before reassembling.
Jerry

I have witnessed the use of heat on the hub, followed up with quenching the screw with dry ice. This method causes extreme expansion and contraction of the parts, creating a gap between the stuck parts, allowing them to be separated. Don't worry if you can't keep the dry ice from getting on both parts. You are only looking to cause expansion and contraction to break the bond (not make one part smaller than the other).
Carl

Not sure how you much more before you hit the threads but sometimes a left handed drill bit will back out the broken bolt or screw as you drill into it. If that's not an option, I would try more heat.

John

Here's what I'm dealing with . The drum you see in the picture is about 3 inches across. The screw is about 1/8 inch in diameter -- pretty small and set at an angle and difficult to get to -- we had very little drill bit actually in the chuck to get as much length as we could... We drilled closed to center but not exactly center and we're about in the threads on one side, so we may end up doing Jerry's recommendation anyway...

But as you can see, there's nothing extending above the edge to grab or weld to. Tig welder ... That's funny, Grigg ...

If I use a very fine flame, can I apply heat directly into the hole we've drilled to heat up the walls of the screw? Or do I need to worry about annealing the hub of the brake drum?

Do you have a Dremel tool handy? I have salvaged some broken scope mount screws on some pretty expensive rifles by using a Dremel and a tiny diamond-coated abrasive bit to core out the screw without damaging the threads, then using a tap to chase the threads. Some of the diamond dust bits are as small as 1/16", and with a set of magnifying goggles, it's possible to be very precise with the core-drilling of the broken screw, particularly when the pilot hole is a little off center. Check Ebay for the diamond Dremel bits. They're pretty inexpensive.

The drum is probably cast iron, so don't worry about annealing it.
Jerry

Thanks Jerry -- What if I can get the screw walls red and then put the easy out to it? Might that work? I've just been putting a lot of torque on the easyout and I'm afraid of snapping it.

We tried the dremel, we just can't get in the hole. Angle is tough and we can't see real well.

That's the best way I can think of to anneal the EZ-out and then twist the end of it off in the hole. How much distance is there between the setscrew and the area where a drill chuck or a Dremel can turn freely? I can probably fabricate an extension shaft for a drill motor or a Dremel that will give you a little more working room. I've got a Foredom gunsmith's flex shaft rotary tool with a variable speed foot pedal and a very small-diameter handpiece- - - -want to borrow it? I've also got some solid Carbide dental drills.
Jerry

Would it be illegal to cut, or notch, the drum so you can go STRAIGHT into the broken screw. If you can notch the drum it'll open up a lot of territory to getting that screw out.

Think you're going to have to drill it out John, with an extra long bit and retap with bigger screw as Jerry says. Next question, I don't see how you're going to grab it to pull the drum off the shaft.

Long bits

Make a puller from of a piece of 3/4" square key stock- - -drill and tap it for a 3/8-24 bolt, and use a set of 1/4-20 J hooks to grab the spokes. Drill holes through the key stock at the proper location to bolt the J hooks to it.
Jerry

I looked at the picture.
Let me weld it before you try anything else. I've removed hundreds of broken screws and bolts like that, some much harder to get to than that. Of those hundreds only a couple didn't cooperate and needed actual machine work, drilling and Helicoil or what have you.

Worst case is drill it out and install a helicoil. I like that better than changing screw size in most cases.

Grigg's on the right path John. I'm dealing with a small
broken tap inside of a steel bushing on my mill. I'm gonna
tig weld a stub to it so I can grab hold of it and pull
the bushing out.
Trying to drill a broke bolt directly on center is difficult
to do without a guide and usually ends up with your drilling
into the threads.
I did have to drill a broken bolt in my 261 harmonic balancer
recently. I used a guide bushing to keep my drill on center:
http://www.pbase.com/dennygraham/image/161629463
Had that not worked I would have resorted to the tig method
like Grigg suggested.
(My lesson learned...always use grade 8's!)

dg

I also agree with Grigg on his ideas.
Helicoil would be the best repair if the need be.

Don

Sounds like a lot of trouble to me, Jerry -- Let me try these other ideas first. Thanks, though.

Alvin -- I think that would tear up the brake band that rides the drum.

I will try one more time and then I think the winch is going to take a little trip to the Old Dominion ...

Don ... This is all your fault, you know ...

John, please don't try one more time, it's real aggravating to deal with a broken easy out if that does happen. Easy out can also expand the screw and further complicate the situation

Chances are real good that welding works and no damage to the part.

I need to round up your 5.14 gear sets anyhow, so a trip is in order one way or the other.

Grigg

Tig welding I swear by as well, everything from threads as large as 1" to under 1/4" I have been able to extract. I never really had luck with easy-outs

John
I'll gladly take the blame for your your pain, busted knuckles, broken tools and the swearing that the 60 year old winch has given you.
I will also take the blame for the joy, satisfaction, learning experience and the pride you'll have, when it is done and mounted on the front of the M-37.

Don

Hats off to you Grigg if you can get in there with a Tig. If you guys are able to get it out, someone plz snap a picture.

If you go in with heat, heat the drum, not the screw. You need to expand the drum away from the screw. Or, if you heat the screw, let it cool before working on it. The heating and cooling cycles should break the rusty grip. Welding does the same thing, only it gives you a place to grab onto.

Grigg is absolutely correct. A broken EZ out will further complicate things.

John

If the TIG welding does not work.Drill it out and recap the hole,or drill another hole in another location and tap it to the same size.Most of the time it does not have to be in the same location. Even if the set screw is on a key ,most of the time it can be moved and a new key way broached in .

There are services that use Metal Disintegrating Machines to remove broken bolts and even broken taps/easyouts.
Might look into it ??

Metal disintegrating machines? THAT sounds kinda cool ... I'd like to see that technology at work ... Have to look into that for my own curiosity (sounds too expensive to apply to a tired old beat up winch, though).

Alright, alright ... your crisis hotline training is working -- I'll put the easy out down and step away from the bench ... Don -- The winch is 62 years old (assuming it was made the same year as the truck). After all that damage to the safety brake cover and the ring gear seal retainer (the mangled piece of aluminum remnants circling the safety brake drum in the picture), I can't wait to see what the ring gear looks like.

Grigg... Your turn.

What's a couple years when you are that old.

Electric Discharge Machines (EDM) have been around quite a while.
I used one in high school and several others in some shops.

http://www.xactedm.com/edm-capabilities/how-edm-works/

Don

Here you go John, feed your brain for a minute and half while
you're finishing your coffee this morning:

Only problem with EDM is you have to be able to put the part up
on the machine, same as you would a milling machine. Sounds
like your project is rather stationary on the truck?

dg

I had good luck with FreeZ-It.Made by Chemtronics

I once had a guy EDM out an "Easy Out" of a rear end housing bolt I'd broken off. Luckily it was out already.
The guy had a set up that let him do the job in the 'yard' not on a bench or table.

easy outs should be renamed "difficult outs or hard outs"






Weeds

How about "Hard Outs Broken Off".

I consider them "rarely easy outs".
Every now and then they have a use, never because a bolt or screw is so stuck it wrung off or stripped out. More like wrung off while installing or sheared off for some reason but not rusted stuck.

I have the winch in the shop, need to clean the oil off and give a go at welding, it does look promising.

On a much smaller scale, here's a situation similar to John's.
And a solution similar to Grigg's.
The steel oil bushing is pressed into and sits flush with
the dogbone. It has a 5/32" thru hole in the middle. Some
idiot broke a tap off flush with the top of the bushing.
I built up a grip of weld on it an managed to pull the bushing
out. Saved me a trip to a machine shop with an EDM.
http://www.pbase.com/dennygraham/image/162392960
Denny Graham
Sandwich, IL

A shop I worked as a tool designer we would sink and thread holes in 62 Rc D2 tool steel when one of us would 'forget' to transfer a hole through details above the die block. EDM's are very versatile machines but not every shop has tapping abilities with their machines.

I've read that a plasma cutter works well on through holes, not sure how effective they are on blind holes.

Very rare do I post on a thread like this..WAY above my pay and knowledge grade … but have trolled on them many times and learned a LOT ..Thanks …
Dan

OK, the job is done and here are the pics.
PICTURE 1
PICTURE 2
PICTURE 3
PICTURE 4

John,
Next time "Please step away from the (so called) Easy outs"
After striping the hex, drilling, and the reaming as result of failed easy out there was very little left to weld to.

It gave very little trouble on removal but took two attempts.
First attempt I only gave half a try, welding to the wider, easy, side of the remnants in hopes it'd come out without much fuss. That got it to move but twisted off. The second and a proper attempt I welded around the entire diameter, more stuff in shear so not as likely to twist off like before. That's all it took.

Grigg

You are the man Grigg. How did you get so much vertical buildup on top of the screw, to give you something to grab with the vicegrips? Thanks for sharing those pictures.

Well played Grigg, well played.

Allen, with a TIG welder with variable foot pedal control the "heat" can be adjusted on the fly. So just hot enough to melt the new filler and not so hot you melt down the pile. Or something like that.. and a little practice though really not difficult if you can run a TIG welder some already.

Thanks Phillip,

Grigg

Good job Grigg!!

One other ideal that I have used before, to get a hardened set screw/bolt out.
Take an old broke off tap and sharpen it like a drill bit.
The web is already there.
Maybe even sharpen it to be left handed, so when it starts to break thru, it will unscrew the bolt.

Again
Great job and John owes you for your skills.

Don