Shock bolt sheared despite Van Compass Baja bracket
- Thread starter BayouSlide
- Start date
Kept drilling today with fractional bits up to the final drill with a 1/2 in. The bolt threads never did release but I got the remaining bolt steel thin enough that I should be able to clean the steel out of the threads with a tap. Ran out of daylight (hence the lousy photo) so will be chasing threads tomorrow, testing with the bolt as I go.
I'm afraid to say I see the light at the end of the tunnel...for fear it's an oncoming train.
View attachment 384827
When you say you were going to chase the threads to clean the remaining steel out, are you using a M14x1.5 chaser or an actual tap?
I haven't drilled a bolt out before. I imagine you need the larger cut outs / clean outs in the tap, vs the narrow cut outs in a chase?
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BayouSlide
Member
Used a M14x1.5 tap and it cleaned out the remaining steel well and left me with good threads. Always got the tap well underway with just bare fingers to make sure I was following the existing threads, not cutting new ones.
Got the Baja Bracket reinstalled; now I just waiting to hear from Teraflex regarding repairs to my Falcon shock.
Any reports of anyone using an induction heater on the exposed end of the threaded frame insert.
Wondering if that could better expand the insert faster than the broken bolt, allowing for better luck with using a bolt extractor? Or will that not get the heat deep enough into the insert to do any good?
or maybe some sort of cartridge/core heater after drilling the initial pilot hole through the bolt, effectively heating the entire length of the bolt (there is 40 to 45mm of bolt remaining in the threads when these break).
Wondering if that could better expand the insert faster than the broken bolt, allowing for better luck with using a bolt extractor? Or will that not get the heat deep enough into the insert to do any good?
or maybe some sort of cartridge/core heater after drilling the initial pilot hole through the bolt, effectively heating the entire length of the bolt (there is 40 to 45mm of bolt remaining in the threads when these break).
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Midwestdrifter
Engineer In Residence
I haven't checked the tech data sheet for that loctite product. However many will soften if soaked in acetone. I would suggest putting a large piece of tubing over the insert, with a slight upward curve, and flooding it with acetone. After 2-6 hours, remove/drain, and see if you can break it loose.
EBS-P
Well-known member
I kept thinking of a way to use weld to the bolt and not damage the threads. Here it is.
use a piece pipe to protect the threads. Then just stack a bead until it’s out of the hole. It may work better in a vertical position. I’m not going to try it first on my shock bolt.
use a piece pipe to protect the threads. Then just stack a bead until it’s out of the hole. It may work better in a vertical position. I’m not going to try it first on my shock bolt.
Yeah the horizontal aspect is a slight issue there.
have seen that video and other similar methods, involving welding a bead shaft, or welding tube from the inside of the tube. But still feel the weld wouldn't hold up to the forces used when the deep extractors aren't working either... 🤷
some sort of heating along the entire bolt length seems to be needed (when these bolts are seized up)?
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A an alternative to drilling out and risking the threads ...
is it possible to tap a left hand bolt into the 14mm sheared bolt, after drilling a through hole...would that provide enough torque factor without breaking? Would that that be a better option than a spiral extractor, or the same?
is it possible to tap a left hand bolt into the 14mm sheared bolt, after drilling a through hole...would that provide enough torque factor without breaking? Would that that be a better option than a spiral extractor, or the same?
Midwestdrifter
Engineer In Residence
High strength loctite can exceed the breaking torque of the parent fastener in some cases. So I am unsure if any type of extractor will work without heat or solvent softening of the loctite.
Midwestdrifter
Engineer In Residence
Here is a chart from the datasheet for loctite 263. Looks like heating it to 150C results in about 60% of the cured room temp strength initially. Which may be enough to use a larger extractor. The TDS suggests 250C for removal (about 480F). A dark yellow color for bare steel.
cc_windsurfer
Gone with the wind
Bolt buster or one of the many knock-offs can be quite effective, especially when red locktite is involved.
I haven't used one, but from videos it looks like it is great on an exposed thread/nut. Not sure it will work deep enough (65 mm?) into the insert to get the end of the threads??
sprint2freedom
2008 NCV3 170ext
I recently bought an induction heater for an um.. project. While it failed to perform the specific miracle I was hoping for, it's a pretty awesome tool to have around. Hold down the button and it gets bolts cherry red in 30-60 seconds. It does need something made of ferrous metal going through the center of the coil for it to accomplish that level of heating. Based on my testing, just pressing the coil against a piece of metal will heat the metal a little but nowhere near as hot.
It's not obvious if you haven't used these before, but the coils are a consumable. The fiberglass insulation burns if/when it makes contact with the incandescent bolt or nut and after that happens to multiple loops, the coils will eventually short out. A frugal option would be to buy a spool of the correct diameter of insulation and refurbish coils now and then.
There are many different units for sale on Amazon. As far as I can tell, they are almost all identical machines slapped with a few different labels and power ratings despite the underlying electronics being the same. The main difference seems to be how many and what size of coils are included, as well as the type of storage case included (or lack thereof). I ended up with this one mainly because it was available quickly.
You can also purchase a flexible Litz wire coil (such as this one) that is designed to be wrapped around an object that is either too large or doesn't provide sufficient access to use a preformed coil.
I'm not sure how to best use an induction heater in this sheared shock bolt situation.. probably what I would try would be to use a c-clamp to squeeze the snapped off bolt remnant against the loctited stub and then heat the spare bolt with the induction, hoping that conduction would be sufficient to heat the broken stub.
If that doesn't work, you could try to add a heat conductive paste, assuming it doesn't burn up in the process. Boron nitride paste rated for 1000C is available and might do the trick.
It's not obvious if you haven't used these before, but the coils are a consumable. The fiberglass insulation burns if/when it makes contact with the incandescent bolt or nut and after that happens to multiple loops, the coils will eventually short out. A frugal option would be to buy a spool of the correct diameter of insulation and refurbish coils now and then.
There are many different units for sale on Amazon. As far as I can tell, they are almost all identical machines slapped with a few different labels and power ratings despite the underlying electronics being the same. The main difference seems to be how many and what size of coils are included, as well as the type of storage case included (or lack thereof). I ended up with this one mainly because it was available quickly.
You can also purchase a flexible Litz wire coil (such as this one) that is designed to be wrapped around an object that is either too large or doesn't provide sufficient access to use a preformed coil.
I'm not sure how to best use an induction heater in this sheared shock bolt situation.. probably what I would try would be to use a c-clamp to squeeze the snapped off bolt remnant against the loctited stub and then heat the spare bolt with the induction, hoping that conduction would be sufficient to heat the broken stub.
If that doesn't work, you could try to add a heat conductive paste, assuming it doesn't burn up in the process. Boron nitride paste rated for 1000C is available and might do the trick.
Midwestdrifter
Engineer In Residence
An induction heater coil will work inside a metal object just as well as outside. If you can somehow wind a coil small enough to go inside the hole, you can use the tool to heat the sleeve from the inside. Not less effective that way. Some of the magnetic flux will leak out and around and heat the face of the bolt as well.
You don't need to get red hot either. Also note that you can typically use a smaller gauge wire to make winding easier. As suggested fiberglass insulation sleeve is cheap and works well. Using small gauge wire will reduce the units output some.
In general you want to scale the current linearly. So if you have 6" of 10AWG wire, then scale the current appropriately for 12AWG, you would compare the cross sectional areas, 0.1019in2 vs 0.0808in2. or 78%. The original 10AWG wire is 0.5mohh, so we want 0.6mohm, or about 5" of 12AWG, with approximately the same number of turns in the coil.
You don't need to get red hot either. Also note that you can typically use a smaller gauge wire to make winding easier. As suggested fiberglass insulation sleeve is cheap and works well. Using small gauge wire will reduce the units output some.
In general you want to scale the current linearly. So if you have 6" of 10AWG wire, then scale the current appropriately for 12AWG, you would compare the cross sectional areas, 0.1019in2 vs 0.0808in2. or 78%. The original 10AWG wire is 0.5mohh, so we want 0.6mohm, or about 5" of 12AWG, with approximately the same number of turns in the coil.
Cheyenne
UK 2004 T1N 313CDi
I was taught a trick many, many years ago to use the carbon rod out of an old fashioned Zinc/Carbon flashlight cell (Not Alkaline or modern versions).
You need a really good 12 V car battery and grip the carbon rod in the positive side of a pair of jump leads and ground the negative close by the broken bolt. When the carbon rod is touched on the broken bolt a massive current flows and the carbon rod glows bright red and transfers the heat directly into the bolt.
This would work for a recessed bolt as long as the carbon rod did not touch the sides of the hole.
Keith.
PS The only problem nowadays is finding a Zinc/Carbon flashlight cell !!!
You need a really good 12 V car battery and grip the carbon rod in the positive side of a pair of jump leads and ground the negative close by the broken bolt. When the carbon rod is touched on the broken bolt a massive current flows and the carbon rod glows bright red and transfers the heat directly into the bolt.
This would work for a recessed bolt as long as the carbon rod did not touch the sides of the hole.
Keith.
PS The only problem nowadays is finding a Zinc/Carbon flashlight cell !!!
yeah - i was wondering if a 120v cartridge heater might be worthwhile in this kind of situation.
Drill through 1/4", insert 1/4" x 2 inch rod ... as long as decent surface area contact, this would get the whole bolt stub to temp more efficiently than playing around with a hand held canister torch from outside the frame. That rubberized corrosion coating likes to flash and smoke pretty good ... plus the brake lines in that area.
Drill through 1/4", insert 1/4" x 2 inch rod ... as long as decent surface area contact, this would get the whole bolt stub to temp more efficiently than playing around with a hand held canister torch from outside the frame. That rubberized corrosion coating likes to flash and smoke pretty good ... plus the brake lines in that area.
EBS-P
Well-known member
I would have used my butane kitchen torch before bought that.
AllanB
Well-known member
Not true. I did work on magnetic fields some time ago and the fundamentals are that the field strength is significantly higher inside a coil than outside. Furthermore, the field strength is a function of coil current x coil turns so changing the wire diameter will affect the current such that the applied voltage will need to be changed to compensate. Furthermore, changing the turns affects the coil induction and raises back-EMF issues so it is not a simple electrical consideration. The power frequency of 100kHz and upwards is not easily obtained from the home workshop junk box either.
If you desire to use electricity to heat this broken bolt then you may do better by passing a high electrical current through the target however attaching the cables could be problematic. I have successfully done this in practice for a gas analysing oven but in a situation where cable attachment was practical. The transformer used supplied about 1.5 volts at 250 amps.
sprint2freedom
2008 NCV3 170ext
OK, so it's been a while.. but since all magnetic field lines are closed, the total magnetic flux outside a coil has to be the same as inside.
Yes, the flux inside the coil is concentrated in a smaller area so the flux density will be higher inside the coil. However we are seeking to heat the entirety of the threaded sleeve with eddy currents in order to defeat the thread locking compound, so I'm not convinced that flux density is the key consideration in this application. I would expect a coil wrapped to closely match to the inner diameter of the sleeve to produce a comparable (though not "identical") total magnetic flux into the sleeve.
Yes, the flux inside the coil is concentrated in a smaller area so the flux density will be higher inside the coil. However we are seeking to heat the entirety of the threaded sleeve with eddy currents in order to defeat the thread locking compound, so I'm not convinced that flux density is the key consideration in this application. I would expect a coil wrapped to closely match to the inner diameter of the sleeve to produce a comparable (though not "identical") total magnetic flux into the sleeve.
AllanB
Well-known member
I'm sorry, I used the wrong expression. I should have said "field intensity" not "field strength". And that is the essence… it is the field intensity applied to the bolt stub that will raise its temperature to satisfaction, not the wider distribution of the external field applying to the surrounding material which is then being dissipated to a greater mass and loss. The intent is to heat the interface between the bolt and spigot not the whole mass.
Besides, an induction coil of 6 or 8mm diameter is not likely to produce enough energy to heat the stub adequately.