Snapped bolt.

[excossack]

I have a trailer axle that has a bolt around 85mm long that passed through a suspension upright, into a round tube which has a stub axle inside and then back out the tube and the other side of the suspension upright. The bolt is about 10mm.

WHile undoing it, the bolt end sheared off about 10mm into the metal work, so I tried removing the nut and that stripped the thread.
So, I ground back the stubby bit of bolt left behind and centre punched and then followed with a drill to start drilling it out.
I did this from both sides.

The bolt head side I am about 45 mm in at 8mm drill bit and the other side, I am about 20mm in, with 8mm drill bit.

I managed to snap a drill bit in the 20mm hole which is now stuck fast and despite trying to pull it out/use a centre punch to release it, its stuck and with drilling I have chipped some away but now its stuck fast and drilling is now existent.

Now the other side, I decided to keep drilling, using Heller Cobalt drill bits I started doing well but now, the 8mm drill bit appears to have ceased to drill (well very very very slowly)

I have been using some aerosol cutting fluid (Techtone C05 or similar sounding stuff)

For the drill I have being using a combo of Bosh 450w drill and cordless Makita 18v with speed control.

For now I have given up with a view to removing the axle and taking it to an engineering place to see if they have more luck as this week I have spent about 10hours drilling & swearing at it!!!

Any tips? Its gone past an easy out, oh and I have tried some heat but its a standard Butane DIY burner.

 

[MrFluffy]

Sounds like the m8 drill bit has met the remains of the original drill bit. Can you not make a parallel punch up from say a long m8 rod and punch the broken bit out from the cobalt drill hole side? It might be stuck INTO the hole, but if you can knock it from the backside applying force that way sometimes they just pop out.
Your in a LOT better position than a ez out in there. Theyre a waste of time full stop.
Also a word of caution, my experience is cobalt bits shatter when they jam as theyre hard but brittle, creating a no win situation. I much prefer to use hss and coolant and a low speed unless the material absolutely demands a hardened bit because your options are better when it all goes south.

 

[rkde]

Normally with stuff like this I weld a but on the end of the broken bolt. The heat helps too

 

[normspanners]

By the sound of this the bolt has rusted in the stub axle if you are confident your deep hole is accurate enough I would drill it to 10mm as far as poss to reduce the pressure on the bolt / hole because as a bolt in an accurate hole, rusts it gets bigger therefore grips the hole, then drift the remainder out with a good quality pin punch

 

[ben8vgte]

Have you tried those special arc rods, for taking bolts out? Have a flux that stops it sticking to the hole, the heat helps a lot too..

 

[steveo3002]

Have you tried those special arc rods, for taking bolts out? Have a flux that stops it sticking to the hole, the heat helps a lot too..

any info on those...sounds like theyd be worth having for such times

 

[Burdekin]

Suspension bolts can be a real pain to get out. Typically what I do is plenty of penetrating oil, heat, hammer and dolly. I assume it's just a bolt that passes all the way through? If so you need to drive it out. I've tried to force them out with a clamping arrangement before but never had much success. I did the rear suspension in my 1966 Volvo Amazon Estate last year and it was a total PITA to get some of the bolts out. Good luck.

 

[ben8vgte]

any info on those...sounds like theyd be worth having for such times

The ones I have are X-ergon, X-Tractalloy I think.. I have no idea where the came from, prehaps a google search?

 

[Chook]

Go to your local hardware shop and buy a few masonry drill bits, the right size.
You must resharpen the carbide insert/tipped masonry drill, just as you would a drill bit for steel. (They have a negative cutting angle when new.)

By drilling with a very slow speed, plenty of cutting fluid and a LOT of pressure, I have drilled out many broken “easy outs” or "taps" that customers have broken off trying to rethread a hole.
Just be very patient, as it is a slow process and keep touching up the cutting edge of the drill bit.
Don’t get them too hot when grinding (or cutting), as the carbide is brazed to the end of the bit.

Good luck.
Cheers Chook

 

[Seano]

Normally with stuff like this I weld a but on the end of the broken bolt. The heat helps too

x 2 on that one, have used this method quite a lot and is usually a success

 

[excossack]

More ideas to work on.

@chook
Someone else mentioned the masonry drill bit method as well, what does a positive cutting angle look like? Not having sharpened drill bits before.

@rkde
I did look at the idea of welding a nut to it, but one side I couldn't get to because It was 10mm below the surface and the other side I thought was too flush and wouldn't work, maybe I should have gone for it rather than drilling it out.

@Burdekin
It is a bolt that passes all the way through, about 85mm OA.

 

[chevy2]

Obviously rusted and bonded itself to the sleeve due to no copperslip being used when last assembled?
generally the only easy way to get rusted and seized bolts out of sleeves is by using oxy/acetylene, it should knock out far easier this way.

 

[Burdekin]

@Burdekin
It is a bolt that passes all the way through, about 85mm OA.

Don't make life hard for yourself trying to drill it out then, old suspension bolts rust in place, best way is plenty of penetrating oil, heat, hammer and dolly. If it's a trailer just tip it up so you can get a decent go at it. If you can get a decent swing with a decent hammer she'll come out no problem. Just watch that you don't bend anything.

If you have another pair of hands, get them to hold a block of wood against the opposite side.

 

[PaulGS1100]

also for the future... drilling out with a left handed drill can help loosen the bolt while drilling (i'm told)... I've just order a 3mm and 4mm to drill out a snapped bolt on my GN250's valve cover

 

[Chook]

Hi like this. Just like a regular drill bit is sharpened.

 

[normspanners]

Hi like this. Just like a regular drill bit is sharpened.

apart from the fact you need a soft stone on your grinder to grind TC bits

 

[excossack]

Thanks for the diagram Chook that explains things. A picture speaks a thousand words etc

 

[excossack]

An update. After removing the axle so I can drill downwards rather than horizontally.
So, another hour or so of more drilling, I managed to get a bit further. Measuring the depths of the holes from either side I wasn't too far off.
Digging around in the tool box I found long sturdy looking poking device with a tapered end.
So, out with a FBH and gave it a few smacks and the poking device moved further into the hole and then with a few more bashes I nailed the sucker!

Thanks to all those who have offered advice


This is what's left of the remaining bolt and the axle it came out of (RHD suspension upright)

 

[Burdekin]

That looks like a tough buggar indeed.

 

[excossack]

It put up a good fight. I estimate I have spent about 10-12 hours drilling, mainly in the evenings, finish work, home, hi to the wife, brew, change clothes and then out to the drive to drill.
New bolts tomorrow and re-assemble with loads of grease/copper slip.