Broken Bolts-Removal

[geneborg]

I have two broken bolts on the #4 carb boot. I have drilled one out and with the other, the upper, I have broken off my "second" drill bit. I had it open and was trying to clean out the hole and enlarge it a bit and broke off that second bit inside the hole. It it difficult to get a straight alignment with the obstructions, size of the drill and length of the drill bit. I am even considering cutting off part of the shank of the drill bit to shorten it for a better alignment.
Ideas please, especially with what is best to use to drill through the bit. The metal is difficult enough but now also the drill bit. I was able to drill through the first bit but with lots of bits and considerable time and energy. I am unable to get all the bolt material out of the holes.
Ideals also, on what will be best to use for the replacement bolts? Should I try and tap new threads or use "helicores:? I have never used helicores. I may have to use different sizes and methods on the two holes depending on how the holes come out, the angles, and making sure the boot lines up properly with the port hole and the carbs fit properly.

[skids]

That is a headache I am sure! Usually, harder bits are easier to break. Did you try a reverse twist bit? The softer aluminum would definately make the bit wander off center and I am sure that is difficult to control.

There is no room in there to use an impact screw driver? If there is, that could be the ticket. Maybe heat followed by penetrating oil and ice to draw in the oil. Then, I would try a dremmel with a good quality tip to get the driver tip a place to bite. Maybe use a little grinding compound on the tip of the impact driver.

These bolts should not be overtightened, so I suspect that the threads are fused due to unsimilar metals. You may end-up using a helicore anyway. (Use Neverseize or similar product...but I am stating the obvious!)

[DGXSER]

My best advice would be to get a dremel, use a carbide or diamond tipped cutter (the ones with a ball or oblong ball type end on them) to "drill" through the dill bit metal.

With the lack of precision available, meaning you can't use a drill press or similar to control the bit) your most likely going to have a larger hole than the one you started with. So you could tapp the hole for larger threads, however, you may also need to open the hole in the boot for the larger bolt.

[tarzan]

Carbide is definitely the way to go here. A carbide bit in a Dremel like DGXSER suggested may be the easiest to get the hole started and centered. Carbide will cut through HSS(drill bit)or even cobalt. Go slow and whittle it out. You will probably not have a good thread after your removal procedure.So, I would tap for a Heli-coil or Tri-sert.
I definitely wouldn't bother trying to drill another drill out with a drill of the same material.That is an exercise in futility.

[Joe Bartelt]

broken drill removal

Carbide is definitely the way to go here. A carbide bit in a Dremel like DGXSER suggested may be the easiest to get the hole started and centered. Carbide will cut through HSS(drill bit)or even cobalt. Go slow and whittle it out. You will probably not have a good thread after your removal procedure.So, I would tap for a Heli-coil or Tri-sert.
I definitely wouldn't bother trying to drill another drill out with a drill of the same material.That is an exercise in futility.

I agree that carbide is the way to go. However I would recommend getting a 1/8" 4 flute carbide endmill. They are about $15.00 at almost any industrial supply house like J&L tool. I've used them in the past in a Dremel to remove broken drills and taps and they work great. You just have to go slow and make sure that you are holding the Dremel as rigidly as possible. The other nice thing about using a carbide endmill vs a drill is that if it does get stuck and break off in the hole you can easily break it apart with a center punch and remove it.

[geneborg]

Broken Drill Bit Removed

I got it out finally today with some of the advice provided by those above. I called Dremel and found out that their hardest "bits" are called Tungston Carbide Cutters". I found what I needed at either Home Depot and Lowe's. I got several different types for I was determined to affect removal.
They are not drills and seem to work best using the sides and being careful and not a lot of force is needed.
But, now I have a bit of a hole that is not very straight. So now back to the Dremel and make an effort to get the hole straighter so the carb boot lines up over the port. Once this is done then to figure out the best way of either cutting new threads or using a HeliCore.
Any further suggestions would be much appreciated.

[tarzan]

If you got the drill out, don't dremel any more. Measure the hole. If you don't have calipers to measure it, use the shank end of drill bits.That will give you a good idea of what size it is. Those bolts are M6X1. Get a heli-coil if your hole is not too bad. A tri-sert will require a larger hole. So go that route if you have to. Tri-sert is actually stronger anyway. But a heli-coil will be easier to obtain and cost a little less.
You just drill the size the kit recommends for the insert you choose. If your hole is already close, just go ahead and tap it.And BTW, this is where you want to be real careful. You want your new hole to be as perpendicular to the head as possible so the bolt will line up when you remount the boot. But the tap should follow the old hole anyway. It really is a simple process.It just seems complicated if you haven't done it before.

[jimbilton]

Broken Bolts-Removal

Here's my advice, for what it's worth:
It is possible that you might not have drilled out the whole diameter of the old bolt. Sometimes, the drill goes slightly off centre, and you end up with a crescent section of old bolt still partially lining the hole. If that happens, you will find it almost impossible to thread the hole with your Helicoil tap. You need to get that shell of the old bolt out - possibly using Snap On picks or similar, before drilling with the Helicoil size drill, followed by the tap. Hope that makes sense!
Anyway, the very best of British luck!