Set up on a lathe for drilling out broken bolts

[Frank S]

My welder mechanic neighbor dropped off a part he had tried to remove a couple of broken bolts in with a torch. He said he had first tried drilling them out, but his drill bits were no match for the hardened bolts, so he decided to do something he has seen me do by burning them out with his torch. People really shouldn't watch me do this and then think they will be able to do it themselves from only witnessing it done once. Maybe I got lucky that one time or I was burning out a hollow dutchman of a broken off pipe fitting or maybe I already had a hole drilled through the bolt.
Anyway he had already created the damage and just needed the bolts out so First I tried to mount the part in my mill but the head on the Enco table mill could not be centered over the holes due to the shape of the part. SO I looked to one of my LeBlond lathes the one I have used to line bore bearing locations with in the past. Again no go, I could clamp the part on the compound with the tool post removed but there was no way to make a second clamping point. Then I looked at my Sheldon 12" and sure enough the Sheldon is made for stuff like this. it has a T slot cut all the way along the center of the top of the cross slide. By removing the tool post and using a 5/8 18 all thread rod in the base for the tool post I was able to use the holes in the part to clamp it down, then with one of the flange nut T nuts I made in the past and one of my 1 1/2" tramming riser blocks I removed the tramming sleeve and bolted it down to the cross slide then C clamped the part to that using soome washers as spacers to get the correct height to the center of the spindle

the part was through drilled which made it easy to align it for drilling



By relocating to the other hole in the part I was able to center up on the second bolt


I have one other lathe that is well over 100 years old still runs great but currently just a dust catcher sine I'm not using it but in looking at the carriage of it today I noticed something I had forgotten the compound and the top of the cross slide can be removed in just a few minutes leaving a milled flat carriage top surface with 4 T slots for mounting fixtures in maybe I need to re think letting it just gather dirt because it Has Frank's special tools written all over it

[DIYer]

Thanks Frank S! We've added your Broken Bolt Removal Method to our Lathes category,
as well as to your builder page: Frank S's Homemade Tools. Your receipt:

Broken Bolt Removal Method by Frank S

tags: lathe, disassembly

[Paul Alciatore]

I have four words for you and your friend:

Left hand drill bit

They are my first "go to" tool for broken screws and bolts. The great thing is you almost never have to actually drill through the stub. They usually just back out from the torque and vibration before the drilling proceeds even one thread pitch into it.

When I said the first tool, that does not mean that I do not give it a good soak with penetrating oil. My favorite is Kroil and I like to give it hours or even over night to soak in. On really stubborn ones, striking it with the center punch while soaking can also help. You need to make a dimple in the stub anyway so using it to help the penetrating oil to wick in is a bonus.

[Frank S]

I have four words for you and your friend:

Left hand drill bit

They are my first "go to" tool for broken screws and bolts. The great thing is you almost never have to actually drill through the stub. They usually just back out from the torque and vibration before the drilling proceeds even one thread pitch into it.

When I said the first tool, that does not mean that I do not give it a good soak with penetrating oil. My favorite is Kroil and I like to give it hours or even over night to soak in. On really stubborn ones, striking it with the center punch while soaking can also help. You need to make a dimple in the stub anyway so using it to help the penetrating oil to wick in is a bonus.

My problem there is I never get the offended part before someone else has had a hand in trying to remove them on their own. Left hand drill bits do work I'll give you that. Most of the stuff that comes to me has suffered every malady a piece of earth moving equipment can endure and more. Far too many maintenance men will impact a bolt into a thread ed hole that has rust dirt and everything else in it, galling the threads on the bolt and the hole the whole time, on top of that they will pour in half a bottle of red loctite before even screwing in the bolt then wonder why they can't tighten the bolt properly or the next time they have to change out something they snap the bolt off with a 1" drive impact. I have drilled completely through bolts with left hand drill bits and stepped all the way up until nothing would be left but the Dutchman of a thread and still not had them come free, but other times when I look at a broken bolt and just dread what it is going to take to remove it the thing will back out on its own accord nearly as soon as the bit touches it.

[Improvised DIY]

Sometimes the threads are so gulled that you can't pull the bolt's threads out even after drilling a thou into the casing's threads. Fine threads are the worst. They almost cold fuse together. I had this issue with a lawnmower. The bolt was broken of at an angle and my mill was too small to fit it in so I had to hand drill it out. I tried easy-outs with no luck. I managed to get just enough threads out to get a tap to bite and break out the bolt's threads with the tap. I wish I had left hand drills but in RSA it's like chicken teeth and very expensive.