drilling out dogleg screws

Mon Sep 17, 2012 5:56 pm

The cub I was repairing the touch control on had a dogleg screw broken off in the steering side radiator casting, but luckily it was the front one which is easier to get too. However when I was removing the rear screw it broke too, which is a little more difficult. I did not have a right angle drill small enough to go in there, nor a bit long enough to reach past the steering housing, so after looking through my assorted junk I came up with this. I had three or four 1/4 inch drill motors that had not been used in many years, so one of them became a chuck donor, I mixed up some JB Weld and spread on the threads of a 3/8 fine thread bolt, then screwed it in good and tight. The JB Weld is so I can use it with a left hand twist bolt if I ever need too. I cut off a dull 5/32 bit and resharpened it, and was in business. I did remove the 2 bolts in the seal holder for the steering shaft to get a little more room. The 5/32 bit is very slightly large for the 10/24 tap, but I did not have any numbered bits, which is what it should have been, but all seems ok.
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Re: drilling out dogleg screws

Mon Sep 17, 2012 6:05 pm

great idea John, I have to look through my scrap bin

Re: drilling out dogleg screws

Mon Sep 17, 2012 6:07 pm

Same thing happened to me. I ordered a 6" long 5/32" bit from Grainger, then retapped after using the JB Weld trick. Worked slick. :wink:

Re: drilling out dogleg screws

Mon Sep 17, 2012 6:50 pm

Good thing the iron ore train did not come by during the drilling :D

Re: drilling out dogleg screws

Mon Sep 17, 2012 7:28 pm

Better to be slightly large in the pilot hole, than to twist the tap off in the hole!!!

Re: drilling out dogleg screws

Mon Sep 17, 2012 8:05 pm

Matt Kirsch wrote:Better to be slightly large in the pilot hole, than to twist the tap off in the hole!!!

BTDT.. :oops:

Re: drilling out dogleg screws

Mon Sep 17, 2012 9:53 pm

John:

Ingenious :!: I like that idea. I have a few old/dead drills that would make good donors. I can see that mod being useful in a number of places.

Re: drilling out dogleg screws

Tue Sep 18, 2012 7:02 am

I like that approach as well, John. There's probably a number of situations where this set up will work. Thanks for the tip!

Re: drilling out dogleg screws

Tue Sep 18, 2012 8:14 am

To those that are not familiar with removing a drill chuck it is a normal right hand thread, and to remove it put the short ind of a large Allen wrench in the jaws and give it a sharp wrap driving it in the same direction the drill turns. A hammer handle, large wrench or crescent seems to work better than a hammer. If you have an impact, grind some flats on a volt for the jaws to grip and use an impact on the bolt would probably work good but I never thought of that at the time. A real old drill that has been used a lot is normally extremely hard to unscrew the chuck from. I hit that one so many times that I finally broke some teeth of the driven gear, and then took it apart and clamped it in my big vise to hold it. No problem though, I had 3 or 4 of them laying around that had not been used in years. If the drill you are taking the chuck off is a reversible drill there will be a screw inside the chuck that locks it in place. You have to open the jaws all the way then reach down inside with a screw driver or allen wrench and remove that screw before unscrewing the chuck. If you don't want to unscrew a chuck form one of your drills, replacements can be bought pretty cheaply form Amazon, Ebay, McMaster, Fastenal, Northern Tool, etc.

Re: drilling out dogleg screws

Tue Sep 18, 2012 8:37 am

John,
...another ingenious idea for dealing with the dogleg screws on the right side.
Plenty of "how to's" on this repair in the archives.
The two most important things to remember in this repair;
1) Patience
2) Don't drill too deep! The dogleg screws are only #10-24 NC x 1/2". Any deeper than necessary and you will puncture the casting and have coolant all over the place. 5/8" is deep enough, put a piece of electrical tape around the bit or chuck the bit so only 5/8" sticks out.

Peter

Re: drilling out dogleg screws

Tue Sep 18, 2012 9:15 am

I was wondering what # size would be right for this job, so I went looking and found this helpfule little piece of information:

http://www.boltdepot.com/fastener-information/US-Tap-Drill-Size.aspx