Jig Needed to Heli-Coil Threads for Farmall SA-140 Cultivator Mount on Steering Box?

[RTR]

Wondering if a jig would be needed to drill, tap, and helicoil the bolt holes on a steering bolster that hold the set screws which hold the universal mounting frame (UMF) tight on a Super A, 100, 130, and 140. I've never had to make this repair before and have seen/read where forum members have a "jig" for doing this on the final drive holes, but also didn't know the purpose of the jig either. I was planning to get my drill and go after it unless someone recommends using a jig (would need to know how to make it), or has other tips and tricks before I dive in. This is my first helicoil repair on anything.

I've got a good 21/32" USA drill bit, the 5/8"-11 helicoil kit, and my Milwaukee M18 Variable Speed Drill with 5.0 Battery.

* Also posted to another Farmall Tractor Forum

 

[kshansen]

While one could fabricate a jig to help hold the drill bit and or tap nice and straight it is not essential.

If doing several of these can think of ways to make one using the adjacent holes and a chunk of scrap iron.

But for a one off repair probably just be careful to keep drill bit nice and square to the surface and same for the tap,

 

[Jim Becker]

Since the part you are drilling is mostly curved surfaces and odd shapes, I suggest screwing a chunk of 5/8 all-thread into the next hole over. It will serve as a visual guide to hold the drill parallel to the all-thread.

 

[RTR]

Since the part you are drilling is mostly curved surfaces and odd shapes, I suggest screwing a chunk of 5/8 all-thread into the next hole over. It will serve as a visual guide to hold the drill parallel to the all-thread.

Thank you!

 

[RTR]

2 freshly helicoiled holes !! Didn’t want to go any farther in cause the insert was just barely protruding through the other side of the hole. Thank you all for the encouragement

 

[Fritz Maurer]

If you don’t like the looks of the helicoil hanging out the top, take a cut-off wheel and grind it flush with the casting.

 

[Hendrik]

2 freshly helicoiled holes !! Didn’t want to go any farther in cause the insert was just barely protruding through the other side of the hole. Thank you all for the encouragement

Congrats; seems like a job well done.

 

[560Dennis]

That’s a very interesting question. The design of the casting in my opinion makes it very difficult to apply the one ,two three principles Of work pieces supporting. Its must be done and you can do this.
Think about the datum the original line of the threaded hole center line the cultivators supports. the tools use to install the heli coil must accurately follow that center line with out any chance of moving Off the center line ,this is a must ,you must create this in your machine shop with your availability. Preparing is 90 percentage of your job ,putting the helicoil will be a cinch .

 

[BarnyardEngineering]

I realize that you've already completed the project. However, I feel it important to mention that the amount you were drilling those holes out is very minimal. The drill bit will tend to follow the existing hole, jig or freehand.

 

[J.Wondergem]

I realize that you've already completed the project. However, I feel it important to mention that the amount you were drilling those holes out is very minimal. The drill bit will tend to follow the existing hole, jig or freehand.

Right. I put them in the three holes the held the starter in on one of my road tractors years ago, and the bell housing was aluminum. It held for over a million miles, still there when I got rid of it.

 

[Hendrik]

I realize that you've already completed the project. However, I feel it important to mention that the amount you were drilling those holes out is very minimal. The drill bit will tend to follow the existing hole, jig or freehand.

That's true for the position of the centerline of the whole; however, the centerline of the original hole and the centerline of the hole you are drilling shall be parallel, and preferably coincide.

 

[kshansen]

If you don’t like the looks of the helicoil hanging out the top, take a cut-off wheel and grind it flush with the casting.

Or like I have done when the insert is longer than the casting would be to trim the thread insert before installing. If you have not broken off the installing tab you could run it out the back side, trim and reinstall.

 

[caterpillar guy]

Only thing I will ad is if those holes have oil behind them you might have wanted a sealer in the threads before the heli-coil went in and now with the bolts to hold the cultivator.

 

[RTR]

Only thing I will ad is if those holes have oil behind them you might have wanted a sealer in the threads before the heli-coil went in and now with the bolts to hold the cultivator.

Not the case here. They are through holes with nothing but solid casting around them.

 

[BarnyardEngineering]

That's true for the position of the centerline of the whole; however, the centerline of the original hole and the centerline of the hole you are drilling shall be parallel, and preferably coincide.

Very few things are built to such tight tolerances that it has to be perfect. Besides we're talking about a stripped thread here not an ovaled-out hole. The hole is still round and straight, and will guide the bit.

 

[kshansen]

Very few things are built to such tight tolerances that it has to be perfect. Besides we're talking about a stripped thread here not an ovaled-out hole. The hole is still round and straight, and will guide the bit.

First a disclaimer that this is not in anyway aimed at the original poster of this thread!!

But I've seen way too many screw-up on thing to say that a project like this can not be messed up.

Like a boss of mine once said: "There are some people so bad that you could lock them in a padded cell buck necked with and anvil and come back ten minutes latter to find a pile of iron dust on the floor!"

I'm sure many here know some people like that!