Stripped thread hole repair question

[lone wolf]

They used to send me catalogs that were 3 inches thick. Doesn't tell me what to buy.

Call them, then IDK.

 

[ZeroJunk]

Another FWIW. P.O. Ackley said that a screw in a blind hole the first 2 threads carried 90% of the load and the fifth one was always loose.

 

[ZeroJunk]

Call them, then IDK.

Stihltech gave me a simple way to do it that makes sense.

And, I have all that stuff.

 

[TLG]

Thin wall keenserts from McMaster Carr. Save all that screwing around. Just look up on the website.

 

[singinwoodwackr]

They used to send me catalogs that were 3 inches thick. Doesn't tell me what to buy.

One of each

 

[avason]

I’ve been having issues with my 372 starter cover holes being stripped. Will watch this again and then make the repair.
Hope you guys find this instructional.

 

[muddy42]

I've always done the same thing with broken or dull taps. Having said that, with regards to heli-coils and the like, it's worth noting that a bottom tap still has a slight taper to the last couple of threads. Its less taper than a plug tap, but its still there. It shouldn't cause a problem, but be aware that the end isn't actually square like it would be if you ground the end off. If I'm putting heli coils in a blind hole, I start off with at least 2 taps, with one being a plug tap. I prefer for the 2nd to be an actual bottom tap because that 1 to 1.5 threads of taper does make it a lot easier to cut those last threads where as an absolutely square corner puts all the cutting force on the leading tooth making it harder to cut, and easier to break. When I'm done, if I'm concerned about it, I'll grind the bottom tap square and go back one more time and cut the very last thread. The only time I went to that much effort was when I was putting inserts in to the engine block on my '83 Ford 1710 tractor. Most of the mounting bolts were loose and the threads were wallered out. It was bad enough that the vibration would wear out o-ring seals on part of the hydraulic system ever 8 to 12 hrs of operation. I installed the longest helicoils I could get, and was thankful that I didn't poke through anything while drilling. Since cast iron threads aren't really the strongest, and the diesel engine on a utility tractor is prone to experience a fair amount of vibration, I wanted every thread I could get and I wanted all of the torque to be going into the clamp force. I've checked them a few times since, and they've stayed tight. Now I get about 24 hrs of use before having to replace that o-ring. Not ideal, but I only gave $2K for the tractor with the loader, so I'm not going to complain too much.

Yes, Ive also made basic taps from threaded steel rod. I cut a slot in the end of the rod and then ensure the threads are clear and edges sharp. If the metal is soft, you can use them like this, but once I went as far as to temper the steel to make it stronger. Works well.

 

[Piotr Pakuła]

Magnesium must be welded in an argon atmosphere, i.e. in a sandblasting box, to avoid ignition

 

[lone wolf]

Magnesium must be welded in an argon atmosphere, i.e. in a sandblasting box, to avoid ignition

Some are magnesium alloy, no? Not all are pure magnesium.

 

[fields_mj]

Yes, Ive also made basic taps from threaded steel rod. I cut a slot in the end of the rod and then ensure the threads are clear and edges sharp. If the metal is soft, you can use them like this, but once I went as far as to temper the steel to make it stronger. Works well.

I'll do that with a Grade 8 bolt, especially if I'm cutting threads into a piece of wood for some project at home or cleaning out threads in aluminum.

 

[Lightning Performance]

Why not use aluminum round stock, it's easier to tap?

Why not use brass or bronze?

It's much more workable. It can be peened over to fill voids. Heated to conform better and etched or roughed to hold fillers around it. I drip feed it into heated aluminum before. Mag will act about the same. Not enough heat to need shielding gas or worry about ignition happening. Once you wet it with tin or something it lays right in. Solder also works here but is softer. Four or five threads is good with solder. Brass needs about three. More than seven threads locks the screws in from distortion and heat over time. Beware of that.

 

[Piotr Pakuła]

Some are magnesium alloy, no? Not all are pure magnesium.

One of them burns a little less intensely