Question on taps for cleaning up threads

[willy3486]

I have been working on my tractor. In the process The bolt threads that holds the hub on and the axles threads got a little messed up about 1/4 inch of the way. I should be able to clean them up. The Case tractor website says the bolt is a 3/4-16 NF x 1-1/4" I take it the 3/4 is the width of the threads, the 16 nf is 16 threads nation fine and the bolt is 1-1/4 long.

From the website this is a discontinued bolt. I am wondering if that bolt could be found at NAPA or is it special threads/bolts? Most of the time if I need bolts I go to tractor supply and get any I need but these threads are tighter.

The other question I have is I found a tap to redo the axle. I am not a tool and die person so I am not familiar if it would work but I think it might. Here is the tap I found, does it sound like it would? Thanks in advance.


https://www.amazon.com/dp/B00UM60674/?tag=atomicindus08-20

 

[threewheelin0070]

Yes the tap your looking at is fine as long as it's not a blind hole your tapping ie...a hole that's not drilled all the way thru.If it is you would use a non tapered tap .
Use oil on the tap so you don't break it and go slowly

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[s14kev]

Don't use a tap. That will just cut off the damaged threads. Proper tool is a thread restorer such as those sold by JAWCO. They push the deformed threads back into a more normal shape.

The bolt you need is available from McMaster Carr for $12 for a pack of 5. They ship inexpensively and are usually overnight for me with standard shipping. This may vary for you depending on location.

 

[txredxj]

Use thread cutting fluid, it will be called Tap Magic at Napa. 3\4-16 is a standard bolt thread and should be easy to find a bolt and tap at Napa.

Start tap by hand and let it find the threads. Make sure it is straight in the hole before you put a tool on it so you don't tap it crooked and double cut the threads.

 

[Muggzy]

Don't use a tap. That will just cut off the damaged threads. Proper tool is a thread restorer such as those sold by JAWCO. They push the deformed threads back into a more normal shape.

The bolt you need is available from McMaster Carr for $12 for a pack of 5. They ship inexpensively and are usually overnight for me with standard shipping. This may vary for you depending on location.

x2. Also a big thumbs up for Mcmaster Carr [emoji106]

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[Richard Cranium]

do not use a tap, use a thread restorer.

 

[Tracs]

Don't use a tap. That will just cut off the damaged threads. Proper tool is a thread restorer such as those sold by JAWCO. They push the deformed threads back into a more normal shape.

The bolt you need is available from McMaster Carr for $12 for a pack of 5. They ship inexpensively and are usually overnight for me with standard shipping. This may vary for you depending on location.

I agree. I've watched too many "restoration" videos on youtube where they run tap/die into threads. They end up cutting more material off and leaving the nuts/bolts re-cut and end up loose.

 

[DFB]

Also look the head marks on your bolts so you match up the grade

Anything in 1/4" increments is often difficult to find as common stock like in any hardware store. The usually just jump by 1/2" inch

NAPA just may have that size don't hurt to give them a call. I once found some special length thread bolts there (they were the only local place)

I have had this problem with HD bolts for years. Worst case scenario have to modify some.

Worth owning a thread restore kit, though the most common kit taps size out smaller than what you looking for. I also have a spindle rethread kit that covers the most common sizes for axles

 

[matt_i]

Couple of things

3/4" is "major diameter" and the -16 is threads per inch. A 3/4-16 is a UNF united national fine thread series whereas a 3/4-10 would be a UNC coarse thread.

I would use a tapered "plug" tap (and not a bottoming). The keys are to tap on the same axis as the original and to tap on the same "lead" as the original. "Splitting the lead" involves carving out good thread crests which really messes things up. So it takes a little feel to find the path of least resistance which is always going to be the original lead. If there's a big gob of smashed metal its a good idea to remove that because its going to interfere. A little dremel tool with sanding drum is a good tool to clean up the ID to simulate the original tap-drill if necessary.

I have had good luck locally at Ace Hardware. They seem to stock a lot of oddball fasteners, I could order them from McMaster but with the ~$8-10 shipping charge the Ace is a better choice for a single item.

As was mentioned above I would go for Grade 5 minimum, 3 hashes, or Grade 8 is also acceptable, it has 6 hashes on the hex head.

 

[willy3486]

I got it fixed tonight! I stopped by Napa on the way home as it was the easiest to get to. They had a bolt with the right threads and a little longer but not much. That will work out great as it had really deep threads. I also got a tap as that was what they had. I tried the bolt but it wouldn't go. I then tried the tap and it cleaned out the threads up towards the end where it was messed up.

I have some oil for tapping holes in a squirt can and I would move it about half a turn then back it out a little then turn again. All the while I would squirt the cutting oil in there. After every few turns I backed it out and then cleaned out the hole then run it again. I has able to get it almost to the end, I stopped short as it was deeper than the bolt.

After this I put the new bolt in and it went in fine. I also got a grade 8 as suggested. So now I can replace the seal and brakes on that side then move on to the other side and replace those brakes. I also have a new hydraulic filter to replace. So thanks for all the advice as it helped a lot.