JIC Fitting Question

[mattgancz]

Greetings Forestry Forum:

I have a hydraulic hard line that has a JIC fitting on the end.  There are two sections of thread: one for the hydraulic fitting, and one for a retaining nut.  The retaining nut holds the hard line in place in a block --- it has nothing to do with the fitting, but the threads are the same.  The threaded section for the retaining nut is galled, and I need to use a die to clean it up, but I am not sure what die to look for. 

Here is what I think I know . . . JIC fittings use UNF threads.  Is that correct?

The outer diameter of the threads was measuring 1.053" on the hard line.  That is not 1", and it is not 1-1/8".  Is there a 1-1/16" UNF die?  Is that what I should be looking for?  If anyone can point me in the direction of the proper die to clean up these threads, it would be greatly appreciated!

Before someone says it, I know that I can replace the hard line with a hose. 



 

 

[Firewoodjoe]

The male thread needs cleaned up? Just use a hack saw blade. 

[mattgancz]

Indeed, Firewoodjoe, I have also cleaned up threads with a wire brush and a file, but in this case I need more info on the thread type.  Any ideas? 

[EricR]

JIC -12. Is a 1-1/16-12 thread. 

[Hilltop366]

There is also thread files.

[GAB]

I have a POCKET REF book by Thomas J. Glover  (ISBN  1-885071-00-0)
On page 389 there is an AMERICAN STD STRAIGHT PIPE CHART and one of the entries is;
Pipe Size 3/4"
Threads per inch 14
Pipe Diameter inch 1.050
Tap Drill 15/16"
I think the inner diameter is less than 15/16" to have the seat that is shown.
Hope this helps.
GAB 

[Old Greenhorn]

If it's as Eric says, and I believe he is correct, you can take your calipers and check the pitch on that thread by measuring along the centerline from the crest of one thread to the crest of the next. If it's a 12 pitch thread that distance should be .083", 11 pitch would be .090", 14 pitch would be .071. 1.050 sounds just about right for a 1-1/16 thread.
 Good luck, let us know if this didn't help and I will dig further, but I think Eric got it right. you can get a 12 pitch thread file and clean that up easy. Also, carefully clean up the nose taper before you put it all back together.

[mike_belben]

You need a small triangle file. Threads are all 60 degree, just a plan ol equal on all 3 sides triangle. Ive been fixing threads with them 25 yrs or so. One good file will do every diameter, pitch, direction and standard or metric. 

A hacksaw will work in a pinch in coarse threads but itll eat up the root in a fine pitch.  

Use marker as layout dye to see where you need to file.  Keep fitting the male on until it binds then unthread and look for the shiny spot.  Buff a little and repeat until its perfect.

[treemuncher]

I learned a new trick from Mr Belben today! I will keep that in mind when I can't find a thread file.

I normally use thread restoration files. They usually come in SAE or metric and have 8 different pitches on one unit. Keep rotating the file until you find the one that matches up with what you have. They limit the depth of cut and restore your messed up threads to a restored, usable unit in most all cases. One of the best tools I keep that I don't use all too often. Super easy to use.

See here: Amazon Thread Restoration File Set
 
For your 1-1/16 12 pitch you will need the file with the 12 tpi

[Old Greenhorn]

Mike's method is a good one, but remember Mike has been doing this a long time and has a brain in each one of his fingers that many folks lack. A skilled machinist can do this without thought, for others, just like sharpening your saw chain, it can take some practice. You need to hold that file at the same helix angle as you find on the thread and be very uniform. Of course a tiny flat spot here and there won't kill you on most threads, but on precision threads with high loads it becomes important. It is also easiest done in a lathe at low RPM and you MUST keep the file moving, using oil helps too. Needle file sets almost always have a suitable tri-angle file in them that will work. Thread repair files are easier to use and more forgiving but remember that helix angle.
 For smaller OD threads such as this one, I often make my own chaser die out of a nut by drilling a hole that breaks out into the thread hole only partially, then I use a needle file to sharpen a cutting lip. They don't hold up long but can be re-sharpened and usually get you through 1 or two bolts without running to the store or ordering something. i.e. They get your machine back on the road while the snowstorm is still blowing, which is what most of us are looking for.

 (P.S. to Mike: YOU know that not all threads are 60° Mike! Acme (29°), Buttress (45°&7°), British Standard Whitworth (55°), American Standard Microscope Objective threads(55°), Trapezoidal Metric Threads (30°), British Standard pipe (55°) , and several others have different thread forms.  :D But yeah, for the majority of common threads here in North America, 60° is the norm. I don't have the data on Japanese threads but I did a project one time that required about 50 English, German, and Japanese versions of various pipe and sealing threads up to 6" diameter all mixed up in this one assembly. Some were 'double contianed' (i.e. a pipe around another pipe) because of the caustics. It was a nightmare getting the fittings.

[mike_belben]

Alright, i will clarify.  Any thread worth fooling with is 60°

;D

[Old Greenhorn]

Agreed! :D ;D

 I know you knew all that, but other folks read this stuff when they search the internet and I was just being clear while also enjoying the opportunity to bust your chops a little. Win-Win. ;D :D Man, I have more of that stuff in my head that I ever wanted and now that I am retired I am desperately trying to replace it with useful information like tree species, log scaling, and other much more useful daily information.

[Crusarius]

its funny, I can file threads like nobodies business, but sharpening a chainsaw chain is black magic.

[charles mann]

We have lots of an and ms, some being a bulkhead fitting and sometimes, replacement isnt an option during an aog event, and we utilize jeweler files (needle files), to clean up a lot of fittings to get us back up and flying. Most of the time our clean up efforts last for years. Just gotta ensure the bulkhead jam nut is tight and stays tight, sometimes using green or blue loc-tite or simply use torque stripe. 

[Old Greenhorn]

Charles, I think you are referring to AN and MS ports and fittings such as are seen on aircraft hydraulic valves and manifolds. These IIRC, are still using standard thread forms, are they not? I know the AN thread system is long obsoleted but still shows up in legacy designs and my previous employer still uses some of them. They have a small root radius in the thread (.005-.007R) if I recall. The pitches are standard numbers (although not 'normal') and major diameters can be odd, like 15/32 or 17/32 with generally finer pitches for what one would normally expect. Needle files, as you say, do work jus fine on them. It is difficult to find the specs for those threads in any of the current myriad of machinist's handbooks, which is why I hang onto my copy from 1962 when all that still was still current state of the art and I used to have the MS port specs in my toolbox for decades, they had some tight tolerances. My first toolmakers apprentice job was making the tool bodies for those special MS porting tools. I used to have every dimension, angle, and diameter in my head, by the dash numbers. More useless information I have long since replaced. :D

[charles mann]

Ok@Old Greenhorn 
Im referring to bulkhead fittings, be it an or ms or whatever style, which is similar in what he is dealing with, a bulkhead style. I was just giving an option to repair the threads that could be a permanent repair without going out buying a die, in stock or a special order. Also adding the fact that bulkhead fittings need to be tightened and rechecked at intervals if a locking method hasnt been accomplished. We are always retightening fittings on a weekly basis. 

We have an and ms scattered throughout our acft, not just in manifolds and valving. When did an go obsolete? Acft makers are still putting them in new manufactured acft. 

[Old Greenhorn]

Yes, and your option was a good one, I didn't intend to imply anything else. I do it all the time too.
 I don't believe he AN standard is obsolete, except in name only. Those threads and port system are, I believe duplicated in the MS series somewhere. The terminology lives on through word of mouth and engineers using the same specs they have always used. There was an AN thread spec that was somehow tied to Porting Spec. That thread spec is long gone, since I think, the early 80's. The engineers at my old plant would put an AN thread spec on a print and I would challenge them every time to give me the specifics. I told them to look them up and put them on the print. They couldn't find them anywhere. I insisted that if they put it on the print we needed to have Major, Minor, and Pitch Diameter clearly called out or they would get bad threads. You can use it, but if there is no common reference, you have to put the details on the print. They used those threads because we had been making similar tools for 60 years and backward compatibility was required. Don't get me going with the issues we had between NPT and NPTF threads. These engineers didn't get that either. Engineering schools these days don't teach much about specs, standards, and how things work. They also never seemed to get that NPTF (or NPT) should not be used for hydraulics over 2,000 PSI and used them all the time on 6-8,000 PSI circuits because "We've always done it that way". Another reason I retired. I don't want to be around when stuff starts blowing up.

[mattgancz]

JIC-12, 1-1/16 - 12 thread, i.e., bolt thread.  I was confused as the thread chaser set I had in front of me jumped from 1" to 1-1/8".  The local hydraulic shop had the oddball size, and let me use it for the 145 seconds it took to complete the job. 

I had to clean up a section of thread with a hacksaw though; thanks, Firewoodjoe.

[tacks Y]

Glad you got it taken care of.

I had a problem with a spindle and used the nut and some valve grinding compound to get it working.