Tenon/thread dimensions for Defiance Deviant???

[Jeffrthehunter]

Getting all practiced up to cut my first barrel tenon and have a few questions, hoping someone could help me out.
1) The Deviant has a built in recoil lug with threads close to the shoulder, is it okay to cut a small thread relief on the barrel tenon? Checking minor diameter specification I was thinking .970" by .100" long. This would give me a great comfort level to not hit the shoulder.

2) Not sure of the exact spec that Defiance cuts to I want to make sure I have plenty of clearance at the thread roots. What major diameter should I turn, with plans for a little polishing after cutting the threads?

3) The carbide inserts I have have a .003" radius, any problem with that?

BTW, I have some Stainless steel bar stock to practice with, so far the threads look great.

Thanks, Jeff

 

[Roeder]

Sounds like you are on the right track. The major diameter can be a little small and this is helpful to prevent the dreaded galling. about 1.055 to 1.058 is fine. There is no benefit to cutting them tight. Polish and clean the threads and use a little lube of some kind when you trial fit the action. If it starts to feel tight or gritty, STOP, back off, polish a little more or take a free pass and try again. There are cases where cutting the threads to a nominal pitch diameter is not quite enough. The few Defiant actions I have fitted were very consistent.

 

[Jeffrthehunter]

Sounds like you are on the right track. The major diameter can be a little small and this is helpful to prevent the dreaded galling. about 1.055 to 1.058 is fine. There is no benefit to cutting them tight. Polish and clean the threads and use a little lube of some kind when you trial fit the action. If it starts to feel tight or gritty, STOP, back off, polish a little more or take a free pass and try again. There are cases where cutting the threads to a nominal pitch diameter is not quite enough. The few Defiant actions I have fitted were very consistent.

Thanks for the info! I have read from others that you want tight threads which has concern me (would hate to seize up an action), a little play is ok?
Jeff

 

[sable tireur]

You can cut a thread relief just don't go too deep...

Please look at the 2nd illustration in the top row, American National. The crest on top of the thread form can be rounded or flat depending on the shape and type of tool being used. The root of the thread form should be either as well. Normally, we keep the crest of the thread form flat so that it doesn't touch the root of that thread, causing it to gall. The simple method is to cut the tenon diameter just a little smaller in diameter while cutting the thread to depth. Some folks use the full diameter then just run a file across the tops of the crest. Remember to dress the sides of the crest after this is done. No matter how it's accomplished, the crest should never touch at the root of the thread.

The lock up is the face of the action and the shoulder of the barrel. This has to be perpendicular to the bore line. Over tightening a thread stretches the thread which can lead to galling also.

Regards.

 

[Roeder]

Thanks for the info! I have read from others that you want tight threads which has concern me (would hate to seize up an action), a little play is ok?
Jeff

A little play (clearance) is not only OK, but is correct and necessary. There is no accuracy benefit to overly tight threads. It seems counter intuitive, but benchrest guys have proven it.

 

[Alex Wheeler]

Thread reliefs are fine, there is no accuracy in thread fit, your insert is fine, major OD is not critcal.

 

[Jeffrthehunter]

Thanks to everyone for all the good information. Cut the tenon and reamed for a 7RM, everything went great. Had a hard time getting a good finish on the threads, will need to try other inserts next time.

 

[jrock]

Not bad. Next time, if you look really close at the front inside edge of the receiver, you'll see they have cut a small chamfer on it. Furthermore, if you measure where the threads start in the receiver, you'll see you have about 0.10" from the shoulder to the first thread. No thread relief is needed even with a tool with a radius. You just have to take the measurement.

Use HSS for a better slow speed finish. A sharp bit and proper tool post angle will leave very clean threads. I tired Cratex embedded abrasive pads for polishing the threads and absolutely them.

 

[Jeffrthehunter]

Not bad. Next time, if you look really close at the front inside edge of the receiver, you'll see they have cut a small chamfer on it. Furthermore, if you measure where the threads start in the receiver, you'll see you have about 0.10" from the shoulder to the first thread. No thread relief is needed even with a tool with a radius. You just have to take the measurement.

Use HSS for a better slow speed finish. A sharp bit and proper tool post angle will leave very clean threads. I tired Cratex embedded abrasive pads for polishing the threads and absolutely them.

Thanks for the info. Just ordered some HSS inserts from Arthur and will look into the polish pads.

 

[Clark]

I cut major diameter at 1.062", and the crests were not even pointy. Fits better than any rebarrelling I have done. No side to side play with just a few threads engaged. Rotates very smoothly. I am impressed with this action!

 

[Clay Target Guy]

You can always thread away from the shoulder. There is a great youtube vid. by Joe something (can't remember his last name. Anyway, sure makes things way easier.

 

[Clay Target Guy]

 

[tobnpr]

Been three years.
He's probably finished the barrel by now.