Truing a Rem 700 Dial in Check.

[25WSM]

Gotcha now. So how do you deal with the bore on the actions being different dia. I haven't had one Remington the same in the front as it is in the rear. That why I have about a dozen bushings that I slide in the front and rear separately. My Mandel fits the bushing perfectly so there is no slop.
Shep

 

[bigngreen]

A solid mandrel sits in the center of the bore averaged over the length, it's setting up on the exact plane your bolt will sit in. I have a set of mandrels which were expensive but game changer when looking for the actual center line and having repeatability.

Using two bushings they sit in the center of two spots then we stick a small rod in between, a straight line between those two bushings is not exactly the center of where your bolt is going to sit on many actions.

 

[25WSM]

If the front of the action is 702 and the back is 7025 how do you get rid of the wobble on the big end.
Shep

 

[bigngreen]

There is no wobble, less than you can measure with the two bushing set up, you pick the mandrel that just slides through, it fits in the exact same plane we want to bolt to.
You can see in the video, no wobble and it repeats with a slip fit.

 

[Mram10us]

All my actions have had smaller front then rear. I do the same way, but accept that there is a touch of play in the rear of the action.

 

[nvbowhunter]

Ryan, Your design and the simplicity of it are a testament of a well thought out system that I'm greatly impressed with and must say envious of. You should consider marketing that!

 

[Edd]

There is no wobble, less than you can measure with the two bushing set up, you pick the mandrel that just slides through, it fits in the exact same plane we want to bolt to.
You can see in the video, no wobble and it repeats with a slip fit.

If your action was .702" on one end and .7025" on the other end and you had one mandrel that was .702" and another mandrel that was .702" with a step up to .7025", would you still use the straight .702" mandrel for the dial in?

 

[25WSM]

In my mind if you put a 702 mandrel in an action that has 702 on one end and 7025 on the other and it doesn't have play then there is got to be a warpage or high spot in the race way to make it snug. With a proper bushing at each end the mandrel goes down the center. The bolt typically is 697 to 698 so there is 4 to 5 thou clearence. If I true up as close to the center of the race that I can the bolt has so much play it will find center. My actions trued this way measure . 0001 to . 0002. I just don't think a one dia mandrel will fit perfect in an action that never has the same diameter at both ends. Most remingtons are . 001 bigger in the rear. I know that's not much but when I use a bushing slightly to small my mandrel has play that I can't dial out. That's why I have bushings in . 0001 increments to use the perfect one. I'm not telling you to do it differently I just fail to see how a one diameter mandrel works.
Shep

 

[tobnpr]

Tobnpr you don't understand what he is doing. You can't use a collet to do this work. The mandrel is in the race way and he is indicating to it to center the receiver race way. The action jig is held in the lathe with the Chuck . The jig holds the receiver. The receiver holds the mandrel. The mandrel is free to move forewards and backwards. This is how it's done.
Shep

I understand completely.
It's not rocket science.
There's no need to indicate anything in a proper collet setup. Just like between centers, the mandrel will run true.
Period.

Stick a mandrel between centers (or the headstock end in a collet). If using a collet instead of a 4-jaw, that end of the collet needs to be turned true to fit the collet size.

Other end of the mandrel in precision live center (or dead center with STP or other lube being careful...)

True/face the receiver.

Slide a sacrificial collar over the receiver ring. True the OD. Place it in the steady. Loosen the mandrel locking screw, slide the receiver forward with the steady so that the lug abutments just clear the mandrel. Lock down receiver to the mandrel and the steady to the bed.

Proceed.

Your "this is how it's done" is condescending, and shows that you not only think there's one way (yours) to perform different machining tasks- but that you lack general knowledge as well.

 

[Edd]

I'm not sure how much a half thousandth matters. I have a Model Seven receiver that I just got back from a Gunsmith. He recut the bolt face, lug abutments, and threads. I don't know what method he used for dial in. A .7025" gauge pin will go thru it end to end. A .703" gauge pin will not start in either end. My bolt measures .700". I can blue the lugs and wipe either one or both of them clean depending on how I hold the bolt.

 

[25WSM]

You can do it that way but not with his jig. When I said this is how it's done I was referring to the type holder he is using. I am very familiar with the way you described. I just choose not to make sacrificial parts and set up a steady rest. The jig is simple and leaves the action open for business when the mandrel is removed. Sorry you feel condescended on but this is how it's done on the jig he is using.
Shep

 

[bigngreen]

Actions tend to have some twist in them, we use a bolt that travels in this race way from tang to lug abutments if we put a bushing on either end and dial it in we are basing those cuts on a straight line from one bushing to another, our bolt will not sit on that line unless we ream the action to that line over the whole race way.
Using a solid mandrel the center line of where our bolt sits in the action is what we dial so all the cuts are made based on what I'd call the functional center line of that action.

 

[bigngreen]

Not sure what point you're making?
I've always used collets for receiver mandrels (with bushings). Collets have always been king when it comes to accuracy.

Precision ground mandrels in a quality collet setup will always have near zero TIR and repeatability.
Why dial in a 4-jaw if the workpiece will fit in a collet?

There are a few reasons now that I see how your doing it. First my lathe isn't in a temperature controlled room like most gunsmiths it's just in shop with normal temp swings, my headstock and bed move more due to temp swings than the accuracy I'm trying to run in, if my tailstock is dialed in to zero in the morning by the afternoon it will be a few tenths of same with my headstock.
This set up allows me to do all the action work in a single ridged set up, no sacrificial bushings, minimal tolerance stack, minimal work or tool deflection.
Generally between centers means the action is being driven by a grub screw through the action to the mandrel, by virtue of the set up your biasing the action on the mandrel, my mandrels are precision tooling guaranteed to a spec and not something I'm tightening anything on, period!
Between centers also means you'll have to move your set up multiple times, my set up is done once for the entire operation which is always the goal in precision machining because each time you move the work piece you've changed it.
Rigidity, repeatability of the finished work, surface finish and time all go into why I do it this way, time is money, I can have an action trued before someone running between centers has the lug abutments cut.

 

[25WSM]

Yup. Like he said.
Shep