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DA Cam not engaging Hammer, Shorten sear or increase let out?


alecmc

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I'd like a little clarification before I start putzing around, S&W sears are impossible to find, the the apex ones are super expensive, so id rather not just go by trial and error on this one.

The sear is taking the hammer all the way up and completing the cycle without ever transitining to the DA cam on the trigger, its just all sear doing all the work.

I confirmed that I didnt take too much off the trigger or something by testing out with another, and I didnt take anything off the apex hammer, just polished it up with a buffing wheel.

Should I shorten the sear on the same angle? Though this seems to me it would increase " pre-travel " wiggle in the trigger till it starts to engage

or

increase let out

Thoughts?

pics and video

11308823596_f65d3258ee_k.jpg

11308855224_729e778131_k.jpg

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Shorten the sear on the same angle. Go slowly, it's easy to take too much off. You want it to be where there is a smooth transition from one to the other when you rock it back and forth.

It looks like you have ground the diameter of the rebound spring down a little to lighten it some.

Edited by Toolguy
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Shorten the sear on the same angle. Go slowly, it's easy to take too much off. You want it to be where there is a smooth transition from one to the other when you rock it back and forth.

It looks like you have ground the diameter of the rebound spring down a little to lighten it some.

Yes, I shave down a 11 lb rebound to lighten it up.

I'll start shortening it down on the same angle.

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My initial thought is that out could be let out a bit. There is a nice picture of how much to let the sear out to in the Kuhnhausen book. Mine is at work, maybe someone else can post that for you don't have a copy.

Looking at your pictures the cam surface on the trigger looks like it slopes back a lot. Has this been altered?

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Yes...do you ever touch the cam with a file/stone ?
On Kuhnhausen book: don't touch trigger cam.

Don't try to resolve DA problem stoning the trigger bevel/cam or hammer part.
Only work on sear.
If damaged, too shorted or in doubt change sear..but I read it's a problem to find it.

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My initial thought is that out could be let out a bit. There is a nice picture of how much to let the sear out to in the Kuhnhausen book. Mine is at work, maybe someone else can post that for you don't have a copy.

Looking at your pictures the cam surface on the trigger looks like it slopes back a lot. Has this been altered?

I have a copy, and the two solutions were either shorten sear, or increase let out.

Good pictures, that's a good idea with the spring. Do you you put a rod or something inside the spring and run it on a grinder?

Yes, I slide the spring on a allen key and shave it down with a sanding wheel on my dremel.

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Alex, there is a drawing in there showing where the seat should point in relation to the hand pivot. I would compare that to your gun before you start work. You may need to do a little of each, let out and shorten.

Was your trigger cam modified prior to installation of the new sear? I only polish them and break the edge with a white Arkansas stone. If it was shortened to correct stubbing on the previous sear you may need a new trigger.

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Alex, there is a drawing in there showing where the seat should point in relation to the hand pivot. I would compare that to your gun before you start work. You may need to do a little of each, let out and shorten.

Was your trigger cam modified prior to installation of the new sear? I only polish them and break the edge with a white Arkansas stone. If it was shortened to correct stubbing on the previous sear you may need a new trigger.

No, Like you - I only break the edge slightly with an Arkansas stone, and buff it up. I confirmed it wasnt boogered up by testing another trigger in this gun.

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Do you have another gun with an "old style" hammer you could rob of its' sear to install here for comparison? I'm accustomed to seeing a radius (somewhat like you used the top of the sear as the center) on the sears' contact surface where the Apex contact suface looks straight (flat?). Interesting how the contact point moves across the surface in the video.

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Do you have another gun with an "old style" hammer you could rob of its' sear to install here for comparison? I'm accustomed to seeing a radius (somewhat like you used the top of the sear as the center) on the sears' contact surface where the Apex contact suface looks straight (flat?). Interesting how the contact point moves across the surface in the video.

I pretty much suck at setting the sear, so I dont know about the radius, I was under the impression it was supposed to maintain the same angle ?

Wel anyway, Toolguy - I kept the same angle and shortened it until it started to transition to the DA CAM about 90% through the pull.

Though , now - I have what I thought would happen - excessive " pre-travel " / wiggle in the trigger from the gap until it starts to contact the sear....

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The take-up doesn't matter as long as everything else is working right. On the plus side, a little extra take-up makes it easier not to short stroke it.

It looks like you're there! I would run with it!

oh yeh I know it's not the end of the world, likely i'll never notice - I've got some other revolvers that were done by a true pro and they are absolutely flawless, super smooth , very tiny amount of take up, and run awesome.

I wanted to keep this particular gun to keep as my little own pet project for learning and experimenting and seeing what I can do myself.

Maybe i'll order a few more apex sears when money loosens up and try more of a " radius " on the sear engagement surface to see what I can do to eliminate the take up.

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I have a small 45 degree breakaway angle cut on the front of most of my sears. The angle will allow it to reset a little quicker and would allow it to pass off to the DA cam a little sooner. Too bad sears are hard to come by now, makes experimenting a little hard.

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I have a small 45 degree breakaway angle cut on the front of most of my sears. The angle will allow it to reset a little quicker and would allow it to pass off to the DA cam a little sooner. Too bad sears are hard to come by now, makes experimenting a little hard.

Exactly, Apex is the only sear you can get right now, and at 30 someodd dollars a pop, it makes the whole experimenting and trial and error thing a bit out of reach.

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And another question about this topic:
On Jerry K. book: Ideal clearance on best let-out angle is (from trigger bevel to sear)
.009-.010 front and .010-.012 back.

What is the front and back exactly? Watching the description I don't understand so good.

Thanks

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I'd like a little clarification before I start putzing around, S&W sears are impossible to find, the the apex ones are super expensive, so id rather not just go by trial and error on this one.

The sear is taking the hammer all the way up and completing the cycle without ever transitining to the DA cam on the trigger, its just all sear doing all the work.

I confirmed that I didnt take too much off the trigger or something by testing out with another, and I didnt take anything off the apex hammer, just polished it up with a buffing wheel.

Should I shorten the sear on the same angle? Though this seems to me it would increase " pre-travel " wiggle in the trigger till it starts to engage

or

increase let out

Thoughts?

The Kuhnhausen SW shop manual has a really good section explaining how to fit the DA sear. Probably clearer than anything that could be posted. Super book.

http://www.midwayusa.com/product/314178/the-s-and-w-revolver-a-shop-manual-book-by-jerry-kuhnhausen

Edited by bountyhunter
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