Hammer & Sear Angles

[Jammer Six]

I've been working on my milspec again, and I have a few problems.

I'm been using a Marvel Hammer & Sear jig, and gazing forlornly through a Yavapai jig at the results.

I have three problems.

My first problem is this: after carefully stoning the hammer hooks in the jig, mating the sear angle to it with the Marvel, the sear doesn't want to drop all the way into the hooks.

It almost feels like there's some kind of tiny debris in the way- I can push the sear into the hooks, and it will go, but as soon as I release pressure, it springs back out.

In frustration, I took the hammer and sear out of my loaded model, and put it under the microscope. Not the same. That hammer and sear drop happily together, and stay there.

So I've done something wrong with my new hammer and sear. Somehow, the angle of the hooks or the angle of the sear is holding them apart, and, of course, without proper engagement, the hammer follows when you drop the slide from slide lock.

Working the sear and the hooks together on dykem blue shows that both hammer hooks are hitting the sear.

The second problem is that the Yavapai jig only allows the microscope to observe one side of the engagement, and I would dearly love to flip the hammer and sear over, and look at the other side, to see if the other end of the angle is hitting before the side I see makes contact. How do you look at both sides?

I have a set of pins to install on the frame, and while I can look at both sides that way, I can't use the microscope on them, and I see things under the microscope that I'd never see without it.

The third problem I have is I don't see how to adjust the angle of the sear primary engagement face relative to the sear pin- if it needs to be something other than parallel, I don't see how to adjust that with accuracy. I have the same problem with the hammer hooks- if the Marvel jig is cutting them at some angle other than parallel to the hammer pin, how would you know, and how would you correct it?

And finally, I now have the Marvel jig, the Brown sear jig, the pin set and the Yavapai jig. After screwing around with them for a couple days, I like the Marvel jig for cutting the hammer hooks (mainly because I have no other way of doing them) and the system it has for setting the primary angle on the sear relative to the hammer is great, but I like the Yavapai jig for tuning it- for two reasons. One, there is no substitute for gazing though the microscope, it really makes it easy to see, as far as it goes. Furthermore, it leaves both your hands free, so you can beat your fists on the bench and swear loudly at the same time, and that's becoming very important to me. :banghead:

And two, on the Yavapai, you don't "loose" the angle when you take the sear out of the jig. In the Marvel, as soon as you take the sear out of the jig, it has to be set up again from scratch to work on it, and there's no way to set it up relative to your last setting- your last setting is lost. With the Yavapai, you just turn the set screw out a half turn, and you have a new angle, a little shallower or deeper than the one the microscope is telling you didn't work.

Of course, that means I spent an hour and a half last night patiently adjusting the angle THE WRONG WAY, but that's why it's so important to be able to beat on the bench and swear. :banghead:

 

[Bill Z]

There is an inherent flaw in the Marvel jig that the creator wasn't allowed to correct. Big 'inside' story about it, but he is not associated with that jig, it just carries his name. He is coming out with a new one. This probably accounts for your difficulty. I could never get it to work correctly either and tossed mine long ago.

 

[Old Fuff]

Jammer

Let's start with the hammer hooks. What are you cutting them with? A file, stones, what? I suspect you have a radius in the bottom or the hooks, and/or the hooks are cut at a wrong angle. If you must practice (and you should) buy some cheap(er) investment cast hammers and sears. They may or may not be any good, but they are great to practice on.

Photographers used to use something called a "light box" to inspect transparencies or negatives with a 30x loupe. They make a great way to inspect a hammer or sear because you get a sharp, black silhouette, and you can flip the parts over to see both sides.

Another trick is to take a square lathe bit, put one flat against the flat on the hammer behind the hooks, push it up against the hooks, and see if you notice any light between the rear face of the hooks and the front face of the tool. This presumes of course that you didn’t alter that flat on the bottom of the hammer.

You shouldn’t have to adjust the hooks that come on better quality hammers these days. If you advance the face of the hooks forward it changes the relationship between the sear and hammer so far as the sear’s primary angle is concerned. When you use a fixture on the primary angle you lower the sear, and in so doing you effect the arc, and that effects the hammer/sear angle relationship. Always remember both the hammer and sear are rotating in an arc, and when the sear nose is lowered or the hammer hooks advanced the angle relationship also changes.

 

[Jammer Six]

Old Fuff, I'm cutting them with set of ceramic stones from Brownell's. The stones supposed to be square, and looking through the microscope, the hooks do indeed appear to be square, and I'm a carpenter. My eye is pretty well calibrated to square.

However, that's one of the sources of my frustration- I can only see the hammer and the sear on one side. I can flip the hammer over, and see it without the sear, and while the hooks both appear square, I don't have a way to see if the sear is hitting one but not the other by looking at them- I have to rely on dykem blue and witness marks.

I may have to give some thought to your light box idea- that would solve the problem of seeing both sides. Since I already own the Yavapai jig, I may just glue together a second stand for the microscope portion of it, so I can use it on a set of pins in the side of the weapon.

This is a McCormick hammer. I returned the first one I bought, because I could see that the hooks weren't square when I got it home and looked at it through the microscope. The second one, however, had square hooks, but the bottom of the cut was rounded, and needed to be cleaned out, and that's what led me to buy the Marvel jig. I don't think I moved the hooks, I think all I did was clean out the angle, but I could be wrong about that.

The Marvel jig comes with a machined block that I've been presuming was square, since you're supposed to use it to set up the hammer in the jig, and I'm going to try your trick tomorrow- that's one of those "why didn't I think of that?" things.

I've been thinking that the hooks are pretty clean, because the sear from my other weapon drops straight into them without any muss or fuss. That's why I've been thinking the problem is with my new sear.

So, does anyone want to buy a slightly used sear?

Thanks, Fuff.

Bill, if your jig didn't work, how do you get around it?

 

[Bill Z]

I have my hammer hooks trued on a mill along with an improved safety shelf depending on the hammer and usually use a Brown jig that I'm not totally thrilled with but make work. Am waiting to see Bob's new jig and have already had discussions with him at Shot! about doong a class with them when they become available. We're down for 12 to 14 copies of them pending availability and pricing.

 

[Jim K]

Hammer notches are cut at the factory with a very sharp mill. I don't know of any hand tool or stone that will recut them and not leave at least a small radius.

Jim

 

[Jammer Six]

I have the Brown jig. I went to the others primarily because I can introduce so much error into the Brown jig.

It occurs to me that part of the error possible in the Brown jig is because of the pin, and I'm not sure how I'll compensate for that.

I'm not going to buy a mill. It needs to be possible to do this by hand. I learned to use a hand saw before I learned to use a skillsaw, I learned to multiply long before I saw a calculator, and in surveying, I learned to draw R.O.S.'s on a drafting board with a T-square before I learned CAD, and the principle has always served me well.

I've told apprentices that "that isn't even close" while they assured me that it has to be so, because that's what the calculator says. But because I can do it by hand, I can tell when you've dropped a digit.

I can just hear it. "They're square. They have to be. We cut them on a mill!"

Power tools are not compentency. They make a competent carpenter faster, but the skill remains in the carpenter. I think that at this point, a mill would simply make it possible for me to ruin more sears per hour. :banghead:

 

[CCW1911]

Brownells hammer squaring file will take care of getting the hooks back to square if they are really bad, and then finish with a stone that has sharp corners on it. Do you have any relief angle on your sear? If not the sear will hit in the corner of the hammer hooks. I'm not convinced you want a strict right angle at the junction of the hammer hooks, would be a good place for it to fail. I always use some color on the sear and assemble the pistol to check if I have full contact with the hammer hooks. Testing on a jig is fine but it's gonna be used in that particular frame and should be tested there. Even pins on the outside don't tell the whole truth. Also I've had more than one sear the the pin hole and the sear surface didn't run parallel

Ross

 

[mikejm]

nt

 

[CCW1911]

I'm agreeing that a milling machine will make a nice square cut, but someone skilled can do it by hand and a surface grinder is even nicer. Did ya know how they true up the ways on the best milling machines? By hand!!!!!!!!!!! But if I can do something on a machine it's my first choice.

Ross

 

[Bill Z]

Jammer, some things are no further away than your mailbox, and in the long run, much less expensive. There are enough fellows out there with mills that do this for a living full time that would preclude you from having to purchase a mill. And to the hobbiest that dream of buying the benchtop mills, forget about it. The tooling life is greatly deminished due to the runout on the spindle, and the accuracy suffers because of it.

Think Priority Mail.

 

[1911Tuner]

Dancin' a Jig

A couple of possibilities with the hammer hooks or the sear...but a little explanation is in order first. Think..."Geometry."

Hammer hook geometry can be in three basic configurations...all of which affect the way the sear grabs'em...and the way the group behaves.

All these descriptions assume that the primary sear angle agrees with...or matches the hook angle. If it doesn't, everything changes.

Undersquare, or captive engagement angle...The hooks catch the sear in such a way as to pull it into engagement. This angle is usually about a half degree under dead square to the face...but it can be much more. This is where your heavy triggers come from because pulling the trigger is actually overcocking the hammer a little. Also has been called a "Positive Engagement."

Square...or neutral engagement angle. This is the angle that triggersmiths
work toward when a clean, crisp trigger is desired...no matter what the let-off weight is. With square hooks, the primary angle on the sear can be massaged a little to provide either the proverbial "Glass Rod" break...or a rollout break.

Oversquare...or negative engagement. This may be what Jammer is experiencing.

The tension on the hammer hooks actually works to squirt the sear away from the hammer...out of engagement. Again, a dial indicator will tell the tale.
This is the one that lends itslef to the full-auto experience if other factors are present.

To see what you have...

Clamp the pistol lightly in a vise. Zero a dial indicator on the point of the
hammer spur. Slowly pull the trigger and watch the indicator. If the needle moves toward the positive side of the dial...the engagement angle is positive,
or captive. If it moves toward the negative side of the dial...it's negative.
If it doesn't move, it's neutral...or square.

Again....All this assumes that the sear primary angle is in agreement with whatever hook angle you have.

Now, to touch on the sear.

Assuming that you have a positive, or undersquare angle on the hooks...and you want to make it square. You set up your mill to cut the hooks...but you go just a wee bit too far with your pass, and cut past the corner, toward the top of the hammer. Even though they're dead square and true...the hooks don't sit on the sear in quite the same way because the effect is much the same as making the sear shorter from the pinhole centerline to the face of the primary. When the distances change, the engagement angles change,
because...as Fuff noted...both parts move in an arc. It's also akin to stoning the rear face of the sear...where it hits the flat face of the hammer at the bottom of the hooks. When you alter the face of that abutment, you allow the sear to move farther back on that arc...and the primary engagement surface no longer agrees with the hammer hook angle, and the hooks no longer sit flat on the sear primary. Adjustment of the sear primary is needed to bring them back into agreement.

This is why that we cut the breakaway angle...or escape angle..AFTER the
engagement angles are set...and we do it with a feeler gauge under the
sear so that the sear's abutment at the bottom of the hooks doesn't change.
The sear doesn't rotate further toward the bottom of the hooks, and the engagement stays the same.

Study on it a little...I gotta get one of the dogs to the vet.

Woof!

 

[Bill Z]

Geeze, for a few bucks you can send it off to the right guy and have him do it right the first time without all of the fuss. Once the hammer hooks are square, you fit the sear, at least you'll have a point to reach. If it still presents a problem, then you may have issues with the pin placement on the frame, which unfortunately isn't too uncommon for a Springer, then you'll either have a choice of working it out or sending the wholething off.

First things first, get the hooks squared.

 

[Jammer Six]

Test Results

Okay, after screwing around all afternoon with this new round thingie, here's what I found out:

Clamp weapon in drillpress vice, clamp vice to tablesaw.Turn the magnet thingie on, which locks dial indicator to tablesaw. Line up push thingie with hammer. Re-position magnet thingie. Re-position weapon in vice. Drop weapon. Pick weapon up, examine it for damage. Drop magnetic thingie. Throw up hands in despair, go get a cup of coffee.

After a long, painful procedure of getting everything set up, and eliminating at least four ways that don't work, what I found was this: it does both.

I had the plunger positioned on the face of the hammer, at the very tip, at 90 degrees to the face of the hammer, where it would slip off as soon as the weapon fired. The tip of the hammer is also where I figured that most movement would occur.

As I squeeze the trigger, first the hammer would move towards un-cocking, about one thousandth, (or, anyway, one of those little marks on the dial. I assumed they're thousandths.) then it would move back past zero to almost two of those little marks towards over-cocking. Then it would fire.

The results are completely reproducible, but the test has to be set up every time- as soon as the weapon fires, the hammer shoves the dial indicator out of the way, and knocks it all higglety-pigglety.

I have no explanation for these results, but now I have a dial indicator, and now I think I have proof that the hammer hooks aren't square. I'm just not sure which WAY they're not square...

I should I do next?

 

[Old Fuff]

I sure wish I had your money ...

Anyway, with all of the stoning and polishing you’ve done I wouldn’t make any bets but …

It has been my experience that when you are dealing with quality parts you will find that the hooks come with the correct angles and are square and perpendicular to the hammer’s sides. That’s because they are milled that way.

However the hole for the hammer pin may be off, and if I suspect something I check with a drill blank and a small square. If the square is held flat against the hammer’s side and pushed up against the drill blank you shouldn’t see light between the square and pin.

You want to be sure the sear nose is the correct length from the hole to the upper tip end. Assuming that it is, you can lay it on a piece of heavy plate glass and slide your square up against the tip. Again you shouldn’t see daylight. If the end of the sear is square, and the hammer hooks the same, you probably don’t want to change them. If you stone the end of the sear, be sure that the fixture or jig is holding it so that you will maintain the original primary angle. And the less stoning you do the better. You do not have to get it baby-butt smooth.

The same is true of the hammer hooks. A little goes a long way, and if you don’t go off of the deep end the hooks will remain square and true, and you won’t get a radius in the bottom corner (with the hammer upside down).

But if you go stoning the daylights out of the hooks and sear it won’t take long to get into serious trouble. I have on occasion replaced a hammer, or sear, or both on a carry gun without doing any polishing or stoning – just cutting a break-away angle on the back of the sear. The resulting pull(s) were between 5 to 5 ½ pounds, which I prefer on anything used as a weapon. As the pull is burnished by use it will usually drop between ¼ to ½ pounds. Of course this is way too heavy for some folks, but to each his own I always say …

I think what your dial indicator was trying to tell you are that the hooks have been advanced (moved forward) and the angle on at least one side in no longer a true 90 degrees. The primary angle on the sear likely no longer matches the hooks so as you pull the trigger the hammer moves through a cycle of plus and minus. Not sure what to tell you except that I depend on high-magnification observing and highly limiting how many times I rub something with a stone.

Last but not least, less expensive poorer quality parts are still fine to use for practice. Few people get it right the first time.

 

[1911Tuner]

Thingies, et al

My head hurts...

Without knowin' any more than what I read....my best guess is that the hammer hooks are square or slightly undersquare...maybe 30 minutes of a degree...and the sear doesn't agree with'em. The tip of the hook doesn't touch the hooks until the trigger pull begins and as the hooks roll off the side opposite of the tip of the sear, the hammer falls forward slightly...which explains the initial indicator movement. As the sear rotates, the tip comes into contact with the hooks...and because they're square or slightly undersquare, the sear tip...moving in an arc...pushes upward on the hooks as it rolls out, and moves the indicator back to zero and beyond.

Remember...The sear tip follows an arc. The tip will tend to lift the hooks as
it moves. Getting the sear primary angle to agree with the hammer hooks will probably eliminate the sear rotation when the hammer is cocked. A breakaway angle will reduce or eliminate the overcocking of the hammer after trigger pull begins. In stoning the breakaway...use a .020 shim under the sear legs and keep the primary angle as wide as possible. I like to see the primary at least twice as wide as the breakaway, though match-type trigger jobs often have the two angles the same width. For my own personal carry guns, I do a very narrow breakaway...usually just enough to break the sharp corner of the tip all the way across...but that's just me.

 

[CCW1911]

Put a set of pins in the frame that allow you to check the hammer and sear relationship. It doesn't matter what they look like in a jig unless the jig has exactly the same pin to pin distance as your pistol. With them held together as would be if the gun was cocked look at what you have thru a microscope. If you can take a good macro picture of the hammer and sear on the frame and post it we could help . Otherwise everyone is just guessing without enough information. Trying to set up a dial indicator when you don't have a clue what hammer and sear relationship you have is not proving anything. In your first post you said the hammer and sear wouldn't stay together that they would spring apart, that tells me that you are way out to start with. You need to at least get in the ballpark before moving on to the more advanced tests. Trigger work on 1911's gets complicated because they're so many factors you have to deal with and all have to be right and every gun can be different.

 

[Jammer Six]

Oh, damn...

'Tuner, that exactly matches what I see under the microscope.

Under the 'scope, the sear nose isn't touching the hammer hooks until and unless you put a little pressure on everything.

'Fuff, now I have three sets of "cheap" parts- the hammer/sear that came with the weapon, the one I put in when I put the beavertail on, and the one I probably just ruined. The second set, I don't think I did anything to the engagement except touch it with the finest stone, just like you're talking about.

So now I'm going to make one of them work. By hand.

This dial indicator is actually a pretty cool tool. I'm a carpenter by trade, and I just used this thing to true up my tablesaw fence. At least, it's true by carpentry standards. We use 32nds, at the most, and the most exacting of cabinet makers uses 64ths, or so, and that's more than ten times the size of a thousandth.

So now I have the most accurate table saw in the city, by our standards. When you're working with a material that shrinks and expands more than an eighth of an inch over the course of a year, accuracy of .002" isn't just impossible, it's irrelevant.

So here's the plan: tomorrow, I'm going to glue together some pieces of walnut I happen to have lying around, and I'm going to create a stand that will take the Yavapai microscope so I can gaze forlornly at the sear/hammer engagement when it's on pins on the outside of BOTH sides of the weapon.

Then I'll make another post, and you can all tell me what I should do next.

 

[mikejm]

nt

 

[Jammer Six]

nt squared

Welcome to our group, Mike.

 

[Bill Z]

Then I'll make another post, and you can all tell me what I should do next.

Send the hammer to Don Williams to have it trued and squared, then play with an entire bag full of sears if you like. You have to have a true starting point. There's no you can tell if the frame is off until you have a true constant. Whether it is or not, get the hammer right and then adjust from there. Consider the hammer hooks the foundation of your trigger work, the sear your load bearing walls. Once you have them adjusted, there is still a lot of work to do, but you are not going anywhere untl the 'inspector' signs off on the foundation.

Priority Mail is your friend.

 

[Jammer Six]

I'm almost certain it's the hooks.

I started looking for error in the jig, and the main error I found was easy to correct, and after a few minutes of stoning, the sear is falling further into the hooks.

It's not done, yet, by a long shot, and it's still going to be a junk hammer when it's done, but it proves the theory.

Haven't set up the Yavapai 'scope on an ambidextrious stand yet. I'm out of time today, I have to go shooting, but I'll try again tomorrow.

 

[1911Tuner]

Playin' Hook-y

Make a U-turn and go back to Jump Street. Get the hooks squared up and adjust your sear jig to stone the primary angle to match. Cut a light breakaway and check for both hooks standing on the sear.

 

[Jammer Six]

Okay, I'll do it.

I have a hammer file on the way, the one made for squaring up hammer hooks.

I'll make the hooks square, and start over.

On another note, how long does it take a set of the ceramic "hammer stones" from Brownell's to dull?

I've heard people say that they don't use them for anything but hammers, and last night I heard a reasonably reliable source say that they're only good for two or three hammers before they're dull.

 

[1911Tuner]

File and Stone

Be real, REAL careful with that file, Jammer...Gentle touches. Matter of fact...I think I'd suggest the stones to square up the hooks. Good quality aftermarket "Trigger Job" hammers should have pretty decent hooks. Can't offer any information on the ceramic stones because I've never used'em. I use a 3/8ths lathe blank and 600-grit lap to clean up the rough spots, and a
second blank custom ground to one degree undersquare on one side. See...
I don't do these kinds of trigger jobs, and prefer to just stick to smoothin' things up a little. If you want a 3-pound, glass-rod trigger, you'll need to
talk to somebody who does that...and expect to kill a few parts during the learning curve.