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Stoning the Hammer

267K views 279 replies 112 participants last post by  Toomany22s 
#1 · (Edited)
To improve feel and lighten your trigger pull, grinding/Stoning the the angle on the area of engagement of the hammer is one way to achieve a smoother - crisper trigger. Best of all it can be done yourself for free (if you already have the tools). The tools you will need are stones, vise and a 1/8" drill bit.

In short: Slide the .125" drill bit through the pivot hole of the hammer then set the hammer in a vise so that the drill rod is sitting on both of the vise jaws. When tightening the vise set the bottom of the sear notch in the hammer level with the top of the jaws. Then remove any material of the engagement area that rises above the the vise by stoning or grinding.

This is how the setup should look:


In this pic note that the bottom of the notch is at the top of the vise jaw (red line) to help achieve this you can insert a razor blade in the notch and push down if the notch is too high.


cletus hungwell said:
I do my rough work w/ either a cheap, super course stone, or just use metal cutting sanding belts (i have plenty of those).... when i get down close, i bring it in to final size w/ a medium india, the buff w/ the paper wheel and compound.....

the paper wheel is the slotted paper buffing wheel sold/used by those knife sharpeners at the gunshows...... great product!!!.....firmer than hardest felt, cheap.....you can get them from texas knifemakers supply, jantz supply, or any of the knifemaker's supply houses........ it comes as a "kit" w/ 2 wheels, one is fine gritted, and w/ lube to cut heat, the other is the buff...it comes w/ le homiedou cr51 rouge....good stuff for alot of gun work......will put the "slick and shiny" on most any metal part, if you've got the skills.....

if you don't want to buy the paper wheel setup, just go up through the fine white arkansas stones...it will be fine for your finish!....
Here are some before and after pics, the difference is not very much.



How it works...
cletus hungwell said:
Changing the angle will reduce pull force required..... the extreme negative angle required to keep the hammer from slipping off the sear when it's dancin on it's pin during cycling is what makes the pull so heavy on the stock guns.......if you take a group out of a gun, you can watch the hammer being cammed to the rear as you pull the trigger...... what changing the angle does is reduce the amount of trigger pull force used to cam the hammer backwards against it's spring......the tighter the fit of hammer/sear to their pins, the less negative angle required......

of course, the combination of the two is what you'd go for when you're lookin for precision over reliability.... it's a balancing act, determined by your intended purpose of the group......

cletus
Why it works...
cletus hungwell said:
the angle is determined by a straight line running from the center of the pivot hole to the BASE of the sear notch....that line is 0deg.....

as most pivot holes i've checked have all been .218", that puts the center @ .109" from the edge of the hole....

(using a .125" rod in the pivot hole of the hammer) my math shows this will give a 3.9 degree angle......use the trig function on a scientific calculator to figure these....

it seems to me that the minimum angle needed will be determined by the amount of slack of the hammer/sear on their pins....the tighter the fit, the less angle needed... i do not have any hard numbers on slack vs angle at this time though......


cletus hungwell said:
any pivoting part's 0deg angle has to be a straight line from the center of the pivot point straight out through the edge..... this is the angle that allows sear movement w/o the hammer moving....... we have to add some negative to make up for the slack in the pins/parts.... to get this, we use a 2nd line, a negative angle intersecting the 0deg at the base of the notch......as this line extends past the base of the notch, the material climbs out over the sear nose, and creates the effect of the springs forcing the sear deeper into the notch....... the amount of angle, and the depth of the notch are selected based on intended purposes of the gun/group.....
Some angles to experiment with...
cletus hungwell said:
or, to get the desired angle, use .004" over center per deg....

0deg=.109", or 7/64's
1deg=.113", or a #33 drill shank
2deg=.117", a #32 is .116", add .001 shim under it!
3deg=.121", a #31 is .120, so, add a thou of shim stock....
4deg=.125"

these are approx figures...shim between the pin and the vise to get additional angle adjustments......

later
cletus
cletus hungwell said:
i'm really amazed, and thankfull to all here, for all the help and knowledge so freely shared.... and, i get a special kick out of pitchin in an idea from time to time.....
I couldn't have said it better myself and Thanks to You cletus for helping me understand this whole "sear notch -angle - engagement" thing.

These quotes were taken and edited from the "My Hammer Grinding Jig" by batmanacw and hijacked by cletus, Markbo, J57ltr, a few others and myself :hide:

If you try this method Please post your results!!!

Good Luck & Thanks, MorlyKrupt
 
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#27 ·
zinn1348 said:
re: peening....... you're just not usin a big enough hammer!!!....

Cletus,

A trick I've used for many years for peening......

I took an old cold chisel about 3/4" and rounded over the sharpened edge and then polished it.

When using it with a metal bench block and hammer, you can precisely locate where you want to peen and stretch, moving the metal.

I used this method when making lockback knives and slipjoint folders, when the lockup was a little loose(locking bar) or out of allignment(stretched the spring a bit)

I elected to modify the chisel to have a rounded edge about the same radius as a 1/8 inch drill rod, so that the peening wasn't to abrupt.

Thomas Zinn
gettin kinda high tech there w/ the chisel, ain't ya!....lol.... just yankin your chain....... but that cold chisel sounds handy!

yep, i learned some stretching from workin on guns, but got my real education on folders/ scissors/ etc, same as you.... it's one of those techniques that is real handy sometimes!!!...

i'm glad to hear i'm not the only one around here that's "crinked" a blade to make it nest right in it's handle!.... lol

did you use a large case Z for a mark???
 
#29 ·
Wow great write up on that.. now i understand the process of stoning a whole lot better...

RWAL the reason the power custom sear broke was becuse i beleave its made out of titanium.. not steel.. *please correct me if i'm wroung here*.. Titanium from what i understand is a PITA to work with as a whole..

well i'm goina be off to the shop after reading this... i'm going to try and accure a coupple spare hammers and sears and start with a set screw then on to stoning if the set screw doesnt go well...

Jess
 
#30 ·
cletus hungwell said:
gettin kinda high tech there w/ the chisel, ain't ya!....lol.... just yankin your chain....... but that cold chisel sounds handy!

yep, i learned some stretching from workin on guns, but got my real education on folders/ scissors/ etc, same as you.... it's one of those techniques that is real handy sometimes!!!...

i'm glad to hear i'm not the only one around here that's "crinked" a blade to make it nest right in it's handle!.... lol

did you use a large case Z for a mark???
Nah, just a little "zinn".... ;)
 
#31 ·
Anarx said:
Wow great write up on that.. now i understand the process of stoning a whole lot better...

RWAL the reason the power custom sear broke was becuse i beleave its made out of titanium.. not steel.. *please correct me if i'm wroung here*.. Titanium from what i understand is a PITA to work with as a whole..

well i'm goina be off to the shop after reading this... i'm going to try and accure a coupple spare hammers and sears and start with a set screw then on to stoning if the set screw doesnt go well...

Jess
my guess would be it's made from A2 at over 54HRC or so......way to brittle....imho

it's more of the heat treatment than the material used.......
 
#32 ·
I went to the range last night and tried the job I did on my hammer. It is a lot lighter with just a bit more creep. The creep that is there is quite smooth as you hardly feel the trigger moving. It has a nice crisp break. I then handed it to someone else to try and he also agreed it is better than factory. It is far from a nice high end trigger such as the one in my Model 52, but it works well enough for me for the time being. After that I'll either send it out or bite the bullet an get a Kidd. Thanks for all the info and the warnig about different triggers groups taking differently to modifications. The next one I do I will take the angle down in smaller steps. Maybe I'll try shortening the notch a little also.

Josh
 
#33 ·
jvett said:
I went to the range last night and tried the job I did on my hammer. It is a lot lighter with just a bit more creep. The creep that is there is quite smooth as you hardly feel the trigger moving. It has a nice crisp break. I then handed it to someone else to try and he also agreed it is better than factory. It is far from a nice high end trigger such as the one in my Model 52, but it works well enough for me for the time being. After that I'll either send it out or bite the bullet an get a Kidd. Thanks for all the info and the warnig about different triggers groups taking differently to modifications. The next one I do I will take the angle down in smaller steps. Maybe I'll try shortening the notch a little also.

Josh
if you're wanting more of a "match" type pull, i'd recomend installing a set screw ala squawsatch/sawdust..... much better than shortening the notch, imho... i reduce the depth of engagement till it's too far, then back into my minimum.... you can find it w/ a search....it's pretty simple to do....

the combo of slicking all contact surfaces, changing the angle of the notch on hammer, instaling a set screw to control depth, and using my trigger return spring mod has gotten me down under 1lb...i've still got a tiny bit of creep, but any semi auto w/ a single stage trigger is gonna.....

hammers are cheap, buy an extra and get brave w/ one!!!
 
#35 ·
big tizzle said:
Great thread.
if you get the chance to try this, pls let us know how it does for ya.... i'm really lookin for a large amount of folks that have tried this to get a better idea of the ideal angles needed for different applications....

i'm gettin pretty close to a semi "2 stage" feeling pull that i'm hopin will resolve alot of the creep issues, and i'd like a deeper data pool to use for my other angles involved..

thx
cletus
 
#36 ·
CLETUS,

was reading one of your earlier posts re; recycling subs, and you mentioned "smoothing" the "bumps" (? ) on the hammer, where the disco comes into contact. are you referring to the sharp angled ridges just outside the groove where the hammer strut / spring resides ??

thanks for any info.








 
#37 ·
I haven't been keeping up on this thread, but I did read the last page.
Cletus is right about doing both instead of just shortening the notch. All my original hammers are just shortened with a slight change of the angle with a dremmel to polish it.
With the angle correct, it feels alot more creepy, but the engagement is alot better. If you then remove the .015", you still have a good engagement, and a very smooth, light trigger. You would have to remove alot more off the dia. to make it the same weight with the hook still there. Mine is 1lb 14 oz. with this set up and absolutely no creep at all. I can easily remove more to drop lower, but the engagement surface is alot larger than if only the tip of the notch was touching the sear. It is much safer. It also resets very well with lower trigger weight.
Ricochet, I stone the entire face of the hammer and them polish it to a bright shine with cratex and a dremel. I also use a dremel cratex point to polish the back of the hammer in the hole that the hammer strut rides in. I also polish the end of the hammer strut to a bright shine. The face of the hammer rides on the back of the bolt to cock the hammer and the smoother it is, the easier to cock it. Radiusing the bolt slightly larger will make it hit the hammer a little higher than stock and give the bolt more mechanical advantage. Also, making it easier to cock the hammer.
 
#38 ·
RICOCHET said:
CLETUS,

was reading one of your earlier posts re; recycling subs, and you mentioned "smoothing" the "bumps" (? ) on the hammer, where the disco comes into contact. are you referring to the sharp angled ridges just outside the groove where the hammer strut / spring resides ??

thanks for any info.
the ones on my particular group were excessively longer than needed to function, and were causing binding of the bolt between the hammer and reciever at the rear of the bolt travel...it wasn't a smoothness issue, but one of dimension..

the length of these have a huge effect on the timing of your action, and shouldn't be messed w/ except when there is no doubt they are causing a problem, and there is no other way to address it!...messin w/ them can cause huge safety/function problems

a thorough understanding of the timing of the action is needed to attempt to adjust these

if you think you've got a problem w/ your's...you may want to take that one to a smith.....atleast to discuss the issue w/ everything in hand...

cletus
 
#47 ·
Lots of Tech. K.I.S._.

WOW Great Pictures.....
I appreciate tech talk and reading of your accomplishments...

I used a 6"x 3/4" red india stone, a little oil. and a flat surface to achieve a 3 1/4 lb pull in about a half hour. I laid the stone on the flat surface (kithchen tabel) and set the notch of the hammer on the stone. With the hammer notch resting on the stone and on the talble. I then moved the hammer in a slow motion back and forth until the notch was clean. This gave me a 3 1/4 pull using trigger pull weights I then used 600 grit embedded with jewelers rouge & light oil to sort of polish it.

When I put the trigger group back together I checked the sear/hammer engagement by looking through a trigger housing hole. The bearing surfaces appeared to be visually parallel and had full contact.

When I finished I had a crisp 3 lb. pull. Suitable to my liking

This gave me time to do more shooting than farting around with a jig I will maybe never use again.

Oh Well, To each his own.

 
#49 ·
applegat said:
WOW Great Pictures.....
I appreciate tech talk and reading of your accomplishments...

I used a 6"x 3/4" red india stone, a little oil. and a flat surface to achieve a 3 1/4 lb pull in about a half hour. I laid the stone on the flat surface (kithchen tabel) and set the notch of the hammer on the stone. With the hammer notch resting on the stone and on the talble. I then moved the hammer in a slow motion back and forth until the notch was clean. This gave me a 3 1/4 pull using trigger pull weights I then used 600 grit embedded with jewelers rouge & light oil to sort of polish it.

When I put the trigger group back together I checked the sear/hammer engagement by looking through a trigger housing hole. The bearing surfaces appeared to be visually parallel and had full contact.

When I finished I had a crisp 3 lb. pull. Suitable to my liking

This gave me time to do more shooting than farting around with a jig I will maybe never use again.

Oh Well, To each his own.



i find a vise and drill bits to be basic shop equipment.... a bit of a stretch callin them jigs/fixtures, imho...

using this method is quick, simple, and repeatable.. it produces a flat surface w/o rolloff from the cut or polish..... using this, and just a couple of other mods will get your trigger into the 1lb range....the only other way i'm aware of to get that is to buy a kidd trigger group..

when you get ready to step up to a "match" type trigger, give these a try

cletus
 
#50 · (Edited)
MY Appologies...By the way

You are cerainly correct. In my viewing of these strings I thought I observed someone's fixture other than the vice/drillbit you had used.

Thank you for the advice on moving up to match grade stuff. I do not believe that I will be setting up my lowly 1022 for match grade additions. But then again, maybe just for giggles and grins. I stopped messing around with match shooting about 25 years ago. Now It's just an off and on thing for my own enjoyment.

What is your opinion on using Delrin as a materiel for 1022 reciever. It is stable, strong and machinable. It is used in the manufacture of bearings and gears. It is self lubricating and exhibits excellent wear qualities as well as being unaffected by corrosive substances. Brass inserts could be used for the barrel retaining screws.

All this supposition is of course assuming the appropriate permits and licenses to mfg. firearms are in place.
 
#51 ·
Delrin though tough is not an ideal reciever materrial. It will crack. I use it in many applications in food service equipment and against metal the wear properties are not that good. We typically use it in wear spots as an easy replacment. One of our applications uses Delrin for a chain guide and we typically have to have end caps replaced once or twice a year to once every 2 years on the machinery we make. What's whether or not we use SST chain or Nylatron chain (it's a plastic as well). I doubt you would get 1000 rounds before you start cracking around the trigger group pins and back of the reciever where the bolt hits.

Jeff
 
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