Need advice on singel phase double set trigger design.

[Jim Kibler]

Rolf,

I would definetly reduce the amount of notch engagement.  This will help with the angle of your front trigger shoe as well.  I think you will find it looks better if it doesn't lean back so far.  Also, it seems the notches engage a fairly sublstantial angle.  With a mainspring in place, it may not stay set well with the angle present.  I would make the notch more or less parallel to a line drawn between the two trigger pivot pins.  Reducing the amount of engagement should help with the notch angle as well.

Jim

[D. Taylor Sapergia]

Your problem is that you have created flat triggers that interfere with each other.  Look at Dan's Roller triggers again.  You'll see that the trigger material is around 5 mm thick, with each of the blades of the front and rear triggers being around 2 mm thick.  The thicker area of the front trigger carries the engagement area for the tip of the blade of the rear trigger.

[Jim Kibler]

Your problem is that you have created flat triggers that interfere with each other.  Look at Dan's Roller triggers again.  You'll see that the trigger material is around 5 mm thick, with each of the blades of the front and rear triggers being around 2 mm thick.  The thicker area of the front trigger carries the engagement area for the tip of the blade of the rear trigger.

Taylor,

I don't believe Rolf is intending to make a set trigger of the double lever variety.  A design such as his can't fire the rifle from the unset position.  This type of trigger is commonly encountered on original longrifles. 

Jim

[ironwolf]

  They still need to sit side-to-side.  The front triger can't move becaose the rear blade is right on top of it.

[D. Taylor Sapergia]

I agree Ironwolf.  The only difference would be the front trigger would be minus its blade.  And in that case, I see what you mean...there is no need for the offset!  But the front trigger must not have the long blade, as Rolf has created out of brass.

[Randall Steffy]

If I am seeing correctly, Rolf's second and third pictures evidence a revision to the front trigger, made after the first picture was taken. This would now allow a non-side-by-side design as Jim was suggesting, limited to firing from the set position.

[Jim Kibler]

Ironwolf and Taylor,

Here is a tutorial put together by Ken Guy.  This might  explain things a bit.

http://americanlongrifles.org/forum/index.php?topic=4616.0

Jim

[Rolf]

Thanks for the input.
Ironwolf & Taylor: I building the same type of trigger as in Ken Guy's tutorial. He calls it a single phase double set trigger. It can only fire when the trigger is set.  Randall is correct, pictures 2 and 3 show the revised front trigger where alot of the "tail" is removed. The mock up works now.

Jim: It's hard to take pictures of the parts without the camera angel causing distortion. I've glue the mock-up together with super glue in set position and placed it on the stock where it's planed to go. The front trigger shoe is about 90^o on the barrel axis. The bottom of the notch on the rear trigger is parallel with the barrel axis. I 'll correct that so it runs parallel with the line between the pivot pins.

After placing the mock-up on the pistol stock, it looks like the rear triggerblade is way to high. I might have to pin the triggers lower on the plate to be able to reduce the height enough.





Best regards
Rolf

[Dave B]

Rolf,
This why its a good reason to make patterns first before the final parts. Your piviot points for the triggers are in the wrong place. here is a example for a good pivot point location. Note that the rear trigger pivot is higher than the front trigger pivot. also note that the front trigger sear edge is just over the center line of the front trigger pivot point.


This next  example is an original. The triggers are wider than most I have seen before the blade sections are 3/16" wide and the shoe of the trigger are alittle over 1/4"

[Jim Kibler]

Dave,

I would like to here your thoughts on WHY you feel the trigger pivot points are in the wrong locations.  The impact of the front trigger pivot point in relation to the notch location has already been pretty thoroughly discussed.  I assume you have read these posts.  What makes the rear trigger pivot location wrong?  My opinion is that the rear trigger will function fine pinned as shown.  I have thoughts on why a higher rear trigger pivot might be of some very slight advantage but I will reserve comment for now.  I'm not trying to be smart here, but I do think that if saying something is wrong, a person should explain why they feel this is the case.  With something like locks and triggers, I feel a sound understanding of proper function, and what is important, is critical to success in building these items.  Copying what was previously done may get you pretty far, but a good understanding is much better.

Jim

[Rolf]

Dave,
Whats the advantage of placing the rear pivot point higher?
TOTW has several set triggers with both pivot points are at the same height. here is a link to one of them. http://www.trackofthewolf.com/Categories/partDetail.aspx?catId=14&subId=156&styleId=706&partNum=TR-500

All the set trigger plans in Pryor Mt Bill's trigger booklet and chapter 22 of "Gunsmith of Grenville County " have the pivot points on the same height. None mention placing the rear pivot point higher than the front.

On page 179 of GGC, Alexander recommends the front trigger point place 1/16" to the rear of the front trigger hook for safety reasons.  On page 68 in "Recreating the American longrifle" they say "The pivot point of the forward trigger must be placed to the rear of the latch  or hook ".Other ALR member recommended placing the pivot point in line with the hook, to get a liter trigger. I've compromised at place the pivot point 1/32" to the rear of the hook.

This is my first attempt at trigger building and I appreciate all advice and help in understanding trigger design.

Best regards
Rolf

[Dave B]

Jim,
I know that you can make many trigger configurations function just fine with pivot points exactly where he currently has them. I was addressing the height issue he brought up.
 Rolf
 My intent here is to be helpful. I apologize if I have offended , I shouldnt have said you drilled it wrong. I can guarantee you that if you build your triggers with the exact pattern the brass is shaped with they wont work with our a strong front trigger spring. I have several original triggers that are built with the rear trigger pivot point higher than the front. Maybe that was just the way some of them did it. There may be a good reason for it I don't know. When some one  says the triggers are seeming to be too high to function,  this change of pivot point will solve the problem by lowering the whole position of the blade relative to the sear. The pattern of the sear contact point you currently have is like the German multi lever triggers use. It requires an additional lever to make it work properly or a very stout return spring.  the third trigger trigger down uses four levers and uses the sear configuration your brass patterns have. One of the other triggers shown also has a high pivot for the rear trigger. The other one has the pivot points at the same height. Really the biggest issue for you right now is only to make the triggers work properly. It is possible for you do it with the patterns you have with some minor modifications. The one That I feel is most critical is the face angles of the sear points.



I was just reviewing the picture of your brass triggers and I may stand corrected the critical angle you may have with regard to the line of front trigger axis to the face of the sear must be 90 degrees for best function. You may have the angle needed to have it hold with out a heavy return spring. The unknown is how will the front trigger respond to the rotational force applied at the face of the first trigger sear faces angle. It will not be at 90 degrees and may cause rotation of the first trigger in response.

[Rolf]

Hi Dave B.
I'm not offended, just confused. I think I understand why the sear (tip of rear trigger) has to change. Your drawing helped.  Why will pining the reartrigger higher reduce the height of the blad?

Best regards
Rolf

[Jim Kibler]

Dave and Rolf,

In my view, pinning the rear trigger high help with the force required to set the triggers.  This is about the only advantage I can envision.  Anybody else have any thoughts on the matter?

As has been posted some time ago, I agree that the angle of the notches are not good in Rolf's mock-up.  I also mentioned that I feel the notch engagment is a bit heavy and I think it would look better if the front trigger were rotated forward a bit.  As far as the notch engagement in relation to the to the front pivot point, here are my thoughts...  If Rolf feels more comfortable with placing it a little in front of the pivot point, I don't think it is going to be necessarily a terrible thing.  With proper notch shape it will insure it stays set and given such a small distance (1/32") in front of the pivot, I don't believe a significant increase in front trigger pull will be experienced.   With this said, I would likely put the notch closer to the pin centerline though.

I think I've said about all I can with regard to this project so I think that I will step aside now.  Good luck Rolf. 

Jim

 

[Dave B]

Jim,
I agree with you on this. I know that force over distance yields a higher impact result when the arch of the movement is greater. This being so maybe that is why the originals have a higher rear trigger pin placement. It is the same as when we make the full cock notch further back on the tumbler to gain just a small amount of force to the cock impact against the frizzen thus producing a better spark. The higher pined rear trigger will slap the sear with a little more force than the one with the pin point lower.

[Captchee]

Rolf
If you look back  to your first page , you will see where I mentioned that if you did not increase the gap   between your trigger bars . The triggers would lock up on you .
 I guess I didn’t make that clear enough or im struggling  as to how to explain it  .
As to the point of pivoted.
  It might be easier for you to think of this as  circles  around the pivoted. Its all leverage applied  to give rotation of those circles .
 Having the pivot point under the notches lines everything up  and you get true rotation .  Having you pivot point to far forwards  means that you applied leverage   works against the circle differently. Especially if you  trigger isn’t inline or directly under the pivot  .
 In doing that what happens is that you end up lifting instead of rotating .

Also keep in mind that while  a set trigger adjust the amount of creep, as you change the angle of the notch , you also  changing the weight of the trigger  pull . The reason for this is that  as that angle changes , the triggers main spring  begins to  apply it force into that angle . IE its  trying to force itself  out of the notch .
 Think of it as applying  a lever to move a big rock .
 You buddy applies his weight to the lever  . But its not quite enough weight to do the job
 So you try . But your weight isn’t enough either .  But it is enough to  start to lift the rock but not roll it
  if  you buddy adds alittle more weight by pushing down on the lever  while your also  pushing down , then the rock flips over .

 Your set triggers do the same thing . The more you change the  angles of the notches from 0, the more  the more wieght of the main spring is being applied  to another object IE your front trigger  which is already in rotation . So as you  pull on the trigger   your not only  providing less creep/ travel  by  reducing the amount of movement the  it takes to  trip the rear trigger bar from the notch . But you  also  have  a lighter trigger because the main spring is  in a since already applying  it force to the rotation .

 Very same principle as making a deadfall  trap . The weight of the deadfall  is your main spring .by changing the angles of the notchs  in the stick that form the trigger . The more sheer effect you get and the lighter the trigger becomes .
 To the point  the  sticks may not be able to hold the weight.  

Its all  about weight and applied leverage

[Dphariss]

Hi Dave B.
I'm not offended, just confused. I think I understand why the sear (tip of rear trigger) has to change. Your drawing helped.  Why will pining the reartrigger higher reduce the height of the blad?

Best regards
Rolf

The Roller triggers have a bend point right in the middle of the triggers and the rear in is lower, as the triggers are installed in the rifle. The contact surface angles on the triggers and their location in relation to the front trigger pin will determine how the triggers will work.
While its not necessary to make double acting triggers putting the adjustment screw to the side allows the triggers to be lower  and will make it easier to get sear clearance. There MUST BE SEAR CLEARANCE. Your mockup has none.



To make a lower profile trigger that works well its better to offset the triggers in this manner.



The rear trigger



The front trigger




The basic trigger layout pictured here was in use for a very long time. With differences in firearms design taken into consideration its the same trigger used in the Sharps and Ballard breechloaders. I suspect that by that time in was already 100 year old.


Dan

[Rolf]

Thank you all for the input. A lot to digest. I'm not sure I understood all of it. I've started  on the the set trigger and will proably have to make several before I get it right. I'll post the results for comments.

Best regards
Rolf

[Dave B]

Rolf,
The combination of raising the rear trigger pivot and lowering the front pivot point will cause the lowering of the trigger bar to engauge the front trigger sear.

[Dphariss]

Rolf,
The combination of raising the rear trigger pivot and lowering the front pivot point will cause the lowering of the trigger bar to engauge the front trigger sear.

Unless the raising and lowering offset each other.

Dan

[Dave B]

As long as the pivot points are kept at the same distance from one another they will only be tipped in the trigger bar in relation to the angle created by there new positions.

[Rolf]

Just an update.
I finally got the keystock I've been waiting for to make the triggerplates. I used 10mm(0.4") squarestock and made a simple bending jig out of some bolts and angel iron.  I heated the steel to 750^oCelsius in my tempering oven, bent the blanks hot and let them cool on the jig. Excess material was removed with a hack saw. Very pleased with the results. It fits the curve of the pistolstock perfect. Made a set of triggers, cold forged from 1/8" mild steel. Next step is cutting the slots for the triggers.






Best regards

Rolf

[greybeard]

Looking really good Rolf.   Bob