Home Tournaments Calendar Weather Merchandise Sponsors

Go Back   Spearboard.com - The World's Largest Spearfishing Diving Boating Social Media Forum > Spearfishing Gear > All About Guns

All About Guns What's your weapon of choice, and why? Discuss the beloved speargun here!

Reply
 
Thread Tools Rate Thread Display Modes
Old 02-09-2020, 08:35 PM   #31
popgun pete
Registered User
 
popgun pete's Avatar
 
Join Date: Mar 2006
Posts: 3,493
Re: Rob Allen Tests Stainless Trigger Mechs

Although not a trigger mechanism look how small contact areas are in spearguns using different means to hold spears and pistons, the contact areas are shown in blue. The metal to metal contacts almost weld the parts together at high loadings.
popgun pete is offline   Reply With Quote
Old 02-10-2020, 01:05 AM   #32
spearq8
Registered User
 
spearq8's Avatar
 
Join Date: May 2009
Posts: 3,132
Re: Rob Allen Tests Stainless Trigger Mechs

MIM is certainly by far the best way to make sear parts for triggers … no question about that at all. You can design the part in 3D and thus you can add reinforcement where it is needed most and can remove metal where it is not needed ... thus you get a lighter part that is also stronger. Since you are working in 3D you can also add intricate shapes to allow for safeties and allow for spring hooks ... even round off edges … and just simply make a better product. The tolerances can also be extremely high, and you can make thousands of identical parts very quickly. Problem is with MIM you need to make a mold that is quite a major cost, and your quantities of scale have to be 5,000 parts or much more for the costs to become reasonable. I have been trying to convince Mario from Ermessub to go the MIM route for 4 years now and have even designed his main trigger to take advantage of 3D advantages … maybe once the economies of scale improve and the design is not evolving any more he will go that route. For now he has switched to EDM wire cutting and that has dramatically changed things for the better as tolerances are 10x higher.

One thing to note is that plastic is really not a bad idea at all when it comes to triggers. If you take the Pathos trigger for example … the Pathos D1 handle uses a plastic trigger sear … this trigger is actually quite good and dramatically better than the more expensive SS trigger in the D2 handle. It has a consistent trigger pull (albeit quite heavy) and works perfectly. The Abellan trigger also uses a plastic trigger sear which works very well. Not all plastics are made the same and if the correct plastic is used it should work well. But there are downsides and limitations to plastic … but it certainly beats a poorly designed SS trigger. Also the Sporasub One speargun (one of the best railguns there is) initially had a plastic trigger sear … but then they "upgraded" the trigger sear to an MIM stainless steel sear because I guess some clients complained that the plastic sear looked cheap … and that had huge problems.

Tolerance is also a huge factor … with molded plastic cassettes you can actually control tolerances quite well between left and right holes as the holes are molded in. With bent SS housing, very often the right and left holes are not perfectly horizontal … so tolerance is added to fix that. Adding big tolerance throws a monkey wrench into the equation as if the sears are allowed to move forward you can have a situation where your circle geometry is off and the loadings will squash your sears into each other and dramatically increase stress on contact surfaces. That is why some triggers can work great with no problems … while others that are on the high end of the tolerance curve will work much worse.

All these things are pretty much fixable with correct manufacturing, but first you have to be convinced that a problem exists. For many manufacturers they don't see that there is a problem. You pull the trigger it shoots … OK so maybe trigger pull gets tougher or harder if you load up the gun … so you just pull harder and end of the problem. That could be true but inconsistent trigger pull and inconsistent rotation break off dramatically changes how accurate a gun is … and am not sure anyone actually tests their trigger for shot accuracy.
spearq8 is offline   Reply With Quote
Old 02-10-2020, 01:30 AM   #33
spearq8
Registered User
 
spearq8's Avatar
 
Join Date: May 2009
Posts: 3,132
Re: Rob Allen Tests Stainless Trigger Mechs

Quote:
Originally Posted by popgun pete View Post
A picture is worth a thousand words.

When you are manufacturing guns in the hundreds if not thousands then economics come into it as in quality fit for the purpose. Guns need a long service life, but nothing lasts forever, including the gun owner! The cassette trigger mechanism being a removable element it can be replaced if and when required.


Hmmm … this design can easily be improved and for sure you would end up with a much more robust trigger. No need for plastic trigger sear … just add a roller at the leading end of the shaft sear where it contacts the trigger sear … and then re-design the trigger sear to work with that. The result would be a smoother trigger pull no matter what the loading is … and of course auto-resetting would be much lighter requiring much less effort. If someone has the actual drawings to scale, I could probably design that in a morning coffee session. Otherwise I would need to have the actual trigger and get dimensions off it.
spearq8 is offline   Reply With Quote
Old 02-10-2020, 01:37 AM   #34
popgun pete
Registered User
 
popgun pete's Avatar
 
Join Date: Mar 2006
Posts: 3,493
Re: Rob Allen Tests Stainless Trigger Mechs

MIM parts shrink when they are heated to densify them, so there are shrinkage rules to consider. Lost wax casting is used for some trigger components and there you have shrinkage rules as well as the cast wax model is always larger than the finished product. However it is a relatively low tech process and has been used for centuries in making jewellery.

When a reasonable speargun with all the required features can still be had for around 300 bucks manufacturing costs need to be contained as there are many competitors in the market snapping the volume up at the lower end. "If it ain’t broke don't fix it" has tended to put a lid on high tech developments, plus there is the nagging prospect of the rug being pulled out from under spearfishing if a future “sacrifice” is required to appease green movements to save fishing in general. Any new marine park proposal and spearoes are the first to be booted out.
popgun pete is offline   Reply With Quote
Old 02-10-2020, 04:26 AM   #35
Rob Allen
Sponsor
 
Join Date: Jun 2004
Location: Durban South Africa
Posts: 259
Re: Rob Allen Tests Stainless Trigger Mechs

Thanks for all your input and spearq8 for your offer to modify the cassette.



As Pete mentioned, we have made many changes to this handle over the years. Many small changes had unknown knock on effects that meant new changes had to be made to compensate. This is the reason we have steered away from MIM components. We do MIM on the line release as this is a simple part and easy to adjust the other systems around it.



The trigger breaking was due to one of these small changes. At first, we had no idea how it was happening, but then found it to be most prevalent on guns that where sent out in boxes with “overzealous” courier companies, arriving at the retails stores with the triggers broken in the boxes. The way they were breaking was from impact on the spear, driving it back into the cassette and over rotating the sear. (boxes being tossed about) To stop this, we reinforced the trigger and set up internal stops to prevent the sear from over rotating, problem solved.



The trigger might look like plastic but, it is a blend of acetyl and Kevlar. This is a composite used in bushings where a low friction coefficient is needed, way more expensive than stainless.



When testing, we run this 120kg load cycle up to a minimum of 10000 shots to make sure the components are well tested. We don’t stop at 10000 because it breaks, we stop because there is no point doing more. We have run this cycling test a few times for more than 17000 cycles. There was still no change in the components or, the pressure needed to pull the trigger. I would have no problem using this same cassette in a gun after this many cycles. After the cycling, we then do a max tension test where we break out the spear. All are still good to +- 6 x 16mm rubbers at max stretch. As Pete said, why try fix what is working?



Regarding other brands with full stainless, I am not saying they are no good, I’m just saying, for our handle with our set up positioning, the stainless-steel triggers are certainly not an upgrade.



We feel our handle is becoming like an AK47, durable in all conditions.
__________________
divefac@iafrica.com
Rob Allen is online now   Reply With Quote
Old 02-10-2020, 09:33 AM   #36
spearq8
Registered User
 
spearq8's Avatar
 
Join Date: May 2009
Posts: 3,132
Re: Rob Allen Tests Stainless Trigger Mechs

No I don't mean to change the cassette ... just change the trigger sear and shaft sear to allow for a roller. The idea being that rolling will always take less effort than dragging. Last thing you want to do is change many things as I fully agree that fixing one thing might end up screwing up 2 other things. But in this case all you are doing is changing friction to rolling and in theory that should help both trigger pull and line release reset and should dramatically reduce wear and tear on the contact surfaces. If the plastic you are using for the trigger sear has Kevlar, you might even be able to use the roller on the plastic.

I don't have the drawings and so just basing it on the picture I got from this post. The scale is probably off by a bit as the picture is not high resolution enough for accurate replication of the parts and there is always parallax in any picture so that might also skew things. But I think this is one way it might be possible to change the friction on the sears to rolling.

First picture is what I think the trigger internals would look like loaded and second is internals after firing. No need to change the cassette or line release or any springs or safety. Of course maybe the roller lever is better a little longer or shorter and the roller a little larger or smaller ... but the idea would be the same. As the egyptians proved many years ago rolling takes a lot less effort than dragging! I think it is worth trying.
Attached Thumbnails
Click image for larger version

Name:	RA trigger_locked.JPG
Views:	58
Size:	68.5 KB
ID:	244929   Click image for larger version

Name:	RA trigger_fired.JPG
Views:	59
Size:	71.1 KB
ID:	244930   Click image for larger version

Name:	RA trigger_perspective.JPG
Views:	51
Size:	89.5 KB
ID:	244931  
spearq8 is offline   Reply With Quote
Old 02-10-2020, 03:37 PM   #37
popgun pete
Registered User
 
popgun pete's Avatar
 
Join Date: Mar 2006
Posts: 3,493
Re: Rob Allen Tests Stainless Trigger Mechs

Quote:
Originally Posted by spearq8 View Post
No I don't mean to change the cassette ... just change the trigger sear and shaft sear to allow for a roller. The idea being that rolling will always take less effort than dragging. Last thing you want to do is change many things as I fully agree that fixing one thing might end up screwing up 2 other things. But in this case all you are doing is changing friction to rolling and in theory that should help both trigger pull and line release reset and should dramatically reduce wear and tear on the contact surfaces. If the plastic you are using for the trigger sear has Kevlar, you might even be able to use the roller on the plastic.

I don't have the drawings and so just basing it on the picture I got from this post. The scale is probably off by a bit as the picture is not high resolution enough for accurate replication of the parts and there is always parallax in any picture so that might also skew things. But I think this is one way it might be possible to change the friction on the sears to rolling.

First picture is what I think the trigger internals would look like loaded and second is internals after firing. No need to change the cassette or line release or any springs or safety. Of course maybe the roller lever is better a little longer or shorter and the roller a little larger or smaller ... but the idea would be the same. As the egyptians proved many years ago rolling takes a lot less effort than dragging! I think it is worth trying.
Not much different to the Omer "Excalibur" mechanism from some time ago, the roller sits on a tiny axle mounted in thin supports in the sear lever tail. I don't think that these guns are around anymore. Omer used a version of it in their "Alluminum" model which has also evaporated.
Attached Thumbnails
Click image for larger version

Name:	OMER Excalibur_diagram.jpg
Views:	228
Size:	77.6 KB
ID:	244933   Click image for larger version

Name:	Omer Aluminium Parts.jpg
Views:	32
Size:	116.3 KB
ID:	244934  

Last edited by popgun pete; 02-10-2020 at 05:38 PM. Reason: "Alluminum" was the name, corrosion did them in.
popgun pete is offline   Reply With Quote
Old 02-10-2020, 04:07 PM   #38
Behslayer
Registered User
 
Behslayer's Avatar
 
Join Date: Aug 2008
Location: Big Island
Posts: 5,028
Re: Rob Allen Tests Stainless Trigger Mechs

Hello Rob,

Can you share any information what the materials used in this test were and how they were cut? Also what is the thickness?

Can we see a pic side by side on a flat surface of your Kevlar Sears and these Stainless Sears?
Behslayer is offline   Reply With Quote
Old 02-11-2020, 03:58 AM   #39
Rob Allen
Sponsor
 
Join Date: Jun 2004
Location: Durban South Africa
Posts: 259
Re: Rob Allen Tests Stainless Trigger Mechs

Hi Spearq8,



Thanks for the drawings, looks great. I had seen this before on the Omer that Pete put up. Great idea in theory. The pivot pin in the roller needs to be larger for it to rotate better. In our case, there is not enough room in the cassette as is so, to do this we would have to modify the cassette mould and make a completely new trigger mould. (or cut a s/s one) Also, we would have a lot of post work on the sear trailing arm to get the roller fitted. We feel, for the application our mechanism is designed for, it works fine as is, why fix what aint broke


Re trigger loads, we need about 2,4kg of tension to pull the trigger at 120kg of tension. To fire a Glock handgun you need around 2,9kg. As the tension lowers on our handle, so does the trigger tension needed to fire. So, if shooting with a single 16mm band at max tension, 60kg, means the trigger pull required will be half. I donít think it is safe to swim around with a hair trigger like that on most riffles. We feel the trigger tension is at the right pressure but more importantly, it stays constant. A reason to change to the roller would be to prevent wear, our current set up has virtually no wear so why change? Many thanks for your input. One day we might investigate it.



Hi Pete,
We did see these Omer triggers out years back and were removed from the market very quickly here in South Africa.


Hi Jon,
Our sear is 6mm 304 stainless plate, wire cut. This trigger we tested was just over 8mm and non-magnetic so I assume 316. It looks like water cut but canít be sure.
What do you want to see in the picture, thickness, shape, top view, side?
__________________
divefac@iafrica.com
Rob Allen is online now   Reply With Quote
Old 02-11-2020, 05:40 AM   #40
spearq8
Registered User
 
spearq8's Avatar
 
Join Date: May 2009
Posts: 3,132
Re: Rob Allen Tests Stainless Trigger Mechs

For sure the design would have to be done more accurately once you have the exact part dimensions. You need to see where the stops for start and end are and make sure they fit. I think it will easily fit in there with room to spare … actually I am very sure it will. As for the trigger pull being too light … trust me that is never a problem. It is very easy to make a trigger pull heavier (just make a thicker spring) but not so easy to make a hard trigger pull light. More important is consistency and rotation break off … or the amount of rotation needed before the shaft escapes the mech. But now since you are thinking that the cassette can also possibly be changed … why not move the shaft sear notch all the way back and gain a couple of extra free cms of band stretch and call it a day
spearq8 is offline   Reply With Quote
Old 02-11-2020, 06:59 AM   #41
popgun pete
Registered User
 
popgun pete's Avatar
 
Join Date: Mar 2006
Posts: 3,493
Re: Rob Allen Tests Stainless Trigger Mechs

Quote:
Originally Posted by Rob Allen View Post
Hi Pete,
We did see these Omer triggers out years back and were removed from the market very quickly here in South Africa.
That drawing, which I saved when those Excalibur guns first came out (circa 2000), showed a sear lever that looked flimsy to me and I thought that they would not be durable with that tiny roller mounted on so little metal. At one time Omer tried folded metal sear levers and these looked not unlike them, so they were not well received by guys who were used to more rugged guns shooting heavier spears with a lot more rubber. Pacific Ocean fish needed something heavier than fish in the Mediterranean Sea.
popgun pete is offline   Reply With Quote
Old 02-11-2020, 01:49 PM   #42
Behslayer
Registered User
 
Behslayer's Avatar
 
Join Date: Aug 2008
Location: Big Island
Posts: 5,028
Re: Rob Allen Tests Stainless Trigger Mechs

Rob, sounds like you have everything under control.

Bottom line is that you used a flawed material or geometry in this test and as such your stainless sears failed miserably after 200 shots with only 2 bands of force. I think we all know that.

Doesn't mean that using a Polymer/Composite Trigger Sear and Stainless Shaft sear is not a good idea for your guns, and it is very commendable that you do this kind of testing on your products.
Behslayer is offline   Reply With Quote
Old 02-11-2020, 02:29 PM   #43
Rob Allen
Sponsor
 
Join Date: Jun 2004
Location: Durban South Africa
Posts: 259
Re: Rob Allen Tests Stainless Trigger Mechs

Hi Pete,


Yes that was a while back. This was the same mechanism with the folded sear. The sear did not fail, the roller would stop rotating after a few shots. The cause was that thin pin bending. Maybe it was designed for a lighter load and our guys just loaded it too high.
You talked earlier of flash chrome brass parts. We had those here in the old Champion Cavelero handles. I thought it was a mistake the went to brass after the previous s/s ones failed. I was wrong. Some of these old brass components are still in use today +- 30 years later. Although brass is soft, it has a great friction coefficient.



Hi Jon,


The material is the flaw, combining stainless with itself is the problem. This is the same with s/s nuts and bolts. Tighten a s/s nut just a little more than it needs and, you can cause the thread to knurl. Try move it more and it can lock up completely.
In terms of the geometry, we have cut s/s triggers exactly to the same shape as out triggers and highly polished the engaging surfaces. It the test machine we had pretty much the same results.
I donít like to compare other brands and wonít mention names but, I have also tested 3 well known brands who offer ďs/s upgradesĒ with the same results. I also had a customer who insisted on using our prototype s/s trigger. After a few days of use he had to take them out and polish to get them to work normally. He has since gone back to our standard trigger.
It is possible that the 120kg tension we are pushing the s/s to is just enough to cause the problem. Maybe we should test at 90kg? I used 120kg just because it is the same load that we already test our standard cassette and components to.



Do you have a handle you want me to test Jon
__________________
divefac@iafrica.com
Rob Allen is online now   Reply With Quote
Old 02-11-2020, 04:34 PM   #44
popgun pete
Registered User
 
popgun pete's Avatar
 
Join Date: Mar 2006
Posts: 3,493
Re: Rob Allen Tests Stainless Trigger Mechs

It would be interesting to see the results of a mechanism with a long sear lever tail and wide pivot pin spacing in a forward cam lock set-up. The question would be how much loading to use, although for starters the same as you use for your own gun. Now not many reverse mechanisms dry fire, they rely on gravity to keep the sear lever down, so running the rig vertically might pose a problem when the shaft pushes back to relatch for the next shot. It would be very interesting to see the double roller put to the test and see if any metal falls out of it if the rollers start to chip. Rollers only have a line contact on the roller that runs across the roller if the mounting axle stays parallel to the lever face that it is opposing, they are not curve matched.
popgun pete is offline   Reply With Quote
Old 02-11-2020, 05:26 PM   #45
Behslayer
Registered User
 
Behslayer's Avatar
 
Join Date: Aug 2008
Location: Big Island
Posts: 5,028
Re: Rob Allen Tests Stainless Trigger Mechs

Hi Rob,

If you are correct, then every Stainless mech out there with more than one band on it would have the same issue and the trigger pull would increase quickly until the trigger was impossible to pull like it did in your test. Which is not the case.

I already suggested a Mech for you to try. Try a Neptonics Tuna Mech and show us that it more than triples in Trigger pull after 200 shots with the force of 2 bands? If you are right and it is the material and not the Geometry, Material Quality, or Manufacturing, then the test should mirror your results.

You are correct that Stainless/Stainless sliding surfaces can be prone to galling dependent on many factors. But logic says that if some Stainless Mechs perform better than your test, then there is more going on here than just materials.

The reason I asked to see a Flat (Side) view of both Sears is because it would make sense to me that something is different between these tested sears and your moulded composite sears other than materials. Normally the culprit would be a slight deviation in Hole position, (Waterjet Cutting favors a slightly larger Pin Diameter than you are using to be truly accurate?).. or slight design variance. You are not certain how they are cut which means they are being made somewhere else. Ofcourse it could just be lousy steel. Were the Sears used in this test made in China?
Behslayer is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 06:23 AM.


The World's Largest Spearfishing Diving Social Media Forum Powered by vBulletin® Version 3.8.1
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Copyright ©2002 - 2014 Spearboard.com