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DougR

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Everything posted by DougR

  1. Yes a decent quality fish scale could work as well. By using a known weight this method isn't subject to the accuracy of any scale. Besides, I had bullets on hand, but no fish scale. I like the fact that both hands are free when using a known weight hung from the rod going through the test spring . I weighed several bullets 8 or 9 at a time on my Dillon digital scale. I determined the bullets actually weighed 182 grains. I did the math and added the proper number of bullets to a small container hanging from the rod with the recoil spring above. If I had other known weights around the house I could have used them, such as barbell weights; I didn't. Even scale test weights will work if they are easily available. I suppose a handfull of nuts or bolts would work as well, once the weight of each nut or bolt was verified. A box of rocks, once checked on an accurate scale would work well. The object is to have a known weight, verified by an accurate scale. I found a close correlation with the test data and formulas used on internet spring engineering sites as well as the formula Joshua Smith presented in a spring post here about a year ago. See cutting springs. It took me some practice to get used to running the formula after measuring the spring wire diameter with a digital caliper, then measuring the outside coil diameter as well as counting the number of active coils and measuring the free length of each spring. Running the formula is not necessary to test any spring. I was interested in how my results correlated with the formula. I was able to calibrate each of the 8 springs I had laying around as well as identify one fatigued spring that calculated out to be 16lbs but tested at just over 12lbs. I'm now confident that this method will identify any 1911 recoil spring accurately.
  2. There are several factors in determining the design weight of a 1911 recoil spring. The below description is a rough method to determine the design spring weight. You'll need a decent digital caliper to measure the wire diameter of the spring to be checked. 1911 recoil springs use music wire of .040" diameter up to .048" diameter. .043" diameter is typically a 14# spring, .044" diameter is typically a 15.5# spring, and a .045" diameter is typically a 17# spring. The recoil spring should be 6 inches long or greater. It should be made up of 30 or 32 coils. A recoil spring of 30 or 32 coils measuring less than 6 inches long is fatigued and is delivering less than the original as new spring rating. A simple tester is a 9/32" hole through an elevated bar or board, with a 10 or 12 inch 1/4" dia rod running through the recoil spring to be tested. The 1/4" rod is threaded at the top to retain the spring with a washer and nut. The lower end of the rod is hooked to hold the hanging test weight. I use a small coffee can filled with 504, 180 grain lead bullets. This weighs 13 lbs. The recoil spring should suspend the weight with close to 2 inches of spring height. Add 40 more 180 grain bullets to raise the weight one pound. Continue to add in increments of 20 bullets (1/2 lb.) until the spring is completely solid. 624 bullets is 16 lbs. A weak fatigued 16# spring will compress solid well before you get to 16#. 7000 grains is one pound. Using different weight bullets just do a little math. I'm talking the bullet only, not including cartridge. Hanging a known weight weight through any compression spring until it is compressed solid tells you what that spring is doing. It's simple.
  3. Hello Josh, I’m impressed with your grasp of the math involved in these spring calculations. I ran the numbers for the 8 inch spring, 32 active coils, .043 wire dia, .430 coil dia, through the Efunda calculator we talked about. The calculator agreed with your numbers after I adjusted Youngs modulus of materials to a value of 150 Gpa. Also after running the cut spring @ 7 inches and 28 active it also agreed with your numbers. Now here is where things change somewhat. An 8-inch spring with a spring constant of 1.93, requires 1.93 lbs to compress it 1 inch. To compress the 8 inch spring 3 inches requires 3X1.93=5.79 lbs. Now we compare the above to a 7-inch spring. It began its life as an 8 inch spring. You cut 4 coils from the original 32. This reduced the length from 8 to 7 inches. By cutting 4 coils and reducing the length to 7 inches, the spring constant went up to 2.20 lbs/inch. With this information we know it now takes 2.2 lbs pressure to compress the 7 inch spring 1 inch. To compress this 7 inch spring 3 inches it takes 3 X 2.2 lbs= 6.6 lbs. 6.6 lbs for the 7 inch spring compares to 5.79 lbs for the 8 inch spring when each spring is compressed 3 inches. OK, but there is good news coming for Josh. A 1911 recoil spring runs 6.55 inches long with 30 coils, 29 active, the rated spring constant from the ordinance print is 2.88 lbs/inch. The wire is rated higher for spring modulus. That is the wire for the 1911 spring is a bit stiffer than the wire in you example. It doesn’t change the principle of our discussion. When the 6.55 inch stock spring is installed into the 1911 it is compressed to a length of 3.72 inches. Or to look at it another way the 6.55 inch spring has been compressed 2.83 inches. 2.83 X 2.88 = 8.15 lbs. This same spring is compressed 2.1 inches more when the pistol is fired and the slide is fully rearward. 2.1 X 2.88 = 6.05 lbs. .................8.15 lbs plus 6.05 lbs = 14.20 lbs total at full rearward........ Now lets cut 2 coils from the stock spring. 6.55”/30 coils = .21833”per coil. 2 coils = .4366” 6.55”- .4366” = 6.1133” is the length after 2 coils cut. The new spring constant is 3.09 from the spring calculator. Install the cut spring into the 1911. Subtract the new compressed length from the original free length, 6.11”- 3.72”=2.3933” We have compressed the cut spring less than the original by the amount we cut, .4366”. 2.3933” X 3.09 = 7.395 lbs initial force in battery. So this is lighter than the stock spring in battery. 8.15lbs vs 7.39lbs. Now let’s fire the pistol. The full rearward motion of the slide is still 2.1 inches from battery. It will vary .050” with a shock buffer and another .050” among different 1911”s. Measure your own 1911 to get exact numbers. 2.1 inches times 3.09 = 6.489 more lbs. 6.489 plus 7.39 = 13.879 lbs ................................Josh you are a winner. 14.20 lbs. vs 13.879 lbs....................... Let’s take 1 coil from the 6.55 inch spring. 6.55”-.2183”= 6.33”. The new spring constant is 2.98 lbs/inch. Install the newly cut spring into the 1911. It becomes compressed to 3.72” from 6.33”. 6.33”-3.72”= 2.61”. 2.61” X 2.98 = 7.77 lbs initial compression. Fire the pistol, add 2.1 inches more recoil spring compression. 2.1 X 2.98 = 6.26 lbs plus 7.77 lbs= 14.028 total at full rearward motion. Close, but the uncut stock spring is stronger by 14.20-14.028= .172 lbs. 2.75 ounces. Josh is still the winner, by 2.75 ounces. The great part is now we know, we really know, what happens when we cut recoil springs. Thanks Josh
  4. Hi Josh, I've been busy with other things today, tomorrow doesn't look any better. I'll get to this asap. I've got an idea we are going to learn some interesting things. I should have something for you by Monday evening. Should be fun.
  5. OK Josh I'm back, After I left I did a simple Google of Spring rate calculators. It took me to a site www/efunda.com. Engineering Fundamentals. They offer a spring calculator that uses several parameters of spring design. I put in the specification for a 1911 recoil spring. Wire diameter .043" coil diameter .430" free length 6.5 inches number of active coils 29 I left the other parameters alone. I then asked for a calculation based upon these numbers. It returned a spring constant/spring rate of 2.65 lbs/inch I then changed the number of active coils to 28 and reduced the length .25 inches to 6.25. Then recalculated. The spring constant/spring rate changed to 2.76 lbs/inch. This compared to 2.65 lbs/inch with 29 coils. The site then asked me to join if I wnted to use the calculator further. I'm not bashful, I got out my AMEX and joined. $10 per month. I realize the term spring constant and spring rate are indeed inter-changeable. The formula you are using is from the simple test of hanging a weight from a spring and measuring the deflection. Then comparing the deflection to the unweighted spring length. The difference is the spring constant. No problem. However it does not address changing spring length, number of active coils, etc. The spring calculator does calculate the variables and shows the effect of changing a single parameter. You can use this calculator once or twice before they want you to join. Membership is cheap. I recommend you look at it. It could even save you a trip to the hardware store. In the interest of knowledge, I would be happy to use my membership and input any numbers you want. I don't know if it has a print function. If it does I'd be happy to post the results. As I said before, I'm not interested in an internet pissing contest where no one benefits. Together, we can put away the ego's and search for the truth. I'll be back to this site tomorrow and hopefully we can understand this together. I feel better now, I hope you do to.
  6. Josh, It is not the fault of any University that you fail to understand such a simple concept. Apparently you have chosen to put your limited knowledge against the spring engineers and manufacturers that publish their information and specifications through out the internet. I have supplied you with the facts using the spring manufacturers information. If you choose to ignore the very people that do this kind of work for the rest of the world, then it has become your problem, not mine. If you are truly interested, take a few minutes from your keyboard and try this simple screen door spring test. If the test doesn't change your mind, I can't help you. Read the web sites of the manufacturers and engineers. I trust if you are willing to learn, rather than let this become a pissing contest, we'll all move ahead. I'm out of here,
  7. Josh, You are making this more complicated than necessary. I defined spring rate already. A physics whiz like youself should have no trouble understanding pounds per inch. I'll discuss this further after you can tell me why it takes twice the energy to pull a screen door spring that is half the original length. You don't need a laboratory to perform this experiment.
  8. Hi Josh, Thanks for your interest. It looks like to me you are using the same spring rate for all three different springs. If all three springs use the same diameter wire, wound to the same diameter coil, but different lengths then the spring rate will vary. As has been said by others here, if you have three springs where everything is the exact same except the length, you will have three different spring rates. The relationship is linear. That is to say a spring that is twice as long will be half the spring rate. If a spring is exactly the same wire and diameter, just like the previous example, but half the length, the spring rate is double. It is somewhat counter-intuitive. Another way to look at it; Whatever the spring length, it doesn't matter for this example. Spring rate is the amount of force to compress that spring one inch. If you are compressing 10 coils, each coil is compressed 1/10th inch. If you are compressing 20 coils each coil is only compressed 1/20th inch. It only takes half the force to compress an individual coil half the distance. Any individual coil doesn't know how many coils are in the spring. It still takes the same force to compress that coil X dimension. It takes twice the force to compress one coil 2X dimension. It takes half the force to compress the coil 1/2X. This is why the spring rate will vary as the length is varied for the the same exact wire diameter and coil diameter. This is why cutting one or two coils increases the spring rate. It's an inverse linear relationship. Just for grins, buy a cheap screen door tension spring. Pull the spring as far apart as you can. Notice approximately the length you are able to pull. Now cut the spring in half, then pull the same spring. Notice the spring is much harder to pull anything close to the same distance. When you cut the spring in half, you doubled the spring rate. Once the light comes on you'll wonder why it seemed strange. When the light come on, the next challenge is to explain it to someone else. It really is counter intuitive. I see the making of a bar trick, with a spring gauge.
  9. Finding accurate, easy to understand info about compression springs can be difficult, but not impossible. I got my information from the people that engineer and build springs. My feeling is they know what they are talking about. I'm being a bit pedantic here because of some of the posts from people that apparently have not studied springs or spring engineering. Most spring engineering priciples are intuitive, such as increasing wire diameter increases spring rate. Another intuitive compression characteristic is as the coil diameter is increased, the spring rate goes down. However the compression and extension spring characteristic that most folks have a difficult time with is the concept of cutting coils and length to an existing compession spring of fixed wire diameter and fixed coil diameter. The concept that cutting a coil from a spring increases the spring rate eludes people. It doesn't matter who says it. I choose to believe the people that actually build springs. The spring manufacturers must know their stuff. Let's look at a standard 1911 recoil spring. The music wire diameter is .043", it has a free length of 6.55 inches, the coil outside diameter is .430", the insde diameter is specified as a minimum of .336". The spring is 30 coils of which 29 are active. The spring rate is 2.88 lbs/inch. The installed length is 3.72 inches yielding an installed initial force of 8 lbs. The spring is rated at 13.55 lbs at a compression of 1.81 inches. The slide actually moves 2.1/2.2 inches from battery to full rearward. The solid length for this diameter wire and number of coils and free length is 1.375. This solid length is over .4 inches from the maximum rearward motion of the slide. No chance of this spring at these specifications of reaching coil bind. Now from the spring engineering site they say: "as the number of active coils are cut from a given length spring the spring compression rate increases". This has been mentioned in several posts here, but somehow has not soaked in or has been ignored. Further the spring people say if you remove a coil the spring rate increase by the ratio of the original number of coils to the ratio of the new reduced number of coils. In the case of a 1911 recoil spring with 29 active coils, cut out one coil and we now have 28 active coils. Doing a little math, 29/28=1.0357. That is the spring rate went up 3.57% from 2.88 to a new rate of 2.98 lbs/inch. The spring is also now 1/30th shorter. 6.2833 inches vs 6.5 inches. Stay with me here we are getting to the meat of this subject. So we install the newly cut spring and the new intial load is 6.2833 minus 3.72" = 2.5633 inches. Multiply the 2.5633 times the new spring rate of 2.98 lbs/inch and we get 7.63 lbs. Less than the original 8.0 lbs. Now we'll fire the pistol and make the slide move fully rearward. 2.1 inches from battery. 2.1 more inches times 2.98 lbs spring rate give us 6.258 additional lbs plus the original 7.63 gices us 13.888. 13.888 compares to the original specification of 13.55 lbs. The force of the cut spring is greater than the longer uncut spring. I'll bet you didn't see that one coming. So is it just possible the folks that make these springs just might know what they are doing? For those of you old enough to have cut coil springs to lower your car and then wondered why it rode so rough, you now know why.
  10. I'm confident Doc Watson didn't realize your friend Jimmy Clark shared his name with one of the greatest Formula One drivers of all time. I do not know of your friend, I'm sure he is every bit the gentleman the Flying Scotsman was. Such are the issues of posting on a pistol site a rememberance of another sharing the same name from a completely different sport. Jimmy Clark, the driver, was a master behind the wheel of these light, powerful Lotus Grand Prix racing cars, during a time when death played a huge role in the open wheel racing sport. It was my privilege to see the driver Jimmy Clark at the old Riverside Raceway, during a Los angeles Grand Prix in the late '60's. Jimmy Clark, multiple Grand Prix World Champion, also a winner of the Indianapolis 500, was one of the major players that revolutionized open wheel racing as it went from the tradional front engined Offy powered roadsters to the Rear engined Ford powered racers. As are the champions of competitive pistol shooting, Jimmy Clark, the Grand Prix driver was one of the talents that comes along once in a generation and is forever remembered for his heroic, legendary achievements. Thanks Doc Watson for reminding those of us that grew up in that golden time. Apologies to friends of today's Jimmy Clark.
  11. Brandon at SVI says the extractor is OK? Who is Brandon? The extractor you pictured has been messed with by some one. I doubt it is even a SVI factory extractor. It didn't come that way from the factory. EBG3 is correct, the extractor has been hitting something. The mark is obvious.
  12. That is one sorry looking extractor. Someone without much knowledge of fitting extractors has been busy with a file or dremel. The firing pin stop notch has been ruined. It looks like an attempt to stop the extractor from hitting the barrel. It's time to come clean, someone has replaced the original extractor with this piece of work.
  13. The link should break before the link pin. As has been covered the link's only job is to pull the barrel down out of battery. The barrel completely down out of battery will be against the VIS (vertical impact surface). At this point the slide stop pin should rotate freely, indicating no load on the link or link pin. If there is a load, the link is the wrong length or the VIS is positioned wrong. This pistol needs to be inspected by a qualified smith. It could be as simple as a defective pin. I would also inspect the slide stop pin for wear. Loads sufficient to break a link pin will show wear at the slide stop pin and possibly the frame holes. I remain suspicious of the pin.
  14. Bill, As you have posted the firing pin is striking the primer low. An offset bushing placed in the slide firing pin port is one method to raise the firing pin to the center of the primer. This of course is a patch for a separate problem. The barrel is being pushed too hign into the upper slide lugs. The KART EZ fit barrel addresses this issue be placing steel spacer dots into the barrel lugs at a 10 and 2 o-clock postion to restrict the amount of upper barrel lug interface with the slide lug. These dots can be welded to an existing barrel. The dots are about .100" diameter and .010"/.015" high. To test proper barrel to firing pin port alignment, there is a gauge tool placed into the chamber with a small pin extending from the rear of the gauge. The pin is centered and lines up to the firing pin port when the barrel is correctly centered in the slide. An alternate method I have used is to place a primerless cartridge into the barrel chamber. Remove the firing pin and simply sight through the firing pin port. The hole in the cartridge is about .050" diameter compared to the .093" firing pin port. It is quite easy to see the relative center alignment. Use this as a guide as to how much the barrel needs to be lowered to line up with the firing pin port. Since the barrel is currently pushed up too high, it is likely the barrel link is longer than the standard .278". It may be possible the barrel is forced up by a longer link and/or lower barrel lugs not reduced. As the barrel is lowered this will need attention. The geometry of the barrel to frame/slide is altered, so feeding of fresh cartridges may be impacted as well. Bottom line fit the barrel correctly, rather than move the firing pin port. It isn't that difficult.
  15. Stockton, Thank you for your reply and link for fitting ramped barrels. I'm afraid I didn't know much about ramped barrel fitting and as a result I opened my mouth when I should have kept it shut. I now understand some of the issues fitting a ramped barrel that I frankly never considered. Hopefully Technetium_99m's smith will help resolve the issues he has posted. Thanks again,
  16. Stockton, Would you care to comment on the .508" dimension reported by technitium-99? It looks like the VIS has been cut considerably past the maximum dimension. I'm not entirely clear on how this dimension was arrived at. However if accurate it would seem the VIS has been cut back too much. Much more than either of our fixes could fix. I would like to hear how using a Clark/Para/Lissner recut and barrel would work. I'm not at all familiar with this barrel and how it fits. Are you saying a C/P/L barrel is compatible with a VIS that has been over cut as this frame seems?
  17. Stockton, ong45 suggested using a longer link AND then filing the slide stop hole of the link upwards making it effectively a short link while in battery. You may have missed that part of his post. The objective here is to determine if the frame VIS has been cut back too far. Most of what I have read indicates it may in fact have been cut back too far. The suggestion put forth by ong45 is a simple fix if the VIS hasn't been cut more than a few thousandth's too much. The .508" from the back of the slide stop to the VIZ is disturbing. As pointed out by benny hill and HSMITH, the VIS may already be cut back way too far. This in my opinion would render the frame seriously damaged, if not destroyed. However the problem needs to be fully understood before any more cutting or filing on the frame. It will be interesting to hear what the original smith has to say.
  18. The title says it all. Are hammers and sears considered consumables? That is, should they be replaced routinely after X number of rounds. Or should a hammer and sear essentially live for the life of the pistol. I understand the "life" of a pistol varies greatly. Is it 20 years and 10,000 rounds? Or is it 2 years and 50,000 rounds? I'm confident some poor trigger jobs may not last long. Or trigger jobs done on poor (soft), steels. Thanks,
  19. Doing a trigger job requires a full understanding of all the issues involved with changing the hammer, sear and thumb safety relationship. Have you tested the safeties before beginning work on a trigger? What is a safe relationship of sear primary angles to hammer notch angles? What are unsafe sear or hammer angles? How much material can be safely removed from the height of the hammer notch? What is the primary and secondary sear angle? How is a secondary angle cut into a sear? What is the minimum safe sear length from the tip of the sear to the center of the sear pivot hole? What is the prefered method of adjusting the sear spring as it relates to the disconnector and the sear? What part does the main spring play in trigger pull? Is it ok to modify the main spring or should the main spring be replaced? Is it ok to modify the firing pin spring? How does the sear pin and hammer pivot pin fit affect trigger pull? What is the correct angle of the hammer notch? Can this angle be safely modified? What is the correct angle of the sear primary angle? How do you test the fit of the sear to the hammer notch? How do you test for hammer follow? How many rounds should be fired to assure you the trigger job is working properly? What to do if there is a misfire while conducting firing tests? How do you test the pistol's safeties? What do you do if a safety isn't working properly. Is the pistol safe if dropped? How do you document the work done on a pistol? There are more, but you get the idea. Now for the an important liability question for doing trigger jobs for a friend. Are you absolutely confident you can make a safe trigger job that will last the life of the pistol? What is the minimum weight trigger job you will do for a friend? What is the minimum weight trigger job for carry as opposed to target work only? Are you liable for any negligent or accidental discharges for any pistol you have modified? Are you prepared to defend yourself in a court of law for any work you have done to a pistol? Even ten years later and several owners later. What kind of paperwork do you need to do if you do a trigger job for a friend? This is only meant as food for thought.
  20. It sounds to me that you have a marginal, (short), disconnector. That is, when the slide is released, the disconnector is not being pushed down far enough by the slide to completely clear the sear. This situation is likely exacerbated by a marginal sear to hammer full cock notch fit. Particularly if the hammer has been reduced below a .020" height and the sear has not been stoned to match the vertical face of the hammer notch. This must be checked very carefully with a strong magnifier or 10x hand held scope. The face of the hammer notch must be truly at 90 degrees and the sear primary face is stoned to match the face, that is parallel with each other, along with a small sear secondary angle, the sear should not bounce out of contact. All this with sear springs set at minimum pressures and light main springs. Which do not help. How about the fit of the hammer and sear pivot pins? Most pins today are at least 1 thou smaller diameter than necessary. I put C&S oversize pins in my pistols. They are actually right on the blue print specifications. .110" & .157" I do not know what the pull weight of your trigger is. However light triggers under 3 lbs are the domain of expert 1911 pistol smiths.
  21. I should have made my 45ACP STI racegun into a 38 super, 12 years ago. Live and learn.
  22. Seth, I don't mean to hijack this thread but, ............ A flat spot on the slide stop could be used to hold the stop in position when in battery. This could only be done when fitting a barrel. Obviously if done after a barrel has ben fitted, the barrel would be loose. Perhaps this is Tripp's method, rather than removing material from the lower lugs. Better to stone and fit a slide stop than a $200 barrel. No need to dimple the slide stop either. Sounds like a good idea to me. This is my take on it. I could be wrong.
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