|
Post by E.T. on May 14, 2008 20:38:44 GMT -5
ET Have you found that the vent liners with the holes slightly off center cause any accuracy problem? I'm saying that the drill bit exits maybe....the most..... one drill bit off center......the side of the hole touches the center. Again, that was only on the last five (of 17) and probably due to the drill wandering as it got duller on one side. Richard Richard As for off center holes that you described I don’t believe that will hurt accuracy any as I have had some that were more extreme off center from RW and they worked fine. The only concern I would have if the hole coming out of the head was almost next to the side of the wall where the hex key fits. I’d be concerned for possible gas cutting here as the gas flow is directed to this location where the hole is. Just my thoughts being expressed. With your knowledge of machining and the way you have already quickly and easily matched my capabilities of drilling vent liners I expect to be learning another tip or two from you now. Ed
|
|
|
Post by Flatland Hunter on May 14, 2008 20:59:17 GMT -5
From everything I have read the PR Bullet vents are off center at times and accuracy is not affected. I have a few that are off by a diameter or so... it will be interesting to see if there is a difference. I do not think there will be though, it is not like it is a 90* turn.
|
|
|
Post by richard on May 14, 2008 21:00:55 GMT -5
They are centered in the hex key hole, but wandered a little off when exiting the other end ;D Maybe I should not stretch my use of the drill bit and only do 12? By the way Flatlander, I just ordered a dozen of those Bosch drills from your source, Improvementdirect.com Great price at $13/doz even with the $7 shipping. Thanks Richard
|
|
|
Post by Flatland Hunter on May 14, 2008 21:04:43 GMT -5
Mine are the same centered in the key hole but wander off at the other end. KerryB is due the credit for the bits and screws! He posted the links a while back I just brought them back up for air
|
|
|
Post by edge on May 15, 2008 17:22:29 GMT -5
I have posted this before, but I might as well add it to this thread. If you want to make your own vent BUSHINGS, and can press them in yourself, then buy some 5/32 or 3/16 W-1 Tool steel. A 3 foot piece will cost about 5 dollars. Cut them off about 3/8 long and drill your 1/32 hole through it. Now heat it up to a Cherry red, it will almost seem translucent, and with pliers drop it into a pan of salty water. When you take it out, run a file across it and the file will not damage it. Make sure that there is nothing in the hole to stop flow and insert into your breechplug. Some might question W-1 Tool steel. W-1, unlike the "better" grades of tool steel is not fussy on heat treatment. It does not hold dimensions as well as O-1 or the other grades, but there is no, long drawn out procedure to heat treat it......and if it distorts a little or is more brittle as a punch...who cares edge.
|
|
|
Post by richard on May 15, 2008 20:31:45 GMT -5
Just spoke with my friend up in NJ who is a "retired director of engineering" from Johnson & Johnson and one heck of a machinist. He also builds the finest rifles you have ever laid your eyes on. Anyway, I enlightened him on ventliners and questioned him about how to make them harder (yes, I mentioned what edge has already written) I explained the type of screw we were using. He said these screws are made with oil hardening steel. Heating them cherry red and quenching them in oil will make them harder. More so with thiner oil than thicker oil. But, since we do not need to retain the tensil strength, he suggested quenching in water. This would make them even harder. So, tonight, I hardened five of the ones I had drilled. When I get my ML back, I will put them to the test. This should basically make them as hard as a hardened drill bushing? ?? And, you don't have to send the BP out to get a new one pressed in when it wears out! Richard
|
|
|
Post by Flatland Hunter on May 15, 2008 21:06:56 GMT -5
Great information Richard... keep us posted!
|
|
|
Post by KerryB on May 15, 2008 21:46:33 GMT -5
KerryB is due the credit for the bits and screws! He posted the links a while back I just brought them back up for air Thanks for the credit buddy! The information you are currently providing is very valuable as well and that is what this forum is all about............passing along what we each have learned so the next guy doesn't have to "rediscover the wheel"!
|
|
|
Post by richard on May 16, 2008 22:06:17 GMT -5
Edge: You are probably right on that hardness. It was just a guesstimate on my part; I'm not a metallurgist ;D However, here is a test I did today. I took one of the screws Rockwell C38-44 and tried to file it with a new file. And, the file did cut it. Then I tried to file one of the water hardened screws? It would not phase it! That sucker is harder than a "wedding D&*#^%K!" By the way Edge, whats with the salt water vs. regular water for quenching? Richard
|
|
|
Post by rrbou on May 17, 2008 6:14:31 GMT -5
I found this artical.
Hardness is a function of the Carbon content of the steel. Hardening of a steel requires a change in structure from the body-centered cubic structure found at room temperature to the face-centered cubic structure found in the Austenitic region. The steel is heated to Autenitic region. When suddenly quenched, the Martensite is formed. This is a very strong and brittle structure. When slowly quenched it would form Austenite and Pearlite which is a partly hard and partly soft structure. When the cooling rate is extremely slow then it would be mostly Pearlite which is extremely soft.Hardenability, which is a measure of the depth of full hardness achieved, is related to the type and amount of alloying elements. Different alloys, which have the same amount of Carbon content, will achieve the same amount of maximum hardness; however, the depth of full hardness will vary with the different alloys. The reason to alloy steels is not to increase their strength, but increase their hardenability — the ease with which full hardness can be achieved throughout the material. Usually when hot steel is quenched, most of the cooling happens at the surface, as does the hardening. This propagates into the depth of the material. Alloying helps in the hardening and by determining the right alloy one can achieve the desired properties for the particular application. Such alloying also helps in reducing the need for a rapid quench cooling — thereby eliminate distortions and potential cracking. In addition, thick sections can be hardened fully. Quench Media
Quenching is the act of rapidly cooling the hot steel to harden the steel.
Water: Quenching can be done by plunging the hot steel in water. The water adjacent to the hot steel vaporizes, and there is no direct contact of the water with the steel. This slows down cooling until the bubbles break and allow water contact with the hot steel. As the water contacts and boils, a great amount of heat is removed from the steel. With good agitation, bubbles can be prevented from sticking to the steel, and thereby prevent soft spots. Water is a good rapid quenching medium, provided good agitation is done. However, water is corrosive with steel, and the rapid cooling can sometimes cause distortion or cracking.
Salt Water:
Salt water is a more rapid quench medium than plain water because the bubbles are broken easily and allow for rapid cooling of the part. However, salt water is even more corrosive than plain water, and hence must be rinsed off immediately.
Oil:
Oil is used when a slower cooling rate is desired. Since oil has a very high boiling point, the transition from start of Martensite formation to the finish is slow and this reduces the likelihood of cracking. Oil quenching results in fumes, spills, and sometimes a fire hazard.
Polymer quench:
Polymer quenches that will produce a cooling rate in between water and oil. The cooling rate can be altered by varying the components in the mixture-as these are composed of water and some glycol polymers. Polymer quenches are capable of producing repeatable results with less corrosion than water and less of a fire hazard than oil. But, these repeatable results are possible only with constant monitoring of the chemistry.
Cryogenic Quench:
Cryogenics or deep freezing is done to make sure there is no retained Austenite during quenching. The amount of Martensite formed at quenching is a function of the lowest temperature encountered. At any given temperature of quenching there is a certain amount of Martensite and the balance is untransformed Austenite. This untransformed Austenite is very brittle and can cause loss of strength or hardness, dimensional instability, or cracking. Quenches are usually done to room temperature. Most medium carbon steels and low alloy steels undergo transformation to 100% Martensite at room temperature. However, high carbon and high alloy steels have retained Austenite at room temperature. To eliminate retained Austenite, the quench temperature has to be lowered. This is the reason to use cryogenic quenching.
|
|
|
Post by richard on May 17, 2008 20:29:30 GMT -5
Thanks Randy! That was just what I was looking for. Richard
|
|
|
Post by dave sutton on May 19, 2008 19:09:06 GMT -5
;D ;D ok so if i get a non flamable can of pressurised air turn it upside down and bleed me off a bowl of the supercold non-flamable liquid( which boils on the end of my finger) could we use that to cold quench these screws??? or salt water solution chilled in a ice/salt bath(like old ice cream was made) ?
|
|
|
Post by rrbou on May 19, 2008 19:43:20 GMT -5
If I am not mistaken in order for Cryogenics to do any good you need to reach a temperature of -290*f.
In all other quenching it is how fast you can bring the temperature to under 200*f. As the article states the salt water helps the bubbles to break up letting the water get back in contact with the hot metal faster. For what we are looking for it probably would make little difference in plane water quench verse salt water quench. That and considering the small size of the vents.
|
|
|
Post by edge on May 20, 2008 5:42:29 GMT -5
Just two minor thoughts.
1) The harder you make the vent liner the more brittle it will be, don't over torque it as you could snap off the head;
2) If you manage to stick the vent liner and it is 50+ Rc, you will not be able to drill it out without a carbide drill.
edge.
|
|
|
Post by rossman40 on May 21, 2008 16:59:51 GMT -5
That is the problem I have with the vents I made. I have a frozen vent and thought I would just drill it out but I do not have a drill bit tough enough here at the house to scratch it.
|
|
|
Post by Flatland Hunter on May 21, 2008 17:35:30 GMT -5
So don't harden the vent liners... check!
|
|
|
Post by rrbou on May 21, 2008 18:45:42 GMT -5
I am going to harden mine, use plenty of Anti-seize, and only tighten them as tight as I can spinning the allen between my fingers. Basically no torque at all. If for any reason I break one or seize one I will get a new plug and rethink my approach.
|
|
|
Post by richard on May 21, 2008 18:46:22 GMT -5
Or, just buy a carbide drill! No big deal? Richard
|
|
|
Post by Flatland Hunter on May 21, 2008 21:19:15 GMT -5
I know... but I wasn't going to harden anyway... I have 98 vents! If I get through those in my lifetime I will feel blessed!
|
|
|
Post by richard on May 22, 2008 11:17:41 GMT -5
I hear you on the 98 vents ;D I am going to try one of my hardened ones just to see how many shots I can get. Richard
|
|
|
Post by zakjak221 on May 22, 2008 15:06:34 GMT -5
Let us know your results Richard!!
Mark
|
|
indyml10
Eight Pointer
my buck
Posts: 182
|
Post by indyml10 on May 22, 2008 19:28:04 GMT -5
how would supercooled ethelyne-glycol do?
|
|
indyml10
Eight Pointer
my buck
Posts: 182
|
Post by indyml10 on May 22, 2008 19:42:11 GMT -5
or dropping into dry ice? i never snug the vent just barely spin it by fingers in after i lube the snot outta it with ford high nickle anti seize and take it out and make sure its totaly covers all the vent threads and breech plug threads
|
|
|
Post by E.T. on May 22, 2008 21:15:16 GMT -5
Richard
If you don’t mind doing a destructive test to one of these screws to see what brittleness you are dealing with just use a hefty hammer and give it a medium whack. If it shatters instead of deforming you will know what to expect. Suggest safety glasses and a little shielding for the body when trying this.
I see you are way ahead of me again with something I planned to try later this year. I also plan to do some tempering to mine by heating them up to 400F for 30-minutes after quenching. An old toaster oven outside in the garage should do the trick, I hope.
Ed
|
|
indyml10
Eight Pointer
my buck
Posts: 182
|
Post by indyml10 on May 22, 2008 21:37:49 GMT -5
i have 300 of them already made BUT i only get 30 shots per liner I want to get at least 100 shots out of them so i am looking at salthingyer quenching or antifreeze and supercooling either solution but in drilling the hole it exposed the soft core of the screw so i need to toughen up the hole so to speak i was thinking kerosene BUT i see bad in trying that Kerryb has some of my liners to try out we will see i guess any ideas? ??
|
|
|
Post by E.T. on May 22, 2008 22:58:17 GMT -5
i have 300 of them already made BUT i only get 30 shots per liner I want to get at least 100 shots out of them so i am looking at salthingyer quenching or antifreeze and supercooling either solution but in drilling the hole it exposed the soft core of the screw so i need to toughen up the hole so to speak i was thinking kerosene BUT i see bad in trying that Kerryb has some of my liners to try out we will see i guess any ideas? ?? I believe you have what is classed as case hardened screws. To see what hardness can be reached you would need to identify the material to start with. The screw material Richard and I currently have is Grade 4140 and can be hardened over RC 50. From charts I have seen of this material if it is tempered to around RC 50 this would make it one tough vent liner without the undesired level of brittleness. As for the current steel screws you have heating them cherry red and quenching in oil would be my first go to see what can be achieved with them. Ed
|
|
|
Post by edge on May 23, 2008 5:39:27 GMT -5
IMO, an OIL quenched 4140 will not be too hard, the problem is the cross section at the intersection of the tapered head, the start of the threads, and the 0.031 hole. You WILL be able to snap this off if you over torque your screws. Just use lube and the SMALL end of the Allen wrench to tighten finger snug. Don't shoot 100 shots before loosening and you should be fine. As I recall we got about twice as many shots on a hardened screw vs just drilling, but it was subjective as to how hard folks really got them. If you are concerned, take your worst off-center vent liner, heat it and quench it. Then screw into a 10-32 nut that is locked in your vise. Turn the Allen wrench till it snaps. Now you know how hard NOT to go edge.
|
|
|
Post by KerryB on May 23, 2008 8:28:31 GMT -5
i have 300 of them already made BUT i only get 30 shots per liner I want to get at least 100 shots out of them so i am looking at salthingyer quenching or antifreeze and supercooling either solution but in drilling the hole it exposed the soft core of the screw so i need to toughen up the hole so to speak i was thinking kerosene BUT i see bad in trying that Kerryb has some of my liners to try out we will see i guess any ideas? ?? Indy, I didn't have much luck with your ventliners lasting very long either, especially with 5744, but i never tried hardening any of them. These Holo-Krome screws that i have been recommending last two or three times longer and that is without hardening. I think i will try the salt water or oil hardening process and see if i can extend lifespan a little more too! I have searched for screws even better than the Holo-Kromes, but i haven't found anything better yet. Will let everyone know if i ever locate the "ultimate screw"! ;D ;D KerryB
|
|
|
Post by Flatland Hunter on May 23, 2008 10:12:56 GMT -5
KerryB, glad you posted how long the Holo-Kromes can last. So you are saying they will last about 60-90 shots depending on load?
May try hardening couple of screws myself... but if I can get 50 accurate shots per screw I will be satisfied, more than satisfied even.
|
|
|
Post by minst7877 on May 23, 2008 13:31:25 GMT -5
The Holo-Krome flathead socket cap screw are hardened just like a grade 8 bolt. They are the cream of the crop for bolts as far as manufacturing goes. That was all we used when building stamping dies.
DC
|
|