GTA
General Discussion To Gateway To Airguns => The Shop => : SDale September 18, 2008, 10:49:16 AM
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For the new folks here, especially ones that haven't done a tune yet.
I see that allot of guys post the procedures they went through when tuning a particular gun (me included), and Polishing is THE most prevalent part of a tune. But there's some cautions that go along with it.
This is mainly common sense but... First off, make sure not to take off too much material in the smoothing process. Getting too carried away makes for a sloppy fitting part! Just take off any high spots and get the part niiiiice & smooth. This especially goes for Trigger Parts.
Secondly, you shouldn't polish to a mirror shine and leave it that way. I know it seems that if it's mirror shiney, whatever it is would slide silky smooth. But this isn't the case, especially on parts that have faces that fit tightly together. Like the Trigger Sear for example. If both surfaces are polished to a mirror shine, when they mate they'll squeeze out any lube that's there and go metal to metal. There maaaaay be a very small boundry layer of lube left, but not enough to do any good.
What I do is polish the part to mirror shiney or as close to it as I can get then rough the surface back up with 800 or 1000 grit wet/dry sand paper wet down with a bit of mineral oil. 800 grit on pistons, guides, tophats etc and 1000 grit on trigger parts. The extremely fine sanding marks do the same thing as the crosshatch in the compression chamber. They hold a bit of lube, but aren't deep enough to catch on the ones of the corresponding mating surface and create any drag. That is, unless you forgot to lube the parts! hehe
Anyway, just throwin my small bit of knowledge out there.
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Good advice bud thank's for sharing. On polishing the trigger and sear I do polish every part on just the B3 trigger and sear without changing the angles. I even polish the inside of the trigger housing and pins. There is no drag on my trigger's, very smooth pull and I use very little lube but just enough to make it happy. All my "B" trigger's get this treatment and are pulled every couple months for inspection. This is just the way I've done it after trial and error and the more time I spent with it the better it got. This just go's for my B3 triggers and it's worked for me. Just my pellet's worth.:) Ed
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Your exactly right Sam. If you try to polish out all of the low spots, things tend to get sloppy. It's best to just knock off the high spots, burs and leave it at that.
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Thanks for the tip Sam. Sounds like sage advice to me!!! Hope everyone checks this thread out. Learned another valuable lesson today. Ain't the GTA a great forum?!?!?!? Yes, it is!!!!!!! tjk
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Sam you are right and another thing to consider is the triggers are case harden meaning only a few thousands of a inch are hard and if you go through that the soft metal wears very fast .Marvin
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And I might mention that on Chinese springers the metal used in the trigger is not case hardened... :) They usually are stamped out steel and layered parts which are riveted or spot welded together. Most Chinese triggers you really have to go easy on them or your air rifle will shoot on auto...:) Thats dangerous!
Gene
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Why polish something to then have to rough-it-up again?
You can deburr, smooth and then 'hatch' a part long before you polish it to a mirror finish. Like you mentioned, it's very easy to remove tolerances of .01mm-1mm. That's why 220-400 grit in hand is better than a stone or buffer in a Dremmel. The hatching a part might simply mean leaving a areas roughish. Fractal pores are more efficient holding lubes that are attracted to ferrous metals like steel than uni- or bi directional sanding marks and machine grooves.
Polish doesn't really mean mirror finish. It means just before and then rough it up. Right?
All the best!
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All very good info, thanks
For my arsenal 400 gt diamond in oil and several bar compounds down to about 3200 gt. Have had the diamond for years because it takes so little. It works great on a piece of glass to flatten parts.
CAUTION.... the dremel is probably one of the best AND one of the worst tools in the shop. It is very easy to over cut with these especially working around corners. The wet- dry sandpaper we read about so much here is great for working a surface without messing with the corners. Take the advice folks are giving here about trigger sears X10 :)
Tinbendin' Dave
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I don't even polish triggers and sears. I just stone them with Arkansas Oilstones.
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Jeremy... you are right. The way to do it if you are going to actually polish the trigger contact areas, especially the sear contact points, is to polish it and then burnish it with leather and moly. And if the correct lube is used in any other method, it will work just fine too.
I see people talking about how they polished this and polished that until it shined. In most cases not a good idea at all. Polishing and how and where it id done is very important, however... most people polish to the point that it defeats itself. The proper lube used can be far more effective than incorrect deburring and polishing.
And as far as the piston in relation to the action and it's movement in the action, the moly is in essance millions of microscopic ball bearings working in the carrier. And that is why using the correct moly in the correct amount and in particular areas plays a significant role in lubing.
Also, you should never ever polish the piston except in two areas, depending on the gun and type of power plant. And especially with anything higher than 400-600 grit. In the compression chamber it should never be more than 600 grit and regardless of what anybody says unless a leather seal is used. It should also be cross hatched and done properly if you want it to have a very consistant low spread constant velocity.
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the word polish defines as a smooth or glossy finish, i was mislead by this term when i first heard it used in this context.
crosshatch is the better term for our use.
http://dictionary.reference.com/search?q=Polish&r=66
http://dictionary.reference.com/browse/crosshatch
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Just squirt the trigger assy full of cheap toothpaste and shoot it until it gets smooth. Then you have to clean all that nasty goo out of there.
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The SASS crowd calls it a tooth paste trigger job. It's just fine silica particles. I'm thinking about doing that to my Single Six.
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google trigger jobs in a can. 3 compounds, a few hundred trigger pulls and youre set.
another member mentioned keeping his triggers dry internally.
I believe a mirror polish would be beneficial in this case following the powderburner school of thought.
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I put a mirror polish on the trigger and double action sear of a Dan Wesson .357 one time and the double action pull is amazing.
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The Dan Wesson .357 is a nice weapon, the DA trigger out of the box is HEAVY though.
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But it smooths up so nicely. Wolff makes springs for it, too. Mine is the original design. Actually a High Standard Sentinel Mk 3. Either made by Dan Wesson for High Standard, or made by High Standard to the original Dan Wesson design. IIRC it's the former. It has the bag handle grips. I got it for $75.00 because it had some surface rust and some mild pitting on the outside.
I'm going to either sandblast it and Duracote it, sandblast it and hot blue it, or parkerize it. Maybe parkerize it and then Duracote it. It has a fantastic trigger now. I want to make a carry pistol out of it. I may clean and scuff up the original grip and give it 3-5 coats of bed liner spray. Tough, grippy, and not bulky like the rubber grips, therefore, better suited for concealed carry.
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If you keep it dry, then you definitely need to give it a mirror polish. No matter how much you polish it, there will always be surface imperfections that will hold lube.
I just follow the simple steps of stone it carefully until it feels good enough, without altering the geometry of the bearing surfaces. If that doesn't get it smooth enough, I may polish it. Here lately I don't even go to the trouble of polishing.