February 12, 2008 at 3:42 am #1507
I threw together a quick drawing for a new hammer.
If I had a way to fill this gun, I’d be shooting it instead of taking it apart and looking at every little piece!
That’s what I’m a thinkin’.
The “back” end is to fit and slide inside the aluminum tube like normal.
The front end is sized to be a sliding fit on the 12mm barrel tube at the largest area.
The rim in the middle is smaller than the 1″ tube bore so it doesn’t touch, only gives the end of the spring a resting point.
The “tail” is a sort of a spring guide, the length is to avoid crashing when the PW is at max setting.
I’m thinking about making this out of Delrin, but I don’t know how good the weight will be. I like McMike’s brass hammer with delrin tips, but I’m hoping to go all delrin to be simple. My goal is a lot of shots at 900 fps with 8.2 to 8.4 gr .177 pellets. Maybe Kodiak match at the heaviest.
Anyhow, lay it on me. Tell me where I screwed up. I’m thinking I can get this made before I actually have air in the tank! First air will probably be Friday night at the earliest… Waaaah! C’mon brown truck!
JimFebruary 12, 2008 at 6:35 am #33654cudaParticipant
How about this one use a stock hammer drill from the spring side. About 3/4ths of the length deep and use fine shoot (like they use for skeet) and wieght it to stock. Use 6 to 8 holes to fine tune and balance it to what ever tophat spring you want to use. Just make sure that lead has room to move. A plastic washer can hold the shot in. When the hammer hit it should act like a deadblow hammer. No bouce when it hits and it might get rid of some tank ping. Should hold the valve open a little longer to improve the shot to shot. Anyone can fine tune thier own hammer thier gun easaly. 😉 What you think? CudaFebruary 12, 2008 at 1:44 pm #33662bodhisdadParticipant
I have something very similar to that made by a tuner now gone. Works well, keeps th espring where it needs to be, and comes in at 75grams. Made from brass, delrin cups on both ends.February 13, 2008 at 4:27 am #33734riffraffParticipant
One question I have thinking about when having the hammer ride on the barrel instead of inside the frame:
Wouldnt this introduce impact vibration to the barrel? When the hammer hits the breech plug, any impact vibration would go straight to the barrel. The effect would be slight, but I would think the vibration would be less if the hammer didnt touch the barrel.
I know the breech plug touches, but it is in contact via o-rings.
I know people have built hammers like this with great result, however the question remains in my mind. I wonder if weight being equal and the only difference being contact points, which design would have less effect on the barrel?February 13, 2008 at 2:01 pm #33761bodhisdadParticipant
I should learn to read, but i like the pictures 😆 . Have you been to Leupy’s site from the UK? He has a design which runs on the barrel, maybe stop by there and take a look for inspiration, ideas and such. He has one which has a liquid interior, which to me says no more bounce and would take a lot of hammer slap out of the noise. Something similar has been done in anti earthquake dampening systems for structures. He also has a teflon or nylon lined sleeve to reduce friction. This definately has to be addressed if the hammer is going to run on the barrel. Check out his site if you haven’t already. Gallery and all he has alot of great ideas and the work speaks for itself.February 13, 2008 at 4:30 pm #33769
Thanks all for the neat ideas so far.
It took me a while, but I see what you’re saying. Drill a bottomed hole lengthwise from the spring end and fill it with loose lead shot. Kind of like a dead-blow hammer, right? That sounds like a good idea, but I don’t know if I can drill that far and not break through a wall. Another possibility based on your suggestion is to maybe use 1/8″ brass rods in a .130 hole. The brass rods could either be fixed, or allowed to slide for dampening.
I’ve rough calculated this to be at 29 grams if it were made entirely out of Delrin. I’m thinking a light hammer might be best for my application where I want to “blip” the valve open quick. At least I think that will get me more low power shots – I’m probably wrong somewhere though.
Vibration is a valid concern. However, if all the motion is fore-aft, and very little motion is allowed side to side, I would hope that there would be little vibration or motion applied to the barrel. If I make the barrel contact point only a few thou larger than the 12mm barrel, I should be able to control its movement side to side.
Yeah, I got to looking at Leupy’s site last night. What, 238 pictures of Stealth type stuff? Wow! I didn’t see any liquid interior, although I probably missed it. I did see a “Waisted brass hammer with oil filled nylon central core” but I took that to be more like the oil impregnated bushing material. Oil or liquid inside would be fun, until it got out that is. Kind of like a FluiDampr(R) harmonic balancer sort of? I also saw his teflon wrapped models, with teflon around the outside. We had some teflon shrink tubing at work a few years ago. Cool stuff, but you had to get it HOT to shrink it. Pricey as all get-out too.
My main observation for this was that body of the stock the hammer can get out over the reduced portion of the barrel. When it’s there, the inside won’t have anything to ride upon. That’s why the “tail” is there, and it also seemed like a good place to put a spring guide to reduce spring vibration, like on a springer air rifle. Being made out of Delrin, it should have very good self lubricating qualities.
Hopefully I can get some lathe time in and crank out an attempt. If it works, great. If it don’t, I still will have had fun!
JimFebruary 13, 2008 at 5:32 pm #33776walkonkingParticipant
Doesn’t Leupy’s hammer ride on the 12″ barrel only?
The concept does not work on the bigger barrels due to the diameter being to large…..Is that correct?February 16, 2008 at 5:39 pm #34055
I think this idea should work on any of the barrels if you make the thru hole large enough and the barrel sliding portion to fit the barrel (+0.003 maybe?).
If you look where the hammer is in at the cocked and then fired position, you will see that you need the extension or one end of the hammer will be riding on nothing. I.e., the barrel necks down to allow the breech block to slide ~ 1″ when cocking.
I ended up making the hammer out of UHMW for the first go-round.
Still don’t know the actual weight. Scale is in the mail…
I finally got my fill adapter and wanted to get to shooting, so pretty much everything else is still stock.
The TH is still at 0.093″
The PW was at 7-7 for this string.
I haven’t fine tuned anything yet.
This is a .177 with the 12″ standard barrel.
I aired it to 2200, shot a string, then reaired to 2250 and shot it down a ways, but not completely. (Got hungry last night)
7-7 seemed to be a decent spot for the PW. Lower and the high pressure shots would go nuts. Higher and the fps stayed the same, so no gain other than wasted air, right?
I did notice that the shots in the nice linear zone were plenty loud. I don’t have any washers currently being stored, so that’s probably to be expected.
In the graph, there are a couple shots that I’ve clipped out. These were down in the 500’s or so. They were my fault because I bound the breech handle. I’ll be making new parts to keep that from happening.
JimFebruary 18, 2008 at 3:57 am #34210
I took it apart tonight to swap back to the stock hammer.
It looks like it’s wearing perfectly, with little or no noticeable wear on sear contact part. The part that was sliding on the barrel appears to have worn very little if at all. I lubed the barrel contact point with some light teflon grease.
You can see how much the breech block rides back on the barrel tube, and you can also see why I made the “tail” on the hammer like I did so it could ride on the larger part of the barrel.
I like the way this hammer worked, but now I’m playing around with the stock hammer to get some datapoints. I’m sorry but I don’t have any targets yet as I’ve been chronying in the shop and it’s too friken’ cold outside to shoot targets.
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