GTA
Airguns by Make and Model => Crosman Airguns => Topic started by: Rivers3Plinker on May 21, 2014, 09:50:38 AM
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I'm going to put a 1701P trigger frame assby on my 2289 and understand I need to modify or make a hammer weight that's solid without the groove normally used for the sear on the 13xx trigger group. The 1701P sear uses the front of the hammer weight. For the time being I will modify a stock hammer weight filling with JB weld, turning it down, polishing it and going through that process so I can get the gun built and enjoy the new trigger.
I had another idea pop into my head this morning for making a hammer weight and wanted to throw it on the forum for some feedback. Mods, this might be more appropriate in the machining section but you can make that call and move it if you feel necessary.
Since the OEM hammer weight is heat treated and hardened for impact with the valve stem, I thought about fabricating one out of mild steel rod, drilling out the center, counterboring the backside for the spring to the OEM depth and threading the remaining through hole to the face of the weight. I could install a grub screw into the hole threading it forward until flush with the face of the weight and loctite red it. This would provide a heat treated and hardened surface for contact with the valve stem. I would grind the tip of the grub screw flat and flush with the face and polish it too. I am almost certain something like a 3/16 grub screw is heat treated and plenty hard for this application but I could be wrong.
Unknowns:
- Haven't measured the OD of a hammer weight to see if it's a common available size for steel rod. I want to say it's 5/8?
- Would need to drill for the hammer pin and measure OD and figure out a solution for this possibly threading it and screwing a piece of drill rod into it or similar
All this without a lathe using only a drill press and a bench top belt sander. If necessary, I could turn down a piece of larger than necessary OD rod but hopefully wouldn't have to do that.
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Your idea is not that far fetched as that is the basic design of the 1701p hammer as it comes bored/threaded to accommodate the striker, which screws into the hammer and has an allen key end to allow for hammer throw adjustments for those platforms. I would recommend looking at the 1701p or P-rod drawings to get a visual.
I checked my 13xx hammer and it measures 5/8 inch.
Here's a picture of the stock 22xx hammer (left) and a P-rod hammer (right) which shows the tapped bore. I don't have a shot of the non-modified striker, but the second picture shows it in place and ground down as the head was too thick for the 22xx. But it shows the exact same approach as you outlined.
(http://i720.photobucket.com/albums/ww209/doogie65/ModifiedP-rodhammer002_zpsf301c6dc.jpg)
(http://i720.photobucket.com/albums/ww209/doogie65/Triggerinstall2400kt001_zps46769936.jpg)
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Wow - I honestly had not seen pics of the 1707P hammer weight prior to this. Thanks for the OD numbers and information. I think this is entirely possible to fabricate and when I do it, I will post pics assuming it's a success.
Thanks again!
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An advantage to the design of the 1701P hammer is that it provides a way to change stroke length in addition to hammer spring tension. At least in CO2 and PCP builds, this additional adjustment is useful in tuning the gun for better efficiency. I have not used a hammer with this configuration in an MSP.
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The hammer in a 2289 is a bit under 5/8", so you will have to remove some material to get it to fit.... You can make it just a cylinder with the 22* tapered shoulder on the front for the sear to catch on.... I don't really think you need to harden it, I never bother with my prototype stuff, and it never seems to dent.... but your idea of installing a screw for the striker surface will work.... As far as weight goes, not really an issue on a pump-and-dump design, you aren't going for the subtleties of trying to get a shot string.... However, make sure it isn't too tight a fit in the tube, or vent the area between it and the hammer, to prevent an air cushion effect which can cause hammer bounce....
Bob
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The hammer in a 2289 is a bit under 5/8", so you will have to remove some material to get it to fit.... You can make it just a cylinder with the 22* tapered shoulder on the front for the sear to catch on.... I don't really think you need to harden it, I never bother with my prototype stuff, and it never seems to dent.... but your idea of installing a screw for the striker surface will work.... As far as weight goes, not really an issue on a pump-and-dump design, you aren't going for the subtleties of trying to get a shot string.... However, make sure it isn't too tight a fit in the tube, or vent the area between it and the hammer, to prevent an air cushion effect which can cause hammer bounce....
Bob
Great information, thank you Bob.
In particular the shoulder chamfer angle will be helpful. I really should have ordered a 1701P hammer weight to reference but you guys are helping me along and I think I can make one now.
You really think I don't need to harden it? I guess if I start seeing damage I could try heat treating it. I think my neighbor has an Acetylene torch. Wouldn't hurt I suppose if I get it made and it seems to work properly.
Thanks again
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I doubt the Mellon hammer in my gun is heat treated as it appeared to be made from stainless stock.
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1377 hammer dimensions.
FWIW, you can heat treat 400-series stainless (420, 440, etc.). I don't think Charles uses 400 series though, probably 300 series. I don't have one of his hammers, so I can't comment on its hardness.
JMJ
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More great info - thanks a bunch. Saved and uploaded that jpg to my Google drive for future reference. I just picked up a 3' section of 5/8 dia hot rolled carbon steel from the local metals store ( Alro ) for less than $5.00 OTD.
That should be enough to make a lot of prototypes and mistakes as well. Still debating the set screw idea for now but based on how things go for me typically, I have the feeling I will end up doing it when I get started in the shop.
I can also heat treat the hot rolled. Have thought about using my charcoal starting chimney and some lump charcoal. Take the shop vac and use the exit air connection to blast furnace it a bit before dropping in water or oil. Not sure which would work better for this metal. I didn't get a alloy number, they just told me hot rolled.
Thanks again!
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Probably ASTM A-36.
http://www.metalsupermarkets.com/metals/consumer-guide/hot-rolled-grades/ (http://www.metalsupermarkets.com/metals/consumer-guide/hot-rolled-grades/)
JMJ
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Probably ASTM A-36.
http://www.metalsupermarkets.com/metals/consumer-guide/hot-rolled-grades/ (http://www.metalsupermarkets.com/metals/consumer-guide/hot-rolled-grades/)
JMJ
Yeah I did a bit more looking online. I don't know how much to be gained for the hassle with this particular steel and probably a better idea to use the set screw for contact surface instead.
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Search term "Superquench" It's a formula for hardening A-36. It'll get it to about 42c. Or you can just case harden it.
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will the P-rod hammer work in a 2289/13xx ?
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will the P-rod hammer work in a 2289/13xx ?
No... the 13xx hammer is a smaller diameter. But it is a direct fit for 22XX's.
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Search term "Superquench" It's a formula for hardening A-36. It'll get it to about 42c. Or you can just case harden it.
Thanks Bart!
I've learned something new. DIY quench recipes!
So the steel I bought was only $4.75. Should I be concerned about wear from the sear enough to justify getting a different alloy and not bother hardening it? Maybe stainless instead? What I'm getting at is should I start with something else instead of this mild steel alloy.
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Search term "Superquench" It's a formula for hardening A-36. It'll get it to about 42c. Or you can just case harden it.
Thanks Bart!
I've learned something new. DIY quench recipes!
So the steel I bought was only $4.75. Should I be concerned about wear from the sear enough to justify getting a different alloy and not bother hardening it? Maybe stainless instead? What I'm getting at is should I start with something else instead of this mild steel alloy.
I have not a clue. I do know the older Crosman sears were soft enough the striker would chew them up, if you polished the green Teflon coating off them. If you are going to use another alloy, 4140 is not too expensive. In some places 1045 is even less. In the stainless grades 440C is the best for heat treated parts. (I am making a Marauder striker and some other parts from it) A good source of heat treatable alloys is the local auto repair shop, ask for some of the scrap, used parts. Struts and shocks have very good material in the main rod. Half shafts and axles need to be heated to soften them before they can be cut. :o Even used head and suspension bolts, come in handy as turning stock. ;D ;D
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Search term "Superquench" It's a formula for hardening A-36. It'll get it to about 42c. Or you can just case harden it.
Thanks Bart!
I've learned something new. DIY quench recipes!
So the steel I bought was only $4.75. Should I be concerned about wear from the sear enough to justify getting a different alloy and not bother hardening it? Maybe stainless instead? What I'm getting at is should I start with something else instead of this mild steel alloy.
I have not a clue. I do know the older Crosman sears were soft enough the striker would chew them up, if you polished the green Teflon coating off them. If you are going to use another alloy, 4140 is not too expensive. In some places 1045 is even less. In the stainless grades 440C is the best for heat treated parts. (I am making a Marauder striker and some other parts from it) A good source of heat treatable alloys is the local auto repair shop, ask for some of the scrap, used parts. Struts and shocks have very good material in the main rod. Half shafts and axles need to be heated to soften them before they can be cut. :o Even used head and suspension bolts, come in handy as turning stock. ;D ;D
Interesting ideas Bart. Scrapping to re-purpose instead of for money!
I have a box of used head bolts and studs from small block Ford motors but those are all 1/2 inch so no use to me here.
I'm buddies with an auto-repair shop across the street from my work. I'll see if they have anything lying around that will work.
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What if I started with something like an 18-8 stainless steel, unthreaded spacer?
http://www.mcmaster.com/#unthreaded-spacers/=s2ro3o (http://www.mcmaster.com/#unthreaded-spacers/=s2ro3o)
McMaster-Carr part number 92320A189 - 18-8 Stainless Steel Unthreaded Spacer, 5/8" OD, 1-3/8" Length, #10 Screw Size.
This would have a through hole close enough to the tap size for a 1/2-20 to tap it an install a set screw in the face and for chucking it up to machine it with a drill or a drill press. The hole will be centered and straight already so boring it for the rear spring pocket would be easier and everything is relatively straight and true. The material is harder than the carbon steel I bought. The OD and length are pretty close to where I need it. The hardest part will be the drill and shallow counter bore for the rear pin.
Cost with shipping is more than a Mellon Air piece though.
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how about a 5/8 bolt with a long shoulder ?
(http://www.homedepot.com/catalog/productImages/400/f3/f3631c4e-af9f-48b0-9f5a-25c7d8419dca_400.jpg)
cut the head and threads off and cut a piece or 2 the same length as the 2289 hammer . then smooth out the ends making the front edge beveled to play nice with the sear and a depression in the rear for the spring seat ... then the cocking pin hole ?
maybe even use a yellow #8 bolt ??
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how about a 5/8 bolt with a long shoulder ?
(http://www.homedepot.com/catalog/productImages/400/f3/f3631c4e-af9f-48b0-9f5a-25c7d8419dca_400.jpg)
cut the head and threads off and cut a piece or 2 the same length as the 2289 hammer . then smooth out the ends making the front edge beveled to play nice with the sear and a depression in the rear for the spring seat ... then the cocking pin hole ?
maybe even use a yellow #8 bolt ??
Thought bout getting a grade 8 or even a grade 5 shoulder bolt.
I've not tried to drill a hole in one in a long time, but I think I should be OK using cobalt bits.
Thanks for the suggestion.
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how about a 5/8 bolt with a long shoulder ?
(http://www.homedepot.com/catalog/productImages/400/f3/f3631c4e-af9f-48b0-9f5a-25c7d8419dca_400.jpg)
cut the head and threads off and cut a piece or 2 the same length as the 2289 hammer . then smooth out the ends making the front edge beveled to play nice with the sear and a depression in the rear for the spring seat ... then the cocking pin hole ?
maybe even use a yellow #8 bolt ??
Thought bout getting a grade 8 or even a grade 5 shoulder bolt.
I've not tried to drill a hole in one in a long time, but I think I should be OK using cobalt bits.
Thanks for the suggestion.
just want to clarify that this is just a idea i have , i haven't done it myself and don't know of anyone that has .
i was thinking again (get's me in trouble sometimes) .....
rather than drill a hole for the spring to go in , use a drill bit that will fit inside the spring . drill small holes till you get up to size then super glue the top/smooth end of the bit in the hole and cut it to length for a hammer spring guide , then round/taper the end so it moves smoothly in the spring coils . the guide/hole will need to be centered and pretty darn straight though . it'll also add a little more weight to the "hammer" rather than losing it making a hole for the spring seat .
BTW , can anyone suggest how long a hammer "spring guide" should be ?
again just thinking outloud here , but if it's doable it kills 2/3 birds with one stone .
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Here's a copy of a spring guide I found over on CAPOF a long time ago. I made one out of Delrin, but the base was a bit too thick and the total length was a tad too long. This one is meant to sit at fixed end, but could easily sit in the hammer itself.
I'd knock .020" off the overall length to be safe.
JMJ
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thanks JMJ :)
so a hair longer than 5/8 inches ;)
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On my third attempt prototyping from the carbon steel. Don't think using a grade8 bolt is worth the difficulty in drilling or sizing compared to mild steel. So far looks to me like the JB weld filled stock weight is a better way to go unless you have a lathe or know someone who does. I've already wasted a lot of time at it.
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Hot and cold rolled steels (1011, 1018) are poor candidates for hardening because they are low carbon, to get a good surface hardness carbon must be added. Products like Cherry Red and Kasinit add carbon to the surface during process and it's possible to get a good case up to .007" deep with some effort.
Grade 8 bolts will drill easily with standard HSS drills. The key is the correct rpm, too fast and the bit will heat up and die. Gr8 bolts are only moderately hard so they make a good choice.
An easy to machine tool steel is 01 and is referred to as drill rod. Because it has a higher carbon content, it only needs to be heated to cherry red and quenched in oil for good results. It is inexpensive and readily available most metal or industrial supplies.
Tom
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On my third attempt prototyping from the carbon steel. Don't think using a grade8 bolt is worth the difficulty in drilling or sizing compared to mild steel. So far looks to me like the JB weld filled stock weight is a better way to go unless you have a lathe or know someone who does. I've already wasted a lot of time at it.
Ya, you would be shooting by now.
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Well not quite. I don't have the trigger frame assby from Crosman yet. Otherwise yeah, I'd be shooting it already.
Parts should arrive today or tomorrow. I've been trying to beat the delivery so I can assemble it with the new striker.
In the interim I have a new idea to at least properly turn down a piece of 5/8 rod I'm going to try today.
If this works, I'll try making one with a section of the Grade 8 bolt.
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OK,
Parts arrived yesterday and I must say the Prod trigger setup is pretty interesting. I am still trying to figure it out but I plan to take it apart and polish the trigger body for some added bling. I need to learn how the adjustments work on this thing too. It feels nice and I've figured out how the sear releases but it's very different from a 13xx trigger.
As for my machining adventure I am almost there from two directions.
First of all I have a stock 1322 hammer weight with a second coat of JB weld hardening on it. This is the backup plan.
Second is my 5th attempt on making my own out of steel and I'm almost there!
I finally figured out the best way to make it and if this one has any issues after it's installed, I think I can get it perfect on the 6th try.
I bought a 5mm end mill bit off Amazon and it looks to be the perfect size for the rear pin counter bore. At this point I have made the weight with only a couple minor differences over stock. The OD is .615 which is fine. The length is about .020 short which should be no problem either. It's round enough and smooth enough, but not exactly pretty. I hope to have the pin hole and counter bore done tonight. I have experimented previously with the bit and made an almost perfect counter bore on prototype fail #4.
Also I've learned the Grade 8 bolt material is actually easier to machine than the mild steel, which I did not expect. It cuts cleaner and drills without binding up the drill as easily. I've been using sand paper, files and a hack saw so far. Cutting it with a hack saw does take longer but the case hardening has something to do with that. You can actually see the layer of hardened steel when you cut it.
Prototype #5 was made entirely using a cheap little mini wood lathe. Normally this is used for making pens and and the like. I have a barracuda 4 jaw chuck on headstock and a Jacobs chuck in the tailstock for drilling. Yes it not worthy and it's not made for this but I figured out a way to use it. For starters, the barracuda on the head stock is probably .030 out! Chuck up anything round in it and get a tool near the material and it just bounces. This alone has added challenges to the project.
Anyway, pics coming if successful unless I find them embarrassing because this is not my best work, but it should do the job.
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Going with the JB weld option on a stock hammer weight. I just can't control my machining processes accurately enough with the tools at hand to make it worth the effort. I know if I kept at it I'd eventually get one that works but I have better things to do with my time, starting with shooting and ending with some cold beers.
Thread closed now and moving on to assembly after I have the final coat hardened on the weight and put it together.
Can't wait to start shooting it.
Thanks for all comments and replies.