GTA
General Discussion To Gateway To Airguns => The Shop => : moe1942 May 07, 2008, 02:14:48 AM
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I have an antique Cometa and a Norica and would like to tinker with them. Make them shooters if possible. My problem is where to get the mainsprings and seals. I have looked everywhere and there doesn't seem to be a source for these brands or even generic parts. I have the equipment to modify and size if not a drop in fit.
If there is a place that gives the dimensions of the available springs that would work..
I've never owned anything that I didn't take apart and try to improve..
TIA
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Moe, is your seal leather, or synthetic? There is a spring size chart and a how to a leather seal guide, in the library. If you have a syn seal you may be able to get an apex seal from Maccari and resize if needed.
Mike
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Thanks Splash. I saw the chart in the library, what I need is specs on available springs so I can match up. I haven't taken the Cometa or Norica apart yet but would bet the seals are leather. I can probably make those. I just got a Super Streak and it needs some attention. Just trying to get my ducks lined up before I do surgery..
The usual tuning sites have springs but I wouldn't know which one would fit since they are for other brands. There has to be a source for ordering by specs..
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Moe:
The following spec's. are for the Crosman spring (Crosman Part #C1K77-010) that fits all C1K77 (Quest1000, Storm, Sierra Pro and Remington Summit) models priced at $5.70 ea. and are only a 585-657-6161 phone call away. (They can resume sending me my quarterly commission check any time now-hehe)
New unset free length-10 1/4" +- 1/32" and 36 complete coils (no partial coils).
.121+-.001 wire size (diameter)
.732+-.003 spring Outside Diameter
.487+-.003 spring Inside Diameter
Note that the I.D. is more critical then O.D. as it should be neither too loose or too tight on the guide. Although a new guide could be made to fit the spring if necessary. Also as a reminder, all compression springs expand in diameter when compressed and expansion is proportional to the amount of compression.
I have found that manufacturers rarely if ever publish these spec's. so you will probably have to disassemble your rifles in order to take the necessary measurements. As a second reminder, note that the length of used spring you remove will be shorter than it was prior to assembly at the factory. There is info in the library on determining maximum spring length. However I don't recall if that info mentions that a "bound" spring has its life and reliability significantly reduced.
Perhaps this info will help you along.
Mike
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Thank you very much machinist. That is good info. And I found the spring info in the library. I think I am accumulating enough info to tackle this job without screwing up..
I'm new to this game and I think it will be a great sport and hobby.
I have a mill and lathe so I can make what I need within reason. Figured I'd have to make a spring guide..
I hope y'all can tolerate asnother newbies questions.. Thanks to all.
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Moe:
I made a serious mistake on my previous post - Believe the medical term to be "Cranial Rectosis".
"I.D. is more critical then O.D" is wrong. The spring I.D. must fit the guide while uncompressed or slightly compressed in assembly (uncocked). The spring O.D. must not be so large that it binds in the piston when the spring is in a state of full compression.
Also, please note that I do not know what the IDEAL compressed spring O.D. to piston I.D clearance should be. I would strongly urge anyone wanting that ideal/proper clearance info to contact Gene Curtis or Bob Werner as they are the experts.
Mike
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I knew what you meant Mike. And yes I was wondering about coefficient of expansion on a compressed spring. This hobby is going to challenge my brain cells.I think I'm trying to make the parts aquisition more difficult that it really is.. Thank you for any and all info..
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Moe:
Another thing not mentioned but may need some clarification about spring O.D. increase upon compression is that the amount of diameter increase is dependent for the most part on coil pitch or pitch angle. The greater the pitch, the greater the overall diameter increase as it is compressed.
As a coil is flattened that given length of wire required to produce a given helical circle is now used to form a circle shape in a single (or flatter) plane so that original amount of wire now makes a bigger circle thus, the longer the helix the bigger the circle. I better stop there because even though spring making isn't exactly voodoo, it is out there somewhere between an art and a science.
If Jim McCarrie actually did the R & D and winds the springs he sells, he has earned every nickel he gets for them.
Mike
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Mike I had the same questions but I have yet to find any formula or data on the subject. Seems like springs and info are a secret fraternity. Guess I will have to do the testing myself. I'll build a spring compressor that allows me to check expansion as well as effort to compress a given length. Like I tested valve springs when I overhauled engines. Only didn't have to worry about expansion there.
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Mike if you see this I show two replies hung up in my PM outbox. You may get several or none depending on how this site works..May have to start using Email..