Question about spring guides...

[daved]

Okay, I know that virtually every tuner out there makes spring guides out of Nylon or Acetal.  So my question is, how come?  If plastic is the best material for the application, why do some manufacturers use steel guides?  And it's not just cheap guns that get steel guides, my TX 200 Mk. III had a steel guide in it, and at the other end of the spectrum, so do at least some of the Gamo's, or at least, they used to.  So far, I've come up with the following 3 possible reasons for using plastic vs. steel:

1. It's cheaper
2. It's easier to machine
3. It does a better job of dampening spring noise/vibration

In the long run, it seems logical that a steel guide will stand up to the abrasion of spring steel better than plastic.  And as long as the steel guide is fitted properly, it really shouldn't transmit much noise, and should still do a good job of damping vibration.  This seems especially true for guns that have a hollow guide for a latching rod, like the TX, the HW's, and the Diana's.

BTW, I'm not trying to pick a fight with anybody here :-).  And up to this point, it never occurred to me to even question using plastic for guides.  But now that I have the ability to machine my own guides, I'm curious about the underlying reasons for using plastic, and questioning whether or not it really is the best choice of material.  But I'm not big on reinventing the wheel, so any info here would be appreciated.  Later.

Dave

PS  Just to clarify, I'm ONLY talking about springers, here.  I asked a similar question on the YF, and someone started talking about a Daystate Airwolf.  Go figure :-).

[Magnum]

Good question Dave, That thought has occured to me before and I figured nylon, delrin type material was more or less about same cost with less friction via spacer washer, noise and a possible benefit less sprung weight. and wow a daystate airwolf!? that must be the one with extra power:)  Tony.

[tjk]

Interesting thought Daved. I figure plastic is easier to make in a mold injection machine with less cost in raw materials , plus the cheaper cost in re-cycling parts that don't pass inspection. It would also seem that the factory plastic would reduce the spring buzz more. But with the plastic guides used by some makers, it is nothing like a custom made guide that the pro tuners can spin on a lathe. Also seems to me that the custom made guides (nylon, delrin, etc) offer more resistance to wear and actually posess lubricating properties that plastic OEM guides don't,...nor a steel guide either,... like in the case of the HW made rifles.
Veering off the subject a bit, I've heard varrying opinions on how tight or snug a spring should be on the guides. Some instances where you actually have to force the spring on with much effort, and some that the spring just be snug enough that if flipped upside down,..the spring with remain on the guide and not slip off. Somehow I think this plays a role in different springer makers ideologys/theories on how the firing cycle progress's, and how the springs movement is figured into how the guide is made. And as usual, it may look great on the drawing table,...but if strict tolerances aren't adhered to in the production phase, the whole things a bust,.....or a "Buzz" in the case of lower end rifles like Crosmans, Gamo's, Daisy's, etc, and so on. I'm interested to hear others opinions on this subject. Great topic for discussion Daved,  tjk

[Truman]

Bit of my background was a setter on capstan auto lathes and sliding head lathes (Turret autos)! To produce tophats on a machine like either of these out of steel would be quick and easy using standard cams and basic tooling!  You could produce bucket loads of these cheaply and quickly! The only advantage that the plastic moulded part would have is the price of the raw materials! Now performance wise, I have no idea but I saw the state of my plastic Gamo tophat after the spring broke and it was pretty torn up! Maybe time to make a stainless one with a few stainless washers to go!

[kiwi]

Hi....
steel is alot more ridged than plastic..
as has been said set a auto capstan lathe up with a bar feeder
and walk away...very quick & cheap..
Top hats are steel because of the weight required..
rear guides in some cases because of other componets
that are molded in as well as the guide..IE.rear plug saftey unit..

Pete

[daved]

Still don't know which is the best, but I sure discovered something interesting machining the different plastics.  Nylatron is a PITA to work with!  At least, it is with the tooling I'm using.  Instead of anything like a chip, I get a continuous nylon thread that is surprisingly tough, and that insists on balling up around my work piece and cutter.  Occasionally, it will immediately wrap around the work piece, which is better in some ways, but then I have to unwind it when I've finished my cut.  Do you suppose this is how they make monofilament fishing line :-)?   Delrin is a lot easier to work with, but both give a very nice surface finish with slow feed rates.  The nylon seems to be a little harder and slicker, but that's a purely subjective assessment.  More later.

Dave