Delrin Back Blocks

admeech29 · 12-05-2006, 07:24 PM

What are the advantages and disadvantages of a delrin back block?

Adam

howling phantom · 12-05-2006, 10:44 PM

I guess it would be the bennifit of a light back block, thus equaling a bit faster cycling rate. But Im not sure, so dont quote me on that.

Surge-NS · 12-05-2006, 10:51 PM

Lightening the amount of reciprocating mass on a cocker increases the rate at which it can fire usually, so long as the springs are adjusted to compensate.

Railgun · 12-05-2006, 11:09 PM

Yes that's all good but bear in mind that delrin is not as rigid as aluminium. And since the push from the cocking rod is off to one side only you could easily get unwanted flex in the back block that would lead to side loads on the bolt. I'm not saying that it would not work but I'd want to study the numbers along with the bending and other modulus of delrin as well as other plastics and the various fiber filled plastics and compare them to aluminum as well as looking at the loads around the various contact points. For example the cocking rod often only has about 1/4 inch or less of threads engaged in the back block. The loads are all concentrated in that small area so you really need to study and analyse the physics of the whole thing. Or try and test a lot of options with particular attention being paid to wear and any deformation of all the parts involved.

For example staining a part or area with felt pen ink and then cycling through X number of shots for all the options and study how much the ink is wiped away is one way to tell.

B · 12-05-2006, 11:19 PM

It is a poor performer over the long run with rapid fatigue and flex in this application . Go with a skeleton or P block for longevity and reliability.

admeech29 · 12-05-2006, 11:30 PM

Thank you very much for your help.

Adam

12-05-2006, 07:24 PM	#1 (permalink)
admeech29 Active Member Join Date: Nov 2006	Delrin Back Blocks What are the advantages and disadvantages of a delrin back block? Adam

12-05-2006, 10:44 PM	#2 (permalink)
howling phantom Active Member Join Date: Jul 2006 Location: Jax	I guess it would be the bennifit of a light back block, thus equaling a bit faster cycling rate. But Im not sure, so dont quote me on that. __________________ "For 25,000$, it better come with a midgit in the box to blow into the NeS so the games will play properly" NO SPOON!

12-05-2006, 10:51 PM	#3 (permalink)
Surge-NS Devious Penguin Mod Join Date: Mar 2006 Location: Brookfield, IL	Lightening the amount of reciprocating mass on a cocker increases the rate at which it can fire usually, so long as the springs are adjusted to compensate. __________________ Now that's special. One case; One kill. What do you want, a cookie? [QFD] Do not, I repeat, DO NOT read any handgun magazines or any magazines related to guns. These rags thrive on making people feel outgunned and underarmed and if you read any of them, before long you will be trying to figure out how to conceal a .44 magnum under a t-shirt and shorts without ramming it up your ***. [/QFD] I am Scourge! Mod: Ask The Experts, Events, PBC Reviews, The Dead Zone

12-05-2006, 11:09 PM	#4 (permalink)
Railgun MCB Member Join Date: Oct 2006	Yes that's all good but bear in mind that delrin is not as rigid as aluminium. And since the push from the cocking rod is off to one side only you could easily get unwanted flex in the back block that would lead to side loads on the bolt. I'm not saying that it would not work but I'd want to study the numbers along with the bending and other modulus of delrin as well as other plastics and the various fiber filled plastics and compare them to aluminum as well as looking at the loads around the various contact points. For example the cocking rod often only has about 1/4 inch or less of threads engaged in the back block. The loads are all concentrated in that small area so you really need to study and analyse the physics of the whole thing. Or try and test a lot of options with particular attention being paid to wear and any deformation of all the parts involved. For example staining a part or area with felt pen ink and then cycling through X number of shots for all the options and study how much the ink is wiped away is one way to tell. __________________ Model airplanes are cool too!

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12-05-2006, 11:30 PM	#6 (permalink)
admeech29 Active Member Join Date: Nov 2006	Thank you very much for your help. Adam