Planet Airgun

General Airgun Categories => Maintenance, Modifications and Upgrades => Topic started by: svendogg on January 02, 2018, 09:29:53 PM

Title: Synsg piston seal
Post by: svendogg on January 02, 2018, 09:29:53 PM
Can someone confirm what size it is please?
Title: Re: Synsg piston seal
Post by: Gambo on January 02, 2018, 09:44:05 PM
I'll give Lyn a text to see if he knows....and I'll pass the info onto you sven. ;)
Title: Re: Synsg piston seal
Post by: svendogg on January 02, 2018, 09:48:53 PM
Thanks very much..... I had it in my head it was 28mm, but now I think that's drastically wrong. Meaning the 28mm Aussie seal that's currently enroute is..... Errr...... Too big!
Title: Re: Synsg piston seal
Post by: Gambo on January 02, 2018, 10:23:46 PM
Deffo isn't 28mm....that's nearly as big as a HW80!!! :o
Title: Re: Synsg piston seal
Post by: Gambo on January 02, 2018, 10:35:44 PM
I've sent a text.....just awaiting a reply.
Title: Re: Synsg piston seal
Post by: svendogg on January 03, 2018, 09:10:32 AM
I'd been reading a lot of Diana threads, since it's cloned off a Diana 34 I believe. Got it in my head it was 28mm lol
Title: Re: Synsg piston seal
Post by: Baggawind on January 03, 2018, 10:33:26 AM
Google SMK syng and they say it,s part of the 208 range. If that,s the case , it,s deffo 28mm, same as my 208 , to which I fitted an Aussie seal.
Title: Re: Synsg piston seal
Post by: svendogg on January 03, 2018, 04:07:19 PM
So I haven't buggered up then! Sweet!

Thanks guys!

How'd your Aussie seal fit, did you need to size it at all or just bang it in?
Title: Re: Synsg piston seal
Post by: Gambo on January 03, 2018, 08:18:56 PM
Got a reply from Lyn earlier.

Yep it is 28mm, same seal as fitted to the Remington Express. You can also use a Diana 34 seal.

Hope that helps.
Title: Re: Synsg piston seal
Post by: svendogg on January 03, 2018, 09:11:51 PM
Great, the the one I've ordered is a 28mm Diana 34 one, the custom air seals ones now are apparently a new material which is moly impregnated. Won't fit it immediately, want to shoot the gun as it is for a while first, then strip polish and reseal. Will keep notes on my progress of course
Title: Re: Synsg piston seal
Post by: Gambo on January 03, 2018, 09:14:54 PM
Yep, that's the pukka one sven. 8)

Yes, please keep us informed and up to date, as it'll be interesting to hear of your findings with the SYNSG
Title: Re: Synsg piston seal
Post by: Baggawind on January 08, 2018, 10:18:13 AM
So I haven't buggered up then! Sweet!

Thanks guys!

How'd your Aussie seal fit, did you need to size it at all or just bang it in?
I bunged mine into a cup of hot water for a few minutes then smeared it with a little silicone oil before pressing it on. I also had to size  it a little as it was quite a tight fit from new.
Title: Re: Synsg piston seal
Post by: svendogg on January 09, 2018, 08:56:06 AM
How'd you go about sizing it? And how do you guage if it's too tight?
Title: Re: Synsg piston seal
Post by: Baggawind on January 09, 2018, 10:54:42 AM
I,m fortunate in having a lathe in which i can hold the piston. I spin it up then use various grades of wet and dry to reduce the seal diameter. As for fit, it,s all down to feel. Hard to explain really but i like to make it a not too light push fit. Some people like to make them just tight enough to bear the weight of the piston , spring and guides when held upright. Personally, I don,t think that allows for eventual wear so I make them slightly tighter. Remember, you can take it off but can,t put it back on
Title: Re: Synsg piston seal
Post by: seagate on January 09, 2018, 06:28:19 PM
If you've no lathe , you can can get by using a drill clamped in a vice.
Title: Re: Synsg piston seal
Post by: Gambo on January 09, 2018, 08:53:10 PM
I,m fortunate in having a lathe in which i can hold the piston. I spin it up then use various grades of wet and dry to reduce the seal diameter. As for fit, it,s all down to feel. Hard to explain really but i like to make it a not too light push fit. Some people like to make them just tight enough to bear the weight of the piston , spring and guides when held upright. Personally, I don,t think that allows for eventual wear so I make them slightly tighter. Remember, you can take it off but can,t put it back on

A very well known tuner uses this technique.....

The piston and resized seal should stay stationary in an empty upturned cylinder when the transfer port is blocked off with a finger. Then, when the finger is removed the piston should drop.

This sounds like the seal may end up too loose...........but the seal expands when under pressure whilst compressing the air, making the prefect fit. :)
Title: Re: Synsg piston seal
Post by: Baggawind on January 10, 2018, 10:24:02 AM
Yes, I forgot to mention the finger bit. ::) :-[
Title: Re: Synsg piston seal
Post by: Gambo on January 10, 2018, 07:37:40 PM
Yeah.....and I meant to say the perfect fit....not prefect fit!!! Doh!! ::)