I just made a peek poppet for my AEA, it has an aluminum seat as well and I had to chuck up the poppet in a drill and burnish it into the seat to get it to seal. I pulled it out to look at it and the poppet barely had a mark on it and the aluminum seat still had the anodizing on it. Delrin seems to seal easily in comparison.
comp. tens. Izod water Ball coeff. wear str. str. impact hardness abs. density indent friction factor ----- ----- -------- --------- ------ ------- ------ -------- ------UHMW-PE 2000 3100 no break D62-D66 0 0.034 5700 0.14 0.1 PTFE ? 3900 3.5 D50 0 0.078 - 0.09 4080 ABS 5000 6500 7.0 R105 0 0.038 13500 ? ?polycarb. 12000 9500 13.0 M70, R118 0.12 0.043 16500 ? ?nylon 6/6 12500 11500 0.6 M85, R115 7 0.042 20000 0.25 162 w/30% GF 20000 27000 2.1 M101 0.7 0.049 30000 0.31 150acetal 15000 9500 1.0 M88, R120 0.2 0.051 19500 0.21 340PET-P 15000 12400 0.5 M93, R125 0.07 0.051 19500 0.20 121PAI 19000 13000 1.0 M113, E75 0.35 0.053 ? 0.35 637PEEK 20000 16000 1.0 M100,R126 0.1 0.047 27500 0.27 467 w/30% GF 26000 15000 1.4 M103 0.1 0.056 37500 0.25 187PEI 22000 16500 0.5 M112 0.25 0.046 ? 0.39 605Sources: http://sterlingplasticsinc.com/materials/ http://www.matweb.com [url]https://www.polytechindustrial.com/products/plastic-stock-shapes[/url]
I did the sharpie trick (or actually polishing paste on the seat) that Nervoustrigger suggested and indeed there's a section of poppet edge that's not touching the seat properly. I guess that was the problem although I can't quite understand how i managed to do that when spinning the poppet in a lathe. Still, that PEI sound quite interesting, perhaps I'll give it a go in the future as the PEEK rod I have is only 9.5mm in diameter so I need to order something bigger anyway.
Yup ... RAZOR sharp HHS tooling I've found best for such materials.Minimal rake and place on work piece center line of ever so *slightly lower for best finish.
I made a 10.5mm delrin poppet and it sealed right away. So, poor machining from my part.
Quote from: rkr on January 25, 2023, 02:53:25 PMI made a 10.5mm delrin poppet and it sealed right away. So, poor machining from my part.Indeed higher yield materials shape shift easier and there for seal easier.So folks understand while reading this post ....We go to harder materials because it takes less strike energy to get poppet to come off the seat, wears far better yielding greater service life.
Quote from: Motorhead on January 25, 2023, 03:36:16 PMQuote from: rkr on January 25, 2023, 02:53:25 PMI made a 10.5mm delrin poppet and it sealed right away. So, poor machining from my part.Indeed higher yield materials shape shift easier and there for seal easier.So folks understand while reading this post ....We go to harder materials because it takes less strike energy to get poppet to come off the seat, wears far better yielding greater service life.I'm using this peek poppet in an AEA VARMINT and the bolt is incredibly hard to pull. Just using this poppet, I have been able to back off the hammer spring 4 full turns and keep the same velocity, 850 fps.The bolt is still stiff but it's now not such a chore, the trigger lightened up a smidge too. I also got 4 more shots off a fill which may not seem like a lot but I'll take it!