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FX valve seat angle

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JumboPellet

Member
May 18, 2020
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Ohio, United States
I'm looking to make a valve seat polishing tool like the one from member bigHUN :

valve_polishing_tool.JPG


The question is, does anybody know what the conical angle is? Unfortunately, I don't have any metrological gear capable of measuring it off the valve pin accurately.
 
JumboPellet said:
I'm looking to make a valve seat polishing tool like the one from member bigHUN :

View attachment 356935

The question is, does anybody know what the conical angle is? Unfortunately, I don't have any metrological gear capable of measuring it off the valve pin accurately.
Click to expand...




Screenshot_20230516-221457_Gallery.jpg

I have these screen shots in my mobile .The pictures are not mine . Is from another member buy I cant remember who .

He describes the angle as well but probably is for mkii because is few years ago .
If you don't have the latest valve housing of power block kit probably is the right angle 48°.
Maybe for the latest valves as well angle is the same .
I hope I helped......

Screenshot_20230516-221445_Gallery.jpg
 
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Back in time when I did my modifications on the Rear Block + Valve House I made the polishing cone 45 degree.
The difference between 45 or 48 is so small, and regardless - the peek poppet edge touches it only.
This what the peek looks like after some 15K shots = 2 years of range time ... the radius disappeared (both the black and the baige were the same) and visible sizing on the 2mm head.

valve puppet wear.JPG
 
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JumboPellet said:
Many Thanks!

For my purpose, I will be enlarging the throat diameter in the lathe. From past experience, when boring seats, it may leave a bur resulting in a slow leak. Lapping and polishing will usually prevent that. I would rather just go ahead and do it since the valve housing is already chucked in the lathe....
Click to expand...
For sure if you make in the lathe a tool with the right angle you will have better performance.
Just for your information I am using just a wooden rod with 3m polishing cloth starting from 600 and finishing with 2000 .
It can dissapear any bur in the valve seat without too much effort.
Screenshot_20230517-090650_Gallery.jpg
 
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bigHUN said:
Back in time when I did my modifications on the Rear Block + Valve House I made the polishing cone 45 degree.
The difference between 45 or 48 is so small, and regardless - the peek poppet edge touches it only.
This what the peek looks like after some 15K shots = 2 years of range time ... the radius disappeared (both the black and the baige were the same) and visible sizing on the 2mm head.

View attachment 357163
Click to expand...
Quite interesting. Judging by the wear offset on the peak seal, the peek is fully supporting the pressure. The steel cone is probably just for centering and to provide the shoulder to pull back the the seal? I was planning on replacing the C1 bumper with peek. Seeing this, I should probably do both. Now I wonder about enlarging the balancing piston on the end :unsure: Edit: That's not a balancing piston.

I bored out a crown valve seat a few years ago to about 6.3mm, but didn't give much thought to the contact area. I just assumed the delrin seal was there as a backup. That thought came from back in the day when I modded Hatsan rifles. Those valves and poppets were steel on brass, but the conical angles were a few degrees off to help minimize the contact area. We've come a long way in the last 10 years... Long live the BT65 :sneaky:
 
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