I finally got around to bleeding my brakes using the Canyon / Aaron method that was linked a while back. The rear brake on one of my sets of my Mavens always felt a bit soft to me, and when I used this method it seemed to firm it up quite a bit. It was pretty shocking at how many bubbles I was able to draw out using this method of isolating the caliper then the lever (so much that I wondered whether I had a leaky connection but I'm pretty sure that wasn't the case given that I never saw any leaks when pressurizing, and that the amount of bubbles steadily decreased). I'll definitely be switching to this method from now on.
I never said it's a replacement. I said PEEK is used as a counterpart material to steel in gears. Meaning one gear is steel, the other...
I never said it's a replacement. I said PEEK is used as a counterpart material to steel in gears. Meaning one gear is steel, the other is PEEK. I'm not an expert in geartrain design and obviously you don't see PEEK gears in car transmissions and the like, but I did hear a steel/PEEK combo has been used in an eBike drive unit to quite things down, which is the role PEEK plays - use it where you need a quiet geartrain but also need more strength in gear the usual plastic materials give you. COnsidering you don't see aluminium gears, there must be something on PEEK that gives it an advantage, I'd bet it would be surface hardness or something along those lines.
Considering this (PEEK being used to pair to steel gears) while aluminium is neve used for gears, I said PEEK might be a bit hard, i.e. used as a brake master piston it might scratch up the bore too, just like a steel, titannium or probably even aluminium piston would. But I don't have any experience with it and it might be empty worries...
As for CTE, if that is an issue that arises with a master cylinder in the brake, there are bigger issues than CTE itself... With the way seals are done on a master piston, there should be quite a bit of clearance radially between the bore and the piston, shown by pistons being scratched on only one side. One exception here is Sram's piston selling and jamming, but year... In either case, POM is also used as a master piston material from what I've seen and the CTE of it is about twice as big as PEEK's. If CTE was an issue, everybody would be using aluminium pistons anyway...
You are correct, you did say counterpart. In the example that you gave the reason why is correct for certain applications, but I can guarantee that it's not neat PEEK, i.e. unfilled virgin PEEK. Most likely its carbon or glass filled with ETFE or PTFE added as a lubricant, but I would bet that more often than not its PPS, without carbon black added both materials look nearly identical in color, have very similar mechanical and chemical resistance characteristic, but PPS costs 1/2 that of PEEK.
PEEK is not harder than aluminum. Pulling from my material DB here at work, we have a hardness tested calibrated for Rockwell A and B, 6061-T6 ranges from 56-62B. PEEK doesn't even move the needle on the Rockwell B scale, at all, It's not even close. LOL.
CTE is something that any competent seal designer should take into consideration, especially when designing a seal gland where the seal is being used as a rollback spring, let alone one that can see as aggressive temp swings as I would presume that a disc brake piston would be subjected to. Having to design anything around a moving target is tricky and ends up being an exercise in compromise.
I finally got around to bleeding my brakes using the Canyon / Aaron method that was linked a while back. The rear brake on one of my sets of my Mavens always felt a bit soft to me, and when I used this method it seemed to firm it up quite a bit. It was pretty shocking at how many bubbles I was able to draw out using this method of isolating the caliper then the lever (so much that I wondered whether I had a leaky connection but I'm pretty sure that wasn't the case given that I never saw any leaks when pressurizing, and that the amount of bubbles steadily decreased). I'll definitely be switching to this method from now on.
You are correct, you did say counterpart. In the example that you gave the reason why is correct for certain applications, but I can guarantee that it's not neat PEEK, i.e. unfilled virgin PEEK. Most likely its carbon or glass filled with ETFE or PTFE added as a lubricant, but I would bet that more often than not its PPS, without carbon black added both materials look nearly identical in color, have very similar mechanical and chemical resistance characteristic, but PPS costs 1/2 that of PEEK.
PEEK is not harder than aluminum. Pulling from my material DB here at work, we have a hardness tested calibrated for Rockwell A and B, 6061-T6 ranges from 56-62B. PEEK doesn't even move the needle on the Rockwell B scale, at all, It's not even close. LOL.
CTE is something that any competent seal designer should take into consideration, especially when designing a seal gland where the seal is being used as a rollback spring, let alone one that can see as aggressive temp swings as I would presume that a disc brake piston would be subjected to. Having to design anything around a moving target is tricky and ends up being an exercise in compromise.
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