
It may well be PTFE is not suitable, in the next couple of days I'll run one up, I have 11 working SP-10's so no issue. In the meanwhile I trust PKI to do some research, in fact we may end up with a different material altogether ?
To my surprise the ball measures 7.147mm which is as near as 9/32" (7.14375) as we could get. 😉
Dave
Where is the polar bear anyway? Haven't seen him round these parts in a while...
Visit from my son, deadline for an article, and (of course) the last weekend of the regular season for the NFL. Oh yeah, and four concerts in two weeks. I need rest. I'll get back to the SP10II project in two weeks or so.
In the meantime (and I'm an experimentalist, not a theoretician!), user501's choice of a filled Torlon looks like a really good idea. I would be leery of Teflon. I may have some tweaks on lubricants- Rocol has been an education for me!
Is that a tool to take the bearing cap off in the pic? Did you make it?![]()
It may well be PTFE is not suitable, in the next couple of days I'll run one up, I have 11 working SP-10's so no issue. In the meanwhile I trust PKI to do some research, in fact we may end up with a different material altogether ?
To my surprise the ball measures 7.147mm which is as near as 9/32" (7.14375) as we could get. 😉
Dave
Torlon sounds like an interesting option and one I am interested in as well for my two 124s. How does in tolerate standard petroleum based oils (20 or 30 wt SAE non detergent oil)
How does in tolerate standard petroleum based oils (20 or 30 wt SAE non detergent oil)
Extremely well. It has some sensitivity to amine-based chemicals, but lubricating hydrocarbons are no issue even at high temperatures.
Is that a tool to take the bearing cap off in the pic? Did you make it?
Yes it is ! A friend made it for me. 🙂
I will check it out guys tonight if I have a moment (after all I have a PhD in polymer physics).
A question to PKI: I'm not fixated on PTFE but would like an expert opinion on the wear compared to Torlon ? If it's close I'll use PTFE as it is slipperier and potentially quieter?

Thanks
Dave
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Technics SP-10 Mk2A, a project by 6L6
Dave, from what I can see Torlon is superior in terms of mechanical qualities, however, PTFE has lower friction. What I was thinking and Google says it should be possible is to use synthetic Teflon plus graphite lubricants, so we can get the best of both worlds!
Again, I had no experience working with actual materials under real conditions, so I am just looking into all sorts of data sheets. Some additional practical knowledge can direct us a bit.
From what I can say looking into user510 experiments, there is no that much of a difference in sonic performance, I would be mostly focused on mechanical reliability.
Even if we look into friction data, the difference is in "dry numbers", if we add some lube things are leveling out.
Dave if you have a batch of these things produced already, use them. They should last for many years (there will be 3d printer using all sorts of plastic by that time 🙂.
P.s. I will keep looking... We should investigate all sorts of lubricants, I would say.
Dave, from what I can see Torlon is superior in terms of mechanical qualities, however, PTFE has lower friction. What I was thinking and Google says it should be possible is to use synthetic Teflon plus graphite lubricants, so we can get the best of both worlds!
Again, I had no experience working with actual materials under real conditions, so I am just looking into all sorts of data sheets. Some additional practical knowledge can direct us a bit.
From what I can say looking into user510 experiments, there is no that much of a difference in sonic performance, I would be mostly focused on mechanical reliability.
Even if we look into friction data, the difference is in "dry numbers", if we add some lube things are leveling out.
Dave if you have a batch of these things produced already, use them. They should last for many years (there will be 3d printer using all sorts of plastic by that time 🙂.
P.s. I will keep looking... We should investigate all sorts of lubricants, I would say.
Again, I had no experience working with actual materials under real conditions, so I am just looking into all sorts of data sheets. Some additional practical knowledge can direct us a bit. ... We should investigate all sorts of lubricants, I would say.
Fortunately, those are both my professional specialties. 😀
The filled Torlon is a good choice. Another material worth trying is Ketron PEEK HPV.
Great to have you with us!
Is your (useful) practical knowledge agrees with my (useless) theoretical conclusions? 🙂
Is your (useful) practical knowledge agrees with my (useless) theoretical conclusions? 🙂
OK, PKI and SY, can you point me to some numbers on Torlon, PTFE and anything better please ? Also how slippy they are ? 
I can get anything made out of anything, but my skills are electronics not mechanical engineering ! I do have friends that owe me favours with NC machines.
Thanks
Dave

I can get anything made out of anything, but my skills are electronics not mechanical engineering ! I do have friends that owe me favours with NC machines.

Thanks
Dave
Friction depends on the material that's being slid against the surface. There are some standard measurements, but they will not necessarily follow when one uses a different combination. And they will be VERY different for different grades and different fillers.
Here's a nice guide on Torlon:
http://www.hycompinc.com/PDFs/Torlon Design Manual.pdf
Here's a nice guide on Torlon:
http://www.hycompinc.com/PDFs/Torlon Design Manual.pdf
Yes, exactly my point. And as I understand test conditions are not always relevant with our TT applications.
If SY confirm, I would say Torlon is a pretty good choice. Maybe there is something better out there, but not by much...
If SY confirm, I would say Torlon is a pretty good choice. Maybe there is something better out there, but not by much...
I would absolutely agree. A grade like 4301, which has PTFE filler, is just great for bearing use, and a little lubricant makes it even better. Low COF, low creep, high compressive strength.
How smooth a surface should be for our applications? What would you thing the ultimate lubricant should be for let say Si3N4-4301 or steel-4301 contact? SAE20 oil or something more advanced?
A petroleum oil for sure. Maybe an ester base. The secret will be in an additive package I have in mind... Some experimentation is in order for sure. I'll order up some of those Torlon jobs and (I hope!) get some measurements to prove out the optimum choice.
Feel free to email me to discuss- it's always useful for me to talk with other polymer guys.
Feel free to email me to discuss- it's always useful for me to talk with other polymer guys.
If different combinations of materials are in discussion and if friction noise is criteria, wouldn't it be good to put noise draining also in to consideration ? Not sure, just guessing. Some materials having lowest friction may have high impedance to noise.
Regards.
Regards.
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