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Any idea if this laminate would be suitable for bearings?

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#1 chrislon_geo

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Posted 16 January 2025 - 04:22 PM

I am building a 10" dob and am looking for alt/az bearing material to use. I came across a posting on FB Marketplace with large sheets of laminate for a good price. The code on the back is K073FL-C65. Does anyone know if this material would be suitable? If not, I think my club has some spare FRP that I could use. I have attached the photos from the listing (sorry for the bad image quality). Oh, and whichever material I choose will be paired with standard teflon pads.

Attached Thumbnails

  • lam1.jpg
  • lam2.jpg

Edited by chrislon_geo, 16 January 2025 - 04:24 PM.


#2 ShaulaB

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Posted 16 January 2025 - 04:33 PM

A classic is a record album. My 10 inch Dob has one for the az bearing, with teflon pads on the underside of the rocker box. Teflon pads for the alt bearings.



#3 TOMDEY

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Posted 16 January 2025 - 06:32 PM

It looks promising from here.

 

PS: Maybe never discussed why it works well >>> The varying sizes, locations, and heights of those little convex surface bumps integrates over the relatively large footprint of the Teflon. This almost entirely prevents (the integrated) "stiction" where the coefficient of static and sliding friction differ significantly for smooth contact but far far less for structured contact comprising myriad discrete convex quadratic ~islands~, randomly distributed in lateral location, size, and height. The arcane theory regarding the details is interesting and pretty well understood. The complimentary material (the Teflon) must be compressible and tolerate wear gracefully... indeed it must wear, of the whole principle falls apart. So, when you see a wee bit of Teflon powder around your bearings --- that's actually indication that it's working as intended and provides that ~buttery smooth~ motion that we all celebrate.    Tom

 

Closely Related >>> glass polishing using a pitch lap and Rough slurry. Nearly the same principle!


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#4 Dale Eason

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Posted 16 January 2025 - 07:29 PM

That look like the right stuff to me.  Give it a try.  


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#5 chrislon_geo

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Posted 17 January 2025 - 08:28 AM

A classic is a record album. My 10 inch Dob has one for the az bearing, with teflon pads on the underside of the rocker box. Teflon pads for the alt bearings.

I was worried that the 12" diameter would be too small. Right now, my plans are for a ~20" diameter az bearing



#6 Dale Eason

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Posted 17 January 2025 - 03:22 PM

A 20" base sounds excessive to me but the bearing diameter need to be almost that big.  The larger the bearing diameter the more stable it will be but it needs to be close to the edge to get that stability.  So If you really want a 20" base then the bearing needs to be close to 19".  The base on my 10 F3 in the avatar is 17" with a 15 inch ring.  In my case the ring is 3D printed PETG printed with segments that interlock.  




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