Articulated Hollowing tool Bearing?

[Gary Conklin]

What do you think the better bearing is to use on a homemade hollowing system:

Needle Thrust bearing
http://www.bearingthrust.com/wp-content/uploads/2010/07/ro_bearing.jpg


OR

Pressed Fit Double Sealed
http://thumbs3.ebaystatic.com/m/mJjKYvKWLHzntNPfjlQCPoA/140.jpg

[Ken Fitzgerald]

Gary,

I'm sure some mechanical engineer or machinest will come along and tell you that my opinion is wrong but if one part of the articulating arm will rest on that bearing, I would think the needle thrust bearing would be more appropriate.

[Thomas Canfield]

Gary,

I bought bearing washers (washer with needle bearings) and a pair of harden steel washers(0.06" thick) to fit at each bearing point for my homemade articulated system and used a hardened split lock washer to provide spring load on the bearings. You need the hardened washer for the small bearings to run on when using normal hot rolled steel which is too soft for bearings. The bearings and washers are available at McMaster Carr or local bearing suppliers. I used 3/8" diameter bolts and washers that fit the 1" square bar.

[Rich Aldrich]

Gary,

I think a needle thrust bearing would be better. Make sure the bearing comes with complete as shown in your picture - two races (washers hardened to normal bearing hardness - I cant remember what that hardness number is) and obviously the rollers with the cage.

We had needle bearings on one of our piece of equipment at the paper mill where the needles ran on a pin which acted as the inside race. We replaced the pin, bearings and associated parts every 9 months. I redesigned it so the needle bearing ran on the actual inner race (and the pin was inside the inside race) that was supposed to be purchased separate. We replace these bearings about every 5 years now.

[Steve Vaughan]

Of the two choices given, I agree on the needle thrust bearing. But I've just completed my articulated hollowing tool using info I've gotten from this group. Having said that, I've noticed here and read somewhere else (I think) that other options with their homemade systems might be - nylon washers, bronze washers, and then this one: there is a thrust bearing that uses ball bearing in a groove. Someone on this site shared a link for those and for the life of me, I cannot find that link, I think I deleted it. Google "thrust bearings" and you'll get lots of sources. I used these (http://www.amazon.com/gp/product/B002HAPIY4) from Amazon and ordered these (http://www.amazon.com/gp/product/B002IAKTFG) matching washers, two per bearing. I used 1/2" I.D. stuff with an O.D. of 15/16" which fit perfect on my 1" material. Good luck and let us know what you come up with!

[Gary Conklin]

I have seem the other builds using the needle thrust bearings, but my main concern was dust. Anyone know what the Big Boys are using in their rigs? I have looked at pictures of the Monster and Elbow, and can seem to see a hint of the bearing used.

[neil mackay]

probably better off with a angular thrust bearing, as this type of bearing does the job of both your bearings shown. Using only the needle beaaring wont help you over come the friction of the left to right action.
If you have a inertia type sander have a look at the bearings and you will notice that they have the double sealed variety, generally two of them. As the most action is one of twisting nature and the needle roller set up is best for a squashing or compression action.