Bearing for 4th Axis Tombstone

G

G00 Proto

Hot Rolled

Joined

Feb 18, 2013

Location

Dirkdirkistan, ID

• May 27, 2019

• #1

I would like to make an "A" shaped support for the outboard end of some tombstones on a 4th Axis (Vertical Mill... kind of tough to do for a Horizontal). I built one a while back and used ball bearings, and felt that I got a bit of chatter from the play in the balls (I know, I said playing with my balls). Anybody ever done these. Tight tolerance plain bearing, roller bearing... I don't want to use a live center, it uses up too much table.

 

Cole2534

Diamond

Joined

Sep 10, 2010

Location

Oklahoma City, OK

• May 27, 2019

• #2

Opposed tapered roller bearings seems ideal, no?

Sent from my SM-G973U using Tapatalk

 

g-coder05

Titanium

Joined

Mar 5, 2006

Location

Subic Bay

• May 27, 2019

• #3

The ones I have made have just been oil light bronze for the bearing. No moving parts and hone to size.

 

T

thesidetalker

Stainless

Joined

Jan 11, 2015

Location

Bay Area, CA

• May 27, 2019

• #4

Plain bronze bearing works fine on mine. Split clamp to keep it relatively snug and close fitting.

 

S

SRT Mike

Stainless

Joined

Feb 20, 2007

Location

Boston MA

• May 27, 2019

• #5

I used a mounted pillow block bearing from McMaster, P/N 5057N1. I'll post pics a bit later... but I also used an off-the-shelf dowel pin (also from McMaster) press-fit into the end of my fixture. The bearing has set screws to keep it snug, but it's already very snug on the pin. I drilled/tapped 4 jack screws on the corners of the bearing block to align it and dial it in perfectly.

Works perfectly.

 

L

Larry Dickman

Titanium

Joined

Jan 30, 2014

Location

Temecula, Ca

• May 28, 2019

• #6

I went up to Napa auto and bought a bolt in front wheel bearing for a Honda something or other. Works great and it was only about $50.

 

Ox

Diamond

Joined

Aug 27, 2002

Location

Northwest Ohio

• May 29, 2019

• #7

I have used a 2" pillow block a cpl times before.
Not sure that would be any better than what you had before if you are blaming the bearing for chatter tho?

Those double roller tapered bearings (look like a beer barrel) as mentioned above sure have a LOT of surface area!
But they aint cheap either.


-------------------

Think Snow Eh!
Ox

 

g-coder05

Titanium

Joined

Mar 5, 2006

Location

Subic Bay

• May 29, 2019

• #8

Ox said:

I have used a 2" pillow block a cpl times before.
Not sure that would be any better than what you had before if you are blaming the bearing for chatter tho?

Those double roller tapered bearings (look like a beer barrel) as mentioned above sure have a LOT of surface area!
But they aint cheap either.


-------------------

Think Snow Eh!
Ox

Click to expand...

I wonder how a double row angular contact bearing would work?

 

Mud

Diamond

Joined

May 20, 2002

Location

South Central PA

• May 29, 2019

• #9

g-coder05 said:

I wonder how a double row angular contact bearing would work?

Click to expand...

There is still clearance in them because they are built to run at speed. I think the rear hub and axle end from a 1 ton truck would work great, would be cheap, and you could adjust the clearance as tight as needed. How big is this going to be? Maybe a 60s Jeep front hub?

 

M

Milland

Diamond

Joined

Jul 6, 2006

Location

Hillsboro, New Hampshire

• May 29, 2019

• #10

I'd play it simple, just a good polymer bearing of decent size (say, 1.5" OD, 1.25" ID, 1" W) with a heavy press fit into the A frame and a line to line in a polished post on the end of the tombstone. No clearance for chips to get in, but you'd have to check for swelling if the plastic is one that absorbs water from the coolant. At worst, a rebore after some time in use.

As long as it's a Delrin or PEEK-like material (not super soft), you'll get great load capacity and it'll last forever at the speeds you'll be spinning the fixture.