Another topic for discussion is the seals on the spindle ends. Do you all think we should use rubber oil seals or a labyrinth seal? Rubber seals are much easier but put a drag on the spindle and create more heat, while the labyrinth seal is more difficult to machine but creates no drag or heat. Are there any other seal options? I have done both types and have a preference , but would like to hear ALL options and opinions.
-
Welcome back Guest! Did you know you can mentor other members here at H-M? If not, please check out our Relaunch of Hobby Machinist Mentoring Program!
B
Bill Gruby
Forum Guest
Register Today
Double Row Angular in the noes and Single Row Angular at the rear. The bearings I am sending you Mark, all have a 1.000 Bore.
Let's briefly talk about Preload and why it's needed. The preload on the bearings is to minimize shaft deflection under load. It will be extremely minimal if we go with the Double Row bearing up front. Before someone jumps in with a comment about no deflection will occur, it is always there. There are only two was to minimize it, one use a specifically designed bearing. Too expensive. Two use preload.
"Bill"
Let's briefly talk about Preload and why it's needed. The preload on the bearings is to minimize shaft deflection under load. It will be extremely minimal if we go with the Double Row bearing up front. Before someone jumps in with a comment about no deflection will occur, it is always there. There are only two was to minimize it, one use a specifically designed bearing. Too expensive. Two use preload.
"Bill"
I agree with that ,Bill. Is the double row have the rows opposing or do they face the same way ( if they are angular contact) or are you speaking of putting a pair in the front ( face to face) so they preload themselves when clamped together in the nose.
B
Bill Gruby
Forum Guest
Register Today
The double row bearing has the contact angles facing each other. Sort of an "X" arrangement in the center of the bearing. This places the angular contact opposing each other making a more rigid contact resulting in less deflection and requiring less preload.
This is how it works, the downward force on the wheel creates the opposite on the shaft. The deflection is upward. The upward force causes the front balls toward the center and the rear balls aleo go toward the center. These two forces are actually opposite if each other front to the rear, rear to the front. These two opposing forces stabilize the shaft requiring much less preload.
There are standards and formulas for figuring the exact preload needed for a specific application. This would be a subject for another thread on bearing fundamentals. If you can find a set the "New Departure Handbook" Vols. 1 & 2 will be a great help and go a long way in explaning bearings and their applications.
"Bill"
This is how it works, the downward force on the wheel creates the opposite on the shaft. The deflection is upward. The upward force causes the front balls toward the center and the rear balls aleo go toward the center. These two forces are actually opposite if each other front to the rear, rear to the front. These two opposing forces stabilize the shaft requiring much less preload.
There are standards and formulas for figuring the exact preload needed for a specific application. This would be a subject for another thread on bearing fundamentals. If you can find a set the "New Departure Handbook" Vols. 1 & 2 will be a great help and go a long way in explaning bearings and their applications.
"Bill"
Last edited by a moderator:
B
Bill Gruby
Forum Guest
Register Today
No, it must still be calculated Radial bearings are normally what you are referring to. Angular Contact are a whole different animal.
"Bill"
"Bill"
- Joined
- Dec 8, 2013
- Messages
- 2,651
Wouldn't the rubber provide better protection against fine abrasive dust? Maybe rubber on the front, labyrinth on the back?
- Joined
- Dec 8, 2013
- Messages
- 2,651
- Joined
- Dec 8, 2013
- Messages
- 2,651
Actually , I don't think so. The labyrinth seal is A small gap and there are several grooves in a row. The oil provides a seal between the housing and the shaft between the grooves. they are very good at keeping junk out with no resistance turning. On a 3450 rpm shaft you need the rubber seals with springs and they put extra pressure on the shaft creating more heat.They are both good seal systems. I have used both on projects and they both work good. I can tell the difference turning the shaft with the rubber seal, it adds a good bit of resistance. another option is an o ring in the end cap that is the same ID as the shaft. this has less resistance.