Linear bearing shaft

Other Hardware Motors, Mechanics, Power and CNC
1

Hi,

I have a linear bearing and a shaft. The weight of the end product is critical.

This is the bearing: http://www.amazon.com/Linear-Motion-Bushing-Closed-Metric/dp/B002BBF9FW
Can I use instead of this http://www.amazon.com/Linear-Motion-Length-Chrome-Hardened/dp/B002BBIHPG/ref=sr_1_1?s=industrial&ie=UTF8&qid=1392480747&sr=1-1&keywords=linear+motion+shaft+6mm shaft, a hollow one, like this one: Sierra Modellsport - Teava alama D6 x d5.2 x 1000 mm?

Will it work? It could spare me from extra weight. It doesn't involve much force in the system.

Thank you,
Robert

2

If it fits neatly and it's round then the answer is yes
The only way you are really going to know is to try it.

3

jackrae:
If it fits neatly and it's round then the answer is yes
The only way you are really going to know is to try it.

Linear bearing shaft is precision ground, hollow tube is generally not.
Hollow tube will also give more deflection.
Depends on your required precision.

Edit, and if its not hardened , lifetime will be limited.

4

No, you need precision round rod like the first link, the tolerances are 0.01mm or so.

BTW if you don't need such tolerances there are some very cheap chinese linear
bearings on eBay, but they are not precision in any sense of the word. They are
cheap in several senses though!

When you have precision linear bearings on proper round rod you'll find it slides
lengthwise easily (but tightly), but strongly resists turning around the rod, since
the balls are preloaded into compression and act like wheels.

5

MarkT:
No, you need precision round rod like the first link, the tolerances are 0.01mm or so.

BTW if you don't need such tolerances there are some very cheap chinese linear
bearings on eBay, but they are not precision in any sense of the word. They are
cheap in several senses though!

Yes, however by drilling and tapping the pillow blocs for a set screw its possible to get a tight tolerence fit which works well.
Need to be careful about cage plastic as well. Some have poor temperature resistance.

Otherwise i have good results from cheap chinese ones.
A proper spindle is a must though,

Not sure what you are doing but if its a milling spindle , normal practice is to spec 16 mm dia rod.
I have sucessfuly replaced. That with 12 mm supported rail for one machine though.

Im not clear what the op is trying to do though.
300 rpm for a spindle is ridiculously slow.
I run at 30000 plus.
Edit
Sorry confusing this post with aanother one

6

I clearly don't need precision.

It's used to move a robot arm for 1 cm. As an actuator is used a servo. It's linked through a rod. That's all.

7

Ok try it.
The tube not being precision ground though may bind with the bearing.

8

Hmm, than I'll choose aluminium instead of brass. It's tougher.

9

I have always found brass to better dimensionally then other metals.
I have sucesfully used it to make very good sliding fits in the past.
Graded sizes used to be available to make telescopic type assemplies possible.
I used to get it from model engineering suppliers.

This is pure brass not plated.

10

This the sort of stuff i mean.
http://www.hobbytools-direct.com/acatalog/Brass_Tube_-_Round.html

11

Aha. It's just as the one in my first post.
"Alama" in Romanian means brass.

12

Ahh i inderstand.
The bearings you linked to, i have sucessfuly used those on brass rod before with good results, not tried with tube though.
Iv never had satisfactory results with ally or steel though , unless ground finished of course.

13

Well, I'll come back and tell how it went. On Monday or Tuesday, I'll go buy them. I'm going on the tube.

14

Boardburner2:
Ahh i inderstand.
The bearings you linked to, i have sucessfuly used those on brass rod before with good results, not tried with tube though.
Iv never had satisfactory results with ally or steel though , unless ground finished of course.

I would worry steel balls would wear a groove into brass rod, its far softer. Aluminium
too (unless thickly anodized).

15

Did you find out on your own? What do you suggest? I can't buy another type of bearings, since there is just one model around here.

16

Have you tried looking for bushings ?