[mdreitzusa]

i purchased some bearing that have these specs.

Static Load (LBF): 1080
Dynamic Load (LBF): 2148.75
Limiting Speed (RPM): 17000
Closures: METAL SHIELD
Cage/Retainer: STEEL
Lubricant: GREASE
Balls/Rollers: CHROME STEEL
Bearing Material: CHROME STEEL
Width (mm): 12
Outer Diameter (mm): 40
inner Diameter (mm): 17

my question is witch is the downward and witch is the side loads.
i got them for the through shaft spindle i'm making for my cnc.
did i pick a good bearing.

[2muchstuff]

Nothing is shown for the side load. Static load is the downward load when at rest and the dynamic load is the downward when in motion.

[mdreitzusa]

thank 2muchstuff,
do you think that these bearings would work in a cnc spindle.
i made a test core for my cnc and am now building the mounts.i mounted it in my lathe and did a spin test.it runs very smooth.but the real test will come when i put it to work.here are pics of core and small test cnc.

[2muchstuff]

Those numbers on the bearing, what are they. Looks like 62**

How fast do you plan on spinning the shaft, the wall thickness where the bearing is pressed in looks a little thin. There should be a internal retaining clip with a wave washer holding the bearing in and an external clip on the shaft also. You wouldn't want anything to come flying apart at speed.

[mdreitzusa]

the number on the bearing is 6208 they are from (vx bearing).
thanks for the help i will turn the bearing pockets a little deeper so i can install clips.i was planning on a speed of between 2000 and 3000 rpm.here is the core in its mount.the mount will get pinned to the core.right now everything is pressed together.thanks again i will fix the core with rings.
not to bad for a first time though.

[ESjaavik]

Leave the 6203 (not 6208) floating (endwise) on one end. Then use 2 thrust or angle contact bearings at the other end that fixes it endwise. Thus the temperature changes will not affect preload./clearance.

The 6203 can take very little axial load. You need a thrust or angle contact bearing for that. Thrust bearings with ID=15 OD=40 go up to 4100RPM (in grease), so would be good enough in your case.

The thrust bearing should be on the top end of your spindle, and it's good practice to support it with a standard bearing at the same end.

[mdreitzusa]

sorry mistyped the number.i still need to make a motor mouting plate.could i place a thrust bearing between the drive pully and the mount plate.

[ESjaavik]

That would only restrict the spindle from moving down (falling out). Then you need another bearing restricting it from moving up (pressure when drilling / downfeed).

I'll see if I can find a picture showing it.

[mdreitzusa]

thanks for the help.my shaft has been turned down to go through the bearings so it can't fall out. maybe this one would work for my pcb router/engraver.
thank again for the helping hand.

p.s. i think i will use this one for the pcb router.(very little down pressure)
i will take all that i have learned and all of the pointers to make a longer and stronger vertion for my cnc router table.
i will keep taking notes.

[2muchstuff]

I did some searching on the 6203 bearing and couldn't find anything with an actual figure regarding the axial load. What I did find stated that anything greater than 25% of the static load figure that you should contact the factory. Lotta help that was.

I did find a direct replacement for the 6203 in a angular contact type, 7203. A preload of 7 LBS.(light) to 88 LBS. (heavy) with a 22 LBS. as normal.

Thickening the area where the bearing is pressed in will help, 1- pull heat away from the bearing when in use increasing life, 2- lessen the expansion of the metal as things heat up and allow the bearing to become loose in it's holder (increased side play), 3- making things more rigid.

If you have the capability, making the holder/mount out of one piece would be prefered, a piece of square bar stock. Then you could drill thru the bar in several places to attach it versus the "u" shaped bracket that you had constructed. Nothing against what you already have done, great job. If you want to handle heavier jobs you need to build it beefy.

[mdreitzusa]

the prototype is all aluminum and the case looks thin but the tub has 1/4" walls.i turned a pocket in the end to receive the bearing.
i started work on an upgrade.it is longer to accept thrust bearing.
and i dubled up the bearing on the tool end.that will put 3 bearings on the shaft.with thrust bearing this should make #2 more staible.would it disipate heat better if i put stacked fins on the sleeve like a motorcycle engine.

my mind has been running over time on this project.and was wondering if these would work as spindle bearings.but they don't list rpm or load.
http://www.vxb.com/page/bearings/CTGY/Tapered-Roller

(i need to find a spell checker for firefox)

[2muchstuff]

Tapered roller bearings are generally used for slow speed, heavy load applications, like the front wheels on your car. The amount of surface contact area is much greater than with a radial type bearing therefore limiting its top speed.

[mdreitzusa]

i tought it would be a good low cost alternitive.but after my post i did a little more research and found out what the bearing speed is at 60 mph.its not even close to the low speed we need on a mill.oh well, it was just a wild idea.
i made a spindle for my router using 2 bearings on the tool end and 1 on top.i hope this will be strong enough until i have the parts to make a stronger and more accurate one.
i also made a smaller lighter spindle for my engraver using double rollerblade bearings on both ends.

[2muchstuff]

Don't feel bad, been there-done that. The router has been a learning experience for me also. I've had plenty of those wild ideas also.

The double/single bearing arrangement in your spindle will be a good one.

[mdreitzusa]

thanks for the help 2muchstuff.
my first cnc was gas pipe and 1"x4"s.it wasn't much to look at.but i learned a lot.
after three refits i found the jgro plans and made my second(13"x36"cutting area).it just needs motors and controls.
while i am saving for motors.i started my third mini cnc for engraving/pcbs.its cutting area will be about 6"x12".the x axis is asembled and i got the y test fitted.kind of a different idea.i made a square tube latter frame.
here is a pic of the frame.

[mdreitzusa]

here are a few pics of the remade engraver spindle and machine.this spindle uses roller blade bearings.the x and y axis rales are 1"square aluminum tubing.the z axis is 3/4" square tubing.
the rollers in pic2 are 2 peices of cutting board matirial and 2 roller blade bearings. i made them to fit the tubing.

[mdreitzusa]

the rollers are installed

[mdreitzusa]

motor installed and z axis finished