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AlexK
03-19-2010, 05:12 PM
I have 20" floor Dayton 3z919 drill press.
When I run it there is a slight grinding noise when spindle is
in "6 o'clock" position.
You can barely notice if you rotate it by hand but when it is under power it gets pretty bad.

I took the spindle assembly out. It looks something like this(not mine):
http://www.fignoggle.com/machines/round-column-mill-drills/figNoggle_quillSpindleAssem.jpg

External splines look good.
I manually rotate the inside part (where the drill chuck goes in) and I don't feel any grinding. It is not not exactly smooth but no grinding or rubbing feel.

This drill press has a front pulley that sits on bearings too. When I rotate it (while spindle out) there is no grinding. It is pretty smooth.

But when I put it all together(spindle assembly back in place) I have the same "bad bearing" noise/vibration coming somewhere from the top of spindle or from under the front pulley.

Can any one help me to solve the mystery?
BTW All bearings in the spindle assembly were replaced 3 years ago and this drill press did not see a lot of use.

Black_Moons
03-19-2010, 05:23 PM
does the pully on the splines have its own bearings? Maybe the grinding noise is only present when theres a sideload on the bearings.

EdC
03-19-2010, 05:27 PM
maybe it is affected by the drive belt tension. My only other thought would be some kind of interference under the pulley.

AlexK
03-19-2010, 05:37 PM
Front pulley does sit on bearings.
There is no noise when I run under power with spindle assembly out. (belt is on front pulley)

Toolguy
03-19-2010, 07:37 PM
Can you put the spline part in the lathe chuck and hold the quill? Maybe you could spin it that way with the lathe and tell where the noise is coming from.
If it has tapered or angular contact bearings you may just need to tighten the nut on top to adjust the preload.

Ted Coffey
03-19-2010, 07:42 PM
Could be a bent shaft.

Ted

RobbieKnobbie
03-19-2010, 08:14 PM
most bad bearings are broken during assembly...:(

Putting angular contact bearings in backwards

Pressing bearings into a bore by the inner race, or onto the shaft by the outer race

over lubrication or not running the grease in

installing the wrong grade bearing

any number of things could have been done by the guy who put those new bearings in. Sounds like you've isolated it to the spindle bearings, so it's time to swap them out for a good pair.

J Tiers
03-19-2010, 08:26 PM
Bearings should feel smooth when spindle is hand turned. it may feel stiff, or 'viscous", but it should not have any irregularity to it.

if you feel irregularity, there is a problem, possibly with the bearings.

A grinding or rubbing with hand turning would be a very extreme case, bearings don't have to do that to be bad. Or totally wrongly assembled.

wierdscience
03-19-2010, 08:33 PM
Grinding or rubbing could also be one pulley or the other rubbing on the sheetmaetal belt guard,this is common on Asian imports and some lower end US units.

If that's not it,then drop the quill assembly out of the machine and run the spline drive by it'self.

If that checks out,then it's most likely the quill.

On the otherhand unless it's something odd the new bearings to cover the whole assembly shouldn't be over $40.Most use plain vanilla 6xxx series bearings,even the US units.

CCWKen
03-19-2010, 11:46 PM
Did you check the motor bearings?

AlexK
03-20-2010, 03:48 PM
Motor's bearings are fine. Motor runs nice and smooth.
I disassembled the spindle.
Tow radial bearings feel smooth.
Thrust bearing feels "irregular".
This thrust bearing is not shielded or sealed and any dust can get to it easily through the hole in the spindle.
I know when bearings where replaced last time the thrust bearing was also bad.
Sounds like bad design to me.


The thrust bearing is described as "2906 Thrust bearing", part number "0497.00" in the Manual (http://www.metalworking.com/dropbox/Drill_Press_Dayton_20_inch_floor_model_3z919.pdf)
Where can I find this thrust bearing in a sealed version?
I don't see any "2906" bearing online let alone sealed version.

Thank you guys for all your help.

AlexK
03-25-2010, 11:22 AM
Here are some pictures of the disassembled spindle and new bearings:

http://lh3.ggpht.com/_gzA6aeqk3VE/S6t7XZhWeMI/AAAAAAAABHQ/v65AEUuCLjc/s800/DSC_0010.JPG

http://lh5.ggpht.com/_gzA6aeqk3VE/S6t7cTIg_jI/AAAAAAAABHU/PLM9IWYQWjI/s800/DSC_0009.JPG

http://lh6.ggpht.com/_gzA6aeqk3VE/S6t7iAXOSbI/AAAAAAAABHg/CHrjI0Ln1pQ/s800/DSC_0008.JPG

http://lh4.ggpht.com/_gzA6aeqk3VE/S6t7pcILhOI/AAAAAAAABHk/lsqDC15zU8k/s800/DSC_0005.JPG

If you carefully look at the spindle where top bearing seats and splines begin you can see a couple of "bumps" Whoever was changing the bearings before banged up the spindle and then press fitted the bearing over the bump.
Should I carefully file off these bumps?

lakeside53
03-25-2010, 11:40 AM
yes... use a stone.

J Tiers
03-25-2010, 09:21 PM
or, better, a burr file.