Worn router bearings?

Lexicologist71

Lexicologist71

Rabid Schuler fanatic
Silver Member
I have been having issues with shafts coming out egg shaped (noncircular cross section). Once upon a time, I did not have egg shaped shafts. I just discovered that my router has some play in it. Does this typically cause the issue I have with my shafts or am I in deeper doodoo than I thought? I've been fighting with this for quite a while and have been operating under the assumption that the root cause was something else entirely.
 
I would start there with the bearings. Most routers are pretty easy to replace the bearings. I would bet money that your issue will go away after doing that.
Dave
 
If the play is feelable in the shaft, that is too much.
Then replace the bearings.
Dull cutters will also cause havoc along with not the right cutter geometry.
My thoughts,
How out of round are you talking about?
Neil
 
Anything not right will cause trouble but to much end pressure on the shaft will definitely cause this.

Dick
 
There is about 0.015" difference between measurements 90* away from each other. I don't really have any end pressure. I use one finger on my lever (Hightower lathe) and only close the gap. I don't apply any pressure. After locking the lever, I make sure I don't have any slop in the wood to tailstock interface.

Looks like I'll be trying to find time to rebuild my router. Grrrrr.

Thanks y'all. I didn't expect an easy fix, but I sure was hoping for one.
 
Lexicologist71 said:
There is about 0.015" difference between measurements 90* away from each other. I don't really have any end pressure. I use one finger on my lever (Hightower lathe) and only close the gap. I don't apply any pressure. After locking the lever, I make sure I don't have any slop in the wood to tailstock interface.

Looks like I'll be trying to find time to rebuild my router. Grrrrr.

Thanks y'all. I didn't expect an easy fix, but I sure was hoping for one.
Click to expand...

Is the dead center in the head stock running true?? Is the shaft smooth or do you have a barber pole effect on it??

I remember that I had a bad time when I was first turning shafts. It took me long time before I figured it all out.

Kim
 
Lexicologist71 said:
There is about 0.015" difference between measurements 90* away from each other. I don't really have any end pressure. I use one finger on my lever (Hightower lathe) and only close the gap. I don't apply any pressure. After locking the lever, I make sure I don't have any slop in the wood to tailstock interface.

Looks like I'll be trying to find time to rebuild my router. Grrrrr.

Thanks y'all. I didn't expect an easy fix, but I sure was hoping for one.
Click to expand...

Bearings typically get NOTICEABLY louder as they go bad. In a laminate trimmer, failure is almost always caused by too big of a cut. Even good bearings start to fail this way. I put THK's in my Rigid and they are now making plenty of noise after some bigger cuts and I have noticeable runout.
 
Whether you're cutting from the side of the router bit (slot cutter or straight bit) or cutting end-on, I'm having a hard time understanding how bad router bearings are causing the shaft to come out egg-shaped. Router is spinning at what? 20,000 rpm give or take and the shaft is spinning at 300-400rpm, right?
Isn't this more often a problem with the headstock bearings being out or the jaws not having been bored true?
And you did say " I've been fighting with this for quite a while and have been operating under the assumption that the root cause was something else entirely."
Of course, I've been all wet before:yikes:
Gary
 
Lexicologist71 said:
There is about 0.015" difference between measurements 90* away from each other.
Click to expand...
That is a lot of movement, and even if it's not THE problem, it definitely is a problem to fix before troubleshooting any further, IMO.
Dave
 
If you get a piece of something that is the same length, but use a single point tool, not your router, what kind of shape are you getting.
I just have a really hard time getting my head around that much runout/change in dimension.
So if you put a dti on the live center at the point, how much does it wigggle or move , sideways or when rotating ?
If you put the dti on the side of the head stock is there any movement there?
I just can't see that the bad bearings in the router is going to cause a 90 deg change in size on the shaft and be consistent.
Neil
 
I have to agree with everyone else. Although you may have bad bearings, most likely you center is off.

First. If it is noticeably worse on one end, and I assume it is, then there is where your problem lies.

Jeez it's late and my mind isn't working BUT. IF IT'S ON THE CHUCK SIDE: You can take some drill rod and measure the TIR of you chuck OR you can chuck up a piece of alum/brass rod and put a 60 degree end on it. If your TIR is .015ish then there is your problem. If you can't measure and the machined(don't take it out after you machine it)dead center in you chuck fixes it. Then that is you problem.

If it's on the live center end, then it's the live center.

.015 should be obvious though, as it IS quite a bit.
 
What are you using for the router and the router bit?
If you put a piece of straight material in the router, then put the dti on the bottom of the test piece, wiggle the test piece and rotate it to see the total movement. It should be less than a total of 0.002 inches.
If that seems ok, I would be looking at the cutter you are using.
Have you got a picture of the cutter you are using,? is it really sharp?
When the router is running, how much vibration is there over all?
Neil
 
Just a follow-up... Let us know... What did you find out? Have you solved the problem?
 
The results you're getting are more than likely related to push off and not router bearings.

First, if you're using a slot cutter, make sure it's not on backwards. I've seen this more often than you would think. Also make sure it's set pretty much at the center height.

Next, of course, it needs to be fairly sharp.

Also something that seems obvious but often comes up is, are you making a full cut? Meaning is the cutter removing material all the way around the shaft. If the shaft has a lot of runout, it might not cut all the way around, and you will certainly not have a round shaft if it doesn't.

I'm assuming you're cutting solid maple. If you're cutting laminated maple, this is very often the result. The edge grain is so much harder than the side grain. I've see shafts come out almost square when cut with a dull blade. Our new shafts use solid maple spliced together instead of the laminated, and they cut so much better.


Push off can come from lots of things. It amazes me that a shaft can turn at 150 rpm and move around that much, but they do. I guess it's harmonics.

Anyway, good luck and let us know what you come up with.


Royce
 
As it turns out, my live center had some play in it. When I swapped for a new one, the problem disappeared. Thank you all for your efforts in helping me straighten this out.
 
Thanks for the response and the final fix. Something else to add to a check list then.
With the amount you were talking about, I would have thought you might have been able to see that amount of runout.
But recently, I have been made aware of a phenomenon called scene change blindness.
In this, something can change quite markedly, yet the person is totally unaware of the change. Quite an interesting thing to learn about. It may well be why people have accidents and were not aware of what was happening.
Neil
 
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