Planer bearing getting hot

[Joe Weiss]

I recently bought a used Delta DC 380 and replaced the cutterhead with the Grizzly spiral cutterhead. Per Grizzly's recommendations I replaced the bearings on the cutterhead. I got the bearings from Accurate Bearing because Delta no longer stocks both of them. After a few minutes of running the planer (mostly without load), I noticed one end of the cutterhead getting quite hot to the touch (hot enough to burn my hand). The only thing I can figure is that excess friction is generating heat in the bearing and conducting it to the cutterhead. I confirmed with Accurate Bearing that the bearing numbers match the originals. Aside from tearing it apart again and replacing the bearing with a new one I am at a loss for what to do. I'd appreciate any thoughts or suggestions for next steps.

[Matt Day]

How does the cutter head feel when you turn it by hand (belts off of course)?

[Jerry Bruette]

Is it possible the bearing wasn't seated all the way and you have excessive side load which is causing it to get hot?

[Lee Schierer]

Did you check the speed rating of the bearings you purchased to see if they were acceptable for the rpms of your cutter head.

[Joe Weiss]

The cutterhead turns easily and smoothly by hand with the belts off. I hear a faint noise but attribute that to the helical gear turning the feed roller gears.

I spoke on the phone with the bearing supplier and they asked the RPM. I estimated 5,000 and they said it should handle that without any issues. The bearings were a good Japanese brand.

I think the next step is to pull it apart and check the seating of the bearing.

Thanks again.

[Martin Wasner]

Is it possible the bearing wasn't seated all the way and you have excessive side load which is causing it to get hot?

That was my thought, too much side load.

A bearing can get warm, but if it is uncomfortable to touch something is incorrect.

It could be a bad bearing too. It happens.


Since you're taking it apart anyways, I'd examine if it is an assembly issue. If it is, I'd replace the bearing even though it's new. You've likely cooked the grease and scored the races, no point in leaving it in there.

[Bruce Wrenn]

If the bearing is on the belt end of cutter, check for loose / worn belts. In your application, bearing shouldn't be any warmer than surrounding machine parts.

[Jim Andrew]

According to my mechanic, bearing quality is not what it once was. He says some are assembled with no grease.

[Joe Weiss]

Update: I did the tear down tonight and there is a bit of play in the bearing between the cutterhead and the transmission housing. Looks like I'll need a replacement.

[Joe Weiss]

I think you are right. There is a rubber seal mounted to the transmission on the cutterhead-side to keep sawdust out and this means you have to press the bearing into the transmission housing first and then press the cutterhead into the bearing. In pressing the cutterhead I think I unseated the bearing and tightening the helical gear onto the cutterhead shaft must have put excess side load on the bearing. I'll be sure to check that before reassembly with a new bearing.

[David Kumm]

I vote for either a poorly seated bearing or the outer got bunged up when put on. Those are small bearings with a speed limit far above what the planer runs. The next one will likely go on fine and you will enjoy the machine. Dave

[Lee Schierer]

If the bearings are hard to get on, get some dry ice and place it on the shaft for several hours before you try to slip on the bearing. This will shrink the shaft slightly and should make the bearing slide on easier. Work quickly as the shaft will warm up fairly fast where it touches the bearing. Also wear gloves when handling dry ice and the frozen shaft. It will not hurt your shaft or the bearing as long as you let it warm up before use.

[David Kumm]

I use a bearing heater but you can set them on a light bulb too. Heat the inner. Dave