Is it normal to have a bit of oil weeping out of the front seal of something like the HRT310 rotary? I use it a lot running unclamped while doing spiral milling, and run it for an entire day. It leaks enough that would saturate 4 ordinary paper towels, a few tablespoons, I suppose.

I'm supposing that this might be normal, due to running unclamped (maybe creates a bit of clearance, or something) but I don't know if a brand new one would behave this way. I bought mine used, in apparently excellent condition, but with an unknown amount of hours on it. I wonder if there is a worn seal or one that has 'gone hard' and should be replaced.

It does not leak when sitting unused.

Does it get warm while it is running? This could act to push oil out through the seal. Something the diameter of the seal on a 310 can be expected I think to show a bit of weeping; calculate how much it is losing per inch of seal length per rotation and I bet it is a very tiny number. I know if I was encountering a few paper towels full per day I would make sure I had a supply of oil to top it up and not do anything else. If it was leaking anything overnight while not running then I would look into it.

Thanks for the reply, Geof.

The unit is stone cold, as it is turning very slowly.

I did get a pail of oil, so I suppose it seems suitable to keep sopping up what seeps.

I have a HRT160B new in 06. Never leaked a drop running or sitting. Are you using the Haas oil?

I just changed the oil on a 210 its been running for 2 years and never leaked a drop oF oil. But The other day air was leaking out the back. So order the 2 diffrent o rings pulled the cover and there was a lot of rust. The bigger O ring was the one where it was leaking but the o ring looked fine I replaced it anyway and everything is fine now.