Gallery, Projects and General > Project Logs
Building a New Lathe
vtsteam:
I was asked about chatter. I've debated whether to answer. It's easy to make generalizations, and it's always the specifics that matter. You have to be observant and, well, flexible.
In a small lathe or flexible boring operation, yes chatter happens. But it's not necessarily a negative. Chatter is nature's way of telling you to slow down. Or sharpen your tool angles differently to suit the material. Or increase the feed. Or reduce the tooth profile. Or check that some part of your setup is starting to get loose. Or that you need to increase pressure in your gib screws. Or that you're too impatient. It's an alarm bell. You shouldn't get mad at it. It's there to help you do something different than you're doing.
It's something to figure out. It's something to make you a better, more skillful and knowledgeable operator. It's a set of instructions for lathe design. If things work out perfectly, you don't learn anything.
The first thing I produced after building my Gingery lathe was chatter.
Then I learned more about tool sharpening.
awemawson:
When pressing a bearing into a close fitting journal a LITTLE bit of chatter marks on the bore is a distinct advantage. The tight fitting bearing will slightly deform the ridges, and if you are using Loctite the troughs give it somewhere to sit without being wiped off.
vtsteam:
Intetesting, Andrew. I had clean cuts on the joutnal, and I never did switch to a 3/4" bar. I would have,
though, if chatter had been present near the end.
I didn't intend a press fit, also. The bore gauge was about a half thou oversize, according to my cheap caliper. And the final fit felt close, but not tight. I haven't done tapered roller bearings before, and this is a split housing anyway, with shims present, so a drive fit didn't seem necessary. I'm assuming, that tightening up on the axial nuts in a close fit journal is sufficient pre-load, and bearing retention for the purposes of this lathe.
PekkaNF:
--- Quote from: vtsteam on June 19, 2018, 08:16:35 AM ---.... I haven't done tapered roller bearings before, and this is a split housing anyway, with shims present, so a drive fit didn't seem necessary. I'm assuming, that tightening up on the axial nuts in a close fit journal is sufficient pre-load, and bearing retention for the purposes of this lathe.
--- End quote ---
Exactly. Idea of just a retention is good. No matter how good we hobbyis are, we still strugle to make bearing seat more round than bearing is. Tight fit is the professional way, when close to nominal loading is used, but then bearing seat must be made and measured to accuracy, that is pretty much out of reach. And because of modern glues no need to. Mechanical retention is the other good choise. We can fiddle with shims, nuts and stuff way longer than it would be practical in a professional seting.
Pekka
vtsteam:
Thanks Pekka! :beer: The only iffy part in this whole construction for me was going to be using tapered roller bearings. Plain bearings I'm very used to. I'm very happy with how close the fit is on the gauge, at least. It feels proper for the job. Now if I can just do the same for the other journal, everything else on this lathe will be a piece of cake!
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version