[My first post in a long, long, while. It may be lathe envy (I've been hankering for a bigger, heavier lathe). I'm still on my first: a very nice but pretty light 10" Logan.]
I'm still a comically incompetent beginner, but there are a few things I wish I'd known when I first got my lathe. Top of the list is all about tool bits and grinding: nothing will detract from fun on a lathe faster than a poorly ground tool.
The most useful (and most used) lathe tool accessory is a bench grinder. [The second most useful lathe tool, IMHO, is a vertical mill, but good ones aren't cheap and while you're hunting for a bargain you can get an awful lot done with a four-jaw chuck, faceplates, and centers. Work-holding and tool-holding creativity is the second most useful skill after grinding, and nothing teaches you the former better than the lack of a mill!]
Grinding an HSS lathe tool properly is
not hard (usually). It
can be done freehand (with practice). A few degrees difference in rake or clearance angles
won't make a difference (except when it does). Experienced grinders know the reasons behind all the angles and can troubleshoot and correct troublesome tool bits. Unfortunately, a clueless newbie has about a 0% chance of offhand grinding a tool bit correctly to begin with, and only a minuscule chance of correctly diagnosing problems. Problems are exacerbated on a light lathe with any flex in the machine (ask me how I know).
Apprenticing with someone would get you over the hump, but I suspect most of us hobbyists are alone in our shops, so the best options forward are one of the following:
1. You can forego some of the pain (or at least exchange it for
much more pain in your wallet) with carbide inserts and tool holders. Perhaps surprisingly, though, carbide inserts will never be as sharp as a well honed HSS tool (meaning you can't take as fine a cut with them) and you still need to know an awful lot about cutter geometry to select appropriate inserts (there are a
lot of choices). You guessed it: the best way to learn about those geometries is by grinding your own HSS bits.
2. You can take my route and begin a "YouTube apprenticeship." If you accompany watching videos and reading forums/blog-posts with
actually grinding bits and making chips, you'll eventually become reasonably competent. I took the longer route of always grinding freehand, but if I had it to do over again I know it would have gone a lot faster if I'd taken the time to build a decent jig or grinding rest. It's a lot easier to figure out which changes help when results are repeatable and exact rather than random (and once you can grind a decent RH turning tool for mild steel you can pretty much just lock down the jig settings as that's all you'll need 90% of the time). I've just started building the
Acute tool sharpening table from Eccentric Engineering. I'd also considered building
Harold Hall's sharpening rest. I can also highly recommend
the advice from Conrad Hoffman though I've not tried building his jig for honing.
Unfortunately, you'll need decently ground tools and modest skill to build any of these, which can be a bit of a chicken and egg problem for an absolute beginner. If you've got deep pockets, you can go the buy vs. build route with
a tool and cutter grinder like this one. That would be an awesome investment for the shop. Even a rank beginner could grind perfect HSS lathe tools from the start (buy two while you're at it, and send one to me!). A used Deckel T&C grinder off of eBay might be a better choice, but probably won't cost any less.
3. You could build or buy a tangential tool holder and grinding jig like the
Diamond Tool Holder from Eccentric Engineering. Like most people, I initially thought the diamond tool was just a gimmick, but if there was
just one thing I could go back and tell myself right after acquiring my lathe it would be to go out and buy one of these to get started. Sharpening a bit could not be easier: just insert a tool bit into the grinding fixture and push it into the grinding wheel. You only need to grind a single face! Once you set the height on center in your toolpost, you're immediate set up for all turning and facing tasks (
without needing to swing the toolpost around to switch between turning and facing). While it won't completely eliminate the need to grind your own HSS tools for special tasks, it will satisfy the all important need of
demonstrating how a properly ground tool behaves on your lathe. Seriously, I now use a tangential tool for almost all of my lathe work — it rarely comes off my toolpost.
I suspect many beginners go through these options roughly in this order (1, then 2, perhaps never getting to 3). I know starting out, I just wanted to start making chips, so insert tooling seemed attractive. The sheer number of insert options was intimidating, though, so I started learning how to grind my own HSS tools freehand. The experience gained was incredibly useful, but it was definitely tedious and frustrating — I went a long, long time before I could reliably produce a reasonably performing result.
So my advice is to keep all those tool bits you acquired (never throw away any bits of decent HSS) and learn how to grind them, but
start by acquiring a tangential tool and use that to build the parts for a grinding jig/rest/fixture as an early project. That is, 3, then 2, and perhaps eventually 1 as required. Treat those rusty old bits you have as a source of HSS stock. Often the trickiest part of machining is figuring out how to get a cutting edge where it needs to be (clever work holding and tool holding). Some of those weird offhand grinds make a lot more sense when you see them applied to their specific situation. Don't be surprised if you eventually find yourself rooting around in that pile of bits looking for something close to what you need, then taking one to the grinder for just a light touch up.
Have fun.
