Yes. Chuck is turning clockwise viewed from tailstock for all scenarios in the video.
Edited to correct error noted by @Tecnico.
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First crash
- Thread starter Chawbeef
- Start date
Yes. Chuck is turning clockwise viewed from tailstock for all scenarios in the video.
Edited to correct error noted by @Tecnico.
That’s backward??
Is that an Australian lathe?
D
Ya, my bad. Fixed on my first post. It is turning CLOCKWISE AND TOOLING IS UPSIDE DOWN IN ALL VIDEO CLIPS.
Parting is almost worse than thread cutting for getting people's faces in knots. The solution, really, is to practice until it becomes just another habit.
If using inverted tools, you run those upside down, on the back side of the work, often on a second tool post. Handy when you need to make a lot of very similar or same parts, you can face off the part with the regular tool, offset to the rear tool post, and part off, rinse repeat. Another strategy that I have used for a very large (for my lathe) parting job is to make a support that can be clamped between the end of your parting tool (I had over two inches of stickout on a HSS Parting tool blade) and the table of the cross slide. Doesn't compress worth much, when you get it working, so, almost no flex that would have been there with an unsupported blade.
Cannot accurately tell you how many landing gear bushings and shims I have made over the years, surely well in excess of my body weight, in 17-4PH Stainless, and in various brass and bronze alloys. The shims were parted off tube a bit over 2 inches od, wall thickness near half and inch, and were required to be in a range of sizes from right around .005" thickness, up to just under .080". We would heat treat a load of foot long sections of the parent stock, and proceed to face then part off dozens at at time. The faced off end was taped onto a trued in place mandrell, then the shims were faced to thickness.
Geometry to suit your material, esp with brass, is critical if you want to avoid drama. If you only have a parting tool that has some rake on it, as simple a thing as stoning (or, my fave, using a diamond grit file) a flat right at the very edge of the cutting edge, converting the last 5-10 thou of the blade into a zero rake tool. Same goes for drilling brass. A couple strokes to the cutting edges, parallel to the axis of the drill, makes those edges zero rake, and you no longer have misery drilling brass.
I have made and used parting tools as thin as .015" from HSS blanks. Not hard, with a little practice.
If using inverted tools, you run those upside down, on the back side of the work, often on a second tool post. Handy when you need to make a lot of very similar or same parts, you can face off the part with the regular tool, offset to the rear tool post, and part off, rinse repeat. Another strategy that I have used for a very large (for my lathe) parting job is to make a support that can be clamped between the end of your parting tool (I had over two inches of stickout on a HSS Parting tool blade) and the table of the cross slide. Doesn't compress worth much, when you get it working, so, almost no flex that would have been there with an unsupported blade.
Cannot accurately tell you how many landing gear bushings and shims I have made over the years, surely well in excess of my body weight, in 17-4PH Stainless, and in various brass and bronze alloys. The shims were parted off tube a bit over 2 inches od, wall thickness near half and inch, and were required to be in a range of sizes from right around .005" thickness, up to just under .080". We would heat treat a load of foot long sections of the parent stock, and proceed to face then part off dozens at at time. The faced off end was taped onto a trued in place mandrell, then the shims were faced to thickness.
Geometry to suit your material, esp with brass, is critical if you want to avoid drama. If you only have a parting tool that has some rake on it, as simple a thing as stoning (or, my fave, using a diamond grit file) a flat right at the very edge of the cutting edge, converting the last 5-10 thou of the blade into a zero rake tool. Same goes for drilling brass. A couple strokes to the cutting edges, parallel to the axis of the drill, makes those edges zero rake, and you no longer have misery drilling brass.
I have made and used parting tools as thin as .015" from HSS blanks. Not hard, with a little practice.
I think many of us would like more info on this idea Trev. Totally intriguing!
How do you clamp the blade to the support?
How do you stop the support from grabbing and causing all hell to break loose?
Pictures?
Me too, but they were not very long. I've had more success making much bigger parting blades.. It's fun to add a chip breaker!
Another thing I used to do was to grind a snakes tongue on the cutting edge. This allowed me to move the cutting blade from side to side to manage deep cuts.
Picture a framing square.
Long end of said square is in the tool post/aka:the actual blade of the parting tool..
Short end points down at the deck of yer cross slide, but gets cut off where it meets.
What you are going to make, is the short end. Vertical from under the parting tool, down to the deck.
Make it a few thou long, so that when you position it under the loose parting blade, it gets clamped down when the tool holder gets tightened.
File (with afore-mentioned Diamond files, I like Eze-Lap) the cutting edge back down to center (because if you have already made it to center, the clamping action is gonna raise it a tiny wee bit).
Plunge! Listen for a sound like frying bacon. Sizzle! If you have power cross feed, even better, set it at a mild feed rate and watch quarter sized coils drop in the chip tray!
It really all depends on your ability to make a couple decently square ends on a section of cut-off tool blade that matches the one in use. If yer really worried about interference, skim a little off the wide side of a parting tool blank, before or after you have made the 'support'.
We went through a couple or three blade and insert sets a month, in our shop, using carbide insert parting tools. We got to using the sets, because they sold for a reasonable price, and we usually had a few inserts left over by the time the blade had been crashed enough that the insert seat was no longer capable of being of use. Which is to say, in the hands of someone learning, you are NOT going to solve all your problems by throwing money at a carbide (or HSS) parting tool insert set.
Every skill only gets better with practice, not at all, with avoidance! I have had apprentice tradesmen (strangely, never the tradeswomen, who seemed pretty efficient in "Read the Instructions, Follow the Instructions!" for some reason...) wander the shop for hours on end, poking through drawers, and in supply cabinets, convinced that we were hiding 'the right tool' from them, when they had paper in hand that said, in less blunt words, "Make it yerself!".
That is more or less what I pictured. What I had trouble with is the "clamp the support to the blade" part. How does a clamp fit inside a deep parting groove?
I think you saying though, is that it gets clamped between the parting tool and the cross-slide by tightening the tool post. I don't think my BXA would do that but I've never tried it.
I would think a groove along the bottom of the parting blade, and a central edge on the support would keep them together as the cut progresses.
Fundamentally, this is a really cool idea Trev. It makes deep parting possible.
On the other hand, a crash would be phenomenal.....
That is the idea. Only needs to be tight enough to hold it in place when there is no cutting load. When cutting, the load on the tool will cause it to flex a wee bit and will grip the support solidly.
I would bet that if you biased to holder on the tool post with hand pressure, when you clamped it, you could pretty solidly clamp down on the support section as the toolholder was tightened on and squared itself up on the dovetails.
A fella might get all fancy and make a support that had a base, and a wee bit of adjustment, if he was keen on the idea...
Or maybe make the support the parting blade and push it with something in the tool holder.....
With all that rigidity, I'm wondering why it sizzles?
I have a parting job coming up that requires parting a 3" bar. That's a 1.5" plunge. I was just going to use the bandsaw but I may give it a whirl then instead.
The sizzle noise, is pretty much the sound of the cut, and when you hear it, and see that the cut is going smoothly, AND leaving a nice finish, it kinda clicks in yer mind. It's a GOOD sound to hear!
No rule says you cannot do some of both. Gotta run whut ya brung! Y'know, like the old adage that the guy who only has a hammer, sees every problem looking like a nail!