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- Dec 26, 2015
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- 2,079
Perhaps the attached will help you.
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Dumb things you own, and never use
- Thread starter dewbane
- Start date
- Joined
- Mar 2, 2018
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- 232
The tool pulled out of the holder sideways and crashed everything. That has happened repeatedly with this particular tool. There's nothing wrong with the tool holder. Aloris tool holders are expensive, but they're nice. I'm sure the parting tool is nice too, but it just doesn't work well on my lathe.
As far as that goes, I did study the problem a little since writing the other day, and the problem with this parting tool on my lathe is that it's very rigid, and the lathe isn't. A parting tool should be rigid, but I've been relying on the fact that HSS parting tools bend a little, side to side. I finally saw it happen, and it clicked what's been going on. When that happens with this beefy carbide tool holder, that's when it goes boom.
I never thought to try actually indicating the parting tool to get it dead nuts perpendicular. I should try that. Maybe that's part of my problem.
Anyhoo, I don't think I could ever get my setup rigid and dialed in enough to have a fair chance with that particular carbide insert holder. The tool holder itself is fine, and I finally ground out that crash mark and made it pretty again. I put a HSS parting blade in there. Parted the part right off. It is what it is, I guess.
- Joined
- Mar 2, 2018
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Indeed, I have identified some problems with my technique, and new things to check and try.
One of the big ones is feed rate. I try to be consistent, but I don't have power feed, and cranking by hand is a fundamentally variable process.
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- Jan 25, 2015
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- 2,558
There’s something about your parting technique you just haven’t quite sorted yet.
I part 1018 and 6061 on my Atlas 10F without drama. Thats with a hss cutter and a holder like the one you’re using for the insert.
The 10F is well known for a lack of rigidity, at least when parting and making heavy cuts. So I’m skeptical that the problem is your lathe is too “flexible”.
I also usually cut dry or a few drops of oil at most. When I use lots of oil its usually to try and make the parting smoother or to try and keep the temp down so the tool doesn’t loose its temper. I don’t like slinging oil all over or breathing in oil smoke, so I minimize the use of oil as much as I can. Others may differ on that. Different strokes…
What made the biggest difference for me was learning that the feed rate is much higher than what you would think.
You’ve got to force it into the material pretty hard or you’re going to get lots of chatter.
Lots of guys are a bit “shy” when starting the feed and that just sets up chatter. Especially so for home machinists, where you get condtioned to make light cuts to compensate for “hobby grade” machines.
I’ve found ya just gotta jam ‘er in there and keep feeding. As if that isn’t confusing enough, if you do get chatter you have to feed even harder to get under the chatter marks you just made or the chatter will just build on itself until you think the whole lathe is just going to flip over, explode and throw pieces to all 4 corners of the shop.
The way I picture it in my mind is you need to get a good sized chip started or the blade is going to “pop“ that “thin” chip off and the blade with bounce/vibrate when it does it. Another thin chip after that and you can see how chatter starts and builds. If you think about a washboard road, its kind of a similar effect: it gets a few potholes and the more cars that drive over it, the bigger the washboarding gets. That might not be exactly what happens, but its what makes sense to that bundle of nerve cells perched at the top of my neck.
The parting blade needs to be perpendicular to the material. All I do is pop a 123 block against the chuck face and get the tool holder up tight to it and flush. Then lock it all down. You can go all out and tram the parting tool, but I’ve never found that necessary. Might be a different story if you’re working with something harder than 1018.
I tried a couple carbide parting tools and holders, but each was only a matter of time before it grabbed or chattered and either snapped the insert or the end of the insert holder. Went back to a generic hss blade and never had a crash/jam/grab again. I’m accounting that to the fact that I usually grab the blade before each cut and give it a touch up on the grinder and/or a quick stone. I find carbide parting inserts are kind of a “ya get whatcha get”, so when it starts to get dull you either get poor performance or (in my case) grabbing/jamming/ snapping.
Tool stick out is also important. You need to keep stick out to the absolute minimum to cut the depth you need. Excess stickout lets the blade move and flex, which induces chatter and the risk of breakage. If I have to make a deep part, I’ll do a short stick out and when it bottoms I’ll re-adjust and give it more stickout, but as little as possible. I’ll keep doing that until its done. It allows you to minimize the stickout (and flex) when doing deep parting.
The tool also needs to be on center. And I mean dead nuts on center. Too low and the work can ride up on top of the cutter, which leads to all kinds of bad things happening. Too high and you’re just polishing the work where the blade contacts It.
I’ll likely get a lot if “flack” for this, but I will also use a live center if not cutting right up by the chuck. Like an inch or less up by the chuck. More than an inch or so and I use a live center. For me, it eliminates that little bit of flex/bounce/deflection the work will get when working away from the chuck. You just have to be watching and waiting for the part to finish or you risk getting a jam when the piece drops. It’s not a panic moment to shut down, but you need to be ready when it does drop to kill the power. My lathe runs a dc motor with dynamic braking, so when I kill the motor it stops in just under a single revolution.
The other thing that made a huge difference is that I removed the top compound and made a solid plinth to mount the qctp to. That eliminated the “flex” the top compound had and made parting a breeze. Truthfully, the solid plinth works so well I leave it on all the time and only swap to the top compound when I need to cut a taper or angle. Nearly every other operation I use the solid plinth. It just works soooo much better than the “flexible” stack up of slides on a stock 10F.
You really want to eliminate as many “joints” as you can when parting and lock down every gib you have except the one you are using to feed.
I also never power feed. I’ve tried it and all I get is lockups and crashes. Personally, I need to “feel“ the work face when feeding to know whether I need to feed harder or back off for chatter or lockups.
The last thing I’ll mention is I always part in back gear and almost always around 100-150 rpm spindle speed. I can go faster, but it just seems to introduce problems on my little 10F. Keep in mind its sfpm you need to get right and as you plunge into a large diameter that sfpm changes as you get deeper into the part.
Keep at it, you’ll get it. Took me nearly a year to figure it out and now I tend to prefer the parting blade to the band saw, if I have the choice.
Whew. That got a little longer than I intended it to be…..
Last edited:
- Joined
- Mar 29, 2017
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- 737
Me too. No doubt the single most effective change in my technique or set-up.
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- Dec 26, 2015
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IMO all aspects discussed in the attachment I posted earlier are important contributors to successful parting. There is no “magic bullet” cure-all - every aspect of alignment, rigidity, feed rate, lube, tool, and material type, etc. contribute in varying degrees.
- Joined
- Jun 15, 2017
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- 525
I don't have any problems with parting, but then I do what I was always taught to do. I ram the blade in there with no mercy and no pauses, and I use a lot of oil. It always feels wrong, but it works.
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- Mar 26, 2018
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- 8,407
OK, i'll play.
I too have a swivel large mill vise. I guess it could be for a large drill press. I don't use it.
The grinder is a peace of sh17!
The wheels are off a Delta 6X48 belt sander I no longer own.
The drill press was a gift, I can't sell it and have no space for it, don't need it.
Oh, there's more......
I too have a swivel large mill vise. I guess it could be for a large drill press. I don't use it.
The grinder is a peace of sh17!
The wheels are off a Delta 6X48 belt sander I no longer own.
The drill press was a gift, I can't sell it and have no space for it, don't need it.
Oh, there's more......
Attachments
- Joined
- Jul 12, 2015
- Messages
- 287
I just recently retired myself. I know of an exact copy of that person from my old job. I vicariously enjoyed that quite a bit! In my dreams there is an accessible mud puddle beside that broken down car.
- Joined
- Mar 16, 2022
- Messages
- 3
LOL.. I was in HF last weekend for the end of the Labor Day sale and picked up a pack of 7 or 8 10mm in various size / depths.
First time i'd ever seen a set of nothin' but 10mm. Whoever thought to package them that way, was a genius.
I've never owned a vehicle that didn't eat 2-3 of them.