Cutoff tools... - Printable Version +- MetalworkingFun Forum (http://www.metalworkingfun.com) +-- Forum: Machining (http://www.metalworkingfun.com/forum-5.html) +--- Forum: General Metalworking Discussion (http://www.metalworkingfun.com/forum-6.html) +--- Thread: Cutoff tools... (/thread-2390.html)

Cutoff tools... - alanganes - 11-30-2014 New to this board, but figured I post a bit on what brought me here in the first place: So I was whining on another forum I frequent about my hit-or-miss results when using typical HSS cutoff blades in my lathe. Much of the time it worked fine, but just often enough something bad would happen and either ruin a part, snap the blade, or both. I was debating getting myself a carbide insert cutoff tool. There was much discussion on the topic, and in the midst of that I was contacted by Ken (Pixman) who offered to make me a good deal on a carbide insert tool and some inserts. Turns out that this was a deal way too good to pass up, and on top of that, Ken went a fair bit out of his way to make a trip by my home to deliver the goods and spend some time with me schooling me on some of the finer points of using this thing. I was used to what I was taught in a night shop class I took years ago, run slow, lots of oil, conservative feeds, blah, blah, blah. So when Ken was here and we put this in the lathe, I reflexively suggested that we had to get into a slower spindle speed, and he said "Why?" and did a quick calculation that determined that the top speed of my lathe (early '80s Taiwanese Jet 10x24) was just about fast enough to be in the lower end of the speed we wanted. The part was just a random scrapbox bar of "some type of steel," slightly rusted, 1" diameter, spindle was at 1050 rpm (as high as my lathe runs), power infeed at 0.004"/rev. I got a bit of moaning and chatter from it part way through the cut, so after experimenting feeding by hand a bit I upped the feed a bit to 0.006"/rev. Then it worked like this: MOVIE! Slicing disks off of this bar was so effortless that I made myself a pile of washers, just because I could: My other lathe is a 10" Sheldon that is equipped with an AXA QCTP (BXA on the Jet). The cutoff toolholder was a bit large for the AXA so I had to skim a bit off of it so it could fit the AXA toolpost on my Sheldon. Having done that, I gave it a try with that machine. So me being that deadly combination of excited at how well this worked and also pretty stupid, I incorrectly set up my infeed. The Sheldon infeed sets up a bit differently from my Jet ( I know this but apparently forgot at that minute...), and so it was feeding in at almost double the speed that I thought it was. Dumb move. So I managed to dig the tool in and damaged an insert. My mistake. I'll have to consider that part of my tuition, I guess. The take away lesson is to pay real attention to your speeds and feeds and take the time to find what's appropriate for what you are doing and set up the machine to match. Once I got it right, the results were the same on this lathe as well. Fast and easy. I've never run a cutoff tool at speeds anywhere close to this fast, so it was a bit unsettling at first. But the results were impressive. The bottom line is that this tool is awesome. I would say that if you are on the fence about buying one of these, just spend the money. I got an exceptional deal on this one, but even at catalog prices this would easily be worth it. The ability to do this operation without worrying about explosions or ruining a part that you have invested considerable time into is something of a game changer. The other lesson would be that if Mr. Pixman doles out some advice to you on using your cutting tools, pay close attention. The man knows his stuff! A public thanks to Ken. Great guy and a wealth of knowledge. RE: Cutoff tools... - DaveH - 11-30-2014 Well done Al  nice movie     DaveH RE: Cutoff tools... - PixMan - 11-30-2014 Always glad to help out a fellow home shop machinist (and now and then, commercial shop machinists!) to see what modern tooling can do even on our older machinery. I was telling Alan how his newer "old" lathe was in fact a few years newer than mine although mine is a wee bit bigger. I think that Jet lathe could do even better with a more powerful 3-phase motor and VFD drive. It seems to be built well enough to handle up to about 3HP and perhaps 1600 to 1800 rpm at the high end. For now it's OK with it's single phase motor, though I don't know the HP and seemed a bit weak at the high rpm. Maybe the multi-link drive belt isn't transferring all of the motor's power. I'm not trying to be critical Alan, but given you're an "electrically oriented" kind of guy I think you understand what I'm driving at here. Get the Jet running better and you still have the Sheldon for the "low power, low speed" work. RE: Cutoff tools... - Mayhem - 11-30-2014 Nice work Al. Those tools are fantastic and no need for oil. The deal is so much better when the delivery man also gives you a tutorial. As you have found out, Ken is a great guy, with a wealth of knowledge that he is more than happy to share. RE: Cutoff tools... - alanganes - 11-30-2014 The motor on the Jet is a 1hp, 220V single phase unit. I believe them to be Optimistic Chinese Horsepower, which seem to be a bit different from US Horsepower. It was original to the machine. I don't think I've ever noticed any significant belt slippage with the link belt, I think it is just a less-than-awesome motor that I'm dealing with. As an electrical guy by trade, I've set up many VFD's in the course of my work, I'm a huge fan of them. Yep, a VFD and a larger motor are sitting in the shop awaiting installation. The one slated to go on the Jet is a 2hp, 3 phase unit. I like over-sizing my VFD driven motors so that I can get the "original" HP even at much reduced speeds. The headstock of that machine is tapered roller bearing and I have run it at full speed for considerable time a few times (just to see what would happen) while monitoring the bearing temps. They barely got above ambient temp, so I'm pretty confident that they could easily run at higher speeds. If I'm feeling ambitious I may even get fancy and do tach feedback speed control, which is really cool, but can have it's own set of issues. I had that on one of the DC drives for a bandsaw I set up years ago and could get near full power at most any load over maybe a 40:1 speed range. Almost a servo drive. I had just replaced the VFD in my Sheldon a while back when I started traveling for work. So while it runs, the VFD needs to be dialed in a bit more and the machine needs to be re-leveled and such as I had moved it to work on it. Also in line for that machine is a DRO install, have all the stuff, but you know... Once I get that wrapped up, that will give me a lathe to use while I mess with the Jet motor/VFD. And I do like my Sheldon. It is a very nice machine. And no need to be concerned about being critical, having been married for 30 years and six kids, I'm pretty thick skinned(!).