With the sale of our beloved Haas ST-20SSY, it is now time to start shopping for a new lathe. Ideally, considering the fact that our pens are long, slim turned parts with deep holes, we should be looking for a Swiss machine, and we are but.. before we get there we still need a more traditional lathe capable of running larger parts. In the past year we've had to run a few parts from 1" bar stock or larger and we still do a lot of short run parts and prototyping. In terms of setup and small runs, a more traditional lathe is still something we can do without in the shop.
So what features are we looking for in our new lathe? To narrow things down a bit, let's look at price range. Total price for the machine, delivery and rigging has to come in under $150,000. That's still a lot of money so less is better. We need a dual spindle capable machine in order to be able to run parts complete (or as Jeff from Magnum likes to say, "done in one" operation). We also need a Y-axis and live-tooling. This means that we can machine off the C-axis center line with either radial or axial tool holders. In terms of tool holders, we're looking at a BMT (Base Mounted Tooling) turret. These have the advantage of greater stiffness / rigidity with the live-tooling drive and coolant runing through the turret giving the lathemore clearance. Size isn't a huge factor as our parts tend to be pretty small and even the smallest dual spindle machines will easily accommodate the largest parts we usually come up with. The control is also important although most common machines have fairly robust controls (FANUC, Mitsubishi, Siemens and Mazatrol Smooch C) and all of them will be a learning curve. Availability of a post-processor is a consideration but it's very likely that we'll have to work with a vendor (or work with our CAM provider) for a custom post. Finally, service and application support in Phoenix is a big deal. With out brand new Haas Mill we've had to rely on Ellison Machinery for warranty work a few times already and this lesson has taught me that I'd hate to have to rely on an out-of-town provider.
The contenders:
1) Haas ST-15SY
This machine was demoed at IMTS last year. A fairly small dual spindle machine with BMT-45 turret, it uses my beloved Haas control and looks like a perfect fit. Unfortunately, while I keep pestering Haas (seriously, I've got rock star salesman Handsome Chris Hansen from Ellison Machinery on speed-dial) the machine is still not available. The original story was that it would be ready a few months after IMTS 2016 but Haas has decided that they would go with the NextGen control and do some field testing first.
That said, we do know a few things about this machine. It will use linear guides like the ST-20SSY and not fully boxed ways (a more rigid but more expensive solution). Since rigidity, finish and tolerance were never an issue on the old Haas, this shouldn't be an issue. Linear guides are also faster and easier to service although as mentioned, they are less rigid and less tolerant of holding up to machine crashes (conversely they are much easier to replace in the field). For the relatively small parts and light cuts we do in the shop, this isn't a problem (we've been able to repeat to within .0005" on the old lathe which is well within our needs). Live tooling will most likely be handled by a 5 hp and 6,000 rpm setup like the current ST-15Y. The new BMT-45 turret will most likely be a 12 station setup and be able to support additional stations through the use of additional offsets and used of the Y-axis in multi-tool holders. The main spindle will be 20 hp which means the sub should be somewhere between 5 hp and 10 hp. Rumors also state that unlike the DS-30SSY, the new ST-15SY will be able to support both positioning and full contouring on the sub-spindle. The NextGen Haas control has been out for a few years on mills but is still waiting to be released for lathes. Most of the glitches for mills have been worked out now and it's a fairly solid control with a phenomenal user interface. Since Haas support is provided by Ellison Machinery we're fairly confident that we know the level of service we can come to expect from them. Standard features include everything from rigid tapping and thread repeat to 1 GB or program memory and the ability to run directly from the USB as well as remotely monitored via Wi-Fi. C-axis indexing on the current ST-15Y has an unimpressive resolution of .02 degrees and hopefully will be upgraded in the NextGen control. Typically every CAM company supports post-processors for Haas controls and while it may take a few months for solid posts to become available, they should be easy to come by within weeks of the machine hitting the market.
List price is estimated to be in the $125,000 range. Unfortunately, with no current release date scheduled we're stuck looking elsewhere for our lathe solution.
2) Doosan 220 LSYC
I keep joking that this is the Hyundai or Kia of machine tools but then, if you've driven a Kia recently, you may know that's not a bad thing. Doosan has been around for years and has a solid reputation for making some decent iron. Every forum and blog post I've run across mentioning Doosan lathes has been very complimentary. Everyone who has had a Haas and Doosan lathe ends up commenting positively on the Doosan (as a Haas fanboy, I'm not entirely sure how I feel about this). Adams Machinery in Tempe is the local rep and while they are clearly no Ellison Machinery, they talk a good game and have been in the business for a while and are also reps for Citizen Swiss machines (THE major player in the Swiss CNC game) which means they're no fly-by-night either. This is a relatively small machine, still using the less rigid linear guides as opposed to fully boxes ways (essentially, a rail system for the turret) but that seems normal for machines in this size and price range (the base machine alone lists for $125,000). Since we never had any rigidity or tolerance issues on our old Haas lathe(and we run fairly small parts) I don't really consider this much of an issue. The turret is a BMT-45 like the upcoming new Haas which means that tooling is readily available and to help things along, the tool mounting uses precision ground surfaces allowing the self-aligning tool holders to be mounted without the need for additional dialing it (that's the sales pitch anyway). Another nice touch is that while the turret is only 12 stations, it has 24 indexing points (half-step indexing) meaning that when properly tooled up it is for all intents and purposes a 24 station turret (similar to the BOT / VDI combination turret on our beloved ST-20SSY). The system runs off of a FANUC 0i-T series control which is known to be an industry standard. The interface actually looks like an old Soviet era ICBM launch panel ("Mr. Bond, if you don't tell us the launch codes, we'll cut you in half with a laser.") but is known to be legendary for its reliability and granularity of control. In addition, the control already has every single option enabled (i.e. rigid taping, polygon cutting, thread repeat, conversational programming, etc.) but it does have certain goofy FANUC specific quirks such as being unable to run directly off the USB and being fairly limited in memory (although there is a cute little PCMCIA work around for this). On the plus side, C-axis indexing resolution for the machine is an impressive .001 degrees making machining of precise, complex live-tooled features possible. The FANUC control means that post processors aren't a problem and while there will be a learning curve, it's a fairly common system. The live tooling motor is only 5 hp but it does spin at up to 6,000 rpm (as opposed to the measly 3,000 rpm on our old ST-20SSY). Since we run a lot of small live tooling, this is a big improvement. The sub-spindle is 7.5 hp while the main spindle is a genuine 20 hp and 125 ft/lb little beast. Another nice feature is the ability to upgrade the factory coolant pump to a 145 psi model straight from the factory for $1,460.
3) Mazak QTU200MSY
Mazak is a huge player in the CNC world and they have a LOT of different models. The QTU line is their economy series and the machines are actually made in Kentucky, not Japan (but then again, so is the Toyota Camry). Mazak is rep'ed by Magnum Precision in Phoenix and these guys are a serious player in the local machining racket. They have their own service and support staff as well as their own applications engineers. While Mazak doesn't have a great rep with small shops for support, Magnum seems to have their shit together and I have no doubt that will be able to offer world class support. The machine is still a linear guide setup with a Mazak take on the BMT turret desing. This version does require the tool holders to be dialed in during install and the tool holders are somewhat more expensive than the Doosan (although they do seem very robust). In fact, the entire machine is a bit pricier as the base model comes in at $149,000. The turret is only a 12 station setup but there is a very wide range of static and live tool holders available for the Mazak and with a little fiddling of the tool offsets, it's still possible to run dual stations at each turret index location. The machine is almost 2,000 lbs heavier than the Doosan which bodes well for overall rigidity and accuracy. It uses the proprietary Mazatrol Smooth C control (which run the same basic back-end as the Smooth G but looks like it's a much de-featured version). Still, C-axis indexing on the current QTU is listed as an incredible resolution of .0001 degrees. Mazatrol is Mazak's proprietary conversational programming language but the control supports standard G-code as well. Sadly, control options appear to be a la cart. Rigid tapping is not standard but a paid upgrade, so is polygon milling, thread repeat, etc. etc. Things can get pricey quickly although much of this can be handled in CAM anyway. Another wrinkle is that the CAM software we currently use does not have a post for the Mazak but a custom post should only cost $1,500 - $2,500. The panel itself looks very nice and modern but is not any more intuitive than the FANUC control and may in fact be a little more quirky. The abbreviated keyboard is also not a big selling point for me. The live tooling motor is 7.3 bhp and while it only spins to 4,500 rpm it does have more torque than the Doosan. There is a $2,600 option which looks to be a re-gearing that allows it to spin up to 6,000 rpm but then drops the torque to match the Doosan. Similarly, the main and sub-spindle are 20 hp and 7.5 hp respectively and Mazak has a reputation for delivering every since little horsie they promise. Mazak also has a factory upgrade available in case you want a 230 psi factory coolant pump although at $3,500 it's not cheap.
