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CNC_Geek
01-09-2008, 10:18 AM
Hello Everybody !


In our company, I am part of a team whose aim is to choose the swiss-type automatic lathe best suited for the machining of our parts.

As per the catalogues, the most interesting one seems to be the SR-20RII model from the japanese company Star.

As we haven't yet got any Star machine, we would like to read about other manufacturers' experience with Star machines in general and with the SR-20RII model in particular


Thanks in advance

ghyman
01-15-2008, 01:01 PM
The SR-20RII is a good machine, Fanuc control, sturdy and reliable.
That being said...
All X/Y/Z moves are done from the gang slide's point of view rather than a specific tool's point of view...
The turning and milling tools across the gang are easy enough, but Z plus/minus are reversed from a standard turning machine.
The main spindle live tools are located vertically behind the spindle, and they use (in my opinion) a confusing method of programming/offsetting: the X/Y coordinates are based on the *gang slide* movement... to make a hole in the side of the part with a live drill, it is done with Y axis moves.
From the standpoint of an operator, I guess that makes sense... the gang is moving the live tool, therefore it is a Y axis move.
But from a programmer's standpoint, that seems wrong... moves into the OD of a part should be done in the X axis, and the Y axis should be used to adjust the tool to the C/L of the part, no matter what tool is doing the cutting.

I only say that after several years of working with Citizen swiss machines... they have kept the X/Y/Z axis moves a little more standard... X controls movement into and out of the OD of the part, Y controls the off-center location of those moves. You never need to open the door and see where the tool is physically located in the machine in order to figure out which axis controls what.

Just my $.02

ghyman
01-15-2008, 02:10 PM
Clarification:

For the most part, the bar stock does the movement in a swiss machine, not the tool (turrets and end-working tools being the exception).
In a conventional lathe, to move a turned feature to the left (from the operator's POV), a Z-minus move must be made.
Citizen machines keep the same mindset... to move a feature to the left, it is a Z-minus move. If you open the door and try to decide whether the bar is moving plus or minus, or whether the turret is moving into or out of the part, you will go crazy immediately. Decide which way the feature needs to move on the part, then remember the standard turning machine rule of thumb... left is Z-minus, right is Z-plus. The control takes care of the rest.
Star has departed from that; Z-plus moves the *part* to the right. And with a stationary tool, that means Z-plus moves the features to the left.
Now... the argument could be made that "Z-plus results in a move to the right", but I feel that moving the part rather than the features would be confusing to an operator. I liken this to a mill operator who routinely makes X-plus moves to move a hole to the right, even though the table is actually moving left.
The same holds true to X and Y... In a Citizen, an X-axis move is a radial (or diametrical, depending on your control options), and a Y-axis move is a departure off the centerline of the part. This is the same for a turning tool, a stationary tool, or a live tool. Regardless of the tool's physical location or orientation. Again, the control does the heavy lifting so your brain doesn't need to. In a Star, the gang slide moves up and down in X, which means the live tools located down the side are making moves off center in X, while the stationary tools are moved off-center using the Y axis.

Don't get me wrong... Star is a fine machine, the SR-20RII especially so. But it comes down to preference... I like to program a part or a feature regardless of the tool location in the machine. I like to measure a part and adjust my offsets based on the part. Star forces you to program your part and to make offsets based on the machine.

Again, just my $.02, but I wanted to make sure I clarified myself... swiss machines can be confusing enough without having to stop and look in the machine to decide a simple X/Y/Z move every time you want to do something!

SWISS-TECH
01-18-2008, 02:46 PM
WE HAVE A SR-20R AND I LIKE IT A LOT. FROM WHAT I HAVE READ I WOULD LOOK AT THE SR-20RIII , I BELIEVE THEY ARE REAL CLOSE TO THE SAME PRICE AS THE SR-20RII , BUT THEY HAVE A FEW MORE OPTIONS. IF YOU COULD I WOULD ALSO LOOK AT THE STAR ECAS MACHINES , THEY ARE GREAT.

CNC_Geek
01-22-2008, 03:21 AM
Thank you to both of you, Ghyman and Swisstech for your valuable comments !

cncswiss1
02-16-2008, 11:26 PM
I have 3 sr's and they are fine machines, the 4 station drill is nice on the gang slide, they are a bit of a pain to set the live tools (big reach and don't slip on the wrench).. sturdy, accurate.. the major weakness is the XB axis, it's REALLY thermally active, keep the room temp consistant and keep the machine warm and it'll rock, but if you're room temp change a lot you can forget about splitting tenths. that being said, most machines have that problem when splitting tenths, just more so on the sub.. the parts door tends to be a bit messy, making some internal oil splash covers goes a long way here. you can use the Z live mill attachment and still get the sub to the other cross live tooling, which is impossible on my L's, a nice bonus.. get the 5 place option, gtting the live tools for the sub precludes the ability to use speeders back there. the pneumatic ejector optin has a short stroke and was pretty much useless to me, the stock springy thing works good, but can goober up parts if your not careful.

ghyman
02-17-2008, 03:45 AM
the pneumatic ejector optin has a short stroke and was pretty much useless to me, the stock springy thing works good, but can goober up parts if your not careful.

Ahhh yes -- Ejector pins.
The spring-loaded ejector on the SR series was a pain on surface finish until we learned the secret... make a few dozen pins at once out of aluminum (simple program; I think our local distributor provided it), then drill a hole in the end of one and press in a piece of plastic dowel to keep from damaging the finish on delicate parts. Worked great!
On the Citizens, the high-pressure for the sub is plumbed through the ejector rod; a quick blast would flush the parts out nicely, but DON'T use a pin with a small hole through it unless you want to dig your parts out of the front of the machine... 1500 PSI turns a part into a bullet!
Good times...

cncswiss1
02-17-2008, 11:43 AM
we use the thru coolant to flush parts as well, on both Cits and star's.. we suck out very small parts using an air amplifier and a coffee filter .

we have been amking ejector blanks out of brass and pressing in teflon pads as needed, even with that there can be problems.

PixMan
03-12-2008, 03:21 PM
I just found this forum/website, and was happily surprised to find a Swiss-turn section!

I can offer my experience with both the SR20-II and the SR20-III.

The type 3 is a FAR better machine than the type 2! And, it's light-years faster. More features, more tool stations, and capability.

Don't get me wrong, the type 2 can be a good value, but from my experience with both of those (plus the original SR20), the difference in price is easily outweighed by the overall increase in productivity.

YMMV

machinemike
03-29-2008, 10:00 AM
Ahhh yes -- Ejector pins.
The spring-loaded ejector on the SR series was a pain on surface finish until we learned the secret... make a few dozen pins at once out of aluminum (simple program; I think our local distributor provided it), then drill a hole in the end of one and press in a piece of plastic dowel to keep from damaging the finish on delicate parts. Worked great!
On the Citizens, the high-pressure for the sub is plumbed through the ejector rod; a quick blast would flush the parts out nicely, but DON'T use a pin with a small hole through it unless you want to dig your parts out of the front of the machine... 1500 PSI turns a part into a bullet!
Good times...

I've have re-engineered the parts catchers on Star machines, Tsugamis and Tornos TB Deco's. It seems the engineering stops at part catching as if the machine manufacturer says hell with it let the customer figure out how to catch those little pins. If anyone needs help with this I can show you what I've done.

PacNWSwiss
04-20-2008, 01:59 AM
It’s simple. With a Star you work for the machine. With a Citizen the machine works for you. The Star makes good parts as does the Citizen, but with the Citizen I am not bogged down by the details in running the machine. I am freed to be a better machinist. The Citizen refines the details which allow you to make improvements on your process and not just make it through it.

PixMan
04-20-2008, 07:00 AM
It’s simple. With a Star you work for the machine. With a Citizen the machine works for you. The Star makes good parts as does the Citizen, but with the Citizen I am not bogged down by the details in running the machine. I am freed to be a better machinist. The Citizen refines the details which allow you to make improvements on your process and not just make it through it.

Wow, it's that simple eh? I must be missing something in almost 20 years of Swiss-type machines. I didn't realize Cincom had a lock on this.

I've run them both and I'll agree the Citizen is a little better-thought-out on some things, such as tool setting. Star has some things better than Citizen, such as the "optimization" on the SR-20RIII. Then there's Maier has a base and tool monitoring that's better than both of them, Tsugami has some great software to run their 3-channel machines and many models that switch to chucker mode, etc.

They all have their good points. Tell me what "details" you don't get bogged down with on your Citizens that I'd have to bother with on a Star? I find I have to spend just as much time on either to check parts, keep tools fresh, and setup. They're all pretty good machines, and a few models are exceptional for certain types of work. Your machine's productivity depends upon what work you have, what tooling you have, how much pre-engineering and preparation is into each job before it hits the machine, and the training of the personnel, and the match of machine features to part requirements more than machine brand.

I've worked in shops with multiple brands, and some shops that were all one brand. Those with multiple brands on the floor seemed better able to solve troublesome jobs because they have "a bigger toolbox." When something didn't run well on a Star, try it on a Tornos. If it didn't run well on a Tornos, try it on a Star. Same thing with a shop I worked at that had Citizen and Nomura. Yes, there were some jobs that just did not run as well on the L25 as they did on the NN-25Y.

No one machine stands clearly above the rest for everything. It's not like cars. :p

ghuttja
09-18-2014, 06:25 PM
Hi do youhave any experience on usin rotary attachment on citizen if then could you help me how to set offsets for tool and some milling example on sub spindle side be bunch of help