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Vince Cimo
08-24-2007, 12:22 PM
So I've been trying to make a decision between a ULS Versalaser and Epilog Legend 36EXT and while they both seem like good machines, I was wondering if I could get some technical clarity on the advantages/disadvantages of the different systems they use to position/move the laser. From what i've read, the VersaLaser uses a stepper motor which doesn't require an encoder, while the Epilog uses a linear encoder and servos. I work for an architecture firm and the cutter will primarily be used for precision work necessitating clean and accurate cuts........If you guys could let me know if there is a tangible difference between the accuracy of the two machines, what type of maitenance each system requires (we will primarily be cutting basswood), and maybe some examples of experiences with both machines, that would be great! Thank you.

Bruce Volden
08-24-2007, 12:48 PM
Vince,

I believe you'll find the greater accuracy with the servo motor systems. They rely on "feedbeck" for positioning accuracy via an encoder strip (Epilog). If the strip gets dirty however~fuzzballs/dust bunnies, you'll have the privilege of experiencing VERY erratic positioning behavior with the machine :eek: Stepper motors don't have this "problem" as degrees of angle are part of their "gearing". Servos are quieter, steppers are cheaper......I have both systems in my machines and they perform well enough for me:)


Bruce

Mike Mackenzie
08-24-2007, 1:07 PM
Vince,

I would have both systems cut a series of circles Small, medium, large. This should answer your questions between both systems. Look for the nub.

You will no what I mean when you see it.

Scott Shepherd
08-24-2007, 1:31 PM
I just posted this on another topic the other day. Having an Epilog Helix in my office for 8 months, and now a brand new Universal PLS system installed last Friday, I can tell you that there is no different in encoder vs. stepper motor quality. In fact, the quality of cut on the Universal is as good or better than the cut on the Epilog. Not sure if that's a function of the driver, the beam, or what, but the quality is equal to or better.

If you plan on doing modeling, one feature that's on the Universal that's not on the Epilog that you'll probably use a ton would be Vector Marking. On the Epilog, unless I'm mistaken, you have two modes, Vector (cutting out), and Raster (marking). With the Universal, you have 3- Vector, Vector Marking, and Rastering.

If you were to raster patterns on an object, such as the lines on a ruler (or scale as I've always been taught to call it), you could vector mark those lines a lot faster than rastering them. It's a very powerful feature and I think you'll find for the work you'll be doing, it might be a "must have" feature.

I'm new to the Universal, and I haven't had much time behind the wheel, as my mother had surgery this week, so my time has been limited. But, in the short time I have had it, I can say that there's no comparison when it comes to quality of machine and driver combination. It's way ahead of the Epilog.

Also, the focus method on the Universal is more like a proper CNC machine, where as you set the machine to itself and then just put in material thickness, rather than the old CNC rational of setting the machine up to every single part. You can, of course, manually focus to each part if you wish, but there's no need. I haven't manually or automatically focused one job yet. You just put the material on the table, tell it that it's "X" thick, and hit the go button. No need to focus on that particular thickness because the machine knows where it is. I might be completely wrong on this description, but I'll give it a shot- on the Epilog, the machine has no idea where the Z-Axis is located. On the Universal, the machine knows exactly where the Z-Axis is located therefore, you can do things like just put in material thickness. It takes where it knows the table is and adjusts for where the material is. You could switch material thickness 100 times in a day and never once have to focus the machine.

I could be completely wrong, but that's what it appears to be happening to me.

Just my two cents.

Rodne Gold
08-24-2007, 1:38 PM
http://www.techno-isel.com/tic/H834/PDF/H834P041.pdf

http://www.torchmate.com/motors/electronics_selection.htm

http://www.woodweb.com/knowledge_base/Servo_vs_stepper_motors.html

Ed Maloney
08-24-2007, 2:15 PM
....

If you plan on doing modeling, one feature that's on the Universal that's not on the Epilog that you'll probably use a ton would be Vector Marking. On the Epilog, unless I'm mistaken, you have two modes, Vector (cutting out), and Raster (marking). With the Universal, you have 3- Vector, Vector Marking, and Rastering.

If you were to raster patterns on an object, such as the lines on a ruler (or scale as I've always been taught to call it), you could vector mark those lines a lot faster than rastering them. It's a very powerful feature and I think you'll find for the work you'll be doing, it might be a "must have" feature.



It is available on the Epilog, but is called color mapping. See the tutorial about architectural modeling at http://www.epiloglaser.com/tl_vector_color_mapping.htm. I've been using the technique with the LaserBuzz projects.

Scott Shepherd
08-24-2007, 2:27 PM
Good call Ed- as I said, I could be mistaken, and I was. Thanks for correcting me. Now that you linked to that page, I recall reading the article when I first got the Helix.

Ed Maloney
08-24-2007, 2:35 PM
Good call Ed- as I said, I could be mistaken, and I was. Thanks for correcting me...

Talk is cheap. Send me $100! :D

Scott Shepherd
08-24-2007, 2:38 PM
How about a 100 Lira? :D

Eric Allen
08-25-2007, 5:58 PM
Vince,

I would have both systems cut a series of circles Small, medium, large. This should answer your questions between both systems. Look for the nub.

You will no what I mean when you see it.

I have a little nub on circles and at the end of almost all my completed cuts. It's not huge, but annoying, and mine are servos.

Mike Null
08-25-2007, 6:39 PM
I had a ULS for 8 trouble free years. I now have a Trotec with servos. As far as quality of cutting is concerned there's not a dimes worth of difference.

As far as rastering is concerned the Trotec is quick.

Kim Vellore
08-26-2007, 2:28 AM
I think the only difference you will see between the stepper and a servo in a laser is during rastering. The servos rock in speed, steppers lack the speed during rastering. You will not find much difference in vector cuts between servo and stepper. Good luck making the decision, it is a tough one to decide.
Good problems in life...

Kim

Scott Shepherd
08-26-2007, 8:22 AM
I think the only difference you will see between the stepper and a servo in a laser is during rastering. The servos rock in speed, steppers lack the speed during rastering.

Kim


I'd have to disagree with that. I took the same files I ran on a servo driven machine to a demo of the Universal with steppers and found that the time was actually less. Not by much, but it was less on all jobs. I run a certain type product, almost all rastered, very frequently. On the Servo system, the time was always in the 12-13 minute range and with the new system, it's constantly in the 10:30-11:30 range with better quality. It may be true in some machines, but not in the two machines asked about. I have both sitting right next to each other.

Mike Null
08-26-2007, 9:26 AM
Scott

The raster speed is identified by each manufacturer for each system. My machine runs servos and will raster substantially faster than any ULS machine. It rasters at 140 ips which is the reason I bought it.

I think all manufacturers post their raster speed and it varies greatly, not all due the motors.

Scott Shepherd
08-26-2007, 11:30 AM
Mike, you have a Trotec, which wasn't questioned in the original thread, which I pointed out. If you are comparing the Epilog Helix and the PLS systems, then there is no difference in the Servo vs. Stepper debate. Well, there is a difference in this case, it could be shown that the quality of cut is better on the stepper system.

I seriously doubt the speed/quality has anything to do with servo/stepper motors, but rather how all the pieces are tuned together.

I have no doubt the Trotec is a faster machine, but it wasn't mentioned as a unit for comparison in the original post.

If you have a servo system it doesn't mean anything. You can put a servo system on and then have a crappy motion system and what have you got? Or, you can have steppers with a superior motion system. What have you got? It's all about how it all comes together as one unit, not about one piece or the other. I think there are a couple of systems out there who pull it all together well and I think Trotec is one of them.

I have much evidence of poor quality with a servo system. It's all documented, so I do have more than just my opinion in this case (between the two machines mentioned).

I state my case because I think the debate between servo vs. stepper is a wasted debate. I think it's a red herring that takes the focus off of the real differences between machines. Just because one machine uses a servo doesn't make it better OR worse. It just makes it different. If it meets your application needs, then it doesn't matter one bit. I think part of the debate should shift from motors to motion systems and the quality of such.

Mike Null
08-26-2007, 11:38 AM
Scott I believe we are in agreement.

Kim Vellore
08-26-2007, 12:58 PM
I'd have to disagree with that. I took the same files I ran on a servo driven machine to a demo of the Universal with steppers and found that the time was actually less. Not by much, but it was less on all jobs. I run a certain type product, almost all rastered, very frequently. On the Servo system, the time was always in the 12-13 minute range and with the new system, it's constantly in the 10:30-11:30 range with better quality. It may be true in some machines, but not in the two machines asked about. I have both sitting right next to each other.

Just curious the ULS Versalaser is a entry line laser system and the 36ext is top of the line laser system. Did you run both the raster files at 100% speed?

When I was shopping for a laser, the ULS professional series were way faster than the Versalaser. I am suprised the entry level ULS is faster than the top of the line Epilog, unless I am reading something wrong.

Kim

Scott Shepherd
08-26-2007, 2:14 PM
I thought I said earlier (somewhere) that I was comparing equal machines, the Helix vs. the PLS system in regard to speed/quality. I'm comparing apples to apples, two machines of the same size in the same class.

I will add that just because someone says their machine will do "X" IPS means nothing to me. I've had Epilog tell me many times "slow the speed down to 60%". If I have to slow it down to 60% to get it to raster plastic, then it's really not important to me that it'll run "X" IPS. You really have to take the applications to the machines and try them. In many cases, the times will be close and the quality the same. In other cases, they won't. You won't know what works better for your application from reading a brochure or watching a canned demo.

Thad Nickoley
08-26-2007, 3:53 PM
it always seems like a Ford vs. Chevy vs. Dodge (although we all know that Ford is best) debate. You need to learn all you can and take into cosideration what you are going to do with the sysytem. Then make an educated pick.

Good luck.

Kim Vellore
08-26-2007, 8:44 PM
I

You really have to take the applications to the machines and try them. In many cases, the times will be close and the quality the same. In other cases, they won't. You won't know what works better for your application from reading a brochure or watching a canned demo.

This is what everyone is saying in your application you might have to slow down to 60% to raster plastic but in other applications where you could run it at 100% speed on a servo you will see the difference in speed. You have to remember the same machine can have different power lasers so what you raster at 60% speed in a 40Watt machine you will be doing 100% in a higher wattage machine.

Take an application where you can raster at 100% speed on both machines and see the time difference, that would be an apples to apples comparison on the speed capability.

Kim

Scott Shepherd
08-26-2007, 9:17 PM
Kim, trust me, I used the same materials and tested many different files/materials. Never found one to be substantially faster than the other.

I'm not saying one is better than the other at all. In fact I'm saying that you can't tell the difference. If you put the machines side by side and didn't know which one was which, then I seriously doubt you could tell which one was the servo system by watching it run. The differences are so minute. There are far more relevant parts of the machine to consider than this issue. If you're down to seconds on the run time, and that's important to you, then you should be looking at the Trotec. If you're not worried about seconds, then this issue has no bearing in it, in my opinion.

How about cost of operation? Cost to refill tube? Life of tube? Maintenance costs? Resale value? I bet you my hat that those are much more important issues to consider than the type of motor system. Unfortunately I've had many conversations with people higher up in laser companies lately. Perhaps one day I'll share the things I have been told that make me feel this way. I've heard it straight from the horses mouth. I've been told to run many jobs on various types of plastics at 60% to get acceptable results. How many other people out here would buy a machine thinking you can use it at 100%, the book says 100% on that material, and then the factory says "Try 60%". That's not what they tell you during the sales pitch. That's why I said take your applications there and see it run for yourself.

Kim Vellore
08-26-2007, 11:08 PM
Scott,
I trust you.... I was in Vince's shoes many years back and went with Epilog for the so called 'Speed' even though I had a better deal on the ULS. If I had the real info I would have got the ULS, no regrets but I guess I was in a way Justifying my decision.

Kim