Full Version: servos, steppers and tubes
From: Jon C (JONCASHMAN) [#8]
8 Mar 2005
To: Dave [#1] 8 Mar 2005
OK - I like hearing what a lot of the sales guys have to say about servomotors and steppers. It's always good for a laugh. The best answer I ever got was from a guy that said that if you took a stepper and a servo and put them next to each other, which is better? Neither. They need electronics and code connected to them in order to function. It is not the motor design, it is the design around the motor that counts. Don't let these people fool you. Steppers can run just fine and are less complex, more reliable (ask me how many servos I went through on my old Epilog) and less expensive to replace. The machines need to be repeatable as well. Go test the machines yourself and have them run the same vector engraving file two or three times on the same piece of acrylic. You might be shocked how bad the encoders locate the beam on some of these servo driven machines.
Laser tube differences? What matters is if they are consistent, pulse properly and are easy and inexpensive to replace. It's a difficult question to answer, but the bottom line is that this is blown out of proportion by the sales types in order to push their products. Lasers that are in these machines today all pretty much do a good job.
Operating Systems. Universal seems to be on the ball with updated drivers that work well.
Warranty and afterwards. In my experience, I replaced servos quite often. It seems as though many people have this problem. I haven't replaced the steppers on my Universal. It gets a lot of use.
In the end, it's a total design package and the service and support that I receive that makes me happy. You probably will be happy with any US made machine, but I've run into more people that ended up with a Universal after owning another brand than the opposite.
From: Rodney Gold (RODNEY_GOLD) [#9]
8 Mar 2005
To: Jon C (JONCASHMAN) [#8] Unread
Actually you arent really comparing steppers and servos , you are comparing closed loop feedback systems with no feedback type systems. Whatever the merits of the motor , the feedback system is always a far more flexible system and is undoubtedly better in just about every application. Any poor system will act poorly , damning feedback systems on the basis of poor implementation is a little unfair, apart from which stuff like bearing and motion system tolerances would come into play in terms of repeatability.
I don't have any repeatability problems with any of my machinery that uses encoder based systems and that includes my real cheapo epson printers which manage exceptional registration.
In terms of tubes , beam quality is very important as are the tubes optics , the way the laser pulses , peak power , beam diameter etc all come into play.
There is a tendency for these type threads to devolve into a my brand is better than yours type thing , or folk get a little aggrieved when perhaps a feature on their brand of machine is slagged off which is a little unfortunate. All of these type lasers have issues and some are stronger than others in areas , but at the end of it all , all the laser engravers in the same size/power/price class do the same stuff and do it well.
I don't think the comment that if its USA made its better than other non usa brands , some of the stuff from China is excellent and innovative and best of all good value and the Trotec machine is no slouch either. The rofin source too is as good if not better then offerings from synrad or coherent.
Apart from technical issues , I agree fully with what you say in that it is the total package that counts and IMHO , the deal breaker is the support and warrantee.
From: Engravin' Dave (DATAKES) [#10]
9 Mar 2005
To: Rodney Gold (RODNEY_GOLD) [#9] 9 Mar 2005
Rodney,
These are the types of threads, although very technical to some, that get a bit competitive, but are the most valuable to forum members. My opinion about servo vs. stepper motors has not changed because of this thread, but I am much wiser because of the open dialogue.
Both sides of the aisle have some very good points and you have brought it all together.
This discussion does add credence to what is brought up often, the manufacturer rep and support is often the deal breaker.
Thanks for all the great information.
From: Peter [#11]
9 Apr 2005
To: Engravin' Dave (DATAKES) [#10] 9 Apr 2005
Nothing is is more important than after sales service....not sales service.
We were caught by an Australian distributor of french software and American Lasers engravers, that would not accept responsibility for the breakdowns and lost time encountered by the machinery and software/dongles they sold.
They continually blamed the providers of the software/ dongles and the manufacturers of the Laser engravers in the USA.
In the end it cost our firm over $18,000 cold hard cash lost in sales.
The company in question in Sydney Australia, blamed us, the software company and the Laser engraver manufacturers and in the end supplied us with damaged loan machines...which we had to buy before they would send it out....Yes sign a sales agreemant..then they sent us a smashed machine and wouldnt give us credit until their tech flew in to work out whether " we broke it, or it was done in transit"
all this over several months
We asked them what they would do to help us out..and they offered us 5% off of photograve ( which we could buy anywhere else in the world for more than 30% better than their price)
The end result was the company basically absolved themselves of any responsibility, blamed every one else for their problems and left us out of pocket. They also had the temerity to blame us for all the problems.
We have subsequently found out from trips interstate, that the same company has done the same thing to other Engraving companies, that have told us they will, never deal with them again....ever!
Funny that the only other purchaser of this particular companies products in Adelaide Australia, ( whos employee we have just taken on board) has given us the same story as well...
" oh " we just have to email America because its not our problem".
What the "Universal" problem is that the company in the USA dont realise is the damage being caused by the Australian Distributor of their product is..that, many are choosing other products..
the end result is, you must purchase on local dealer warranties, guarantees and support, ask for it in writing, dont believe the snake oil salesmen..get em to put it down in black and white...coz at the end of the day..the USA companies that manufacture are not going to believe a little purchaser, they will believe the Distributor that has the infrastucture, supply and purchase power to back their machines.
So at the end of the day, whether you have a local, universal, Pinnacle/ GCC, Epilog, xenetech,Gravograph,Trotec dealer.
If they are all about the same price...
Go for the one that will give you the best service, back up etc..all the machines will give more or less the same result..
service, service service....if you are only worried about about a few grand difference in purchase price....dont simply go for price, go for after market service....
and how they will look after you when the machine they sell you breaks down and you are left with thousands of dollars of lost business..
In Australia, it is a Universal question that must be addressed.
regards
Peter