[patriciooholegu]

Hey people. As always, i chech on the web to see diferent motor to buy, electronic drivers to build, and that kind of stuff...
And two days ago i found this:

http://www.mecmod.com/productes/copl...servotube.html

and the web page on Spain(with datasheet´s included)

http://www.mecmod.com/fitxa.asp?Id=346

and i almost lost my head on the moment...
What a speed!! Take a closer look at the one behind the two on the front... Do you listen to the sound of the air being smash by that monster???

What do you think? It´s something a poor cnc builder will be able to pay?
Or even the high speed of that thing is to much for my standard?
Or... They claim the system is cheap.. But is it?
Wath if someone call for asking? (I´m from Argentina and the call will be half month of pay work); just to keep the idea on the mind or just to dont waste time anymore on it (Because i´think ...THAT IS NOT CHEAP AT ALL!!!).

As alway, sorry about my inglish...

[daedalus]

Hi, i have seen those before, copley controls has a patent on the design, which might be worth hunting down if your interested in how they work. They are still very expensive parts, they are only cheap in comparison to other linear motor designs capable of a similar accuracy (around 10 microns if my memory serves). If you check out copley controls website they have specs for them, if your interested.

To be honest if you want to do a DIY linear motor, this is NOT the design you want, U shaped coreless linear motors are relatively easy to manufacture at home, and can produce similar force output. Edit: but just to make clear, linear motor designs are expensive, even with homemade parts, as you need very high resolution linear encoders to get the same result as a low resolution rotary encoder on a high TPI ballscrew (im not suggesting this is a budget approach).

[patriciooholegu]

Well my intention is not to make one...Just to buy it.
One thin that is in my mind is they are mentioning very much about the speed, but wath about torque at low speed?
now that you mention "DIY U shaped coreless linear motors" Do you have some link for it??
May be i´m looking at the wrong place for my needs...
Please i´m waiting for you answer.
About the price: Remember that if i buy 1 stepper motor or even servo, i also have to buy the rest of the tingh to make it work, and with this servo tube NOT.

[daedalus]

ok, well let me explain a few options:

1) servo motor + encoder + ballscrew + servo drive
all can be found surplus on ebay for a few percent of their buy new cost
for example, 200w servo + encoder + servodrive cost me $140
ballscrews can also be found for good prices if you shop around

This is great if your in US or UK, where there is a lot of motion gear listed, not sure if the situation is as good in Argentina.

2) linear motor + encoder
These do come up on ebay from time to time, but usually in USA so have to deal with shipping. I managed to buy 3 linear motors, 35" travel each, with 780N peak force, for $120 each. Encoders for this are $200 each second hand (+ a bit more for the strip). note this is a big set-up.

buy new prices for the same linear motors were $1400 for the forcer, plus $1000 for the track per motor. Buy new prices for the encoders were $1200. To do a 3 axis machine would cost somewhere north of $10k just for the motion gear. Thats without motor drives and linear bearings. Drives alone could easily add another $1500

3) the servotube units
These may be cheap compared to the $12k quoted above, and they do include motor + encoder, but when you get one that produces enough force, it will not be cheap (i wouldnt be suprised if its a similar price considering they are new and theres no competition). Also you will still need external linear bearings for a machining application, as you will be outside of the integrated bearings spec.

[daedalus]

This is an example of a small U shaped linear motor, its an auction i just won (i bid on these for the encoder readheads, which are around £450 new). This particular linear motor is made from off the shelf 1" square magnets, and the forcer coil is just 3 copper windings in a fiberglass carrier, so it would be feasible to make these in a home shop.

I havent had chance to put a forcemeter on them, but they give a reasonable kick.

http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=260401720863