Re: [Emc-users] Making tons of money vs. the most interesting hobby ever.

2008-07-21 Thread Kirk Wallace
On Mon, 2008-07-21 at 01:48 -0400, Organic Engines wrote: Hi, I have made 5 machines so far and I am working on my sixth. Of the two most economically successful parts I have made so far, one costs 50 cents to buy and I use about 20 a month, the other one costs about 9 dollars to

Re: [Emc-users] CNC design questions

2008-07-21 Thread Leslie Newell
tool motion: 120 x 90 x 20 cm (X-Y-Z) Posibly a little small. Remember it doesn't cost much more to go bigger. It does depend raher on what you want to make. frame material: T-slotted aluminum Easy to work with though quite expensive if you can't get it second hand. Remember

Re: [Emc-users] CNC design questions

2008-07-21 Thread John Thornton
Numbers you quote here are better than what I'm hoping to achieve even though I'll try to come as close as possible. .05 mm repeatability on 1m run is probably hard to achieve with stepper motors without positional feedback. It woild be interesting to know what others were able to do with

Re: [Emc-users] CNC design questions

2008-07-21 Thread Kenneth Lerman
Regarding power supplies: Computers use regulated power supplies because the electronics require a voltage within a relatively narrow range. You don't need a regulated supply to drive a stepper or servo (although you might for some of the electronics connected to them). For that reason, the

Re: [Emc-users] CNC design questions

2008-07-21 Thread Ray Henry
Steppers do not consume more electrical power during rapid accel. The biggest draw is when sitting still between the time you stop sending pulses to the drive and the time it switches to reduced idle current, if it has that ability. Once you size the power supply to the full load demands of the

Re: [Emc-users] Making tons of money vs. the most interesting hobby ever.

2008-07-21 Thread Kirk Wallace
On Mon, 2008-07-21 at 12:33 +0200, Rob Jansen wrote: ... snip Someone told me you have to be schizophrenic to do this kind of work. This comes in handy since now I am the team of scientists making the really cool stuff :o) Cheers, Rob Do you answer when you ask yourselves a question? --

Re: [Emc-users] CNC design questions

2008-07-21 Thread Leslie Newell
Sorry Ray but you are wrong. You have maximum current at low speed and stationary but maximum power is at high speed (technically it peaks at the corner frequency) and maximum acceleration. Like any motor, power out = power in - losses. Look at fig.14 in the step motor basics and you will see

Re: [Emc-users] CNC design questions

2008-07-21 Thread Ray Henry
I guess we must be looking at or thinking about different things. Perhaps I did not say it well. The DRAW on the power supply is what I'm saying is greatest at zero speed. After all the comment in the earlier post was that the DRAW on the power supply would be greater during acceleration. That

Re: [Emc-users] CNC design questions

2008-07-21 Thread Leslie Newell
With a switching drive such as a Gecko the current through the motor is regulated by adjusting the output voltage. Below the corner frequency the current is fixed. Above the corner frequency the drive can no longer supply enough voltage to overcome the inductance of the motor so the current

Re: [Emc-users] Making tons of money vs. the most interesting hobby ever.

2008-07-21 Thread Organic Engines
Hi All, Like Kirk I also think there is indeed a lot of value in doing it yourself. I just started to investigate all the opportunities but there is a real market for people who can do both design and prototyping/production. Most people who approach me about prototyping have no idea about

Re: [Emc-users] CNC design questions

2008-07-21 Thread Ray Henry
Nice discourse on current between stepper drives and stepper motors and some of the theory of switching drives. I'm still left with the statement made earlier in this thread by Rafael Skodlar, The reason I mentioned power supply is I'm not sure which way to go, linear or