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Aeroengineer
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Re: Motion solutions: motors- a mammoth post
Aeroengineer   6/24/2014 12:25:48 AM
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"Closed loop control dramatically improves holding accuracy and stiffness. Closed loop control can double available accelerations, but no effect on limiting speed."

 

Though the speed will be present by the very nature that you are using a bldc motor over a stepper.  Though the fact of adding closed loop to the bldc motor will not change its nature in speed, but only increase its accuracy and low speed qualities.

 

On the though of going closed loop and needing an encoder.  I just saw this product announcement on a competing website.

 

http://www.eeweb.com/news/high-accuracy-magnetic-position-sensors

 

 

Aeroengineer
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Re: Acceleration and nozzles
Aeroengineer   6/24/2014 12:15:14 AM
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I had never heard of that type of transducer.  It seems to be a variant of a resolver.  Learn something new each day.

 

As to the wire drive vs belt drive.  The nice thing about the wire drive is that the design space is a lot smaller than for a belt.  There is the issue of ensuring sufficient tension is maintained to control for slippage, but I like it because it is a very space efficient design.  There is another aspect in that it could be set up to carry current.  This is something that would have to be looked at very closely, but could offer some interesting possibilities in that it would be easy to shield this so that you would not have to worry about it being open (unlike carrying power through the slides (which I think is an interesting idea, but hard to shield).

 

The advantage to using a belt is that you can get grooved belts, but they are more prone to stretching and hence might lack in precission.  The would also not have the ability to carry power if necessary. 

Aeroengineer
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Re: Trading speed for size and accuracy
Aeroengineer   6/24/2014 12:02:43 AM
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I have it on good authority that his mighty lordship, Lord Mannion would not consider such an act an act of treason, but would laude such a valient effort to bring forth this mighty, yet mystical machine.

Max The Magnificent
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Re: Trading speed for size and accuracy
Max The Magnificent   6/23/2014 11:32:41 AM
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@Aerospaceengineer: I think that this may be a good thing to do a poll on.  What do you think about that Max?

Let me ask those who don the undergarments of authority and stride the corridors of power -- those magnificient creatures whose names I am not fit to utter...

Aeroengineer
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Re: Trading speed for size and accuracy
Aeroengineer   6/23/2014 11:05:46 AM
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I think that this may be a good thing to do a poll on.  What do you think about that Max?

Max The Magnificent
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Re: Trading speed for size and accuracy
Max The Magnificent   6/23/2014 11:01:53 AM
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@Aeroengineer: What size work area are you thinking of Max?  It seems that we are talking as low as 4"x 6" up to 8"x 10".

Oooh -- that's a hard one -- obviously I would like to have the capability of going as big as possible -- on the other hand most of my boards would be quite small -- it would be rade indeed for me to be making an 8 x 10" board ... and then I think about making an 8x8x8 LED cube...

How about going up to 6" x 8"?

Aeroengineer
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Re: Counterweights ??
Aeroengineer   6/23/2014 10:48:38 AM
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I like the thoughts that you have going on this.  This is one of the reasons that I have not rules out stepper motors and a belt system either as with the belt system, it would be very easy to do the counter balance approach by mounting the weight right onto the belt.  I have not looked into the steel wire method, though doable, usually for higher load parts.

 

The dual heads moving in different directions could be an interesting idea, and could make it very useful in that you would not have to dock heads.  Have to give this one some thought on a general methodology to integrate it.

 

Aeroengineer
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Re: Acceleration and nozzles
Aeroengineer   6/23/2014 10:44:34 AM
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I see that you found more than my twitter page ;)  Yeah, I am an engineer because if I were anything else, I am not sure what I would do.  I love it. 

 

My back of the envelop crazy calcs are just that, crazy, trying to help me understand the absolute limits.  I did a quick calc with a whole sequence last night, including a trap accel.  The accel definitely will play into the time on this machine as the travel distance is so short.

 

The other thing that I need to look into is the PV capacity of the nuts.  Usually they are not just rated for a linear speed, but a value that is proportional to the load times the speed.  This will bring some more reality into this effort.

Aeroengineer
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Re: Motion solutions: motors- a mammoth post
Aeroengineer   6/23/2014 10:40:35 AM
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Good info. I will read this in more detail when I get back to the hotel tonight.  I will see what I can digest and then ask a few more questions.

Aeroengineer
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Re: Oversized I think
Aeroengineer   6/23/2014 10:39:07 AM
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Correct, this was the overall footprint of the device, not the build area.

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