Mechanics

Hi,

I have been "tinkering" with my amp attempt, and it's not going any
way. I am starting over with another design, - so it will definitly
take a while before I get anything running. - I hate it :-(

Well, this was not what I wanted to let every one in on - I would
prefer to hide away all my mistakes, but when I am going to make a
fool out of my self, - then this was a nice beginning.

Here is what:

I took apart some geared servo motors, - just to check out the
encoders. Well, this is embarrasing in a way, - I have seen it so
many times, but I have never thought about it. That is the gears, -
the cog wheels to be exact. They are not machined at a straight
angle, but at 70 degrees I guess.
Look like this:

/////////////// - instead of a normal one like
||||||||||||||| - this one.

It is a dumb question, - but I don't have any good explaination for
this. I guess it will run smoother,
have less backlash. But how do they really work ?
Let's say you could make the teerh to a +/- 2% fit, - straight or
slant. Is there any formula that would tell me how much less of a
backlash I would actual get, by slanting it 20 degree ? 30 degree ?

Can anyone at shed some light on this ?

I have seen it for years, buth I have not really thought of it. I
have seen it on pinion racks too, - there must be a very good reason
for this, 'cause I would believe they would be much more expencive
to fabricate .

----------

By the way, - I have spent some time, browsing the site what I best
could describe as the Norwegian answer to MIT. I was looking for
something I found some years ago, but I was not able to find it. I
think this research facility took out some patents on model making.
I have film clips of it.
They had something similar to a flat bed plotter, but instead of the
table, they had a bath fill with polymer plastic ( something like
the dentist are using ) They used a blue laser, and focused it on
the liquid surface. They plastic hardened. After doing one layer of
a 3D modell, they would just lower a platform inside the bath, -
with - let say 1mm. Then they would bild up a new layer on top of
that, until the model was finished. It was real neat. All the used
was a retrofitted, flat bed plotter, and a step motor to lower the
platform. The process was fast too. The only thing I remember, was
that the plastic polymers they used, were pretty expensive. I think
they sold the patent, and I don't really know if this had something
to do with the plastic material, or what.

Just to brag a little: They do a lot of high tech stuff here. The
cellular phone system has a lot of it' s root here. Erricson - the
Swedish company, bought up almost all telephone manufacturs in
Norway.
They have the european rocket launchers and test site here. The
paperclip, the spaycan, the jet turbine is norwegian inventions. (
The turbine is a less known subject, as Sir Whritle got the credits
for it, - but he said it himself, that he had just use some the
material from the norwegian scientist, and the proof of it is in the
tecnical museum here. ) Another crazy story. Some friend of mine
work in a research lab in Washington on deep dive scuba gears for
the north sea. I worked on a hyperbaric chamber down in Florida
Keys, and to my real big surprice - the Miller hat - dive helmet,
that every one though of as "real" american, was actually fabricated
here for Miller. I have come across so many strange things, because
these things are not common knowledge here. I guess this adds to the
phrase: You never becom a prophet in your own land.

Well, I am actual proud to be american - it's just a shame that I
don't master the language better, - so don't get me wrong, - I don't
really like to "brag" about Norway. It's just that I am always
amazed about all the turns and bends that technology have done.

I am tired, - so then I often just keep on. I am very sorry if I
bored anyone of you with this tale.

//ARNE

By the way, - DAN - I don't think you understood my questions about
the servoes the other day.
I asked if it at tacho feedback, - that is not the same thing as
optical encoders. I refered to a
closed velocity loop inside the servo amps itself. You should make a
principle drawing of the setup, just in block format. The way it is
presented right know - well I would never have bought it - without
further details. What if I needed 4 axis, or just one. The system
deserves a better presentation.
As a small example:
|---------- |
command voltage > ------- | AMP | -----[ ( M ) ]

| |
over current < ------- | |

| |
disable > -------| |
| --------- |

+ Power input/ motor output specs.
+ Adjustment for current, loop gain, zero adjust, etc.
+ All pinouts / signals

It can be done pretty simple, even like this - plain ascii. But as
long as you have to do some assembly yourself, then you need to know
something more than you have put up on your web.

I am not sure, but if it really got what I am "reading between the
lines" - then this one could have been the answer to a lot of the
things I really needed. Now I have to rework all lot of my programs
to run emc, because I had made a stepper system, - but couldn't get
enough "juce" out of steppers.

//ARNE