[dorkbotsea-blabber] Looking for someone mechanically inclined

[Brendan Burns]

You want an exact fit.  Any slop will lead to slippage in the system
which is muy evil...

That's a standard shaft, I'm not sure if there's a name for it.
That's pretty much what people expect.

--brendan

On Tue, Sep 2, 2008 at 2:22 PM, Brett Wagner <brett at madhouse.org> wrote:
> a quick side question or two...
>
> When buying various shaft mounted bits is it best to buy exact fits 5mm
> shaft = 5mm gear boar, or is it better to buy slightly sized up bores, say
> 6mm?
>
> Also is there an industry term for shafts that have.. for lack of a better
> way to describe it, part of their circumference shaved down to form a flat
> bit?
>
> Steve Greenfield wrote:
>>
>> Not sure how to describe this in words...
>>
>> Put a sprocket in the center. Run an arm out from the center (not
>> connected to the sprocket). Put another sprocket of the same size on an axle
>> at the end of the arm. Run a chain around both sprockets.
>>
>> Now if you hold the center sprocket steady and rotate the arm around, the
>> sprocket on the end of the arm will stay lined up with the center sprocket.
>> Turn the center sprocket and the outer sprocket rotates exactly as the
>> center sprocket does, regardless of where or what the arm is doing.
>>
>> Make the arm the Hour hand. Connect the center sprocket to the drive for
>> the Minute hand, and attach a Minute arm to the outer sprocket. Now the
>> Minute hand will be at 90/180/270/360 for 15/30/40/60 minutes regardless of
>> where the Hour hand is.
>>
>> Just extend that with the Second hand with a couple of linked transfer
>> sprockets at the end of the Hour arm.
>>
>>  Steve Greenfield
>>
>>
>> ----- Original Message ----
>> From: Brett Wagner <brett at madhouse.org>
>> To: A discussion list for dorkbot-sea <dorkbotsea-blabber at dorkbot.org>
>> Sent: Monday, September 1, 2008 5:46:17 PM
>> Subject: Re: [dorkbotsea-blabber] Looking for someone mechanically
>> inclined
>>
>> Just to frame the discussion a bit, I want to build a real version of a
>> little piece of code i wrote a couple of moths ago.  Basically it's a nested
>> epicycloid clock: http://islandzero.com/?q=node/3
>>
>> For those not Flash enabled, imagine a clock where the origin of the
>> minute hand rests on the end of the hour hand and the origin of the second
>> hand rests on the end of the minute hand (At noon it would look like a long
>> vertical line but at 6:15:00 it would look something like |_|) .  I'd like
>> to mount the whole apparatus behind a bit of frosted glass and have the far
>> end of the second hand etch the glass using, I assume, a chip of industrial
>> diamond.  The other thought would be to size the whole thing up take it out
>> to burningman and have it etch the playa.
>>
>> Now if I wanted to take the easy way out I could simply put a stepper
>> motor at each origin and drive the whole thing that way. However I'd rather
>> take the route that is going to be both more aesthetically pleasing and
>> mentally challenging and try to run the whole thing from one center-mounted
>> stepper using gearing and roller chain to 'communicate' the motion out to
>> the outer origins.
>>
>> There are a few problems that I solved in software that are puzzlers for
>> me mechanically that aren't solved by traditional clock movements.  You will
>> notice in the refined flash version that I linked that the minute and second
>> had point the "proper" way, independent of their parents (IE at 5:30 the
>> minute hand points down rather than backwards down the hour hand as it would
>> if it were not artificially corrected). I'm thinking this might be a problem
>> I solve in 2.0.  I also have various concerns about hand sag and general
>> lack of machining knowledge thats going to bite me on the ass I'm sure.
>>
>> I'm finding https://sdp-si.com/ to be pretty damned incredible in terms of
>> what can be sourced.  I having to work past some vocabulary issues though.
>> Since I have only the most cursory exposure to any kind of mechanical
>> engineering ( I never set foot in shop class in high school, but I can set
>> up and do basic repairs on a Hilderberg printing press to this day ;) ), I
>> have to hit wikipedia pretty hard to determine what is meant by pitch
>> diameter, hub diameter, face width, etc.
>>
>> ... so yeah, comments, suggestions, odds that I'll ever get the damn thing
>> done to my liking?
>> ........................................................................
>> .........dorkbot: people doing strange things with electricity..........
>> ..........................http://dorkbot.org............................
>> ........................................................................
>>
>
> ........................................................................
> .........dorkbot: people doing strange things with electricity..........
> ..........................http://dorkbot.org............................
> ........................................................................
>