Re: Converting a rotary table

I'm working on converting the LMS 1810. I have the mount made but I
had to send the rotary table back due to the worm binding, waiting
for a replacement.

Basically what I did was disassemble the whole thing and solvent
clean it. Relubricated with quality grease. Removed the handle and
all associated parts leaving only the exposed shaft. The shaft is 8mm
so I need either a Ruland 8mm to .250 coupler or I'll make one.

Took a .375" thick 2.25" square aluminum and bored it to fit the OD
of the worm body for a mount. Drilled for two set screws to secure
it. Using ~ 2.25" spacers to attach the motor to the mount. I'll post
some pics in a few days when the replacement table arrives. I may
remove the worm and machine the the ecentric piece that it fits into
so that I can put ball thrust bearings on either side to reduce
friction.

Resembles this commercially made product:

http://jfettigmachines.com/images/hv1.JPG

From this website
http://jfettigmachines.com/


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Andrey Lipavsky"
<alipavsky@i...> wrote:

> Have any of you converted one of the "Little Machine Shop" rotary

tables and

> would be inclined to share your experience and/or advice? I

scanned through

> the files section but nothing jumped out at me.
>
> Thanks,
> Andrey
>
> -----Original Message-----
> From: CAD_CAM_EDM_DRO@yahoogroups.com
> [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of ibewgypsie
> Sent: Tuesday, July 26, 2005 1:36 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Re: Windows timing subroutines, how do

they work?

> JitteryMonkey pic
>
> Howdy Mariss..
>
> Are ya after my heart and mind? I'll check it out. If you don't

know

> me, I love new toys.. Anything to make my machine better, quicker,
> stronger, shinier.. (I bolted some polished stainless to it)
>
> I found your Jittery Monkey..
> http://home.alltel.net\dec4857\jitterymonkey.jpg
> http://home.alltel.net\dec4857\jitterymonkey1.jpg
>
> My page..
> http://home.alltel.net\dec4857\index.htm
>
> David
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Mariss Freimanis"
> <mariss92705@y...> wrote:
> > David,
> >
> > Has happened already. Conventional constant contouring techniques
> > use "look-ahead" schemes and complex math to move at a constant
> > velocity along a concatened line segment path.
> >
> > The G101 uses a velocity-word stream to the step pulse engine.

This

> > allows for a unique and very simple constant contouring method I
> > call "look-behind". Simply put, the generated velocity-words

(along

> > the concatenated path, no accel/decel) are passed thru a moving
> > average filter whose output goes to the pulse engine.
> >
> > Some advantages over conventional techniques is this method

requires

> > no analysis of the line-segment coordinate data, uses only add,
> > subtract and division by powers of 2 (bit right-shift). It

natively

> > adapts to the requested vector velocity, automatically increasing

the

> > rounding at line-segment nodes the faster it goes. The filter can

be

> > switched in and out on the fly to allow accel/decel where sharp
> > direction changes are required.
> >
> > If you want to see it run, please see www.geckodrive.com, go to
> > the 'support' page and pick the very last item listed (video).

The

> > pen in the video is tracing at 300 IPM on a 6" by 6" XY stage

having

> > 5 TPI screws. The motors are 3A/phase PK268s at 24VDC. The drives

are

> > G201s. It could go much faster but the screws sound very unhappy
> > above 1,500 RPM.
> >
> > The file is about 5 megabytes so having a broadband connection is

a

> > real plus.
> >
> > Mariss
> >
> >
> >
> > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "ibewgypsie"
> > <ibewgypsie@h...> wrote:
> > > What is probably needed? One Timing generator running at a

obscene

> > > speed, smaller processors that get a bluetooth into buffer dump

for

> > > distance or usb, or? Each processor handles one axis, reading

the

> > > encoder to adjust it's own loop-feedback, running pulse ratio

per

> > main
> > > engine. All interpolated, All with a error out line back to main
> > > source to err-out. Each axis dedicated to itself. Then here-we-

go..

> > > Look ahead software that processes speed changes per gcode line

and

> > > pid's it all to that frequency to make desired end of line
> > directional
> > > changes without losing it's interpolation between axis. Ramp

up,

> > Ramp
> > > down each line is not a good way to machine, but the only thing

I

> > have
> > > saw on my machine.
> > >
> > > Will it happen, probably not.
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "caudlet" <thom@t...>

wrote:

> > > > --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Mariss Freimanis"
> > > > <mariss92705@y...> wrote:
> > > > > In my opinion it should not be the task of a PC to do
> > the 'donkey
> > > > > work' of generating step pulses be it Linux, DOS or

Windows.

> > That is
> > > > > a task that belongs to dumb dedicated hardware.
> > > > >
> > > > > A PC is an 'intelligence engine'. It's task is to do a lot

of

> > math
> > > > > and make decisions. Its output product should go to

a 'pulse

> > engine',
> > > > > hardware finely tuned to the task of generating of

producing

> > pure and
> > > > > clean frequencies on demand from the PC.
> > > > >
> > > > > These are tasks are so diametrically opposed it's like

using a

> > claw
> > > > > hammer for a screwdriver. In a pinch you can do it but it's

not

> > > > > pretty.
> > > > >
> > > > > That also pretty much surmises what I have seen from most

PC

> > based
> > > > > CNC programs. The step pulse phase jitter is horrible even

from

> > the
> > > > > most popular out there. The motors sound like a barrel of
> > agitated
> > > > > monkeys and I have the scope pixs to prove it.
> > > > >
> > > > > If things are going to be done right, the PC has to

interface

> > to some
> > > > > kind of step pulse engine.
> > > > >
> > > > > The 'agitated monkey' part. Motors that sound like that are
> > being
> > > > > robbed of their potential torque especially at high speeds.
> > Phase
> > > > > modulation imposes unnecessary torque demands (infinite
> > impulse
> > > > > functions) on the motors. Said more simply, you pay for all
> > that
> > > > > noise in performance.
> > > > >
> > > > > Mariss
> > > > >
> > > > >
> > > > The problem in the past and currently in the present, is that
> > there is
> > > > no "standard" for an external pulse generator so you end up
> > having to
> > > > buy a "system" that is composed of software and matching
> > hardware.
> > > > Your options start to dwindle and if you want/need/desire to
> > change
> > > > the software you have to throw away the entire system. It

would

> > be
> > > > like every car manufacturer deciding to use non-standard

tires

> > that
> > > > only they provided or each TV network broadcating in a

different

> > > > format so you had to buy a set specifically for their signal
> > format.
> > > > From a pure engineering standpoint it might make sense to

hand off

> > > > signal processing to another circuit like a DSP card, but it
> > needs to
> > > > have an open set of standards that ANY software company could
> > write
> > > > to. If it's going to end up as a PC perhipheral then it

needs to

> > have
> > > > drivers or open standards that make it useful with different
> > > > programs. Show me a pulser card that is not single source,

has

> > open
> > > > standards and is supported by multiple vendors (especially

MACH)

> > and
> > > > I'll get in line to buy one.
>
>
>
>
>
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