Thanks for the info Andrew, very interesting but in a sense I have moved on. I have managed to overcome enough of the drive hurdles to get it guiding right but will never be able to overcome its biggest weakness, the forks when polar mounted, no amount of tweeking will fix that. Now I use EQ mounts and refractors (I know I am a woose) for AP and will eventually de-fork the meade tube and use that on a larger EQ mount with decent tracking. I may have some sadistic tendencies but I do know when to call it quits. Mardy I would think very carefully before you take the road you have proposed. It is expensive and will always lead to tears. Take the time to ask a few of the old hands around here, I am sure they will tell you the same thing.
Cheers
Mark
Quote:
Originally Posted by AndrewJ
Gday Mark
( Mardy, the following is still useful to you as PEMPro
has a lash setting screen as well )
The critical part is what were the drive train results, not the %.
( Read lower bit as to why )
> Interesting info about the behaviour under guide commands.
> Are you saying the mount will not respond to a guider command
> to reverse the work to get things back on track?
Not quite. When guiding in RA there are no problems.
In DEC, the motor must reverse at times.
Most guiders now use the "pulsegide commands" where a PC sends
a command to slew "at guide speed" for ddd ms
What "should" happen when reversing is the scope should first reverse by the drive train value, THEN by the requested guide time
ie it should take out all gearslop on reversing first,
before doing the requested guide.
When you do a drive train, the scope measures total gear slop.
The "Percentage" merely tells the scope how much of this to do at high speed on reversing ( and it does it in one hit, its not ramped )
If the percentage is set to 100, then the whole lash is applied, but you also normally get a visible "kick" in the EP, due to inertial braking.
Thats why when setting the lash, you try to set the percentage as high as possible without seeing the kicking.
Ie, this process leave "some" unapplied lash
which is ( 100-%) * Drive train arcsecs worth of slop to go.
Currently, the LX200 firmware only accounts for the high speed portion, and leaves the residual unapplied. Thats what im trying to patch now
This unapplied slop has to be accounted for by the external guide commands, and can cause confusion in some calibration routines.
The better your geartrain mesh ( ie the lower the drive train values)
the less of a problem it becomes.
Andrew
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