[Al_The_Man]

Still not sure what your travel/motor rev is, if from what you say it seems like 2"/Motor rev, which for that weight is quite considerable, For a gantry like that, I usually calculate my maximum motor rpm when going with the highest ratio possible that will give me give the desired max travel speed ("/Min) rate I need.
Al.

[JerryFlyGuy]

How large is your pinion? I'd guess that 3:1 is pretty small. I've got a heavy router [gantry weigh's ~ 1 ton] w/ two motors slave driving it. They are the MCG3304 motors.. 250oz-in cont w/ a 800oz peak [IIRC] and it will drive the gantry at ~75ipm w/ an accell of 22in/s/s. However if I push things harder than that is just doesn't get up to speed. I can also run into corner rounding issues. The major difference is that I'm using 10:1 reducers and 1.5" pinion w/ those servo's.

If that helps as a reference.. my best guess is that you don't have enough reduction on the servo's, however I don't know what kind of spec's you've got on your motors.

Backlash is an easy test. I'm not sure which axis your having issue w/ but for now I'll assume it's the X. You can do this test on any axis you want [to check lash].

Using the MDI jog out away from the home switch at least 1".

Zero the axis.
G1 x-0.050 F25[assuming inches on you machine.. use 2mm if metric]
G1 x0
Re-zero the axis.

Now the test:
Put a dial indicator on the machine such that it's measuring travel on the X axis. You'd prefer to have the indicator partially depressed so that it will register movement +/- from the x=0 position. Once you've got this set up and have noted the indicated # do the following.

G1 x 0.050"
G1 x0

Now read the Dial indicator and whatever deviation it has from the original reading is your backlash.

Some notes in regards to back lash readings.

You want to make your first move in the same direction as your going to take your reading from. Ie; an x+ move, then zero then another x+ followed by the X- move back to zero.
The reason for this is to take up any lash in the system. Then when you zero your DRO you know there is no lash that will effect that first +0.050" move. This allows you to see the difference when you do the x- move.

Hope that makes sense..

J

[gavztheouch]

Had another go at tuning the motors today and noticed some values I had plummed into the GDtool where wildly off ie... I had a value of 1 for the P position gain on the big x axis:nono: So I reread Teros manual and tried again. Now its working great, perfect letters curves and all, and quickly too, a good speed for routering out which is going to be the next step.