Losing Y position

[foamman]

Hey everyone,
I am consistently losing the position of the cutter in the Y axis. Even just running at 2 IPS. I have checked the Z carriage and it slides smoothly when not under power. The elliptical bearings are not to tight as to cause binding but not tool loose as to make the carriage wiggle.

However, when I run a simple material leveling file, I loose a good quarter of an inch by the time the file is done.

Before I take the carriage off to check the sprocket on the Y stepper, I wanted to ask if this could be the problem. It doesn't wiggle when I shake the carriage with or without power.

Also, when I run the leveling file (which is just a pocket tool path), the transition between when running in the X to Y direction and vice versa is very abrupt. It causes the whole carriage to shake. Is there a way to slow the transition between directions? Possibly a way to make the cutter slow when it approaches a turn and then accelerate back to normal after the turn is made?

Like always, any help will be greatly appreciated. Extra much so as I am behind on a project which is why I am working on a Sunday. Why do these things always happen on a day ShopBot is closed?

Thanks
Ben

[srwtlc]

Ben,

Check your ramp settings (VR). You may have a 'too' aggressive ramp setting and could be loosing steps at those transition points. You didn't say what model machine you have, but if it's a standard, this could be the problem. You could choose to reset the ramp values to default and try again.

[foamman]

Thanks Scott,
I will try checking the ramp values. I have a PRS Standard.

Some more evidence is that when I ran the leveling file at .5 I didn't lose any Y at all. At 2 I lost about .25 of an inch. At 5 I lost a whole inch.

What should the ramp values be?

Thanks
Ben

[garyc]

Ben...
When you have the ramp fill in sheet open ( [V] [R] ) the default values will pop up when you hover your mouse over the field.

[foamman]

Problem solved by resetting ramp values. Not sure how they changed but things seem back to normal.

Thanks
Ben