Help with "Step Timing Calculator"

The G0 speeds are set by your max velocity settings in the ini file. This and the acceleration settings for each axis are some of the first places you should look for fixing your missing steps. Don't forget that the velocities in the ini file are in units per second. So if you have set your machine up in inches it will be inches per second (not the inches per minute that your feed rates and such probably use). You may also need to look to be sure there are not any mechanical issues causing problems as well.

your problems are in the max acceleration and and max velocity areas set in your INI files . not the actual stepper driver , as todd suggests
with older drives which are either full step or half step drives , setting at 10,000 to 15,000 should suit fine .

also what stepper motors and stepper power supply are you using , please let us know the ratings ?
also look at the default max velocity and acceleration settings they probably are miles out .

post your current hal and ini files would help .

it the drives appear to instantly lock up then you are trying to either run the steppers far to fast than they are capable . so cut the max acceleration and velocity values way down
it's easier to start with the drives turning slowly and then increase values on these older drives .

the z axis is usualy the most difficult due to the weight it's carrying and the effects of gravity

Todd and Basher,

Thanks for your input so far, I have been marginally successful, so I'm coming back to you for more advice.

I have the Y axis working accurately, as well as X.
The settings supprised me in the end, low speeds, with high acceleration. (Note attached ini).
Z, (as Basher stated), is being difficult.
It's odd, depending on settings it either goes up just fine and down poorly or, up poorly and down fine.
I can't seem to fined a good medium.

I have posted my hal and ini to see if you folks can see something I'm missing.

Thanks

When you were feeling out what numbers you were using for velocity and acceleration, what order did you do it in?

I would do it by first setting the acceleration quite low (10 or less), then find the highest velocity the joint will do reliably, then reduce by about 10%. Now that you have found a good velocity setting, then move up the accel setting in a similar fashion and then reduce by a safe amount like you did for the velocity.

Or if it is still avalible, you could try to dig arround in the harddrive of the old PC to try to find the configuration file from the old control software to get an idea of what they should possibly be. (I think its accel and velocities are in steps/sec.).

Our machines using simular drives and Resolutions of 1018.592 steps/inch for X&Y use MaxVelocity=6 and Acceleration=30 and the Z has resolution of 4000step/inch with V=2 A=30.

That also dose not mean that your machine might not have a mechanical problem causing to much resistance or binding. Miss aligned lead screws or nuts can bind a lot, and so can worn out zero-back-lash nuts and screws. An air cylinder counter-ballance can work wonders on a heavy vertical axis, especially when using lead screws.

I got to thinking about your point Todd, what if I have a physical or mechanical problem.
Looking at the Z axis earlier I noticed there was a rather large amount of grease around the screw and nut.
It was a difficult place to clean as compared to X & Y so I attributed it to that.
(Denial, not just a river in Egypt anymore).

I went ahead and pulled down the Z axis, I have not one but two problems with it!
First a lineal rail pillow block is toast and in need of replacement, not a problem and expected to some degree.
But second, the Precision Nut is in some way fouled, it turns with a great deal of resistance.
The screw looks to be in excellent condition, I'm guessing it's internal.

Can I rebuild one of these?
Or can I get someone on the West coast to rebuild it?
Or should I find a comfortable place to sit down and get a price on replacing it?

It all depends on what you have now, and what you want in the end, and if the manufacturer still exists and supplies parts for this machine.

What kind of a screw and nut do you have now? Is it an Acme screw? Is it an anti backlash nut?

A lot of lead screws with anti backlash nut systems are designed to be self lubricating and ran dry. Greasing or oiling these will usually ruin them. These types of nuts and screws when worn out will usually bind quite a bit. When this starts to happen many people who don't konw any better will put oil or grease on them and this just makes it worse.
You can try to dissasemble the screw and nut, clean it and inspect the threads in the nut for ware? If you think you might want to switch to a ball screw, nows the time to decide. How ever you need to remember that a ball screw will need something to support the axis when the motor is not powered, a brake, a counterballance or both.

Sorry I should have mentioned what I have here.

This is a Rockford R-45 Precision Ball & Screw assembly, it is a recirculating bearing style, and is fitted with a grease fitting from the factory. There seems to be just enough drag on it to keep it from travel when not under power.
Or someone set it up to be loaded as to not let it fall when not under power, no way to know.
The only thing that spokes me about is it is the “preloaded”, I'm not sure I can address that.
I called Rockford and they just want you to buy a new one. (Not cheap)!
I'm sure I can take it apart (I'm good at that), some direction on assembling it properly and where to find parts would be helpful. I wonder what parts could be in there??? (I know a way to find out).

If I can ever get this machine going and make some cash with it, I would like to increase the Z axis envelop as much as possible, so spending a lot of money on this axis would be money wasted.

If a ball screw is so tight that it is hard to turn, something is messed up, probably badly. I have never heard of one preloaded that tightly (at least not on purpose). A ball screws load rating is decreased by the amount of preload put on it.

Clean up the outside of it the best you can and snap some pictures of it. maybe we can offer some advise how best to attack this.

Some ball screw nuts can be very tricky to reassemble. Especially if you don't know what you are doing or have the right tools. (It took me half a day to put one back together once.)

I wouldn't mind spending two days messing with it, it's nearly $2000.00 to replace it!
An Acme screw and nut are $700.00, and I have to cut the rod down and machine the bearing journals.
(So you say you want to get into motion control do you).

Here's some photos.

Thanks for looking and any advice.