[TransJenna]

HI there, I have a G0704 with 5tpi ballscrews running a Gecko g540 and ESS through Mach 3. My steps per inch are set to 10,000. I am using FreeCad to design and generate G-Code.

I was milling this part, and instead of milling the entire width of 5.5 inches, it only came out to about 5.4 inches. And the little cylinders on top are 1.082" diameter instead of 1.125" diameter. Can anyone please help me figure out what the heckin' heck is going on?

[servtech]

HI there, I have a G0704 with 5tpi ballscrews running a Gecko g540 and ESS through Mach 3. My steps per inch are set to 10,000. I am using FreeCad to design and generate G-Code.

I was milling this part, and instead of milling the entire width of 5.5 inches, it only came out to about 5.4 inches. And the little cylinders on top are 1.082" diameter instead of 1.125" diameter. Can anyone please help me figure out what the heckin' heck is going on?

Check your x/y axis motor couplings for play or damage. Check your x/y axis for backlash (lost motion).

Check the squareness of spindle head to Z axis in case it has pitched over at an angle.

Do a spindle trammell check to the table top.

[TransJenna]

I've tried those things already, as well as checking the gibs for slop/wear. Everything checks out.

[Vlod]

If the calibration in mach3 checks out then check the play of the head and if your cutter is the right size.

[cncmakers001]

HI there, I have a G0704 with 5tpi ballscrews running a Gecko g540 and ESS through Mach 3. My steps per inch are set to 10,000. I am using FreeCad to design and generate G-Code.

I was milling this part, and instead of milling the entire width of 5.5 inches, it only came out to about 5.4 inches. And the little cylinders on top are 1.082" diameter instead of 1.125" diameter. Can anyone please help me figure out what the heckin' heck is going on?

You can check the gear ration setting for the affected axis.

[kawazuki]

Are you sure they are inch / imperial screws? A metric screw used with imperial settings would give a similar error ie. a 5tpi screw = 5 turns / 1 inch, a 5mm pitch screw x 5 turns = 25mm which is 0.4mm shy of an inch!

[mactec54]

HI there, I have a G0704 with 5tpi ballscrews running a Gecko g540 and ESS through Mach 3. My steps per inch are set to 10,000. I am using FreeCad to design and generate G-Code.

I was milling this part, and instead of milling the entire width of 5.5 inches, it only came out to about 5.4 inches. And the little cylinders on top are 1.082" diameter instead of 1.125" diameter. Can anyone please help me figure out what the heckin' heck is going on?

You will have to check the Step /Per, using the setting of10,000 may not be correct, it is rarely an exact number like this, the longer the setting piece you use to set the Steps / Per the more accurate it will be, you can use a micrometer setting rod, you can find them quite cheap on Ebay, 255950327179 this is 8" but 12" is better, depending on your axis travel, you can also use a 1 2 3 Block or Gauge Blocks, the longer the test measurement the more accurate you will get each axis, you can do a rough check with a steel scale (Ruler),and a pointer in the spindle

You will find in Mach3 the Axis Setup, Steps / Per by using the settings Tab, across the top of the Mach3 screen. there are videos on how to set the Steps / Per on YouTube there are different ways that are used so just use YouTube as a guide.

[mactec54]

You can check the gear ration setting for the affected axis.

There are no Gear Ratio settings for axis settings.

[metalmayhem]

the first thing I'd do is put a dial indicator on it . If it looks good then it's quite possible the code is the problem

[Jim Dawson]

Are you sure they are inch / imperial screws? A metric screw used with imperial settings would give a similar error ie. a 5tpi screw = 5 turns / 1 inch, a 5mm pitch screw x 5 turns = 25mm which is 0.4mm shy of an inch!

What kawazuki said ^^^^^^^^^^^^^

A 5 TPI (0.200'' lead) ball screw is a bit unusual, but not impossible. Much more common is 5mm lead (0.197'')

[TransJenna]

Now I am second guessing myself. It has been a few years since I bought the leadscrews. They very well may be 5mm pitch. Hopefully that is the issue!

So what would that make the steps per inch setting? 10,152? It is a direct connection to from the motor to the leadscrew. So it should be 1/.197=5.076x2000=10,152.... right?

[CitizenOfDreams]

So what would that make the steps per inch setting? 10,152? It is a direct connection to from the motor to the leadscrew. So it should be 1/.197=5.076x2000=10,152.... right?

10160 steps per inch would be the correct number for 5mm screws.

200 (steps per turn) * 10 (microstepping) / 5 (mm per turn) * 25.4 (mm per inch) = 10160.

[mactec54]

Now I am second guessing myself. It has been a few years since I bought the leadscrews. They very well may be 5mm pitch. Hopefully that is the issue!

So what would that make the steps per inch setting? 10,152? It is a direct connection to from the motor to the leadscrew. So it should be 1/.197=5.076x2000=10,152.... right?

A calculation will get you close, once you figure out what your Screw pitch is, then you go through the setting of each axis doing the Steps Per with the control, that's if you want any kind of accuracy.

Do you have Leadscrews or Ballscrews??

If there is a part number on the Nut this normally includes the screw pitch in the number, you could have either type of Leadscrew ,200" or 5mm you can find either pitch with Leadscrews or Ballscrew, most Leadscrew / Ballscrew manufacturers make both inch and metric.

Post the part number on the Nut we will see from that what the pitch is.