Mach3/madCAM, mill feed rates,homing, and scaleing

[taylorn]

Hello, I have a few problems that you guys can help me out on since I'm still a novice.
1. What should I set my feed rate as in madCAM when making the G code for cutting plastic/machinable wax? I tried changing it from 11 to 50,100, and 500 all of which showed very little increase in speed. What are the units for the feed rate?

2. When I click GOTO Z to go home, it homes the X and Y axis and then the Z. I hadn't thought about it until I clicked home after a test engraving and it put a nice groove across my work. haha. Is there a setting to change that?

3. For some reason, I can't get the mill to make the correct size part. Not even within 25%. Example. I draw a pocket in rhino3d that is 1" by 1", extrude it down .1". Then I make the tool path and then the g code, load it into mach3, and run the code. the pocket comes out to about .25"x.25" square. What are all the settings I need to change?
Thanks
TaylorN.

[teamtexas]

check out this trouble shooting video http://www.machsupport.com/Videos/Ma...elections.html. It has a easy way to set up your machine for proper sizing.

Good Luck
Dan

[taylorn]

Well, I got the feed rate to work for me. But I'm still having problems with homing and scaling. I thought that since my board is set up for 1/8 steps, that something was wrong in mach3, so I scaled the drawing up 8 times in rhino and it made the part bigger, but still not the right size.HELP!!!

[turmite]

Send me a pm with your email address and I will try to help. Don't want to do it here on the open forum.

Mike

[taylorn]

Ok, doing some research and thinking, I think I need to set my steps per unit (inch) to 32000. I'm using a xylotex 4 axis board set to 1/8 steps or 8 microsteps or whatever it came set as ( anyone know), and 1.8 degree xylotex stepper motors. I did the motor tuning wizard or whatnot in mach and it said 32000 steps per unit. When I tried to jog the motors, they just stalled. Am I wrong on the steps or something else.
Thanks
TaylorN.

[ger21]

What kind of screws are you using? 32000 steps per inch would be for 20 turn per inch leadscrews. The steps per unit have nothing to do with stalling. You need to lower your acceleration, and possibly your velocity as well. What are those set to, and what kind of machine is this? What size are the motors?

[taylorn]

Yeah they are 20 tpi screws. Its a taig mini mill. I'll try changing the acceleration and velocity at 32000 steps tommarrow. I cant tell you what those are set to right now because the mill is at my CAD class at school. The motors are xylotex 269 oz.in.
Thanks
TaylorN.