5 start thread? a-axis? 8020?

[NogginBoink]

Can anyone define these terms for me?

[restless1]

Well I am building a Cnc machine that needs two motors to pull one of the axis's in and out (lets call the first motor the x-axis motor) now the second motor that helps it we will call it the a-axis motor and slave it to the first motor in our software so if one side moves the other side moves in tandom!


Now I am making my router table out of aluminum ..
Well I went to eBay and looked up 8020 aluminum extrusion..
Which is basically long lengths of aluminum that I can put together like a Lego set (very simplified explanation ) ... Search on here for aluminum table and such...

Now 5 start thread is actually a screw thread profile...which is used for leadscrews(good for accuracy and high load movements) for let's say your z axis up and down...
Now from my understanding the ratio of starts relates to the pitch and distance one 360 turn travels.. So for a 5 start you would basically move five times the distance travel wise as a one start screw of the same size screw...in one 360 degree rotation
Now wether you want to move faster or slower on a axis is up to you...
But many like ther fast 5 start to get them where they want to go...

[brtech]

Restless did pretty well.

"Starts" affect resolution: for multi-start screws turns per inch is equal to threads per inch divided by the number of starts. For a single start screw, turns per inch = threads per inch.

A axis is a 4th axis (X, Y, Z and then A). In some CNC machines, you use two motors on Y to drive the gantry, one on each side. This is needed when the gantry is wide/heavy. When you do that, the extra Y motor needs its own driver, and the driver needs to be driven from the controller in lock step with Y. Mach calls this "A", but really, A is any fourth motor. Some designs have another axis entirely, effectively giving "Z" an angle and a depth. There are 6 axis machines which use X/Y/Z/A/B.

8020 is a brand of aluminum extrusion. See 80/20® Inc. - The Industrial Erector Set�. Many CNC designs use these extrusions to build their X/Y/Z/A axis. For example, look at the Home : Fine Line Automation designs. The extrusions are light weight, strong, and have built-in T tracks. There are a lot of components available to join these extrusions together and to mount all sorts of stuff useful in constructing a CNC machine.