Milling machine x axis travel shorter than y axis why?

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Koi

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If you guys have notice majority of the milling machine's x axis has shorter travel than y axis.But why,wouldn't a longer travel benefits meaning you can work on broader workpiece on the x axis without needing to change it to the y axis.rigidity reason or because all the milling machine making companies are following the design of the first few milling machine back in the days.
 
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X axis (left and right motion standing in front of your machine) is normally longer than Y. Mike
 
Koi said:
If you guys have notice majority of the milling machine's x axis has shorter travel than y axis.But why,wouldn't a longer travel benefits meaning you can work on broader workpiece on the x axis without needing to change it to the y axis.rigidity reason or because all the milling machine making companies are following the design of the first few milling machine back in the days.
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Are you speaking of a horizontal or vertical mill? Either way, the X axis is the major axis 90 degrees to the Z axis, and the Z axis is in line with the spindle. Y is the minor axis 90 degrees to the X axis -- by long held convention. Table toward and away from the operator is Y on a vertical mill and Z on a horizontal mill. Left to right table travel is X on both machines.
Edit: Letters for the axes are confusing to many operators, and difficult to visualize from one machine to another by many. Left/right, up/down, toward/away, etc., makes for better communication. Your post does not make sense to me...
 
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Oh sorry it should be why y axis has shorter travel than x axis.
 
I'll take a stab at answering your question.

Notice that Y axis motion is limited by the column of the mill. You might be able to get more Y travel by cantilevering the head/spindle outward a longer distance, but that would reduce stiffness. Starting out with the center of the table under the spindle, the "forward" width of the table is usually somewhere near where the spindle will be if the table is cranked all the way back to the machine's column. As for forward table motion, there's no real need to move the table beyond the point where the spindle aligns with the rear table edge.

Now consider the X axis. You could theoretically make the table as long in X as you wanted to, with accordingly long travel. The practical limiters here are (1) the strength of the table and its supporting structure ... don't want the table to sag from a heavy load on one end (or cause the mill to tip over sideways) when it's cranked all the way out. (2) the practicality/cost/precision of extremely long lead screws. (3) Shop space ... The clear horizontal area needed by a mill is roughly twice the X length of the table.

For machines like 3D printers, where the X and Y mechanisms are overhead, supported by posts at the corners of the working envelope, you can make the X and Y travel distances as long as you want to (given whatever limits there are to accuracy, stiffness, etc.)

Hope this is useful to you.
 
hman said:
I'll take a stab at answering your question.

Notice that Y axis motion is limited by the column of the mill. You might be able to get more Y travel by cantilevering the head/spindle outward a longer distance, but that would reduce stiffness. Starting out with the center of the table under the spindle, the "forward" width of the table is usually somewhere near where the spindle will be if the table is cranked all the way back to the machine's column. As for forward table motion, there's no real need to move the table beyond the point where the spindle aligns with the rear table edge.

Now consider the X axis. You could theoretically make the table as long in X as you wanted to, with accordingly long travel. The practical limiters here are (1) the strength of the table and its supporting structure ... don't want the table to sag from a heavy load on one end (or cause the mill to tip over sideways) when it's cranked all the way out. (2) the practicality/cost/precision of extremely long lead screws. (3) Shop space ... The clear horizontal area needed by a mill is roughly twice the X length of the table.

For machines like 3D printers, where the X and Y mechanisms are overhead, supported by posts at the corners of the working envelope, you can make the X and Y travel distances as long as you want to (given whatever limits there are to accuracy, stiffness, etc.)

Hope this is useful to you.
Click to expand...
But if they design the head to be more rigid or thicken the cast iron around the column connecting the head will that solve the stiffness issue.btw does different brand of mill drill of the same size has different table travel particularly the y axis?
 
Koi said:
But if they design the head to be more rigid or thicken the cast iron around the column connecting the head will that solve the stiffness issue.btw does different brand of mill drill of the same size has different table travel particularly the y axis?
Click to expand...

Yes but doing so will considerably add to the cost. The point of mill drills is affordability & a smaller envelope for those who can't/don't have a need for a large knee mill.

And yes there are mill drills with more Y axis travel. Check out the PM-940M (12" Y) & PM-833T (11" Y). Not sure if there are other distributors that carry these style mill drills in your area.
 
The short answer is due to practicality and the cost to build such a machine that is rigid enough to be useful. But, your question begs the question of why would hobby machinists such as ourselves want such a mill?

Tom
 
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