What size rails for these Bearing trucks

[monte55]

I would think there would a standard for X and Y......If you can call them anything you want then no one can really understand what axis you're talking
about unless it is Z. No wonder why some of the posts make sense to me while others do not. It will be difficult for a person to get proper info on the Y axis if the advice giver is thinking X. Am I the only one that thinks this could be a problem. If I can not get a definate answer on a simple thing like this, I'll really be in trouble when it comes to complicated issues like software etc. I know lathes and mills have standards for axis, I wonder how did cnc tables
slip through the cracks.

[Jamie Tranor]

Monte 55,

You are correct about there being a standard for the X, Y and Z axis. I have operated many machining centers and turning centers with multiple axis and they all hold to certain rules. There are grey areas however.

First of all the Z axis is always through the centerline of the spindle; on a lathe this is the centerline of the chuck. This is absolute not matter what machine it is.

Second, the X axis on a lathe is the one that is perpindicular to the Z. This is the axis that dictates the diameter of a part being turned and this is also absolute. Some CNC lathes have this axis on a slant and the turning tools are behind the part as you are viewing it. On a manual lathe the turning tools are on the same side of the part as you are. This is your X axis.

Now the X axis on a machining center is a little different. On a machining center, the X axis is the longest axis 98% of the time. There are exceptions to this. The table on a machining center is longer than it is wide in most cases and the X axis runs across the length of the table. Now planekrazie is building what would be referred to as a gantry type of machine. This means that the milling table is stationary but the milling head moves. Saying this, I have operated gantry type machines where the table was longer than wide and I have operated ones with a square table. The X axis was different accordingly. I say this to let you know that as ger21 and snowshovelbmx stated, this creates the design opening to dictate your own axis layout. If he is creating a square table router, then it is recommended the he makes the Y axis the one where the legs run on the table base and the X axis across the top support. If his table is out of square then the length to width rule would apply.

Many considerations for the X and Y axis. Does the table move, does the head(spindle) move, do they both move(one in Y and one in X)? You can see the more you understand the more complicated it can become. This is what machine tool designers face when producing new machine designs and as budding minds, we here on the CNC Zone.

I understand that we are not building large scale machines here but if you follow my suggestions and rules, you will follow the standard layout for machine tools.

I hope this helps you out.

JT

[ger21]

When everyone here is building there own machine, how do you enforce a standard? From what I've read, the standard for gantry machines is that the longest axis should be X, which was already mentioned. Since the gantry is usually not the longest axis, that makes the axis on the gantry the Y axis.
The problem is that even some commercial machines call this the X instead of Y. Again, how do you force everyone to use the same naming conventions?

As was mentioned in the other thread, it also makes sense for X to be the longest axis, because when using a CAD program, X is usually left to right and is longer than Y in screen size. If your drawing a long part, you'll typically draw it from left to right, along the X axis.

And while yes, it can get very confusing when everyone's calling everything something different, most othr subjects will be much more straight forward.

Bottom line, is set the machine up to work best with the way you want to use itm, and the parts you want to make with it.

[monte55]

Thanks guys ..................that helps a lot. The main thing I've learned is not to expect someone else to know exactly what you mean..........you have to make yourself perfectly clear..........knowing this less mistakes should be made. l

[planekrazie]

Oh well. All I wanted was to know what size rails I needed and we went way off coarse. Good learning for all.
Steve