[planekrazie]

I have 4 THK HSR15 bearings and I am looking for some extra rails. All I need is 2 Rails at 6" for my z axis. What I am having a problem with is finding rails to match the trucks. If anyone has an extra rail at 12" or more, Or know what size and where I can buy. Let me know. I buy them from you or a company.
Thanks Steve

[snowshovelbmx]

I have a rail comming to me with two bearing trucks, but I do not need the rail its 12 1/4" long. Otherwise you would need the rails to be 15mm wide, but each rail profile is different for each model of bearing block and needs to be matched exactly.

[planekrazie]

What price do you want fot the rail.
YOu can call me at work at 1-800-929-0909 from 3pm till 11pm eastern
Steve

I have a rail comming to me with two bearing trucks, but I do not need the rail its 12 1/4" long. Otherwise you would need the rails to be 15mm wide, but each rail profile is different for each model of bearing block and needs to be matched exactly.

[snowshovelbmx]

hi steve
how about 20 dollars plus shipping? let me know.
chris.

[planekrazie]

Sounds like a winner. PM me your address and Ill have the have the money right out. How much would you guess for shipping.? 10.00?
Steve

hi steve
how about 20 dollars plus shipping? let me know.
chris.

[monte55]

I am building a 4' x 4' cnc table...............I understand x axis is where the tool would
move parallel to the tool rails and y axis is what the whole gantry moves on.....is this correct? Some posts I read indicate otherwise. I want to use 2 stepper motors, one on each side to drive y with leadscrews...........1 stepper to move the tool across the gantry and 1 for z. Every time I think I have it correct someone says something to make me think different.

[snowshovelbmx]

monte
You've got your axis right, however I'm not quite sure that you would need two steppers to drive the y axis, I have seen most designs with only one stepper motor in the middle of the table driving the entire gantry. I'm not positive but running two stepper motors on one axis could cause binding issues somewhere along the line, just an observation.

[monte55]

monte
You've got your axis right, however I'm not quite sure that you would need two steppers to drive the y axis, I have seen most designs with only one stepper motor in the middle of the table driving the entire gantry. I'm not positive but running two stepper motors on one axis could cause binding issues somewhere along the line, just an observation.

Thank you for your reply........the weight of the gantry is probably close to
25-30 lb now...it is being driven by 3/4 x 6 acme screws, one on each side.
I'm almost done with the mechanical part of the build. After I complete the Z
axis, I will probably drill lighting holes throughout the structure. All my aluminum is 5/8 thick plate. I have 4 linear bearings in cast iron mounts, 2 on each side on Y, 3 of the same bearings on X all riding on 1" shaft. This all starts adding up in weight. I'm thinking 425 steppers x 4 but what do I know? I should be getting my Lovejoy connectors today. I'm making my own 3/4x6
flanged screw nuts out of bronze. The tap cost $54 but as the nuts wear it
will be a cheap and easy replacement in the long run. After I'm done with the
assembly I will try to come up with a torque value at each leadscrew to move it plus actual pressure required to move each axis. I have a digital torque
meter that goes in between a socket and ratchet . Once I get that info
I'll throw it into the forum for advice on steppers and drives. Sorry for the ramble but since I originally decided to get a table then to build my own after
seeing prices and some negative reports on some I can't get this project out of my mind. It's been about 2 months now. I'll be glad when I'm done so I can obsess about something else. The mechanical part I'm ok with.....it's the computer and program stuff I'm worried about. Thanks again

[planekrazie]

I believe my Y is around 25 LBS+. I am using 200oz per inch steppers through out. Only three steppers total. My table is 4 x 6 with my z At 6"
I was going to use 3/4 rods and slide bushings for my Z but when I try to move it up and down with a small amount of pressure by hand against the tooling it binds. So thats why I want to get the extra rails for my z.
Oh well time will tell how good it will work and as for the software thing. same here. I think its gonna be a good challenge for me.
Steve

[ger21]

I am building a 4' x 4' cnc table...............I understand x axis is where the tool would
move parallel to the tool rails and y axis is what the whole gantry moves on.....is this correct?

The gantry travels along the X axis. The Z axis moves along the gantry on the Y axis. But you're free to call them whatever you want.

[monte55]

I have heard it two different ways on which is X and which is Y in the last couple of posts. Which one is correct?

[snowshovelbmx]

On a milling machine or VMC, from the front of the machine, the X axis is travels from left to right or vice versa, the Y axis is front and back and the spindle is up and down, but as ger21 stated you really are free to call them what ever you want on your router. Since there really is no actual front of the machine and you are the one building it, then it is really up to you.

chris.

[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. :argue: 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