My 1st purchase towards my cnc machine. Did I get a Good deal?

[newpatch]

Hi All,

So after several weeks of reading this forum I stated designing my cnc machine. I want a 24" x 36" working area with the ability to cut wood and aluminum (guitar bodies, necks and brackets).

I was leaning towards round linear supporting rails but I came across a pair of 460mm rails with 4 THK HSR 20 blocks for $85 shipped, used and in great condition. I was just trying to get an idea of how much this machine will cost me to build when I came across these.



I'm hoping to cut them shorter since they will be for my z axis.

Also, I didn't realize how long of a rail I need until I started designing my machine. For example, a 12" rail will not give you a 12" cutting area because you have to take into account the bearing length, 2 for my machine, and the length of the piece you are mounting your bearings to.

Anyway, I hope I'm off to a good start.

newpatch

[HorridHenry]

I'm hoping to cut them shorter since they will be for my z axis.

Heh? your z axis will be to short,unless you mean cut them down for your Y axis

The Z axis goes from left to right
The Y goes up and down
The X axis is the bed length

[HorridHenry]

Also, I didn't realize how long of a rail I need until I started designing my machine. For example, a 12" rail will not give you a 12" cutting area because you have to take into account the bearing length, 2 for my machine, and the length of the piece you are mounting your bearings to.

This is correct,so if you want a 24"x36" working area you need at least 28"x40"

I wouldn't cut those rails down just yet until you have finally near enough built the machine,seriously

[lovebugjunkie]

Heh? your z axis will be to short,unless you mean cut them down for your Y axis

The Z axis goes from left to right
The Y goes up and down
The X axis is the bed length

Most builders in the USA mount their spindle on the Z and it moves vertical to the table. My guess we do that to stay in sync with CAD programs that have the Z doing the same thing.

I think you got a good deal newpatch, and I would not cut them down, just use them as is, never can tell when you might want a few extra inches in the future.

[BanduraMaker]

Heh? your z axis will be to short,unless you mean cut them down for your Y axis

The Z axis goes from left to right
The Y goes up and down
The X axis is the bed length

?

There seems to be some arguments about which is X and which is Y on this forum but I don't think anyone ever has a Z that goes anywhere but up and down.

[HorridHenry]

There seems to be some arguments about which is X and which is Y on this forum but I don't think anyone ever has a Z that goes anywhere but up and down.

There does doesn't there.....

[BanduraMaker]

There does doesn't there.....

You're thinking of a lathe coordinate system. For a mill it's Z up, X & Y parallel to the ground.

machine coordinate system cnc - Google Search

[HorridHenry]

I'm not thinking of anything other than googling for XYZ axis

[BanduraMaker]

Did you even follow the link I posted?

[HorridHenry]

The cartesian method is what I got taught in school.

[BanduraMaker]

The cartesian method is what I got taught in school.

Oh, in that case we'll just have the whole world of CNC change so that we can communicate with you.

To the OP, that does seem like a good price. For a Z-axis, you probably don't need two trucks per rail. One should be plenty strong. If you take one off, be careful though as the ball bearings will fall out. There's a little rail shaped gizmo you can use to remove them without losing the balls.

[HorridHenry]

Oh, in that case we'll just have the whole world of CNC change so that we can communicate with you.

So long as I don't have to get in a space shuttle with you.