Question Cutting slices from an alu square tube?

Hi folks!

I need to cut many 3cm-length "slices" from an alu 6060 square tube (5cm x 5cm, wall thickens = 2mm).
I've done this before with the steppie, result are not so bad. I simply made one transversal cut one side, rotate the tube, cut another side, and so on until all the four sides are done.
Cuts made from alu-services shops are ugly: their cut is always a little bit "diagonal" 'cause they use not well aligned saw.

My need is to maintain the cuts more perpendicular as much as I can in order to get an (almost) perfect slice of the tube. Nevertheless, I always obtain a little step (around 0.1-0.2mm) when I arrive at the fourth cut. This thing make me crazy. In fact, after every rotation of the part, I add always a little error. Grrrrr...

This is my procedure:

1. I make the first cut with a 1/4" milling bit on the top side of the tube (let's say along the X-axis).
2. I stop the bit at the end of the cut.
3. I "unlock" the tube from the vise and I put it away from the table machine.
4. I manually lower the milling bit it a little along the Z-axis (let's say around 1cm).
5. I rotate the tube so the cut just executed is now vertical.
6. I gently put back the tube on the vise in such way that the vertical milling bit now fits inside the vertical cut. This give me the zero position along the Y axis for the next cut.
7. After locking the tube I rise up the milling bit and I go for the next cut.

I repeat, this method works but there is always a little error. I'm short of genial idea... there is no better method to place the tube in the exact position after every rotation?

I would use some pins on a MDF surface, but I do not have any precise on how doing that.

To be more clear, here below the first two steps of my method (the one I don't like so much):

I'd create and mount a stopper to the vice.
You also have to make sure that the vice is exactly square to your moving axis.

I've created a little helper that allows me to attach the vice to the T-slot table very exact.
You can see my setup here

MagIO2 wrote: I've created a little helper that allows me to attach the vice to the T-slot table very exact.
You can see my setup here

WOW! That's what I call a damn good job.
I've started reading the entire thread even if my german is quite rusty.

Anyway I could reach the same result (in my case) by using the pin + MDF-holes method, or not? I mean... I could make two holes in the MDF, used as sacrificial material, and fit two pins in it. In this way I should have a line that is 100% parallel to the longitudinal axis of the tube.
After every rotation I have just to push the side of the square tube against the pins to get its axis perfectly aligned with the Y-axis of the machine. Or there is something wrong in this reasoning?

Honestly I'm short on time in this period, building something like you made is not possible for me...

(Don't disturb me now, I go back to read your posts about the stopper! )

MagIO2, how is fixed your stopper to the table?
How you measure/evaluate if (and how much) the vise is parallel to the Y-axis or not?

Of course you can also use MDF and pins or a block of wood ... whatever ...
The point is having a stopper that allows to easily fix your workpiece exactly at the same position with all axes of the piece being in line with the machine axes.

The stoppers are fixed with the vice itself. I was told later that the vice has removable clamping jaws, so it would be possible to screw the stopper bars i made. Another thread showing the tool I made ...

The vice is very precise, so I think if the front face of the vice is parallel to the machine frame it simply has the right position. (That's what the "Anschlag" is good for)
But ... if you look closer to the pictures ... the stoppers are only a part of the whole thing .. there is a aluminum bar which has a "step" that actually holds the workpiece. This step has been milled while the bars were fixed in the vice. So, these are pretty sure plane to z and parallel to y.

MagIO2 wrote: the stoppers are only a part of the whole thing .. there is a aluminum bar which has a "step" that actually holds the workpiece. This step has been milled while the bars were fixed in the vice. So, these are pretty sure plane to z and parallel to y.

Ah, oh! That is the trick!
Do you mean that you milled two steps in those clamping bars (see arrows below), yes?

Yes.

I push the big stoppers against the vice and the workpiece in opposite direction against the edge milled into the bars with a little presure from top. This way you always have the same zero-point.

Maybe I can add some pictures this evening, showing the details a bit better.

But... the stopper is blocked just from the machine wall on the other side?
I mean... the combination in the photo above, from approx. left to right, is something like

machine wall + stopper + vice

?