Replicator 2X - what are the actual print volume dimensions?

[mi...@dataadvantage.org]

In designing a product concept based on specifications, I have a part that turned out to be 6.375" square at it's base, but my 2X doesn't seem able to print a 6.375" square dimension.

First, Makerware tells me it's too large.  If I ignore the warning, the 2X fails to print/extruding when it tries to print the front edge (near the glass door).  Within Makerware, I had the object centered on the platform, but I tried moving the object around slightly in Makerware anyway, but with no success.

The 2X specifications are a build volume of 9.7"W x 6.4"L - does anyone know what the actual print limitations/dimensions are??  

Thanks,

-Mike

[Scottbee]

The build volume for the 2X is advertised as 9.7" x 6"x 6.1" (L x W x H)

[Jetguy]

All that said, forget the advertised BS, calculate and KNOW what your build volume is.

Makerware stores the config files in the S3G/Profiles folder.

Replicator2X json.

So understand the basics of the coordinate system and homing. If 0mm is dead center of each axis, to get the machine into a know state, we home which simply moves each axis to the endstop. Now, important note about homing. Homing STILL doesn't fix the logical position the bot sees as the current coordinates. ALL homing does is move the axis to the endstop so we know that we physically are at the endstop. There are 2 methods to then update the logical position to match the physical position. One preferred method is to recall homing offsets via the M132 command. This depends on the calibrated value stored in eeprom in the printer. The other way is to make a blanket assumption in the software and use the G92 command to write the current position to memory.

Makerware uses  the both, but since the G92 method is the last command sent, it overwrites the M132 values.

As such, when talking about build space- forget all the other numbers because this is the logical method that matters.

The magic line is:

"G92 X152 Y72 Z0 A0 B0",

Remember, the idea here is we are at the endstop because we homed before this. G92 then tells the machine that we are now at those listed coordinates with the machine homed for every axis. 0mm is the center of each axis and the center of the print bed.  The clincher here isn't so much the X value (because homed, the heads are far off to the right of the bed), but the Y axis value. That Y72 gives you the massive hint that Y advertised volume is BS.

If Center of Y is 0mm and slammed against the endstop is 72mm, then the other way (for 0 to be the center is -72mm). Basically 72mm  times 2 = 144mm

Now last I checked, 144mm isn't 6 inches- not on this planet. Further, you cannot EVER hit the endstop during a print as position is lost. So again, if the offset is 72mm, you cannot GO 72mm from center back. You want some safety margin so safe build area is realistically, maybe 142mm in Y at best if you use automatic centering of the object on the bed and want 100% reliability.

[Jetguy]

Sorry if that's over the top for you guys but right there it is in black and white. It doesn't matter what you tell it the build volume is in the beginning of the config file. That just sizes the bounding box in the interface window of Makerware and triggers when it blows an error at you that you've gone over the  build size.

What MATTERS is that G92 command that you cannot change. It's not that you cannot just haul off and change those values. No, far from it. They are those numbers because that centers the print on the bed because that's what the machine is mechanically capable of.

Everything else should be based off of the numbers in the G92 command- not the tail wagging the dog as it is now.

[Ryan Carlyle]

The build plate is a little bigger than 144mm, but about 8mm at the front are taken up by the mandatory MakerWare purge line. You can print on top of that line if you want, giving you a kinda-sorta 150mm wide build plate. Still not 6" though.

[Scottbee]

I believe that you will find that Y72 does not put you in the center of the available build volume...... and there's part (if not most) of the problem right there (and, of course, you CAN change the G92 command to properly reflect your available axis length and center location).

[Dan Newman]

On 31/07/2014, 7:14 AM, Scottbee wrote:
> I believe that you will find that Y72 does not put you in the center of the
> available build volume...... and there's part (if not most) of the problem
> right there (and, of course, you CAN change the G92 command to properly
> reflect your available axis length and center location).

Or remove the G92 entirely? Is that possible? After all, the "recall home offsets"
alone suffices provided that the home offsets are set sanely. (Which generally
they are and if they aren't, then you can change them via the machines onboard
parameters.) It's anyone's guess why MBI started putting the G92 in. (And why,
having put it in, they left the recall home offsets as well since it is now
superfluous.) Two likely reasons are: (1) to be hostile to modified and look-alike
bots, or (2) because too many users had bad home offset settings for some reason
and this reduced support phone calls.

Dan

[Scottbee]

Checking back on my old prints... "back in the day, before I had a clue"..... the biggest print that I successfully printed with stone-stock MakerWare, R2X, and MBI firmware was 5.975" in "Y".  I remember freaking out because it triggered the endstop on the extreme Y+ moves (but didn't cause a shift.... just "touched" it) and printed over the stock purge line on the Y- moves.  It was a prefect print though.  Newbie dumb-luck.

[Scottbee]

I was told (by Jetguy I believe) that MW checks for the presence of the G92 command and chokes if it isn't there.  I don't think I ever tested that though.  I may be all wet on that.

Since I moved almost exclusively over to S3D I don't worry myself over such things....    ;)

[Jetguy]

No, removing the G92 line causes Makerware to fail upon attempting to create the gcode during the "validation" phase.

There are some checks hardcoded into the system that are not easily editable.

Again, removing the G92 line will cause the export operation to fail.

[Scottbee]

The stock HBP on the R2X is something like 162mm in the Y.  But you can't get to all of it due to mechanical stroke limitations of the axis.... which I believe is  ~152mm.

On Thursday, July 31, 2014 9:11:41 AM UTC-5, Ryan Carlyle wrote:

[Dan Newman]

On 31/07/2014, 7:57 AM, Jetguy wrote:
> No, removing the G92 line causes Makerware to fail upon attempting to
> create the gcode during the "validation" phase.
> There are some checks hardcoded into the system that are not easily
> editable.
>
> Again, removing the G92 line will cause the export operation to fail.

Well, that smells much more like trying to be hostile to modifications
and clones than trying to prevent support calls (due to bad offsets).
(It then causes support calls by folks seeking to modify their profiles
and remove the G92 and then scratching their heads.) So, I'm back to
my original speculation before I gave MBI the benefit of the doubt:
they did that to make life difficult for modified bots and clones.
Good news is that there are other slicers which work quite well.

Dan

[Scottbee]

But if memory serves me correctly you can edit the values of the G92 command and MW will still stomach it.

Also, just because they use a stock Y72, that doesn't mean that the overall Y axis stroke is clipped at 144.  That just sets the "center".... it doesn't mandate symmetry.  As I've already mentioned, stock MW, stock R2X and stock firmware can print ~152mm in Y.  You just need to be careful where you position your model in the slicer.

[Jetguy]

Correct, you can edit it.

 

Defeating the point here. Joe Noob shouldn't be editing his machine.json file just to get "advertised" build volume.

Joe Noob shouldn't have to calculate a position of the model forward of center in Makerware just to get the print to center in the build volume.

 

It simply does not work as advertised.

[Scottbee]

I believe the point is that the advertised Y axis is correct (+/- .02").  The OP for some reason had a bogus number.

The other point is that your rant regarding 144mm was incorrect.

[Jeff Gomes]

I in my wide-eyed innocence once tried to print something 150mm in the Y dimension and had it fail.  When I started experimentally scaling it down to see how small I had to make it before it stopped having problems, it finally worked at 144mm.  So my noobish trial and error experience would seem to indicate that Jetguy's "rant" was actually helpful information that I wish I had known a long time ago.

~ Jeff

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[Scottbee]

Jeff,

If you read my previous post you would see that printing a model that is over 150mm along the Y is completely possible... stock R2X, stock MW, stock firmware....  no exotic settings or modifications of gcode.  There is nothing stopping you except for properly positioning the model on the build plate.

The "144mm limitation" is incorrect information.  Sorry.

[Jeff Gomes]

Regardless, as a newbie it never occurred to me that, in order to use the maximum Y space, I should shift the model 3 or 4 mm toward the front from where the Center button places it in Makerware.  To me, "Center" implies that I have equal build area on either side of that point.  Apparently not the case here in the Y direction at least.  If someone doesn't know that, then for all intents and purposes they are limited to 144 mm until they learn the secret formula (and get very clever at quickly removing the purge line before the print head smashes into their tweezers).

I did not intend to poke a stick into a hornets nest here.  I just thought it an interesting "coincidence" that the 144 mm exactly matched my experience as a neophyte.  I appreciate you sharing how to work around this limitation that apparently exists only in my mind.  But the existence of a work around does not completely absolve those writing the marketing materials and manuals from the responsibility of telling the user how they can actually access the full specified dimensions.  I doubt I was the only one confused by Makerware's very original interpretation of the word "Center."

~ Jeff

[Dan Newman]

On 31/07/2014, 1:37 PM, Jeff Gomes wrote:
> Regardless, as a newbie it never occurred to me that, in order to use the maximum Y space, I should shift the model 3 or 4 mm

Here's the odd thing: for the Rep 1, MBI makes the Y home offset 72 mm for a Rep 1 DUAL but 75 mm for
a Rep 1 SINGLE. That is, they shift the model forward by 3 mm for one of the two models. I never quite
figured out why they distinguished that way between a Rep 1 Single and Rep 1 Dual. But then, a Rep 1
Single (as purchased that way) is a rare beast. (Dave of EEVBlog got one; #318, #326, #327.)

MBI didn't make that distinction with the Rep 2 vs 2X: they just made both of them use the same value.

Dan

[Scottbee]

I agree.. MW didn't make it "obvious" how to use all of the advertised Y axis (if you use the "center" feature). My suspicion is that they (perhaps) moved the center 0 so that people wouldn't readily print over the purge line (which can't easily be disabled).  This way you get the MW "envelope warning" and perhaps will think twice (and ponder the consequences) before you proceed.

As I mentioned earlier, I moved over to S3D as my primary slicer some time ago....  It doesn't put the purge line across the front and by-default it puts Y-0 at 75mm from the switch and has the Y axis length at 150mm.  Still a couple of mm less than reality.