Wednesday, March 20, 2013

So, THAT'S Why They Include a Manual!

After realizing that low relative humidity might be affecting the effectiveness of the Cube Stick, I contacted some Cube managers to ask for an official specification.

It would be embarrassing to note that they pointed me to the manual, except that I'm guessing I'm not alone in skipping over all those details in the rush to get up and printing.  But, it turns out that the issue of relative humidity IS available to us right in the manual that came with the printer.

Hmmmm.... imagine THAT!  Who would have guessed.  LOL!

Cubify Humidity Range

Here's the rub... you don't want a sustained high humidity if you are using PLA. Fortunately, the fact that the Cube's PLA is in a cartridge helps to protect it.  But, at the same time we need to have the humidity high enough that the CubeStick doesn't dry out prematurely.

While the above specs seem to indicate that we could go as low as 9%, it seems to me that I see some negative affects in long print jobs at 16% that would indicate that it's best to aim higher.  So, I will be aiming at 20%-25% and see if I can see any difference in the duration of the stickiness factor.  I'll ramp up from there if I have too.  My PLA doesn't stick around long enough to become waterlogged.  :)

But, given the above information, I probably will NOT be aiming at the 40%-50% relative humidity mentioned in my previous post.

Tuesday, March 19, 2013

CubeStick (2nd Gen Glue) Observations

I don't know if the observations you are about to read are universally true.  But, it has taken a little bit of getting use to using CubeStick as differentiated from the behavior of the heat activated MagicGlue.

Don't get me wrong.  Both work and work well.  But, it seems to me that there are some extra things we can do to make sure that we do not EVER have a failure due to an object coming loose as it's being printed.

Dry the Printing Table Thoroughly

Both CubeStick and Magic Glue are water soluble.

It might be my imagination.  But, CubeStick seems less sticky when applied to a newly cleaned print table.  The print bed is frosted glass.  And, it may be that the very tiny irregularities that make frosted glass frosted might be able to hide and hold microscopic drops of water when we think we have dried the table completely.  It doesn't take a lot more effort to give the glass a few extra swipes with a new paper towel just to make sure the table is as dry as we can get it.

Apply a Thin Base Coat of CubeStick on Newly Cleaned Printing Tables

Just like a primer helps when painting, it has been my experience that if I first apply a very thin CubeStick layer over the whole printing table, and let it sit for a few minutes before applied a final coat of CubeStick that it seems to have significantly better performance.

Create Small Water Channels in Object Bases

CubeStick is water soluble.  So, if there is an object that you know is going to be difficult to remove from the print table try creating a .25mm channel at the base of the object to help distribute water under the object.  This can be created using a small square modified with BOSS CUT or BOOLEAN DIFF.  An object having a  patterned bottom releases more easily than one having a completely flat bottom.  By creating water channels at the base of your objects, you permit water to get under the object, dissolving the glue.

You don't need big channels.  Nor, do you need many.  A few will create isolated pockets of adhesion, allowing the piece to be lifted more easily.

Use the Best Tool

I have found a "painting knife" that works very well to remove stubborn parts. It can be purchased through ACMoore.  But, similar painting knives can be found in any craft or art store.\

Painting Knives for Part Removal
 I had previously used the larger version with the RapMan 3.2,  But, the smaller version is well suited for the 2nd Generation Cube.  The shape allows you to slide obliquely rather than applying brute force that a paint scraper or straight tool might require.

Relative Humidity

The area in which I live, with wide temperature and moisture variations is also a factor in how the CubeStick behaves.  I assume that the optimal indoor relative humidity for proper adhesion without drying too fast is between 40% and 50%.  In the room in which I print, the relative humidity has gone from 16% t0 56%.  Now that I think about it, those times when the humidity has dropped to the lowest points are probably the times when the glue has seemed to perform less than expected.  Now that I realize this, I will keep an eye on the relationship and will use a small personal humidifier in that space.  Of course, I don't want it so high that the humidity affects the PLA.  A balance is the key.

Sunday, March 17, 2013

Nailed an Interfaced Part on the First Try

If you have been working in 3D printing with an extrusion type of printer... including very expensive ones... you will know that one of the historic issues has been the fidelity of the printed output relative to the design specifications.

I had been extremely busy with a very complex design of a system that requires tight interaction with many different parts.  Receiving a 2nd Gen Cube was a bit of a mixed blessing.  On the one hand, I realized that the 2nd Gen Cube has a high level of fidelity.  On the other hand, it meant a complete redesign to take advantage of this new accuracy.

I will be writing about the bigger project very soon.  But, for now I simply want to emphasize the accuracy of the 2nd Gen Cube by relating a smaller project that I'd been putting off for more than a month.

A friend had asked me to print a faceplate that fit into a case in which an electronic board would be mounted.  The part I was to create had to fit the opening of the case with perfect precision.

I am VERY pleased to report that using the design specifications supplied by the case manufacturer, it was extremely easy to match the new faceplate to the box.  In fact, the very first design worked!

That's pretty amazing to me.  I had been used to several iterations of modifying specifications to match real world measurements to the capabilities of a 3D printer.  The ONLY adjustment I made was to round all specifications to the next lower .25mm.


I've abandoned using SAE measurements when designing for 3D printing.  All SAE measurements are converted to METRIC and the final designs are completed in metric.  The reason for this is that it is far easier to make precise adjustments in millimeters.

One reason for this is that the resolution of the printers are specified by their abilities to print in metric increments.  The Cube, for instance, prints in .25mm layers.  Thus, rounding down measurements to the nearest .25mm Z-Axis increment ensures precise height specifications.  Likewise, even with the 1st Gen Cube, we knew that the nozzle extruded a .50mm strand of filament. So, we could make adjustments once we had enough experience with matching design specs to printed reality.

I'm not exactly sure if the X and Y movements are locked in to .25mm increments.  But, if we start with that assumption, we can use small .1mm experiments to check out that theory.


Lastly, I want to say how much I appreciate the efforts of the Cube design team to address the accuracy issue with the new 2nd Gen Cube design.  It has vastly reduced the iterations required to reach a final design.   NICE!

Tuesday, March 5, 2013

2nd Generation Cube - First Impressions

One of the problems I had with attempting to help Cube users is that I only had a 1st Generation Cube.  I have no idea how many 1st Generation Cube owners there are.  But, based on the skyrocketing number of YouTube and CubifyFans Blog viewers since the 2nd Generation Cube was announced and released, I'd have to say that there is a rapidly growing number of 2nd Generation Cube owners,  And, that number will only get bigger.

I was being asked questions about the latest Cube that I could not research, test or answer.  And, since I do not do this as my living, it was hard for me to justify to my wife why I needed a new 3D printer in less than a year.  With her planning to retire in the next month, with a reduced income, that would have been a very tough sell. 

Fortunately, 3D Systems came to the rescue.  I'm grateful to 3D Systems that they have delivered a new 2nd Generation Cube to me so that I can be of help to ALL Cube owners.

And, I am very happy that they have done so,  It turns out that while both are great printers, they have quite different characteristics, as I have learned today as I fired it up and printed some of my own designs on it for the very first time.  So, here are some differences I've already noticed.

The CubeStick Works Differently that Magic Cube Glue

This may not seem like a big change; but, it turns out that 1st Gen Magic Glue owners will have a bit of adjusting to do when using CubeStick.  Magic Glue is heat sensitive.  When the print table cools the glue generally releases, freeing the pieces.  If we are in a hurry, all 1st Gen users have to do is flood the print table with water and the pieces generally pop loose.

CubeStick is very sticky... pre- and post-print.  While water still helps loosen the glue, the pieces don't simply pop off.  A small palette knife may be required to release the piece.

Adjusting the amount of CubeStick we use might also be something that has to come with experience. It's not bad.  It's just different.

Fidelity to the Design Specs

Features printed by the 1st Generation Cube tend to be "fatter" than the specified design by a fairly predictable amount.  Holes tend to be .5mm smaller and posts tend to be .5mm larger.  After a while it become second nature to make adjustment to the design to account for that behavior.

I can already tell that I am going to have to create separate designs for 1st Generations Cubes and 2nd Generation Cubes.  The 2nd Gen Cube prints amazingly close to the actual specifications.  Delicate pieces remain delicate.  If you are relying on a Cube for prototyping, then the 2nd Gen Cube is probably a better fit for your business.  But, as a hobbyist, the difference is not going to make all that much difference.  It all depends on the tolerances off your particular application.

I'm actually going to have to alter my original design to beef up the specs since the 1st Gen Cube did that for me.  Where having a 2nd Generation Cube is going to help me is that it should reduce the design alterations for going to SLA parts, with SLA's absolute accuracy,


The 2nd Generation Cube wins the speed contest on two fronts.  First, the print table does not have to be heated or cooled.  This saves a lot time between print jobs.  Secondly, depending on the print settings, it prints a bit faster.

Ability to Use PLA

The 1st Generation Cube only prints in ABS.  And, with its heated print table it does a fantastic job.  ABS is very tough material.  And, I love being able to print with it.

But, it's also nice being able to use PLA.  It's a far more forgiving material with which to print.  And, it has a bit of a sheen that makes for a nice finish.  The main benefit of PLA is that it is less likely to warp than ABS.

What I don't know, as yet, is how well the CubeStick handles the ABS material's tendency to warp.  Frankly, I have some doubts.  But, that IS pretty sticky glue!  I'll let you know when I try printing in ABS with the 2nd Gen Cube.  It may be that the higher temperatures required by ABS will reduce the differences in accuracy between the 1st Gen Cube using ABS and the 2nd Gen Cube using lower temperature PLA. 

Bottom Line

I love my 1st Gen Cube.  It is a real workhorse.  And, I am not planning to give it a moment's rest even though I now have a 2nd Gen Cube.  But, clearly 3D Systems has made some significant advances in accuracy and speed in just one new design cycle.  

I certainly understand that some 1st Generation Cube owners might be disappointed to know that an improved machine was released just after they purchased their Cube.  But, while I have to recognize that the 2nd Gen Cube is a better 3D printer, it still does not lessen my appreciation of my 1st Gen Cube.  Nor is the 2nd Gen Cube going to take away any of the workload I had planned for my 1st Generation Cube.  Of the thousands and thousands of things that can be printed on a 3D printer, only a small handful require such tight tolerances that having one version or the other will make a difference.

My granddaughters want me to print an owl for them.  It's not going to make one bit of difference whether it's printed on a 1st Gen Cube or a 2nd Gen Cube. 

I'm very impressed by the direction that the Cube is going.  I hope that you feel the exact same way... no matter which Cube you now have.