Sunday, August 29, 2010

Tab Density Explored

Since the eCraft does not use a mat to hold the paper and cut shape in place it needed to have something to stabilize the cut shape while being cut from the base paper.  The designers turned to something they called "Tabs" which are little uncut portions of the shape path that form a bridge between the shape and the base paper from which it is cut.

In an earlier video, we saw that the way the tabs are formed is that the blade of the eCraft is lifted from the material being cut for a split second by the Blade Solenoid.  This action is what causes the clicking sound we hear as the eCraft cuts.


There are two settings that we can use to control the way the tabs are created.  The first of these is the Tab Density.  We've already seen, in an earlier article how we set Tab Density.  Now we will turn our attention to how it behaves while cutting and if it has any significant impact on the quality of the cut.

The first thing we need to know is that Tab Density is only going to be effective with larger shapes.

Tab Density adjusts the distance between tabs.  In smaller pieces, there is little to gain by increasing the number of tabs.  So, it seems to ignore Tab Density in smaller shapes.  Consider this image:

Click on Image for Full Size

This flower was cut at a size of 3" twice.  The first time the Tab Density was set to 1 and the second time the Tab Density was set to 2.  Yet, the number of actual tabs on both is exactly the same, 12 Tabs.  The reason is that the firmware of the eCraft probably knows that the image is so small that putting more tab connectors in place would be a waste of effort and just make the piece hard to extract.

But, does the density behave differently as we begin to cut bigger shapes?  In this next image, we have cut the flower at a size of 5" with a Tab density of 1 and a Tab Width of 3.  This results in 24 tabs.  Notice that the tab density naturally increased to twice the number used for 3".

Click on Image for Full Size

Now, look at this same flower that was printed with a Tab Density of 2 and a size of 5".  A higher tab density appears to have made very little difference.  In fact, the Tab count only increased by a single extra Tab.

Click on Image for Full Size

This is not all that significant a change.  This leads us to question if it's worth bothering with changing the Tab Density at all.  The best way to test this is to try even larger shapes.  And, this time, we will set the Tab Width to 1.  Perhaps the eCraft's firmware first looks at Tab Width and determines if it's going to apply Tab Density based on width.

In this image the size of the cut is 7", the Tab Density is set to 1 and Tab Width is set to 1.  It's interesting that both the 5" shape and the 7" shape, with a Tab Density of 1, produced 24 tabs.  This would lead us to believe that Tab Width probably was NOT a factor.

Click on Image for Full Size

So, now the big test.  Let's look at a 7" Flower Shape cut with a Tab Density of  2 and a Tab Width of 1.

Click on Image for Full Size

The number of Tab produced jumped from 24 to 33.  So, it is obvious that the effect that the Tab Density Setting is going to have is largely dependent on the size of the cut shape.  But, is it all that much more effective?  I'm not so sure.  There seems to be a random aspect to the placement of the additional tabs, at least in this shape, that renders at least some of the added tabs marginally effective.  At the bottom of the image we have two Tabs very close together and the same is true at the far right about 3/4 down.

My conclusion is that unless a piece fails at a Tab Density of 1, I'm no longer going to bother with a Tab Density of 2.  I might change my mind on 11" shapes.  But, it seems to me that shapes at that size face much less stress from tight corner cuts.  Tab Density just does not seem to be all that significant to me based on these limited tests.  Will see if that assessment holds up in real world projects.


Cutting the Flower shape at a size of 7" resulted in an interesting artifact.  The closing cut along the path was slightly offset from the starting cut of the path.  I don't know if this is a path issue or a firmware issue.  But, you can see it at the very top petal of both 7" flowers.  It easiest to see by clicking on the image twice.  The second click will bring up the largest version available.


Denise O'Connor said...

This is a great discovery Tom! I never would have thought to look at this, but it makes a lot of sense! Again, your way of looking at things amazes me!

Tom Meeks said...

That's because I have no choice but to look at from a different direction than all of you with real artistic skills! LOL!

I was a bit surprised. I expected it to just evenly distribute more tabs. But, it seems more random than that.

Anonymous said...

Okay, so we have an issue with our ecraft! The blade trolley doesn't move to the right!! Not to cut and not with the button?!?!? Any suggestions.


Tom Meeks said...

That's definitely a bummer!

I'm sure you are frustrated. That doesn't sound like any fun at all.

Is it a new eCraft or one that you have been using for a while?

In any case, I'll try to take a look to see if I can spot any potential problems in the design.