Thursday, March 8, 2012

The eCraft tearing problems revisited

I have watched from the sidelines as the tearing problems persist. 

Yes, there are work arounds.  And, at least some of the problems deal with cutting points that have dulled.  But, the majority of problems are related to a behaviour in the eCraft that causes the paper to be lifted up by the cutter until it is above the cutting edge of the blade.

I know this because I spent a considerable amount of time observing tearing using a high-speed camera to catch the action in slow motion.  And, I sent these videos to eCraft for their engineers to study.  I didn't say anything because I felt a team that could come up with such a wonderful design in all other respects would figure out how to stop the paper lift.   I wanted to give them the time necessary to do so.

Here is a slow motion video that demonstrates exactly what is happening just before your paper rips.   Notice how the blade lifts the paper!


As ripping still seems to be an issue, I am going to do my best to used what I learned in that research to try to see if I can come up with a solution.  All I can do is to promise to try.  And, at long last, I think I have the means to do so, now that I own a 3D Printer with which to experiment.

One of my goals with my new 3D printer is to come up with a solution to the tearing problems if at all possible.  I'm going to attempt to design a foot that holds the paper down as the eCraft cuts, much like the foot on a sewing machine.  I will let you know if the idea works!

Wish me luck for ALL of us!

13 comments:

purplecinn said...

Good luck. I really hope it works! I am getting better at using my ecraft but there are still times when paper rips or gets stuck. It's really maddening when your cutting a bod for example and it's almost done to the end perfect and then bam it's all over lol
Thanks for trying to help us out!

3D Printer Fan Tom Meeks said...

Thanks Purplecinn,

I will be working on it over the next few days.

It's astonishing to me that they have not addressed the issue in some better way.

After all, their whole message is NO MATS.

ilovemyfamily6208 said...

Wow! Thanks for looking into it! I hope you find a solution. I work with fabric a lot and it is rather discouraging when it happpens. I have found with mine that it sometimes happens on my first try then it's fine after that. First try as in, when I do my first cut after the machine has been turned on. Then it works fine.

Tom Meeks said...

I've created some preliminary designs; but, wanted to refine the print on my 3D printer before printing something for others to test. The tolerances for doing what I hope to do are pretty close. So, having a 3D printer that is perfectly aligned is important.

I should be able to try it later this week.

My 3D Printer Users blog ( http://3DPrinterUsers.blogspot.com ) chronicals my efforts at fine tuning the RapMan 3.2 that I will be using for the project.

Joseph Cleary said...

You do not have the knife guard on ! That keeps the paper down against the cutting bar ! What you are doing now is using scissors with only one blade!

Tom Meeks said...

At the time that video was created, it did not matter whether the cover was on or off. In fact, they LATER redesigned the cover, to little effect.

A LOT of time has passed, so they may now have a completely new cover that works.

sue morris said...

I'm so glad I found your blog because I have been having this same problem and it is really upsetting. I can't even use the cutter anymore. I can't afford to waste any more paper. Have you been able to develop anything as of yet?

Gridlock said...

Right now for small printshop paper cutting the best option looks like either making custom cutting dies from metal and using a squish cutter.

Or going with a CO2 laser paper-burning cutter (very expensive, eats up a lot of floor space, requires ventilation).

Blade replacement, image registration, cutting speed, and repeatability of cuts are all crucial issues. With the eCraft the only solutions to the problems of cutting would be in changing the paradigm.

The most obvious choice is a reverse "Air Hockey" mat that suctions the material to be cut to the surface of the cutter. Doing so would require the flat surface of the eCraft to be perforated with many tiny holes and a suction fan to pull the paper to the surface. Downside is that this makes extra noise and no holes can intersect the cutting path of blade. Also there is the problem of controlling fan speed because too much suction on thin materials results in them staying stuck while the rollerbar rips the material apart. You also cannot use a cutting mat with the reverse Air Hockey surface as this would negate the suction effect.

Gridlock said...

Otherwise the alternatives would be a new paradigm in material holding.

Since the cutting blade can only be in one location at a time, then a secondary holding arm could be used with an automatic lift-up & press-down function per cutting arm position.

Think of this like fingertips pressing down onto paper as you cut.

Except for this to work properly, the fingers would have to press & move precisely in synchronization with the rollerbar or you get material bending or ripping.

The easiest form to make would be like a small smooth tank tread roller, but then the problem comes with synchronization. If it free-spins, but simply presses down, then it will be okay for thick materials. For thin materials, you retain the pulling-warp problems with any lag from the free-spin tread.

Another option is to install another grip arm facing inward with another cutting blade. Two cutting heads equals twice the speed. Sort of like this cheapy ASCII diagram.

eCraft cutting arm current.
============= (pressing bar)
[_]
v

eCraft dual cutting arms.
=============
[_]
v

A
[ ]
=============

Gridlock said...

The classic X-Y plotters & cutters use a vacuum table to adhere their materials for short-run cutting jobs.


This one uses dual perpendicular drop-down presser bars, no suction surface, but only does straight cuts.
M1 Plus - X/Y Ultrasonic cutting machine
http://www.youtube.com/watch?v=4ChsyuoDDe4

Vacuum Table Cutting
Pathfinder Automatic Fabric Cutting 2
http://www.youtube.com/watch?v=T4jj__8kvZc

No vacuum table, but using an ultrasonic knife (fast up-down vibrations)
MultiCam 3000 Ultrasonic Knife and Digital Express Drag Knife Demo
http://www.youtube.com/watch?v=DUG3_Fc-rzc

Vacuum table.
Cutting cardboard With The Donek Drag Knife mounted in a Shopbot cnc router
http://www.youtube.com/watch?v=P8jbtRTV6uw

Laser Cutting Paper Materials
(Oh so fast, but oh so expensive)

Laser Cutting Cardboard
http://www.youtube.com/watch?v=qixvtnFN0HA

Artwork From Robot,JD -Laser Engraver, Cut Paper and cardboard
http://www.youtube.com/watch?v=Cc8vXkxM79E

Laser Cut Paper - Intricate Lace Pattern with an Epilog Laser
http://www.youtube.com/watch?v=ZROT0-gdMM8

Laser cutting invitation cards of paper - Laserschneiden von Einladungskarten aus Papier - eurolaser
http://www.youtube.com/watch?v=LUHqhSEiz80

IDI Laser Sei Paper Blaster
http://www.youtube.com/watch?v=0_3o1OiLcO4

Laser paper cutting
http://www.youtube.com/watch?v=zlQe8iFRlsM

Gridlock said...

Ah one more thing.
If you wanted something like a the cloth hold-down "Foot", then you could use a presser "finger" ending in a Ball transfer unit.
However, the problem with these is that once the ball gets dirty (by touching paper) the little fibers will jam it up. You cannot lubricate it in this application because it would mark the paper.

The OMNI WHEEL would be a less cloggy fix, but would also have problems unless a perfectly spherical surface action can be simulated well enough not to cause weird grip points on the paper feed.

http://en.wikipedia.org/wiki/Ball_transfer_unit

Ball transfer units are omni-directional load-bearing spherical balls mounted inside a restraining fixture. They are identical in principle to a ball computer mouse upside-down, or a trackball, except there is an array of them side-by-side. Typically the design involves a single large ball supported by smaller ball bearings.

http://en.wikipedia.org/wiki/Omni_wheel

http://en.wikipedia.org/wiki/Mecanum_wheel

NB's Ball Splines
http://www.youtube.com/watch?v=FnWmnPeNUic

Tom Meeks said...

I read your comments with great interest. Even though I no longer work with the eCraft, I am still interested in eCraft owners having the most satisfying experience with their machines. And, that means reducing tearing. Thanks for your contributions on this topic.

CroppyCat said...

I would be willing to test it for you... I can not afford a new machine and I too am tired of wasting paper. Thanks for al your efforts!