Vinyl Cutting Blade

[atanguay]

Hi All-

In the interest of getting my shapeoko to be versatile, I've been toying with the of adding one of these blades from a hobby cutter as a 'spindle'.
Here's the one I'm thinking of trying to spring load...

http://www.amazon.com/Cricut-Deep-Cut-B ... d_sim_ac_6

We have this machine here at home, and while it is handy, it's designed to NOT let you use your own shapes. Which is pretty lame. But it cuts paper, vinyl, fabric, and card stock very well. Any thoughts on getting this to work? I'm thinking it will.

Here's one trick we picked up using this thing. To keep your work item down while cutting, this spray product sort of turns a surface into a big 'Post-it'...tacky but not sticky. So in this instance, you could coat something like a paper cutting rubber sheet with this stuff, and put your paper on that. Secure that down, then cut away.

http://www.amazon.com/Krylon-2-Ounce-Re ... B000A8AYO4
http://www.amazon.com/X-Acto-X7761-Self ... B0013CKM2A

FWIW

[alpha]

I would go with a professional blade: http://www.uscutter.com/Replacement-Blade-Pack-3-60-degree-and-3-45-degree-blades-GEBLADEPACK

The size of the ShapeOko is a lot less than letter size... I was thinking it would be nice too to add a knife and see how it works, but most vinyl cutting is done with 24" by some feet or larger cutters.

I do own also a hobby cutter, a Silhouette SD and I'm the coauthor of a open source program to make this plotter work (under Linux, but should work under other OS too) with any SVG file you have: https://launchpad.net/robocut

[lasershark1]

I own a vinyl shop - your best bet is to get a blade holder on ebay (search roland blade holder) - they ship from china for about $10 each, and then get some Clean Cut Blades - best blades out there (cleancutblade.com). I've used one, daily, for a year, and its still sharp.

You'l have two issues to take into account however. Pressure is one... the shapeoko has no real pressure setting. Its not just a matter of distance down, its a matter of how much pressure you're applying. Maybe mount the blade holder with a spring so that once the Z is down, the spring pressure keeps the blade into the substrate?

Second is offset. Blades spin in those holders. Say your shapeoko it cutting "north", then the head picks up. The blade will be facing north.

You then move, and go to cut a line going "west". The blade is still facing north. The tip will enter the substrate a fraction of an inch "south" of your cut, and the end of the line will have a small curve to it as you start moving "west" and the blade corrects itself.

Pro cutters take this into account, it's called offset - it's how far the tip of the blade is from the center of the blade and how much the machine needs to correct for it. Its not really an issue for large shapes, but small, complex shapes will be nearly unusable unless the offset it correct.

Here's a really bad MS paint illustration of what that cut would look like:

[atanguay]

Great info. I see what you're saying about the Pro blade.

I took the blade out of the Cricuit machine and the blade seems to be allowed to pivot, so hopefully that handled keeping the blade facing the cutting direction.

I will try make a mount with a spring too, to keep some downward pressure going. Makes sense.

[JimHung]

This is really interesting reading - I'd like to give vinyl/paper cutting a go with my ShapeOko at some point in the future. Does anyone know of a CAM program that will generate GRBL-friendly G-Code with tangential emulation/support for drag knife offsets?

Jim

[T4b]

I don't exactly understand the point of this, wouldn't it be way easier to just use a thin milling bit (square end, like 0.4mm cutting diameter)? Or for thin paper an engraving bit?

Probably there is a good reason not to do that, but I can't think of one...

[cvoinescu]

Vinyl is soft, so it may not mill cleanly. With a knife, you can get sharp inner corners too. Milling would be difficult to adjust to mill just the vinyl and not the backing paper; the blades are spring-loaded so they self-adjust to minor unevenness of the surface. Put simply, the blade is the right tool for the job.

[jluther]

Does anyone have any designs for mounting a roland blade holder like the one mentioned? I've been thinking it needs to be a tension spring (no idea what k factor here) that is attached to the blade holder (probably using 2 part epoxy...). Then the blade holder rides in a tube allowing pressure to be adjusted. Then the tube gets bolted (or rubber banded, 300mph taped, duck taped... definitely not scotch taped...) to the shapeoko Z-axis... Any thoughts guys?

Although rubber banding the holder to the Z-axis probably removes the requirement of a fancy holder and a spring for a couple cents and a single touch off, as long as the proper rubber bands can be found...

[cvoinescu]

I believe you can buy the whole holder for not a lot on eBay, spring and all.

[jluther]

Well I was able to get a holder like this one for $10 http://www.ebay.com/itm/New-Blade-Holde ... 230da74cce
The problem that I have is the blade sticks in there and has no pressure adjustment (that I can tell). I could mount the holder to the Z-axis no problem but I'd like to be able to adjust the Z-pressure to (hopefully) help with not cutting the backing material on thin films.

So right now I have a PVC fitting that constrains the holder shown above, and a spring that I'm going to rig into a PVC pipe with the fitting so that when the knife contacts the film, lowering the Z further compresses the spring and allows an adjustable pressure on the film. The PVC pipe will be mounted rigid to the z-axis makerslide then.

or maybe I'm overthinking this...