How to homebrew a drag knife for vinyl cutting

[abasir]

Anyone has quick tips on how to make a drag knife to cut vinyl for signmaking? I intend to use hobby knife (pen-like) mounted through normal bearings and slightly spring loaded. Must the knife tip be in exact center of rotation?

Any special software required to ensure proper cut direction?

Regards,

[E-Stop]

I would think it would be best if the knife were in the center. That makes all the calculations a bit eaiser. The knife you plan on using, is it able to cut in all directions? Kinda like a diamond point or etching pencil? When I think of hobby knife I think of an X-acto type with a razor blade in it. So cutting in any direction would mean rotating the spindle to orient to the cut. Just wondering how you do that.

[WOODKNACK]

I may be wrong but say youhad like an exacto knife set up but the blade swiveled by itself. Everytime the machine would move right or left the blade would just follow it. would that work?

[Laff Riot]

Are you planning on using a flat CNC platen or a friction feed gripper system like most vinyl plotters?

Different vinyl types require different depths, an intermediate vinyl is usually 3.2 mil and uses 210 grams of force for a clean cut without cutting the liner. Premiums - 2 mil - 140 gf. Make sure you have a micro adjustment feature that you can set and forget.

I have seen the roto-x-acto which is made by x-acto mounted to a cnc machine. I would be kinda wary cutting anything smaller than .75" or so. The vinyls require a really clean cut on the corners to weed cleanly. Using software that slows down into the corner will help out a lot.

I would suggest buying an adjustable head from a plotter repair / supplier. The last one I priced out... I think... was around 50 US. dollar. Build a clip in holder on your router settup and your set.

Another idea for anyone that self produces small graphics is to buy cutoffs of printable vinyl. Run it through your inkjet printer, clear coat it with UV stabilizer, cold laminate it and then hand contour cut. I use this method to make signs all the time.

[abasir]

E-Stop, no the knife would not cut in all direction (please give me a link if you know one .

Laff Riot, at US50 for the holder + US40 for the blades + US40 for shipping to me (across the globe), it would not be economical for my hobby use. Yes, I do plan to use my basic CNC machine for the vinyl work but if a good knife/cutter design can be found, I may find some old printer to scrap

I'm gonna do some more research on this and possible some test over the coming weekend. Most likely gonna be trial and error approach.

[Laff Riot]

ah - i never look at those pesky locations... its an american thing.
I cannot imagine however that you could not locate a local / regional sign shop that could give you the name of their plotter blade supplier. If your that remote I'm wondering how your gonna get the rest of the parts for a CNC machine

E-Stop is correct in that the knife must be floating to cut into the direction of the plot. Swivel knives are rather common for pattern cutting so I am sure we can track down something close enough to you.

http://www.a2zhobbies.com/Xacto/Knives/XAC-3241.html

Keep in mind - the only time I have seen this rigged up - it didnt work all that hot, but I'm used to our production machine - might work great for your needs.

[cbcnc]

Abasir,

Is it possible to purchase a regular swivel knife (XActo style) used for vinyl cutting and rig up a holder for it?
Look at this:
http://www.dickblick.com/zz574/22/pr...m=0&ig_id=2640


Chris

[abasir]

I'll spend some time this weekend to search for the said knife. Most place I went only have the regular type that does not swivel and that's why I was thinking rigging up a holder with some roller bearing.

Also, the tip is not centered around axis of rotation. I'm afraid that when the knife is lifted and move to a new location, the tip rotates thus creating an offset from the intended position.

Thanks for the links. I don't know such swivel knife exist ;o

[Don C]

If you use a drag knife and you must unless you have a motor to turn the blade. you have to figure in the off set of the blade. the image will be short want ever the off set is for every 90 deg.

[Max]

Here is a link to a sign supply company (US) click on the blades & blade holder catagory. There are quite a few brands of blades and holders offered. The standard is Roland ... easy to get replacement blades. I'm sure that Roland is available in most of the world.

http://www.signcatalog.com

A major consideration is the downward force of the blade into the material ... too much will cut through the backing paper.

Here is another link to give you ideas
http://www.aeronautauto.com/pages/consumables.html
Notice the blade holder at the bottom of the page, it also uses the roland blade.

My thoughts on using the Roland blade is that most software has settings for the blade offsets and tangentigal (sp?) movement.

BTW, I have a Roland vinyl cutter and sign making software. The speed it cuts is amazing.

Hope these links give you some ideas

[ballendo]

hello,

Go to www.cuttingedgecnc.com Taus has a whole thread of photos showing how to make a drag-knife for cnc usage...

Hope this helps,

Ballendo

[JPW]

Hello,
You might try this website. I realise that there is a difference between metal and leather. This machine has the ability to steer a knife blade.

Tool Path GCode (Lindsay Engraving, Inc.)

Thanks for listening.