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View Full Version : Drag Knife anyone?



JoeHarris
15-08-2012, 01:10 AM
Has anyone made themselves anything like this - Donek Tools (http://donektools.com/) ??

I would like to make one eventually as 189 USD seems a bit steep...

boldford
15-08-2012, 10:20 AM
Has anyone made themselves anything like this - Donek Tools (http://donektools.com/) ??

I would like to make one eventually as 189 USD seems a bit steep...
I agree they do seem expensive. I wouldn't have thought a similar gidget would be too hard to make. The only area needing a decent amount of care is to ensure the blade bisects the collet x-axis and the tip of the blade is very slightly behind the y-axis IYKWIM.

John S
15-08-2012, 10:46 AM
Watching the cardboard box video and notice that on every direction change it has to lift Z then plunge down again.
Is that necessary and if so it's a lot of messing programming these moves. I don't know anything about these but after seeing a vinyl cutter doing the signs for my new van it seemed to be a lot faster than this and continuous. Perhaps a search on the Zone is in order ?

Web Goblin
15-08-2012, 02:45 PM
What about one of these cut down?
Xcelite XN-200 Medium-Duty Craft Knife | UKToolCentre.co.uk (http://www.uktoolcentre.co.uk/Shop/p~43308~XN~200-Medium~Duty-Craft-Knife.html?utm_campaign=googleshopping&utm_source=GoogleBase&utm_medium=Product+Search&gclid=CLaRmMHU6bECFY8mtAodIC8ATg)

JoeHarris
15-08-2012, 09:18 PM
What about one of these cut down?
Xcelite XN-200 Medium-Duty Craft Knife | UKToolCentre.co.uk (http://www.uktoolcentre.co.uk/Shop/p~43308~XN~200-Medium~Duty-Craft-Knife.html?utm_campaign=googleshopping&utm_source=GoogleBase&utm_medium=Product+Search&gclid=CLaRmMHU6bECFY8mtAodIC8ATg)

It would need some kind of bearing to allow it to rotate freely.

John I know what you mean about the z movements but if you want to cut card and leather a vinyl cutter isn't going to be up to it?

BikerAfloat
15-08-2012, 10:52 PM
Hi Joe,

That's damn expensive!

Seen it done on plenty of sites, but thought I'd not need it, so didn't save them... Doh! Having said that the Tweakie pages have images of vinyl cutting - can't remeber if he details the design or not :-(

Tweakie.CNC - Vinyl Cutting (http://www.cooperman.talktalk.net/files/8.htm)

From what I remeber of other sites, they use a standard vinyl cutter blade (or sometimes Blade & holder) in a tube with ball bearings to allow it to pivot, the shape of the blade forms the castor. Should be no need to lift of, I pretty sure the vinyls cutters I've seen didn't

Cheers,
Geoff

boldford
15-08-2012, 11:48 PM
. . .Should be no need to lift of, I pretty sure the vinyls cutters I've seen didn't

Cheers,
GeoffI think you are right in that the vinyl cutters don't lift off. With thicker materials and a blade at a shearing angle I think not to lift would mar the material surface.

John S
15-08-2012, 11:55 PM
Yes I can see this but must be a pain to program as each entity has to be cut as an open line so it lifts off [ Z clearance ] at the end of each cut.
But if it does lift, then plunge down to do a cut at say 90 degrees to the first, how does the blade move round if it's just a swivel ?

Did a search on Ebay and you can get a simple tubular knife from the states with shipping for 115.

Cut Sign Vinyl - Drag Knife Bit for CNC Router End Mill | eBay (http://www.ebay.co.uk/itm/Cut-Sign-Vinyl-Drag-Knife-Bit-for-CNC-Router-End-Mill-/230323725652)

Marchant Dice sells the same item for 200

boldford
16-08-2012, 09:37 AM
Yes I can see this but must be a pain to program as each entity has to be cut as an open line so it lifts off [ Z clearance ] at the end of each cut.
But if it does lift, then plunge down to do a cut at say 90 degrees to the first, how does the blade move round if it's just a swivel ?. . . .I haven't any idea how the blade moves round either; however another thing that puzzles me is the very act of lifting off with thicker material combined with the shearing blade angle must leave a small triangular section of uncut material.
Could it be cutting from the ends of each line to the middle?
The device itself isn't too complicated to make but its use may well be far more involved than we think.

Any thoughts?

BikerAfloat
16-08-2012, 09:40 AM
I looked at the videos on Donek tools site again, the knife is still in contact when the machive changes direction, just with a very much reduced DOC, the castor on the blade still has to have some resisitance to operate. Has to be a pain to code!

An eBay search for "Roland Blade Holder" turns up plenty of vinyl cutter holders, not sure if these have the bearings in them, or if the bearings are in the part of the machine that holds them, for the money (7ish upwards) though, they'd be worth a look at least as a basis for thin material.

Still trying to find the links I had for other drag knifes, I must learn to be more organised!

boldford
16-08-2012, 09:44 AM
I looked at the videos on Donek tools site again, the knife is still in contact when the machive changes direction, just with a very much reduced DOC, the castor on the blade still has to have some resisitance to operate. Has to be a pain to code! . . . . . . .Agreed; but that still doesn't completely answer my question about the triangular residue of material.

BikerAfloat
16-08-2012, 12:44 PM
No idea about the triangle bits left over :-(

Here's a diy build: Build Your Tools • View topic - DIY Stencil Cutting Drag Knife Solution - Update 5! (http://www.buildyourtools.com/phpBB3/viewtopic.php?f=8&t=944)

Rockcliff do a holder for $70 here: Rockcliff CNC Machine Inc. (http://www.rockcliffmachine.com/index.php?cPath=25&osCsid=llkq4bq250qlvqv6esbe4jjbu7)

Here's an article from the Rockcliff forum aparently Mach 3 has a tangential knife routine for motor driven blades that does all the lifting and dropping and turning: tangential knife cutting Styrene - CNC Machine Builders ROCKCLIFF Forum, Register it's free (http://www.rockcliffmachine.com/forum/showthread.php?t=440)

Hope these help.

Musht
17-08-2012, 12:52 AM
Drag knife is what a vinyl cutting plotter uses, but material thickness is fractions of mm up to a couple mm mebbe thick, blade just turns around on bearings in its holder, Z is solenoid up / down.
Though plotter makers seem to have no problem with high res USB to stepper interfaces.....

For things with some thickness like foamcore and correx, its CNC with an oscillating knife , drag knife wont go to multiple mm in stiffer materials, which is partly where I started looking at CNC

COMAGRAV oscillating tangential knife (http://www.comagrav.com/oscillating_tangential_knife.html)

For the sort of cash for a drag knife gadget, if you want to cut vinyl not far off a whole cheap plotter for similar cash.

graffian
18-08-2012, 03:15 AM
An eBay search for "Roland Blade Holder" turns up plenty of vinyl cutter holders, not sure if these have the bearings in them, or if the bearings are in the part of the machine that holds them, for the money (7ish upwards) though, they'd be worth a look at least as a basis for thin material.


I have a Roland knife in front of me, I got an old HP plotter off freecycle, to cut the masking for the letters for my number plate[how lazy is that]
I was pleased when I opened the cover of the pen holder to find it had a blade thingie. The bloke told me it was a "Roland knife". The blade is
mounted in a bearing, but it doesn't look like the point of the blade is on the axis of the body! Dragging it around on my thumb[doesn't seem
very sharp] the blade seems to self centre really well, so it turns and is always pointing in the right direction.
I haven't yet tried the thing, only had it about a year;-)
I actually want it in the next few weeks to cut all the masks for some lettering, I can't afford vinyl sticker sets.

Jonathan
18-08-2012, 12:01 PM
Had a small vinyl cutter at school...had some fun making 'test stickers' when they got it :wink:


The blade is
mounted in a bearing, but it doesn't look like the point of the blade is on the axis of the body! Dragging it around on my thumb [...] it turns and is always pointing in the right direction.

The blade will be offset slightly from the axis since that will create a turning force which will tend to rotate the blade into the correct orientation for current cutting direction.

Musht
18-08-2012, 01:54 PM
Should have said Z axis on a cutter actually has downforce adjustment , rather than just up down, allows for cutting vinyl without going right through its backing sheet,

donek
27-08-2012, 04:10 PM
Glad to see our tool is getting some discussion here. I thought I would take a moment to address some of the topics being discussed.

There are a number of vinyl cutting tools available, but they are not typically effective at cutting materials thicker than vinyl. Our tool is capable of cutting to a depth of 6.4mm without tearing your materials. It is being used successfully to cut veneer, leather, cardboard, gaskets, and many plastics ranging in thickness from 1.2mm to 6.4mm. The corner operations can be tricky to program, but we are working on a couple of different programs to facilitate programming the actions with a mouse click. Most objects being cut do not ever require sharp corners, so this is not typically a problem. There is a small amount of material left in corners. This is not typically a problem when separating the parts. swapping parts in veneers and other inlay applications is no problem as the tool has such a small kirf. Unlike laser cut veneers or routered inlays, it is no longer necessary to throw away half the material being cut. If you cut a dark and a light part and swap pieces, you retain two usable parts rather than only one.

There are other competing products on the market capable of doing similar things. Tangential knife products using a motor to orient the blade for cutting in the correct direction are an excellent solution, but tend to be cost prohibitive for the average user. These devices when purchased from other manufacturers typically start at $5000 US and go up very quickly. They require specialized programming and driver software capable of controlling a 4th axis in tandem with the usual 3. This tool is completely passive and accessible to anyone with a cnc router. It simply chucks into your existing 1/2in collet (we have a 1/4in tool in development). Our tool uses a specific,yet standardized blade that is accessible to anyone making the long term operation far less expensive than tools requiring $25 blades. Sorry about the US currency.

We are patent pending on this technology. The duplication of it is actually much more tricky than one might think. There are very important things that come into play in the proper function of this tool. Simply going out and trying to make one might yield some usable results, but to get the results possible with this tool would require a lot of attempts. This tool has undergone a great deal of development. Versions of this tool have over 11 years of use in production in our snowboard production as well as other snowboard manufacturing facilities.

JoeHarris
08-10-2012, 09:03 PM
Thanks donek for the reply. When I finally get my machine built you may have yourself a UK customer!!

donek
08-10-2012, 11:43 PM
Thanks donek for the reply. When I finally get my machine built you may have yourself a UK customer!!

There are a number of guys in the UK with them already. There's even a guy cutting prepreg carbon fiber laminates for race car parts. Let me know if you have any questions. We've added some nice free software tools on the web site for making it even easier to program.