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Thread: Drag Knifes

  1. #1
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    Drag Knifes

    Been looking at the Donek D4 Drag knife, does it have some sort of pressure adjustment setting or spring pressure inside? Seems to be extremely overpriced considering I built a smaller one for cutting vinyl when I had my CNC plasma cutter years ago for less than $40 that used commercial replaceable vinyl knives.
    Retired Guy- Central Iowa. , LightObject 40w CO2 Laser and Chiller, Fine Line Automation 4x4 CNC Router- Mach4 ESS

  2. #2
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    I have the Donek and it's pretty well designed. I'll admit that haven't use it yet to cut...too many other distractions. A drag knife is a bit different than a diamond drag. The latter is spring loaded and designed for engraving. With the drag knife, depth of cut comes into play since you can cutter materials of different thickness. What software you use will impact how to set things up, but for example, Vectric software has provisions for a drag knife so that the corners are handled correctly as well as the off-set of the tip from spindle center, and one must also use a post processor that does NOT turn on the router/spindle for obvious reasons. Tool length is of the same importance as any other cutting tool since it impacts the calculation for "how deep", whether you are measuring from top of material or top of spoilboard. As to the actual knife...it's a utility knife blade.

    There's another kind of knife setup called a tangential knife. I'm not really familiar with that.
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    The most expensive tool is the one you buy "cheaply" and often...

  3. #3
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    Thanks Jim, I use VCarve and it has a Gadget for a drag knife. Is there any king of spring or pressure adjustment for down cutting pressure? The one I made for vinyl I had a spring inside.
    Retired Guy- Central Iowa. , LightObject 40w CO2 Laser and Chiller, Fine Line Automation 4x4 CNC Router- Mach4 ESS

  4. #4
    No, there is no spring on the Donek. I have used mine quite a bit. Mostly for cardboard (~1/16" or so), some veneer, etc. I didn't have real good luck with it for vinyl, but I don't think it was really meant for that anyway. I made a holder for a vinyl cutter (ebay $10 - CB09) and it cuts vinyl pretty well. The cutter is on a linear slide and I can add weights if needed. Same as a spring, but I just adjust the weights. I've used it a lot for cutting stickers and stencils. The Donek is a bit pricey, but it is very well made and it will cut through some pretty tough material. I was really surprised at how well it cut veneer. I did some inlay with it just playing around and it actually looked pretty darn good (kinda like their video).

    Tony

  5. #5
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    There is a Donek on eBay he claims its new and there is someone else selling his version of a shop build one for $80 that looks to be well done. Thanks to both of you for the replies.
    Retired Guy- Central Iowa. , LightObject 40w CO2 Laser and Chiller, Fine Line Automation 4x4 CNC Router- Mach4 ESS

  6. #6
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    Donek has a YouTube video that shows how he cuts vinyl with it...I think the supporting structure he shows is likely why it's working well for him. I have to revisit that at some point because that's the primary reason I bought the knife, taking advantage of a sale at the time. Note that the model number denotes the depth of cut the particular knife is designed for...there are two max thicknesses supported. You can cross reference the model numbers at the Donek site. I believe there are links to his videos, too.
    Last edited by Jim Becker; 12-06-2019 at 10:59 AM.
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    The most expensive tool is the one you buy "cheaply" and often...

  7. #7
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    I just purchased the new D4 never used off eBay. What I am going to do is I have a nice border collie PDF file I am having printed on vinyl and I will cut out the design with the drag knife and also use my router to cut the outline out of 1/4 plywood. Glue vinyl to plywood and its part of the Christmas display outside. Watching over the sheep while the Shepards have a visit to make in town .
    Retired Guy- Central Iowa. , LightObject 40w CO2 Laser and Chiller, Fine Line Automation 4x4 CNC Router- Mach4 ESS

  8. #8
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    Quote Originally Posted by Jim Becker View Post
    Donek has a YouTube video that shows how he cuts vinyl with it...IDonek site. I believe there are links to his videos, too.
    By the way, it’s a very nice lady named Jennifer who designed the knife and runs Donek, even though a male (I believe her husband) narrates the videos.
    Last edited by Richard Gonzalez; 12-10-2019 at 10:33 AM.
    Colorado Woodworkers Guild
    Colorado CNC User Group

  9. #9
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    Quote Originally Posted by Richard Gonzalez View Post
    By the way, it’s a very nice lady named Jennifer who designed the knife and runs Donek.
    Well the one I purchased off an eBay seller as new came yesterday…. and the bearings feel like they are dry or have no lube when turned??? The seller will take back in spite of a no RETURNs posted in the ad. So I am thinking he knew the condition when he sold. ?? I contacted Donek via email but no response yet.
    Retired Guy- Central Iowa. , LightObject 40w CO2 Laser and Chiller, Fine Line Automation 4x4 CNC Router- Mach4 ESS

  10. #10
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    Should...and needs...to operate very smoothly, Bill. Send it back if it's not right and the seller will take it back.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  11. #11
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    Quote Originally Posted by Jim Becker View Post
    Should...and needs...to operate very smoothly, Bill. Send it back if it's not right and the seller will take it back.
    The Seller in spite of his NO RETURNs (will) took it back after I filed a claim with eBay. No questions asked…. I suspect he knew it was bad when he listed. The owner of Donek said she would fix it for free if I sent it back. She also said the 1/2 inch shank ones had a lot of issues with the bearings. But standing behind your product is what counts.
    Last edited by Bill George; 12-10-2019 at 8:28 PM.
    Retired Guy- Central Iowa. , LightObject 40w CO2 Laser and Chiller, Fine Line Automation 4x4 CNC Router- Mach4 ESS

  12. #12
    Uh oh. I hope mine doesn't have that issue! So far, so good.

    Sorry you had a bad experience. I bought mine from Donek (well, Santa did) and I haven't had any issues with it. Actually, quite impressed with it. I used my other drag knife today. I'm experimenting with using Oracal 631 as a template for painting. It worked quite well. The Donek just didn't work as well with the fine detail I was looking for out of the various vinyl products I use.

    One tip is to pay attention to the start points and the direction of cut. You want the drag knife to be pointing the correct direction when it starts. I use Vcarve and it allows you to manipulate the start points. For a detailed design, it can take a while, but it does make a difference. Especially when cutting small stuff. Also, I learned that cutting very slowly helps. Cut quality can be improved by messing around with the offset and the swivel height. You probably already knew all that since you are not a drag knife virgin, but just in case...

    Tis the season....the Donek is great for making custom boxes! You can even make slight cuts for bending lines. I made a small vac table to hold things too. That works good sometimes. I've cut cork, felt, veneer, etc. Great for making templates for furniture too.

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