New Drag Knife

[Cosmos275]

Got a new one out.

About half the price of the leading brand and some cool features of it's own. Unique construction with single piece solid AL body, 2 double sealed bearing. It uses #19 Heavy Duty X-Acto blades which are the same thickness as utility blades (.025") and inexpensive (couple bucks for a 5 pk.). Blade change is easy and blade is located into position with dowels.

Cuts 1/8" material, offset is 3.0 (~1/8")

drag_knife.JPG

Up on my website: http://cosmos-industrial.com/index.p...products_id=20

You Tube video: https://youtu.be/GN1rOmmPcW8

[Thomas Cook]

What's the min radius your able to achieve with this design? Great price so I'm pretty interested.

[gundog]

Looks like a nice design.

[Burkhardt]

Looks good. What I did not see in the video was if the knife is somehow spring loaded or if it is fixed height.

[coryatjohn]

It's probably fixed height. I don't see what good a spring loaded version would be. The height is at the table and anything it runs across (up to .125") is sliced. If it had a spring loaded action, it wouldn't penetrate all the way through the material to be cut.

[myxpykalix]

If anyone buys this i hope you would give us a report on it's quality

[Cosmos275]

Sorry for the delay... auto emails not coming in.

The offset is 3.0mm which is also then the max material and your min radius.

Vectic VCarve Pro and Aspire has a gadget for programming drag knife toolpaths which can do some interesting stuff to optimize the moves.

I picked an offset of 3.0mm (~1/8") as I thought it would cover most needs. I can make one with a smaller offset if you want. I can also modify the design so you can tweak the blade position. Right now, it goes right in to the one position with little wiggle room. I could add wiggle room, but you'd have to pay more attention when setting it up.

Thanks for your interest.

[Cosmos275]

It is fixed height. You want a flat spoilboard under what you're cutting.

I've actually designed up a spring loaded version for a company that makes boat covers. Their machine table are 20-30' long, so they need it to track with the table height. It adds length, which in their case isn't an issue, but probably would be on a CNC router.

Also, if you spring load it, it may go deeper than you want. If you go past the max thickness, it won't corner right or at all.

[919RickR]

Is there any special software needed? What is the smallest radius that it will cut
I watched the videos and on web site no specifics were mentioned about this tool.
I'm interested also
Rick

[Cosmos275]

More thoughts on the design:

For drag knives that are made for use with utility or X-Acto blades (most of them), there are a few defining features:

1. bearing for spin (some would argue the spindle bearing may be enough, but why chance it)
2. blade cutting edge at 45 degrees
3. distance of blade support from tip
4. rigidity of overall device.
5. offset (dictates material thickness and min radius as well)

My design is the same as all the other on #1 and #2. I’m using an X-Acto blade as they are inexpensive and the tip geometry doesn’t vary with many different brands like utility blades.

#3 and #4 are where all the design is and what makes mine different.

On #3, I have the solid AL body taper out to 4.0mm from the tip, so the blade is very well supported. This is important such that when cornering, the device spins instead of just bending the blade.

On #4, I have a solid AL one-piece body design and the blade is locked into position with 2 bolts. It is very solid and there is no play whatsoever.

#5 is just a choice. Because the blade angle is 45 degrees, if you cut more material than your offset, then try to corner, the leading edge of the cutter will have to go backwards to make the corner, hence this is your limit. I picked a middle of the road value, but as I mentioned, I can work with you if you want something different. There are tradeoffs. A smaller offset will allow more intricate work, but mean thinner material and probably means going slower too. My video is very fast (even before speeding up the film) but I’m only cutting card stock.