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Thread: CNC Drag Knife

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Old 12-06-2012, 11:52 AM   #1
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Default CNC Drag Knife

This may not be of use to many, but I thought someone might find it interesting.

I've wanted a CNC Drag Knife for quite awhile. I figured it would come in handy for cutting thin plastic and paint masks on my mill. Most I've seen are in the $100 range, and the replacement blades are about $15.

Then I found this website and thought this was just what I wanted. Something a bit heavier for cutting thicker materials with an inexpensive blade:

Drag Knifer for CNC routerDonek Tools

Unfortunately he wants $230 for one . I searched around and found this forum where someone made their own (scroll down a bit for a picture of what I found for inspiration):

Vectric Forum • View topic - Knives to cut foam core board?

I fired up the Prototrak during lunch and made one for myself. I wanted the blade at 60 degrees, so mine is a bit different. I'll be trying it out over the weekend. Most are spring loaded and use ball bearings, but mine does not. I'm not worried about the spring too much, and I can unhook my motor from my spindle and it turns freely.:

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Old 12-06-2012, 05:29 PM   #2
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Default Re: CNC Drag Knife

so it's sorta like a plotter cutter? When I worked at Middle River Aircraft Systems, they had a CNC plotter for cutting the pre-preg carbon fiber. the cutting blade looked like a HD exacto knife.

Nice work on the machining.
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Old 12-06-2012, 07:22 PM   #3
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Default Re: CNC Drag Knife

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so it's sorta like a plotter cutter?
Pretty much the same idea. I've been wanting to cut thicker styrene with a consistent result, so I decided on doing it on the mill. The girlfriend is gone for the weekend, so I have a bit of time to play downstairs.
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Old 12-07-2012, 11:50 AM   #4
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Default Re: CNC Drag Knife

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Pretty much the same idea. I've been wanting to cut thicker styrene with a consistent result, so I decided on doing it on the mill.


I've wanted to build some type of cutting rig that was based on an old drafting table, something with guides for the X and Y movement.
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Old 12-07-2012, 01:20 PM   #5
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Default Re: CNC Drag Knife

Whats the spindle speed on that puppy?
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Old 12-07-2012, 01:50 PM   #6
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Default Re: CNC Drag Knife

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Whats the spindle speed on that puppy?

Zero
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Old 12-07-2012, 01:52 PM   #7
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Default Re: CNC Drag Knife

Well that's no fun at all.


That is a pretty nifty idea though. I might have to make one too. What gets placed underneath the material you are cutting?
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Old 12-07-2012, 02:01 PM   #8
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Default Re: CNC Drag Knife

I'll probably use a large sheet of plastic. I've seen some people use wood or laminate. As long as it's flat, it should work.
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Old 12-07-2012, 02:02 PM   #9
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Default Re: CNC Drag Knife

Oh that's sweet, I used to have a sticker cutting machine that had a miniature version of yours.
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Old 11-25-2013, 04:10 AM   #10
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Default Re: CNC Drag Knife

Quote:
Originally Posted by C*H*U*D View Post
This may not be of use to many, but I thought someone might find it interesting.

I've wanted a CNC Drag Knife for quite awhile. I figured it would come in handy for cutting thin plastic and paint masks on my mill. Most I've seen are in the $100 range, and the replacement blades are about $15.

Then I found this website and thought this was just what I wanted. Something a bit heavier for cutting thicker materials with an inexpensive blade:

Drag Knifer for CNC routerDonek Tools

Unfortunately he wants $230 for one . I searched around and found this forum where someone made their own (scroll down a bit for a picture of what I found for inspiration):

Vectric Forum • View topic - Knives to cut foam core board?

I fired up the Prototrak during lunch and made one for myself. I wanted the blade at 60 degrees, so mine is a bit different. I'll be trying it out over the weekend. Most are spring loaded and use ball bearings, but mine does not. I'm not worried about the spring too much, and I can unhook my motor from my spindle and it turns freely.:

I too need a Dragknife and I too found the Donek item but living in the UK there is shipping costs and import tax AND Value Added Tax!!!! so I need to find a solution like you have. How did it work out?
Thanks
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Old 04-19-2014, 07:56 PM   #11
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Question Re: CNC Drag Knife

can this knife be used for engraving on brass ?
thank you
Richard Westerfield
richwest70@gmail.com
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Old 04-19-2014, 11:53 PM   #12
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Default Re: CNC Drag Knife

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can this knife be used for engraving on brass ?
No. The knife does not have an rpm and cannot achieve the cutting mechanics of engraving.

You will need this
Anatomy of an Engraving Cutter
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Old 04-20-2014, 08:02 AM   #13
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Default Re: CNC Drag Knife

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Originally Posted by wings_of_fire View Post
No. The knife does not have an rpm and cannot achieve the cutting mechanics of engraving.

You will need this
Anatomy of an Engraving Cutter
Correct. This is designed to be dragged along with the blade cutting the material...much like the wheels of a shopping cart follows the direction you push it in.

They also have spring loaded, diamond point engraving tools like this:

Diamond Drag Engraving Bit for CNC Machines - Use Your CNC Machine to Engrave Metal, Plastic, Glass, and Granite - WidgetWorks Unlimited
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Old 04-21-2014, 03:27 AM   #14
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Default Re: CNC Drag Knife

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Never used or herd about diamond drag engraving until now. That is nice.Thanks, learnt something new
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