3D CAD (Solidworks) and Knife design (Newbie question)

[Scott M Lewis]

Hello, all.

First post to the forum. Thanks in advance for your help.

I have a license to Solidworks 2013 and want to design knifes (mainly fixed blade and tactical). I am new to blade/knife design. Any online material geared toward blade/knife design and 3D CAD that might be of assistance to someone with my level of experience?

One question concerning the parallels between knife fabrication and knife design: When designing a knife in a 3D CAD program do you approach the design the same as fabricating a knife using stock reduction? Example: In Solidworks, do you first create a x*y*z solid block and then sketch/project features and contour the block into the desired geometry?

Thanks again for any assistance.

 

[NeilJBorja]

I'm only slightly less of a newbie than you Scott but I would think that unless you're doing multiple versions (like if you're having your blade blanks water jet), then I think CAD ends up slowing you down instead of making things faster. I used SolidWorks to design my first (and only) liner lock, but I don't really see why you wouldn't just sketch things out on cardboard for fixed blades. As for having a box around your designs, sure, if your workflow works that way. Usually though you make a design and then order stock right? So wouldn't you just find the dimensions and then order that size steel?

 

[Augus7us]

Hi Scott,

This is an interesting question and something I was thinking about myself recently. I'm also new to knife making so take this as an uneducated opinion. As far as blocking out the knife, you could do that. To me that is more of a modeling preference, I'm trying to find a reason it would help you in grinding a knife out. I've done both grinding and 3d modeling as hobbies and there really are no parallels to sculpting in a 3d app vs grinding metal on a grinder. There could be some benefit if you're planning a complicated knife or folder and want to see which order to grind something or how parts may fit together. This wont eliminate all the problems you may run into but it could be very beneficial, if you're planning something complicated like a hilt made of many pieces and want to view it from all angles first to check the design. Eliminating any potential pitfalls in a 3d model could help avoid a costly mistake.

As far as designing in 3d, absolutely! The most complicated buildings, machines, etc are all designed to exact spec in some sort of 3d program first now days. I don't think it is at all necessary to produce an outstanding knife though. I personally have decided to dust off the 3d app and try it out. I feel that I won't get the most out of it until I undertake more complicated projects and doubt I will design a majority of my knives in it, at least for now. I think it is also a personal preference. If you're the type of guy that likes to rough sketch a design and grind from there finishing details as you go, I don't think it will be as beneficial. If you like to have precise measurements and are constantly checking your work with micrometers and surface gauges then I think it would be very beneficial. There are plenty of both types of makers on this site and both produce amazing knives.

And I have to respectfully disagree with Neil. If you are familiar with the application and hot keys you could design knives much faster in 3d than using rulers and graph paper! Especially if you were to make base model templates for full tang, hidden tang, bowie, or whatever your designing and just modify them from there. Now that I think about it I may just do that

Good luck and if you make a model please share it with us!

-Augus7us

 

[Augus7us]

Hey Scott, I reread your post and see now that you weren't really asking if it was beneficial to use a 3d app but more what technique doh

Hopefully my long blurb will be of some use to someone contemplating using a 3d app!

As far as technique goes, and again I'm a hobbiest modeler and in no way an expert or even close, I was going to use several base shapes and welding or an extruding and slicing technique. Hopefully those terms translate as I've never used solidworks.

-Augus7us

 

[Brett Mathews]

I would start with a 2D cad program first and work your way to 3D. Do you already have solid works experience. Its a very complex program and easy to get lost in.

 

[Bob Ohlemann]

I have a pretty fair amount of CAD/CAM experience and model parts frequently but, I don't bother for knife design. I find Adobe Illustrator to be far faster at giving me what I need on fixed blades and folders.

Bob

 

[Brett Mathews]

double post

 

[NeilJBorja]

RangerBobTX has the right idea with Illustrator. SW will work, but it's a parametric CAD program, which will cause you more headache than you need if you're just designing knife profiles. I'm no pro, but engineering CAD programs also tend not to like splines, which are how you get your nice smooth knife curves. They tend to prefer arcs, circles, and lines.

 

[IrishSteel]

Scott, Solidworks can absolutely work for making knives. Although, as many have said if you are doing it by hand typically making a 2D file for the knife blank if faster and gives you what you need if you aren't familiar with the program. I've had decent results by making some basic designs. I'd start with making a 2D sketch of the profiled knife blank first, and then using other functions to cut away and make the bevel, edge, plunge, etc. You can start with a rectangular block, but you can save yourself a step by just going straight to the blank profile.

I don't have home access to Solidworks at the moment and haven't made many knife designs in it, but I use 2011 exclusively at work for other engineering projects, so if you really get stuck let me know and I may be able to point you in the right direction.

Unfortunately, I haven't seen many online tutorials for knife modeling, but I'm sure a handful are out there. Honestly, just learning some of the functions like making new planes, splines, sweeps, and loft cuts will get you a long way.

Also, in my experience Solidworks and most professional CAD packages actually handle splines quite well, much easier to make and manipulate than in free programs like Draftsight. However, experienced makers who use CAD though almost always suggest making the blank design by hand sketch first and then scanning and tracing the blank in CAD in order to have a more organic feel to the blank.

 

[Kevin Wilkins]

With all due respect, it doesn't sound to me like the OP knows much about Solidworks, parametric 3D modelling OR knives. Makes kind of hard to offer suggestions.

 

[P.Brewster]

Assuming your knife will be symmetric along a central cutting edge, a good workflow is as follows: (a) make a 2D sketch of your profile with cutouts/holes, (b) extrude that sketch into a 3D solid that is half your final thickness, (c) add 3D features such as the bevel and any edge chamfers/radii, (d) mirror your solid to create your final design.

Using arcs, rather than splines, on your original profile will make everything easier down the line. Modeling the bevel can be done as either a simple chamfer operation or a sweep operation. Use google - here is a start http://youtu.be/_nh9BMsjBNQ

 

[Nathan the Machinist]

RangerBobTX has the right idea with Illustrator. SW will work, but it's a parametric CAD program, which will cause you more headache than you need if you're just designing knife profiles. I'm no pro, but engineering CAD programs also tend not to like splines, which are how you get your nice smooth knife curves. They tend to prefer arcs, circles, and lines.

Pro/E will do splines, which is how I get my nice smooth knife curves.

A discriminating eye can see the difference in the quality of the flow of the knife. Straight lines and constant radius arc are unnatural looking. They look fine on a tactical or military type knife, but most designs benefit from the use of splines, NURBS etc.

Using arcs, rather than splines, on your original profile will make everything easier down the line. ]

Arcs and lines are necessary if something is going to be programmed manually using G01, G02 and G03 commands. But practically nobody is doing that today.

I haven't run into a shop that had problems importing them as high resolution polyline. Hell, it's just 2D data. Mold shops deal with the same sort of thing in compound 3D data without any trouble.

However, experienced makers who use CAD though almost always suggest making the blank design by hand sketch first and then scanning and tracing the blank in CAD in order to have a more organic feel to the blank.

:thumbup:

 

[timos-]

I have been using solidworks 2013 more and more in my designs.
Using splines is a great way to get nice curves. With splines use as few points as possible. Two points will get you an amazing array of curves if you use them correct. If you need to send a file to a waterjet place just save the file as a dwg and check the box import splines as polyline.
For the steel and blade shape I just draw my profile and extrude in two directions for desired thickness. I dont bother to model the bevels, no benefit for me.
For the handle I do model the shape I am starting out with and then model in the cuts I will make to get the finished shape. It works well for me so I can use the Model tree as a sort of order of operations. So it is beneficial to not just model the handle but model the cuts you will be making.
Another feature I use frequently is to import my sketch using the tools>sketch tools>sketch picture so I can use my own scanned drawings as a basis for my models.

As others have stated it works best for handles with multiple pieces. I dont bother with simple full tang and scales unless I need an approval drawing for a customer.
Solidworks is fun, fast and powerful, good luck!

 

[C_Claycomb]

I use UG NX 8.5 at work, and used to use AutoCAD. Mostly I find it easier to draw up knives with pencil, paper, ruler and very importantly, a couple of French Curves. Lots faster and more intuitive than on CAD. The thing you are drawing is always the right scale, 1:1, on the page, the curves are smooth, and when you are feeling your way, you can lightly sketch in different ideas and profiles.

I DID use CAD for the blade reprofile/redesign I did for Spyderco, along with curve analysis to ensure the splines were smooth. I also sketched, scanned, photo overlaid and traced while tweaking the profile. It was slow and felt more like technical work than creative fun. That was good for that job, but I wouldn't want to do it that way for a hobby.

If you need precise profiles for water jet cutting, you can always scan and trace pencil sketches into CAD once the rapid iteration creative part is done.

 

[P.Brewster]

Pro/E will do splines, which is how I get my nice smooth knife curves...I haven't run into a shop that had problems importing them as high resolution polyline. Hell, it's just 2D data. Mold shops deal with the same sort of thing in compound 3D data without any trouble.

I used splines for years; it brought me nothing but grief. The problems I encountered:
(1) Splines caused my CAD program(s) to glitch more than arcs. My 3D program is not parametric so I sacrifice nothing by using tangent arcs instead.
(2) Laser or WJ cutters were unable/unwilling to work with spline files (example: Leading Edge Fab as of 2013). In fact, many are unwilling/unable to work with ellipses.
(3) Converting to polylines/arcs/lines is problematic. If you go high-res, your file is full of nodes (i.e. intersections). A laser or WJ pauses at each node, leaving a minor but noticeable defect. If you go low-res, you have fewer nodes but many of the components will not be tangent, again leading to a noticeable defect in the blank. Letting the vendor convert your spline file into a polyline file can be disastrous.

 

[Nathan the Machinist]

I don't think that laser or water jet pauses at each node. The last controller I saw that did that was made in the 80's and read Dylan code.

I'd be confident in saying that all modern controllers feed through points (constant velocity) with no problem.

My guess is the minor defect you see might be a facet caused by too low a polyline resolution.

It is true that sending people a spline can be a recipe for disaster because the way the spline is generated in another person's program can differ. But you can still work with splines in your program and simply export it as polyline.

20 years ago there used to be a real problem with importing and exporting data like this, but modern programs and modern controllers have regulated that to a thing of the past. This is just 2D profiling, which is CNC at its simplest. Practically every controller made since the turn of the century is capable of complex motion in three dimensions simultaneously, polyline is trivial.

 

[zhyla]

I've been doing 2D designs in AutoCAD and then printing them out to use as templates. I'm terrible at hand drawing and used CAD for years so it's just more natural. I then go at it with normal tools -- band saw, belt sander, files, etc. With this approach the 3D aspect of the design isn't very important unless you have difficulty visualizing stuff in 3D (which many people do).

My eventual plan is to convert my mill to CNC and at that point I'll want to crank 3D designs out of AutoCAD so the mill can do all the hard work for me. So the primary grind of the blade needs to be in my 3D model. I've done one of these models and what I did was a 2D profile, extruded it to the thickness of the steel blank, and then swept a V-shaped profile along the edge of the blade to give it the grind. This seemed like the most logical CAD approach, but obviously different CAD programs may lend themselves to different approaches.

Good luck!

 

[PEU]

I'm fairly versed in SW and CorelDraw, and if you let me choose, my no brainer choice would be Coreldraw.
For fixed blades or folders its very powerfull and if you want, after finishing the design, you can export the profile as dwg and make a 3d model out of it...

99% of the designs I make start in coreldraw, once I profile the blade, I use my flatbed scanner and paste into coreldraw the real version of the blade to adjust details of the bolster and handle.

Also the same for the sheat, here is the finished knife

Pablo

 

[bndshardr]

I don't think that laser or water jet pauses at each node. The last controller I saw that did that was made in the 80's and read Dylan code.

I'd be confident in saying that all modern controllers feed through points (constant velocity) with no problem.

My guess is the minor defect you see might be a facet caused by too low a polyline resolution.

It is true that sending people a spline can be a recipe for disaster because the way the spline is generated in another person's program can differ. But you can still work with splines in your program and simply export it as polyline.

20 years ago there used to be a real problem with importing and exporting data like this, but modern programs and modern controllers have regulated that to a thing of the past. This is just 2D profiling, which is CNC at its simplest. Practically every controller made since the turn of the century is capable of complex motion in three dimensions simultaneously, polyline is trivial.

I CAD my knives up in Pro/E (now Creo) and export them to my neighbor, who laser cuts my blanks at his sheet metal shop. He did complain that splines make his programming difficult and that he basically recreated the splines using a series of tangent arcs. Since then, I do that before sending them to him. I'm not sure what software he's using, but I doubt he's programming it on punch cards.

 

[P.Brewster]

I don't think that laser or water jet pauses at each node. The last controller I saw that did that was made in the 80's and read Dylan code.

I'd be confident in saying that all modern controllers feed through points (constant velocity) with no problem.

My guess is the minor defect you see might be a facet caused by too low a polyline resolution.

It is true that sending people a spline can be a recipe for disaster because the way the spline is generated in another person's program can differ. But you can still work with splines in your program and simply export it as polyline.

20 years ago there used to be a real problem with importing and exporting data like this, but modern programs and modern controllers have regulated that to a thing of the past. This is just 2D profiling, which is CNC at its simplest. Practically every controller made since the turn of the century is capable of complex motion in three dimensions simultaneously, polyline is trivial.

The 20-yr old Cincinnati laser I programmed and operated paused at each node - to clarify, I'm talking about a fraction of a second pause. If the two CAD curves in question were not tangent, the defect was even more noticeable. The Flow waterjet at the same shop was from the late 80's and used the original software/controller. I think there are plenty of shops running 20 year-old machines and controllers.

Furthermore, I have definitely received laser-cut blanks with choppy profiles which clearly indicated the spline-to-polyline conversion resulted in non-tangent geometry.

I base my comments on the experience of having over 5000 knife blanks cut over the years at various vendors, and my day-job experience programming/running tens of thousands of parts on various machines using customer CAD and native CAD.