The Cutting Aid is a tool designed for cutting without using the muscles in the hand/fingers. This product was originaly designed for someone who loves working in the kitchen but sufferes from a muscle limitation in the fingers. We have redesigned this original cutting aid to a more flexible setting, from wich anyone can make his/her own personal cutting aid (for your personal knife).
- M5 x 25 bolts (2)
- M5 tee nuts (2)
- Bolts & nuts (knife)
- Velcro (2cm width x 35cm length)
- Velcro (2cm width x 40cm length)
Knife (personal choice)
Knife holder (PMMA lasercutting)
Arm splint (wood milling)
Screw aid (3D printing)
- 3D printer
- Milling machine
- Hammer, scissors, ruler
Step 1: Stripping Your Knife
First of all, you need to know wich knife you want to be used in the Cutting Aid. You can take a knife you love, or a blade you have laying around.
(You can also make the blade yourself if you want the Cutting Aid to have a more personal style or you can use another object to be put into the Cutting Aid, as long as it is similar to a knife blade)
Dismantle the knife carefully and make sure there are at least two holes in the handle of the blade. The holes must be at least 3mm in diameter because bolts and nuts smaller than 3mm are hard to find. If there are no holes in your knife, make two holes yourself!
Step 2: Taking Dimensions
All you realy have to do is take a few dimensions of your knife's blade and fill these out in an excel template (appendix: CAD-file: snijhulp_advanced*).
There is one dimension in the excel template called "vingerbreedte", this is the distance between your hand and the knife. Make sure this is at least 30mm.
The excel template with your dimensions is linked to a CAD-model wich will adjust itself to the excel template. To make the CAD-file adjust itself to your dimensions: *in the CAD-file go to : tools / part families / edit part family / EXCEL / fill out the measurements / invoegtoepassingen / apply values / your new model is ready)
This part can easily be lasercutted out of a PMMA (perspex) plate of 10mm thickness. Find someone who knows how to lasercut, using a 2D view of your part. The result should look like this (see below).
Step 3: Lasercutting Your Part
Make a 2D file of your adjusted CAD-part (like a pdf, png, jpeg,...). This must be the top view for the lasercutter will follow the contours of your part. Ask someone who is familiar with lasercutting to help you prepare your 2D file for a nearby lasercutter. (example in appendix: Lasercutting example)
You can easily cut a PMMA plate (10mm thickness) with a lasercutter. Make sure the speed of the lasercutter is set on a relatively fast adjustment. This will result in a clean cutted, strong and transpartent part in wich you can mount your knife with screws (see next step).
Step 4: Drilling the Last Holes in the PMMA Piece
Anchor the lasercutted piece precisely so that the drill is perpendicular to it and the location of the holes are exact. Protect the workpiece with scrap wood or something else so that the piece doesn't break or gets scratched.
Use a 5mm metal drill and drill without using any force. Using a column drill is recommended. Be gentle, let the drill do its work.
Step 5: Milling the Arm Splint
To mill the Arm Splint you must cut a piece of wood to a size of: 30 x 8 x 3 cm.
Take wood of some sort you like, or take a piece of scrap wood. Look out for knots, they will define the finishing degree of the milled product.
The file you must use for the milling machine is in the appendix.
Step 6: Standard Parts: Bolts, Nuts & Tee Nuts
To mount your knife to the lasercutted knifeholder-part, you can use standard bolts and nuts with a radius equal to the hole sizes of the knife. For instance: if your knife has holes of 5mm in diameter, you can use M5 bolts etc.
Warning: if your knife has holes smaller than 3mm in diameter, drill them out to 3mm. This is because bolts and nuts smaller than 3mm are hard to find.
To mount the knifeholder to the arm splint you must use two couples of an M5 bolt and a tee nut.
Step 7: 3D Printed Screw Aid
To make sure one can mount the knifeholder to the arm splint independently, there is a 3D print file in the appendix (3D_print). Put this file on a USB-stick and simply plug it into a nearby 3D printer to print it!
Step 8: Assembly
First hammer the M5 tee nuts in the arm splints holes. Protect the tee nuts with a piece of wood and anchor gently with a hammer.
Place the knifeholder into the arm splint and fasten using the 3D printed screw aids and the two pairs of M5 bolts and nuts.
Attach the knife to the knifeholder using the matching bolts and nuts.
Now use glue to attach the velcro to the arm splint. As soon as the glue is dry the cutting aid is ready.
Test the cutting aid!