Introduction: Plexi-glass Lettuce Knife

Picture of Plexi-glass  Lettuce Knife

I found a great place for plexi glass scraps and other plastic sheet goods, and brought home a bunch of random pieces. With some of those pieces made a lettuce knife. 

Step 1: Gather Your Materials

Picture of Gather Your Materials

You need clamps, CA adhesive (Cyanoacrylate (super glue)), scrap plexi glass wet sand paper belt/disc/drum sander or maybe a dremel, plastic polish, buffing wheel. 

straight acetone works better for glue up of plexiglass, not to mention MUCH MUCH CHEAPER THAN CA adhesive...
just make sure you clamp it good.

Step 2: Cut Your Scrap Pieces to Uniform Size and Glue Them Together.

Picture of Cut Your Scrap Pieces to Uniform Size and Glue Them Together.

Now, to make things easier, cut all the pieces for the handle to uniform size to make them easier to work with. Draw the outline of the knife onto the plexi glass blade and remember the blade will continue through the entire handle.
Now glue one of the scraps between two other pieces of scap, to make three layer scrap sandwich. Do that twice and let them sit...

Step 3: Sharpen the Blade

Picture of Sharpen the Blade

Now its time to sharpen the blade. I did this on a belt sander and its not that tough, just ake sure you keep your bevel straight on each side and grind away untill you have a nice clean edge. Then sand it up to 400 then take it to the sink with some 600 wet sandpaper then i polished it.

Step 4: Now Glue the Handle Pieces to the Blade

Picture of Now Glue the Handle Pieces to the Blade

Basically do the same process as the handle glue up, make the blade the middle piece. After its clamped, walk away...

Step 5: Shape the Handle

Picture of Shape the Handle

Tape off the blade to prevent damaging it during handle shaping.
I shaped the handle on my belt sander to a rough shape then cleaned it up by hand with some 80 grit. After the shape is nice and the way you want it, wet sand the handle all the way thru 600 grit. 

Step 6: Time to Buff and Polish

Picture of Time to Buff and Polish

I use a taper in my lather with a 1/2" mandrel. It works great with most buffing wheels. But use a white jewlers buffing compound until it shines like glass and points out EVERY SINGLE FLAW YOU MISSED while sanding. After that its time to finish polish it with some plastic polish, i used hut crystal coat. But after that it is all done and ready to make salad!
I doubt it will hold up in a dishwasher. And i dont now how long the edge will last but time will tell..
thanks for looking!


Palace64 (author)2015-11-13

just a question, is it legal to make a knife that would be invisible to X-rays at an airport?

audreyobscura (author)2012-12-14

Does Supegrlue work the same as solvent cement?

The word "solvent" makes me think of plastic models i made when i was a kid, that glue would actually kida "melt" both pieces of plastic and fuse them together. If that is how a solvent works then no, i would say superglue doesn't work that way. But i am no expert in glues... Lol

Dr Qui (author)SlickSqueegie2012-12-17

CA glue would not be as strong as the solvent cement, it still should be reasonably strong bond but it will be interesting to see how well it stands up to use and washing etc.

SlickSqueegie (author)Dr Qui2012-12-17

I have not yet used a solvent cement for plexi. But i will say that this is seamless.... If i had not used different colors you would not be able to tell that they were glued at all... Ill have to look into solvent cement...

Dr Qui (author)SlickSqueegie2012-12-18

I have not used it either, a technology teacher showed my the stuff once in a school i was on work placement in, it melts both surfaces and you get a perfect bond between layers once the solvent evaporates, he told me that the key was to avoid air pockets. I have used CA glue on perspex before I find again the key is avoiding air pockets. I think the real difference is that when solvent is used you don't have to clamp as tightly thing can be held together with tape or rubber bands.

SlickSqueegie (author)Dr Qui2012-12-19

Ifit really works that well, i have got to get some... I could in essence glue up a segmented plexiglass bowl if the glue actually works that well... This opens up a whole new ballpark in my turning materials... Thanks for this info... Do you now what the best solvent would be to get... The place i got the scrap from sells the glues for plexi, but it is costly.... More costly than ca adhesive... I cant wait to try this stuff for a segmented bowl....

Dr Qui (author)SlickSqueegie2012-12-19

I wiki'd it and it says that the solvent disolves the plastic and it becomes a fusion weld which is invisible (if you get it bubble free), if you can get scrap cuttings it would be worth buying a few liters of solvent, they guy who showed me it had a squeeze bottle and just flooded the surface and pressed the sheets together and wiped the excess away. Ill ask my friend Cliff, he is a fountain of knowledge on engineering based solvents and such.

It certainly would make the turning more interesting if i could make perspex blocks.  it would turn very well on the little metal lathe.

I recon you would get away with turning blacks laminated with CA glue on a pen mandrel as the mandrel would keep the blank in compression while turning.  I picked a pen mandrel up on eBay last year  for about 12-13 GBP inc postage, checking now the same thing is up to about 15 GBP now,   Never used it to turn a pen yet but I have made a pipe and a few hollow spindles from laminated blocks.  One of those tools you may not use that much but cheap enough to get as it expands your capabilities if you think outside the box.

SlickSqueegie (author)Dr Qui2012-12-20

Oh yes,i have already thought about the pen blanks, i have a mandrel already, and just like a chuck you increase your capabilities for your lathe many times! Another mandrel i find a very nice addition is a simple little wine stopper mandrel... But after i bought mine i can see that it would be simple to make that one...
I appreciate that video, i don't like the dry time, but i could make one hell of a nice segmented bow with this info... The place i got the scraps from has literally tons of scrap pieces of all different colors and thicknesses...

Dr Qui (author)SlickSqueegie2012-12-20

Yeah the dry time is about 24 hours, but you got to look at it from the turners point of view again I suppose, like turning wood blanks spending a few hours one day gives you a number of blanks ready for another days turning. I forgot to say the the teacher told me that the sheets where held together with rubber bands or masking tape until the solvent cured. Dry time is a bit long but its cheap yet as strong as it gets, I will be revisiting a plastics company myself now looking for some acrylic scraps

SlickSqueegie (author)Dr Qui2012-12-24

I went and grabbed a qrt of acetone to give this a try. It works quite well, though you still need to clamp to get rid of the bubbles. But the seams are quite nice here is a pic of two blocks glued up with acetone before wet-sanding and after.

Dr Qui (author)SlickSqueegie2012-12-26

Is there much of a difference in the price of acetone and the stuff the stuff the professionals use? That looks exactly like the blocks the CDT teacher showed me.

SlickSqueegie (author)Dr Qui2012-12-26

I paid like 7 dollars for a qt of acetone. I dont know what the pros use, but the bond that this gives is tough!

Finish sanded and buffed..
I will add, rubber band clamping gave a great bond, but i did get a few bubbles. When i clamped a block in the vice, no bubbles. So you still need to clamp, but it is in fact a much better, safer, easier to clean up, not to mention cheaper alternative to ca adhesive... Thanks again...

Dr Qui (author)SlickSqueegie2012-12-25


Dr Qui (author)SlickSqueegie2012-12-19

Acetone, that's what the school teacher used. you should be able to pick that up cheap enough.  

The fountain of knowledge that is the interments once more providith the answer.

Dr Qui (author)Dr Qui2012-12-19

That video is exactly what the teacher showed me, he was notoriously tight with money so it would have had to be cheap or the kids would not have been using it, I checked on eBay and it was £8 for 500ml, £10 for 1ltr and £20 for 5ltr. a little goes a long way by the looks of things so it would be worth the expense.

hats9994 (author)2012-12-23


Dr Qui (author)2012-12-19

Hang on a moment!!!!!

I just noticed the red neck contest entry. Is a perspex lettuce Knife not rather high end on the being  sophisticated scale to be considered red neck?.......   Deliverance would have been a whole different film if those rednecks had been carrying plexi-glass lettuce knives.... lol

Still voted though

SlickSqueegie (author)Dr Qui2012-12-20

Thanks for the vote! I do appreciate it!

Orngrimm (author)2012-12-20

Does it get dull fast or stays it sharp with normal use?

SlickSqueegie (author)Orngrimm2012-12-20

Well, the edge hasnt changed it is as sharp as it was at day 1. If i put a serrated edge on it i do believe it will dull very fast. And if you make the cutting edge too sharp or thin, im sure it will wear faster. I added the step of wet sanding and polishing the blade after it was sharpened, if i had not done thati do believeit would cut alot better but be a little uglier and could possibly dull even faster, so basically there is a dine line between too sharp and too dull you gotta find the middle....

desertsniper (author)2012-12-14

very cool, currious how it will hold up

Yeah, me too... It should have a serrated edge on it to make it work better for cutting, but it works great...

Dr Qui (author)SlickSqueegie2012-12-17

You could use the widest sanding drum of a dremel to add serrations like those on a bread knife, it would take a while to do though.

SlickSqueegie (author)Dr Qui2012-12-17

Nice... It actually works just fine as is. That is an excellent idea though. Thanks for the idea.

SlickSqueegie (author)2012-12-17

Also note:for this instructable, the key to making the layers of plexiglass look like one solid piece, is evenly clamping your pieces and don't peel the paper off until the very moment you glue it...

The Box Store Craftsman (author)2012-12-14

Pretty cool project! I will probably add this one to my list.

Thanks... It was fun... I learned how to do this (glue and shape plexiglass layers) in 7th grade...

About This Instructable




Bio: I've built houses, decks, custom cabinets, furniture of all types. Ive done furniture repair and restoration, residential and commercial remodels, restaurant seating and tables ... More »
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