Vikki wrote in with a tough question. She has an older precision knife of some kind that she believes dates back to around the 1940’s, and she needs to find replacement blades for it.
I tried my best, but couldn’t find exact replacement blades. This could mean that I’m not looking in the right places, or that the blades have a proprietary interface.
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Vikki writes:
The attached photo is of a small utility knife and 2 rusted replacement blades used by my Great Aunt as a Draftsman for Shell Oil in California back before, during or just after WWII.
It has “Crescent USA” printed on the larger blade, and the black plastic handle has a knurled screw knob to secure the replaceable blades, but all my online searches have found no replacement blades.
I am currently in Australia so am unable to search in person anywhere until next year when I return to the USA.
Perhaps you can help me identify the product more precisely or where such blades might be available, as I would like to use the tool in my activities (kind of as a tribute to my very creative Aunt).
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The blades look almost like scalpel blades, except from the bottom. The image is from Ted Pella, an excellent microscopy and science tool company I have had the pleasure of ordering from before.
Vikki’s precision utility knife has open-bottomed blades, while modern scalpel blades have closed bottoms.
Here’s a closer look at the modern scalpel blade interface shape:
My search for open-bottomed scalpel blades turned up empty. It looks like the knife might work with modified scalpel blades, or maybe a similar but not identical type of blade.
What I’m afraid of is that the interface is dissimilar enough such that scalpel blades – as-is or modified – won’t work. If the precision knife is as old as Vikki believes it to be, and the interface is a non-standard proprietary one, it might be impossible to find new or like-new replacements blades.
Have you seen knife like the one shown above, and if so, where can Vikki find replacement blades for it?
Steven
Is it too difficult to snap off the lower portion of the blades?
Clamp it in a flat vice, hammer etc to shear it off.
Stuart
That’s one potential option, IF the spacings and angles are compatible.
I also would never advise hammering of knife blades like this. If you don’t secure a blade perfectly, you could shatter parts of it, leading to sharp flying projectiles. A better way is to score with a carbide or diamond scribe and then snap with wide flat jawed pliers, but that could result in flying parts too. I’d do this with safety goggles on, and my hands inside a large Ziploc bag (like one of those super large multi-gallon-sized bags), and even then there’s some risk.
Bill
“Ziploc bag”?
Why not simply a wear some gloves? Using a plastic bag as a glove offers little protection, certainly less than gloves, and a slippery one at that.
Stuart
Cheap and easy containment.
I’m not saying that you wear Ziploc bags over your hands in place of gloves, but that the work is done inside the bag. Both hands, and the work, is inside the bag. That way, if a piece does fly off, it’ll likely be contained. Beats having to build a glovebox just for convenience purposes.
Brandon
I’m sure the plastic bag is to catch flying pieces, not protect his hands
Brandon
Ah… Stuart, you replied since the time I posted. Please disregard.
Jerry
Don’t hammer on a blade, itmay shatter. Safest way to cut one is to clamp it in a vise, cut ‘almost’ through it with a Dremel tool with a cutoff wheel, then snap with pliers.
Nathan
I think I’d need to see a few more pictures of the device.
I would take a try at sharpening/lapping the blades she currently has.
finally I too think standard scalpel blades trimmed/clipped down might work OK. It’s worth a try if nothing else.
the blades in my “craft” knife are all straight, full tang devices and I can find them all day. course that does make me wonder does this product need that stamped out shape or is that just incidental?
Justin
Just to throw it out there, the blades you pictured may work if you remove the set screw entirely, then reinstall once the blade is in position.
JamesB
You are right and I hope the person reads your suggestion.
JamesB
To add to the link Stuart posted about similar Craft and Hobby blades, I would include these ones also:
Havalon Knives
http://www.havalon.com/hobby—craft-blades.html
and
Havel’s
http://www.havels.com/havel-s-original-stainless-steel-surgical-blades-hsgrp.html
Farid
I won’t be surprised, if the screw is backed off far enough, that you’d be able to insert standard surgical blade in. It would have to be one with fairly straight tang, such as #11 or 15. Probably worth a try.
Vikki
Thank you all for your thoughts and ideas….I will ‘have a go’ at fully removing the screw and trying the fit of current blades available.
Your thoughts and the links provided are much appreciated.
Cheers
Vikki