Originally Posted by apocalypsenow
Apparently he missed out on the fact he can buy needle-tips and or syringes over the counter and stock those too... Hey Cranky, how do you resharpen a hypodermic needle? I'd be interested in knowing.
Originally Posted by Single_and_Available
Needles can be re-sharpened. It's a 19th and early to mid-20th century thing.
We are going to keep this short and sweet.
I had relatives in the day who used glass luerloc syringes, and when I was a Phlebotomist training to be a MedT back in the day, you could still get lessons in how to sharpen needles.
There are two approaches: flat grind and compound (curved).
is easy to teach and locate parts for, but it dulls faster and pulls/sticks a little more (hurts slightly more). In the day we used water on a fine Arkansas stone. Nowadays you use water on a plastic base diamond grit stone. Find one with a solid-grit sharpening area for tiny tools.
DMT is one company that makes these: http://www.sharpeningsupplies.com/DM...kr02e8NaHc3Kz2
You set the needle in a holder at the angle of the needle tip (use a neoprene cork if you have nothing else) and you draw the needle point first
along the stone. You want the tip to be razor sharp and the inevitable tiny burr that accumulates to occur above the tip and opening.
You can then strop that burr off without touching the tip, so it stays sharp. Sterilize and you are good to go.
You may ask "why draw the needle tip first?". Reason one is you don't want the burr anywhere near the cutting surface that is going in the arm, it will be hard to remove without damaging your new edge. Reason two is that the sharpening process leaves tiny, tiny grooves in the needle. If you sharpen to the side, that roughness will act like the teeth in a pair of pliers, pulling on the skin and generating more discomfort. sharpening with the direction of the tip avoids all that.
With practice you can get fancy and side sharpen to reduce the pulling of the needle, which starts pushing you into compound sharpening territory, or use a sewing needle sharpener before you get to work on the blade surface: http://www.tooltron.com/products/Needle-Sharpener.html
They made little hand operated needle sharpeners in the day that did this: http://www.gilai.com/product_1262/Hy...edle-Sharpener
generates a hollow ground point and is advantageous in terms of sharpness and less pain, but the point is far more fragile, it wears the needle up faster and is very difficult to do without specialized tools.
Modern disposable needles are hollow ground and that is one reason they are single use: the edge wears very fast and the tip fails if you look at it hard.
You will need a TINY fine grit round stone or a small diamond barrel grinder for a rotary tool and a good holder to lay the tip onto the barrel. I cannot begin to tell you how much more complicated this operation will be. You will need to build a jig to hold the needle and the device driving the barrel. You will need to select a barrel appropriate to the needles you are sharpening, and get multiple barrels for multiple needle diameters. I would say that if you are a machinist this will be easy and if you aren't it will be a pain in the ass- go with the flat grind.