Introduction: Repair/ Sharpen and Modify Spade Bits
As avid makers/ fixers and accomplished cheapskates we have become fond of spade bits because.
- easy to re sharpen
- easy to reuse after drill life has ended.
After searching Instructables and not finding any (this doesn't mean one doesn't exist i just couldn't find one) how to sharpen or reuse spade bit projects hear one is.
The life of a spade bit in my possession. the first picture is basically in order of the flowing steps.
- new = is used for fine wood working projects.
- dulled = is sharpened.
- sharpened = if sharpening went well (it doesn't always work)
fine wood working projects repeat sharpening until failure, if sharpening went poorly it gets used for general use.
after general use = abuse time, gets thrown into the things we use for electrical work and is used to drill trough cement, sheat-rock and whatever else we can grind our way through. see the green bit above that is rounded over and the sides are worn badly.
regrind into a new tool = we have ground into punches, chisels and shaped drill bits.
We will be using power tools (I hope yours are less farmer rigged then mine (for your safety))
YOUR SAFETY IS YOUR PRIORITY, IT IS YOUR JOB TO TAKE THE PRECAUTIONS THAT FULFILL YOUR SAFETY NEEDS.
I wear safety glasses, earplugs and remove my wedding band. (gloves as needed and safe (have two uncles missing fingers from gloved table saw events))
You will need to sharpen.
- dull spade bit/s
- vice and file or grinder (its faster)
To regrind into new tools.
- badly damaged spade bit/s
- vice and file or grinder
- a marking tool (I use sharpie)
- if symmetry is needed a way to make that possible (get creative)
Step 1: How to Sharpin a Spade Bit Crash Course.
Get your dull spade bit/s this one was found in a can of random bolts in the leaky corner of a shed. (was almost turned into a chisel) (eye and finger alert)
First picture was after it got wire brushed.
In this case I had to gently do a little face and side grinding to remove the pitted surface.
- Face try to uniformly grind away rust until pitting is removed without rounding edges. (see pic 2,3,4)
- Side grinding should have a slight negative angle to prevent burning of hole sides from friction. (were fixing cutting tools so all working edges should be sharp ish)side grinding also changes the drilled holes diameter. (see pic 4)
Make it a functional bit.
To do this summitry is critical. So gently hold the point on the edge of the wheel, then grind a new cutting edge. (this is hard to describe but intuitive when your doing it) see pic 2
Flip and repeat on the other side holding the same angles you used before.
Congrats you just resharpened spade bit and it's ready for more abuse.
Step 2: Creating a Shaped Spade Bit.
Shaped drill bits can be handy if you want a specific profile that's circular.
I use shaped bits to drill the chamber for smoking pipes.
It is not recommended nor do I condone the consumption of mind altering chemicals through combustion of any kind.
Though I do recommend making pipes (it's fun and a good skill builder).
Making a Shaped Spade bit.
- get hands on a trashed spade bit. don't use a new one because it would not be fun to ruin a new bit if you messed up.
- decide what shape you want to make and draw it on the bit. (be creative found a ~3/4 in neodymium magnet stuck to the light switch box and used that to trace the lines to grind to. I aligned the magnet up with the edge of the bit and the point/ blade crotch to help provide symmetry.) (pictures 3,4)
- rough out the pattern with a grinder. (eyes and fingers alert)(pictures 5)
- finish by creating a cutting edge much like the bit sharpening process. It is easier to sharpen to the point well if there is one.
Step 3: Test Your Fresh Spade Bits
It can be useful to have an example of the shape your bits will produce. The best way I found to do this is to clamp 2 pieces of scrap together (pic 1) and use a hand drill to drill a hole that follows the joint between them (pic 2,3). Once unclamped you can easily get a precise bit profile for your renewed bits. (pic 4)
Pipe making Note
It is not recommended nor do I condone the consumption of mind altering chemicals (including tobacco) through combustion of any kind.
The reason not to use a unshaped spade bit or forstner bit to create the chamber is that the corners produced (colored in black in pic 4) will fill up with burned and unburden material leading to pore smoking characteristics and plugging.
Participated in the
Fix It Contest