I decided to make myself a new parallel bit and thought some of you might like to see how I do it.
WEAR GOGGLES AND GLOVES
When choosing your blank take into consideration the length of the bit you want to make, Dublin and Parallel bits need to be longer because of the taper. Quality is also important, you need some good steel to hold the edge, the ones I use are Swiss made.
Mark a centre line on the bit.
Use a computer drawing program to create a pattern, print it and cut it out.
Glue the pattern in place and leave to dry.
Although best done on a bench grinder the bit can be shaped using a disc mounted in a drill, the drill needs to be firmly held.
Once you have trimmed down to the line on the bit shorten the shank, a short shank means less vibration.
The fun part begins........
Mount the shaped bit in the drill and spin it up, if you have another drill use it with the disc (spinning) to balance the bit, an angle grinder is better. This is easiest on a lathe with an angle grinder.
Once you are happy that the bit is shaped and balanced properly it is time to set the edge at an angle of 10-20 degrees. There are a lot of ways of doing this, on a bench grinder you angle the rest and work with the fine stone, in a vice you can use files or a Dremel and cut by eye, the important thing is to go slowly and accurately. Work your way down until you are almost at the edge and switch to a sharpening stone of some type, I have a diamond ‘stone’ somewhere which is great for this.
Once you are happy with the edge, the sharper the better, mount the bit in the drill or lathe and spin it up, do a visual check to make sure it is still balanced. If all is ok you should be able to drill with it, on the first drill take it slowly and take note of any spots on the bit which judders. If you have any judder or burning it means the two edges need to be checked for high or low points and sharpness.
After this first drill it is obvious that something needs checking, the burning is the giveaway.
Much better, a bit more sharpening was needed, fine shavings and no smoke.
The finished bit and holes.
Have fun trying this.
David.
The Next Instalment
Reduced shank blacksmith drill
Converting Spade Bits-How I Do It.
Re: Converting Spade Bits-How I Do It.
If I may, one comment. Using any power tools for the shaping or sharpening be careful of building up heat. If you build up too much heat (you may see color appear in the steel) you can take the temper out of the steel which softens it.
--Work in short segments, don't just keep going and going and going.
--Check the temperature of the steel by hand-cautiously! it can burn you.
--Use fresh abrasives- worn belts or pads dont cut as much and build up heat much faster.
Sorry -I guess that was more than one comment
--Work in short segments, don't just keep going and going and going.
--Check the temperature of the steel by hand-cautiously! it can burn you.
--Use fresh abrasives- worn belts or pads dont cut as much and build up heat much faster.
Sorry -I guess that was more than one comment
Re: Converting Spade Bits-How I Do It.
All good points Philthy, I assumed people would know that.
Assume= ass of you and me.
Having little feeling in my hands I don't notice the heat that much.
David
Assume= ass of you and me.
Having little feeling in my hands I don't notice the heat that much.
David
Re: Converting Spade Bits-How I Do It.
I like what your showing.. I created templates also with visio but failed to think further about it and spent about an hour cutting the templates out and place them on the bit and draw around them.. slap in the head.. didn't think about glueing them on.. I guess I missed the obvious..
Nice detail though.. I have a cheap little Euro 20 grinder I bought at a grocery store here for grinding the edge in.. the only bad thing about the machine is the stone is not designed for long life.. I'm hoping the replacement stone will last longer.
After the initial shaping I've use the grinder.. with the stabilizing plate set at about 10 degrees to put the edge on... works like a dream... about 8 month ago though I realized I had 'fixed' my first modified spade bit with the edge on the wrong side.. man did it scream at me while drilling until I figured that out.
Nice detail though.. I have a cheap little Euro 20 grinder I bought at a grocery store here for grinding the edge in.. the only bad thing about the machine is the stone is not designed for long life.. I'm hoping the replacement stone will last longer.
After the initial shaping I've use the grinder.. with the stabilizing plate set at about 10 degrees to put the edge on... works like a dream... about 8 month ago though I realized I had 'fixed' my first modified spade bit with the edge on the wrong side.. man did it scream at me while drilling until I figured that out.
Re: Converting Spade Bits-How I Do It.
Great post! Thanks for the high-quality photos. I have ground a few bits, but did do as an exact job as you did. I will employ your method for my next one.
My pipe of briar, my open fire, A book that's not too new. Robert Service
- Dixie_piper
- Posts: 389
- Joined: Wed Aug 25, 2010 7:34 pm
- Location: Hartwell, GA
Re: Converting Spade Bits-How I Do It.
Awesome! Can't wait until I can try it your way. My first attempt failed miserably, lol.
Bravo on a very informative post
Bravo on a very informative post
Regards,
Adam
Veo Vendice
&
Deum Timete
(family motto)
Adam
Veo Vendice
&
Deum Timete
(family motto)
Re: Converting Spade Bits-How I Do It.
Awesome tutorial!!
Many thanks for posting this!!
Many thanks for posting this!!
Dotter, Croatia
Re: Converting Spade Bits-How I Do It.
DMI... thanks for the tutorial...
nice..
nice..
Re: Converting Spade Bits-How I Do It.
Thanks for the time you took and the details on this fine tutorial!