HELP!! Grinding/Filing 101 question

[Maccabeus]

My goal:  Turn the nail file on a Wenger Junior 09 (that will be my son's first knife) into a file/flathead screwdriver combo similar to a vic classic sd.

My problem: I have no idea what I'm doing and have almost no tools for the job.

In the pic below, you can see the full range of tools available to me other than a few sheets of sand paper.  (And a Cutco pair of scissors that can cut through a penny, but I suspect would be totally useless in this context).

Can these tools do the job?  Better to grind or file?  If I need something else, what is it? 

In terms of the file itself, will it be a problem to have the edge of screwdriver tip run right through the fingernail groove?

Any help on this 101 task would be appreciated!  (Searching this site and google last night mostly resulted in complex mods that assume I know proper grinding and filing techniques or pulled up countless hits about grinding files into knives.  Neither told me quite what I want).

PS - I would really like to do it right the first time, because I've already had the blade engraved for my son and would prefer not to flush that money down the toilet with a botched mod.

[Live fron NY]

A bench grinder?  You can either do a lot of good, or a lot of bad with one of those.  You should be able to take the point off the nail file with that, and get the rough work done in a couple minutes. Maybe take the top of the point off, and grind a shallow flat taper in the edges to make the transition from full width to your screwdrivers´s width a little smoother.

By all means wait for a few more opinions, but I think the hardest part will be doing your work in short enough intervals, with rest time in between to let your work cool, so you don't over heat the blade and change the heat treatment.  You can use a big piece of metal as a heat sink to suck heat out of your work in between. 

Save the file and fine sandpaper for the final finishing.

[jzmtl]

If you are handy you can do it easily with just the bench grinder, key things are light pressure and never grind for more than a few seconds before dipping in cold water. Probably also try with a scrape piece of metal first.

Also as it is the tip will work with small phillips and non-recessed flathead anyway, so perhaps a mod isn't needed.

[Quartz]

You'll definitely need to grind and polish it with proper tools. You probably don't need to invest in a bench grinder though if you're not doing this stuff often- some kind of Dremel or equivalent with a handful of stock attachments will get the job done.

As for the nailnick question, I also turned the file on one of my Wenger's into a flathead. You really don't need to take it down that far to where the nick is an issue. Just take the tip off and it's fine.

[Maccabeus]

Live, jz, and Quartz-

Thanks for all chiming in with your various comments.  I am definitely NOT handy in this particular area, so everything you've shared is helpful.  I don't even remember how and why I came to own the bench grinder.  I do recall using it once for something about 10 years ago.

I'm talking to someone who does some welding and other metal fabrication who should have better tools.  He may help me out.  If not and I give it a try by myself, I will keep your various comments in mind.

Thank you!

[tattoosteve99]

Look in the sticky or search for Harryf3. He did this I think and it turned out nice.

[Maccabeus]

Look in the sticky or search for Harryf3. He did this I think and it turned out nice.

I saw his post where he mentions doing it but not one with any details.  A couple of his other pic-filled posts were informative for picking up some general insights.
Thanks.

[tattoosteve99]

If your handy with wiring, you can buy a dimmer switch and put it inline with the grinder. That makes the grinder run slower so you can grind down a little at a time. It works as I use it on several power tools I have that work at high speed only. Never had a problem.
Also the nail file is also thin for a screwdriver so maybe just grind it down a little, to the point where it just meets the nail nick.

[Maccabeus]

If your handy with wiring, you can buy a dimmer switch and put it inline with the grinder...

Also the nail file is also thin for a screwdriver so maybe just grind it down a little, to the point where it just meets the nail nick.

The dimmer switch is a great idea! While I hadn't thought of anything like that, it would be no problem to pull off. I'm much more comfortable with wiring and electricity than working with metal.

I came to the same conclusion about only taking off the first part of the tip.
Thanks!

[jzmtl]

If your handy with wiring, you can buy a dimmer switch and put it inline with the grinder. That makes the grinder run slower so you can grind down a little at a time. It works as I use it on several power tools I have that work at high speed only. Never had a problem.
Also the nail file is also thin for a screwdriver so maybe just grind it down a little, to the point where it just meets the nail nick.

I thought only some type of motors can be slowed? If it works on all I'm so adding one to my belt sander.

[tattoosteve99]

You can but it will cause premature burn out if you run it on low to long. I use a modified sander with my bench grinder. The bench grinder has a built in slow speed switch. My advice is to start out on high then go lower. A capacitor start motor don't work so well with these, but most bigger motor have that.

[Cupboard]

I thought only some type of motors can be slowed? If it works on all I'm so adding one to my belt sander.

You're right.
There are a few different types of single phase motors (pretty much all inferior to three phase but that's another story). The idea is that you've got a "main" winding that gives the motor its power, and a secondary winding that kicks it off in the right direction. The secondary winding needs to have the AC advanced or delayed in relation to the main winding and the motor usually does this with a capacitor.

The most basic type of single phase AC induction motor is "shaded pole" motor and this actually doesn't use a capacitor. They have a very low starting torque and you never really get big ones but you might get one in a small bathroom extractor fan. You can control the speed of these.

You've then got capacitor run motors which use a capacitor to create the secondary phase and this is active all the time. You can control the speed of these pretty easily too because the capacitor is rated to be capable of being "in the loop" over the entire range of motor operation.

Then you've got the types that can't really be speed controlled and these tend to be the bigger ones. Capacitor start motors use a capacitor to create a secondary phase but only whilst the motor is starting up. Once the motor reaches a percentage of its rated RPM the secondary winding will be disconnected. This means that the secondary windings and capacitor only have to be rated for the start up and that is only for a few seconds every now and then. If you keep the motor much below its full speed you'll kill them.

You get similar problems with capacitor start/capacitor run motors. These include features from the two types of motor that I've just mentioned, they start up with one capacitor and once up to a speed will change over to run with a different one. Advantage being you can have a relatively high starting torque with one capacitor but that isn't then in the loop whilst you're running. Again, if you're running this at a speed where the start capacitor is active for an extended period you'll have problems.

you can actually get single phase inverter drives specially for the speed control of single phase motors: http://www.inverterdrive.com/group/AC-Inverter-Drives-230V/?filter=Output|230Vac+1ph