Grinding bespoke tools from files, screwdrivers, chisels etc

Hello,

What it says in the description basically. I need some bespoke pokers, scrapers etc. and I plan to grind down some old blunt unused tools. Question is do I need to soften (anneal) these before grinding and then re-harden? And if so how do I go about doing it?

Thanks

No. You don't want to grind soft material but you would if filing to shape

On another forum there was some discussion about modern (<50yrs) files and their suitability for making knives. Some of the comment was that the steel used now is rather specialised to optimise the file making process so heat treating well is impossible by the traditional simple methods. There is probably going to be a lot of variability between the materials though so some might work while others don't. I can never wuite bring myself to condem a file.

Edited By jason udall on 08/10/2013 12:40:44

Thomas

If you are going to grind 'old' tools to make scrapers etc then be careful not to let the tool overheat when grinding as this could destroy the temper or hardness of the cutting edge of the tool. A good grind stone with a well dressed wheel will help remove material efficiently and frequent quenching will help to keep the tool edge cool.

Cheers

Martin

I made quite a few of my wood turning tools from old files. Also engineers scrapers. One scraper was made from the outer race of a large ball race, straightened out, and reheat treated, a tang welded on one end, and a wooden handle fitted.

Old Philips screw drivers (self tapping screws play hell with screw drivers, they are hard), regrind to plain screw driver, awl (pointy tool), reground one for a special screw, similar to Philips, but with 3 lobes instead of 4.

Dremel tool is handy here, it will resharpen a Philips screw driver, or put a square end on an old one for Robinson head screws (think that's what they are called).

Ian S C

Edited By Ian S C on 09/10/2013 11:34:54

On the subject of Phillips and Pozidrive screwdrivers, in my experience there are two common errors which can ruin them. One is using a Pozidrive driver on Pillips screws; these don't have the extra slits of Pozi screws, so they quickly ruin the Pozi driver. I don't think doing it the other way causes damage, so if in doubt use a Phillips (crosspoint) driver. The other is using a driver size smaller than the screw. This was one of my wife's favourite tricks, it took me years to get her out of doing it. Of course this also applies to slotted screws/ drivers, where also using blunt and rounded drivers also ruins many screws and makes them harder to remove and impossible to re-use.

Sure you know this Ian, just that your comment prompted the thought.

David

Edited By David Littlewood on 09/10/2013 12:31:31

Gotchya, no heat treatment needed. That certainly makes my life easier. I am advertising on freecycle for disused tools that I can mod, will be interesting to see what I get.

David - nice curve ball I believe another defining difference between Pozi and Phillips is that the Pozi teeth are straight whilst the Phillips teeth are tapered. Meaning that the pozi (supposedly) won't want to slip out of the head if there is little axial force. Also if you have the right driver you can fit a screw snug onto the bit before taking it to the work, useful for hard to reach places.

Thomas

David I know the difference, I ruined a few screw drivers on Philips head PK screws on inspection panels on Cessna light aircraft, Then I found a screw driver with a better quality of steel, it's still OK 40 or so years on, it didn't cost any more than the other supposedly good quality tools, It's main difference was , it has a wooden handle, and the shank is hexagonal, and the tip fits in a socket. The only reason I'v removed it from the socket is to fit it in a 1/4" socket extension for a long reach.

I'v got some little centre punches, and chisels made from bits of chainsaw files. Ian S C

G'day Thomas.

One treasured tool that I hunt for at the Sunday markets is old files.

They are usually made from good old fashioned carbon steel and the tang is left soft (it bends, unlike the working end).

For really sharp lathe tools (great for machining plastics) carbon steel can take a very keen edge. That is why chefs prefer carbon steel blades vs stainless ones. It boils down to the grain size. Check out Tubal Cain's excellent book, Hardening, Tempering & Heat Treatment. (Workshop Practice Series #1) for further information.

Of course, the downside is that the hardness is only viable at lower temperatures compared to HSS, so one requires a slow cutting speed or lots of coolant. For home made scraper use, I doubt if cutting speed is an issue. Also, rust can be an issue if you do not look after steel tools.

The heat treatment is pretty basic so give it a go.

Regards from the land of the kangaroo

* Danny M *

Word of caution- the files , if carbon steel may have micro cracks in the surface layers which can propagate if stressed. The advice in turning circles is to soften and then retemper after grinding. Makes the shaping easier too ! Unlikely you would stress a scraper too much to fracture it but I have been told of it happening if not suoppoorted close enough to the (wood ) work.

I have also made great awls etc out of old pozi drivers but they're hardened not carbon steel.

Some one told me that Pozi drivers are designed to "cam out" of the screw heads before you reach the point where the screw head will shear off- don't know if that's true or not - any ideas anyone ?

Well done training wife to use correct size- after 20 years I'm still trying !!!!

Regards Ian

Pozi drivers don't cam out if the bit is in good nick, and using modern wood screws, which are hardened, snapping them is pretty easy with a decent power driver, especially if your trying to stick the screws into a wooden pallet that's come from China! No idea what sort of wood it was but we've had power saw blades go dark blue trying to cut it. Ali is easier to machine!

Keith

.

Ian,

Whoever told you that was absolutely wrong

Phillips screwdrivers are designed to cam out

PoziDrive was designed specifically to not cam out.

I say this with some confidence, because my Dad was involved when GKN developed the system.

The crucial difference is: On a Phillips driver, each "blade" is tapered in section; but on a Pozi, it is parallel sided.

... The little nicks in the corners of the Pozi recess [matched by points on the driver] are a clear distinguishing feature, and should prevent "cross-dressing".

Here endeth the Sermon

MichaelG.

It was the Phillips that were designed to cam out, which is why Pozi was invented. I've twisted heads off with a good Pozi driver and screw. As for using a Phillips on a Pozi, well 'nuff said.

Phillips has been called the most misused fastener system ever. It was designed for power driver assembly before the days of sophisticated clutches et al. - I hate it

For he sake of pedantry, I should correct my typo

PosiDrive should read PosiDriv

MichaelG.

.

P.S. here is the page about PoziDriv, on the Phillips website.