george wilson
08-09-2012, 5:07 PM
I hate to break brand new tools,but finally I clamped a new 8" HF bastard cur file in a machinist's vise and broke off 1 1/2" from the front end.
For sure,it is hardened all the way through. Nice,very fine grain fracture,with no color or grain variations anywhere.
I hit the file with an 8 oz. machinist's hammer,and it easily snapped off. This caused me some concern because files I have broken off for special use generally have had some resistance to breaking,and frequently took a second or third attempt swinging the hammer harder(or,get a bigger hammer,as they say!)
This makes me wonder if the file was hardened,but not tempered at all. If so,the edges of the teeth could microscopically break away in use on metal,causing the file to seem to get dull too quickly.
When I made rifflers(which are quite small),I'd harden them,then dip in water,and heat till the water sizzled,wait a second,and quench. Old timers called this "Taking the snap out of it),but leaving it plenty hard.
I haven't tried using these files on steel yet,but if you find that they don't hold an edge,I recommend placing them WITHOUT their handle,into an oven at 275º for 1/2 hour. The trouble is: most kitchen ovens can be 75º off. Let them air cool and see if they hold up better.
A better way to temper smallish parts with simple means,is to buy a high temp. Thermometer with a long probe on the back and insert it into a slot on the back of a toaster oven. ONLY rely on what the high temp. thermometer says,NOT on what the toaster's thermometer says. You can get these from Brownell's Gunsmith Supply. A wise investment. They go up to 1000º,or so. Great for producing a beautiful spring temper blue.
I still think the HF files are a good deal,and could easily be heated in an oven if a bit more toughness is needed. You can't easily fix a file that is too soft,like the Mexican Nicholsons. But,too hard isn't a big problem.
For sure,it is hardened all the way through. Nice,very fine grain fracture,with no color or grain variations anywhere.
I hit the file with an 8 oz. machinist's hammer,and it easily snapped off. This caused me some concern because files I have broken off for special use generally have had some resistance to breaking,and frequently took a second or third attempt swinging the hammer harder(or,get a bigger hammer,as they say!)
This makes me wonder if the file was hardened,but not tempered at all. If so,the edges of the teeth could microscopically break away in use on metal,causing the file to seem to get dull too quickly.
When I made rifflers(which are quite small),I'd harden them,then dip in water,and heat till the water sizzled,wait a second,and quench. Old timers called this "Taking the snap out of it),but leaving it plenty hard.
I haven't tried using these files on steel yet,but if you find that they don't hold an edge,I recommend placing them WITHOUT their handle,into an oven at 275º for 1/2 hour. The trouble is: most kitchen ovens can be 75º off. Let them air cool and see if they hold up better.
A better way to temper smallish parts with simple means,is to buy a high temp. Thermometer with a long probe on the back and insert it into a slot on the back of a toaster oven. ONLY rely on what the high temp. thermometer says,NOT on what the toaster's thermometer says. You can get these from Brownell's Gunsmith Supply. A wise investment. They go up to 1000º,or so. Great for producing a beautiful spring temper blue.
I still think the HF files are a good deal,and could easily be heated in an oven if a bit more toughness is needed. You can't easily fix a file that is too soft,like the Mexican Nicholsons. But,too hard isn't a big problem.