paul
Member
Posts: 8
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Post by paul on May 17, 2008 19:31:58 GMT
I made an experimental boring bar today using a piece of silver steel for the cutting bit and copying by eye the angles of a standard HSS boring bar
I was impressed with the results on a trial piece but I wonder if the bit should be tempered after grinding?
Is forging over the end of a silver steel rod and then grinding cutting a point likely to yield satisfactory results for boring (I was thinking about small diameter (say <8mm) blind holes that required a decent finish)? I have seen similar tools used with a vertical slide for creating slots.
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Post by Tel on May 17, 2008 21:14:22 GMT
Yes - I usually rough grind, harden and temper and then finish grind very carefully, keeping the grinding heat right down.
As to t'other - I make little tools out of spent chain saw files that way quite often and the results are usually good. Again, heat 'em up, bend, rough grind, re-harden & temper, finish grind.
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paul
Member
Posts: 8
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Post by paul on May 17, 2008 21:31:21 GMT
Cheers Tel. I found a picture of the forged 'slotting tool' I was on about....  Something similar with the angles ground for boring would be a useful quickie - must try it! |
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Post by circlip on May 18, 2008 6:15:09 GMT
It's more of a "Groove" cutting tool Paul. Silver Steel, or Drill rod as the turkey breeders call it was used extensively for making cutting tools before HSS and now Carbides became readily available. Still have the first milling cutter I made as an apprentice/slave for cutting grooves in Gauge plate dies (Flat ground finish Silver Steel) for a wire forming machine to make wire "circlips"
After forming and filing to shape, Heat to cherry red, plunge into cold water - NO, THE TOOL, - polish the cutting tip and temper to light straw and quench, stone to a keen edge. Don't try to "Cleave" with them, if you get the tip hot you'll have to harden and temper all over again
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paul
Member
Posts: 8
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Post by paul on May 18, 2008 6:46:55 GMT
OK Ian I'll give that a try thanks (I'll try not to jump into my workshop plunge-pool like I usually do  ) |
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Post by jgb7573 on May 19, 2008 8:07:27 GMT
Hi Paul,
Back in the days when I lived in a bedsit, I had a small lathe on a baseboard which lived under the bed. This was the only machine tool I had, and hence no grinder. All my lathe tools were made out of silver steel, mostly 1/8" diameter. I'd file them to shape, then harden and temper. Hardening was done with a small propane torch. Tempering with a spirit lamp make out of an old salt pot and a piece of thin walled tube. The tool bits were then honed on a stone, using a home made jig to keep them steady. They cut very well and gave a very good finish as long as I didn't rush the honing bit. The tool bits were held in 1/4" square steel with a 4BA allen screw. I did make a toolpost boring tool in the same way, but the tool bit was only 1/16" diameter. It worked pretty well and could bore out a hole 1/4" diameter.
John
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Post by Tel on May 19, 2008 8:45:20 GMT
The traditional method of tempering is to put your item in a shallow pan of tallow and burn the tallow off, then plunge cool. Works fine for gun springs and the like, but I've never tried tool bits with it
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