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Joined: Feb 2003
Posts: 10,424 Likes: 7
Campfire Outfitter
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Campfire Outfitter
Joined: Feb 2003
Posts: 10,424 Likes: 7 |
I just bought the Chrome Moly barrels. There was not trouble with that steel. 20 years ago I bought [4] light varmint taper [2100] Lothar Walther 257 barrels from brownells. https://www.brownells.com/gunsmith-...rrel-blanks/rifle-barrels-prod15610.aspxWe put them on VZ24 Mausers. They shot very well on targets and were easy to chamber in 257 Roberts Ackley, but were too heavy to hunt. 10 years ago I bought [1] sporter taper [1300] in 7mm and made a 7mmRM VZ24. I shot antelope and deer at long range and am happy with it.
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. -Ernest Hemingway
The man who makes no mistakes does not usually make anything.-- Edward John Phelps
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Joined: Jun 2004
Posts: 7,203 Likes: 6
Campfire Tracker
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Campfire Tracker
Joined: Jun 2004
Posts: 7,203 Likes: 6 |
GD, You seem to be well experienced in this stuff, I have learned mostly by the Braille system....with predictable results. If you were contouring a CM barrel, and your 2nd objective was to minimize stress... do you prefer a cut that produces a continuous chip or do you prefer a lighter, higher fpm cut...keeping in mind the home shop is not capable of proper stress relief. ?? First off, I am of the opinion that stress relief has to have occurred prior to machining and, if the tool performs as it should there is no stress induced by the machining operation; where material is cut away cleanly and not displaced. When everything is right, the ideal is to produce a uniform rolled chip (like a coil spring) which breaks off at about six inches in length. A chip which does not break, while it is nice from a smoothness standpoint, is not safe. A person has to have been whipped in the face by a long chip which has wound around the work, to really appreciate this! A tool which is performing as it should will see most of the heat carried away in the chip. I like to run at about 240 to 320 rpm (depending on diameter), cut about 35 thou and feed at ten or so. Mitigating chatter is always one of the most difficult tasks and this will often take precedence over everything else. Again, stress is not induced by this operation but any stresses which exist in the material are removed with the material or, alternatively, will begin to affect dimensions as material which had been holding the stress in check, is removed. I have probably mention, at some point, doing a kitchen range stress relief attempt on a pair of carbon manganese barrels. I baked them at 550 degrees for 2 hours and let them cool overnight. While not 100% successful, it allowed me to turn these blanks which were unusable otherwise. Stainless is a bit different to work with since the chip is more difficult to control. Stainless doesn't break like CM will and the chip tends to wad up on the tool. Also, stainless is a lot harder on tooling. GD
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Joined: Aug 2021
Posts: 3
New Member
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New Member
Joined: Aug 2021
Posts: 3 |
Cutting threads with Tool steel ,
I have always sharpened the HSS to what I thought was sharp and left it at that, recently I was machining up some 1/4 x 32 TPI stock screws so I made sure the HSS steel was really honed Sharp and precise and finished up on a stone to make sure all cutting edges were as sharp as I could make them I even used a diamond wheel to get the desired result. Boy those HSS tools cut so well and last so much longer, I now employ that technique on all my HSS Tool steel that I sharpen and I find the HSS being so sharp cuts really well and tends to resist the tendency to become blunt .The thread is noticeably smoother no tearing of the metal You get with an improperly sharpened tool. Hate china but I have bought some of their 60 degree cutters for 1/10 of what I would expect to pay. they are very hard and brittle but at $1.50 an insert who cares They do not seem to like plunge cutting so I may experiment with Offset cutting technique.
Cheers Vaughn G
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Joined: May 2003
Posts: 3,288 Likes: 5
Campfire Tracker
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Campfire Tracker
Joined: May 2003
Posts: 3,288 Likes: 5 |
GD, You seem to be well experienced in this stuff, I have learned mostly by the Braille system....with predictable results. If you were contouring a CM barrel, and your 2nd objective was to minimize stress... do you prefer a cut that produces a continuous chip or do you prefer a lighter, higher fpm cut...keeping in mind the home shop is not capable of proper stress relief. ?? First off, I am of the opinion that stress relief has to have occurred prior to machining and, if the tool performs as it should there is no stress induced by the machining operation; where material is cut away cleanly and not displaced. When everything is right, the ideal is to produce a uniform rolled chip (like a coil spring) which breaks off at about six inches in length. A chip which does not break, while it is nice from a smoothness standpoint, is not safe. A person has to have been whipped in the face by a long chip which has wound around the work, to really appreciate this! A tool which is performing as it should will see most of the heat carried away in the chip. I like to run at about 240 to 320 rpm (depending on diameter), cut about 35 thou and feed at ten or so. Mitigating chatter is always one of the most difficult tasks and this will often take precedence over everything else. Again, stress is not induced by this operation but any stresses which exist in the material are removed with the material or, alternatively, will begin to affect dimensions as material which had been holding the stress in check, is removed. I have probably mention, at some point, doing a kitchen range stress relief attempt on a pair of carbon manganese barrels. I baked them at 550 degrees for 2 hours and let them cool overnight. While not 100% successful, it allowed me to turn these blanks which were unusable otherwise. Stainless is a bit different to work with since the chip is more difficult to control. Stainless doesn't break like CM will and the chip tends to wad up on the tool. Also, stainless is a lot harder on tooling. GD It is called chip control, you learn it in basic machine shop
+Professional member American Custom Gunmakers Guild
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Joined: Jun 2004
Posts: 7,203 Likes: 6
Campfire Tracker
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Campfire Tracker
Joined: Jun 2004
Posts: 7,203 Likes: 6 |
Nothing like a bit of condescension to add some substance to a thread. Thanks, Jim! GD
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