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Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work. |
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Need knurling information
I'm refreshing some lawn & garden small engines, and I am wondering if it is possible/adviseable to knurl the pistons on a lathe. I understand it was common practice at one time but has gone out of favor these days. Some of these small engine parts are obscenely expensive. I mean its just for mowing the lawn. I've been honing out the taper with a rigid hone and the pistons have good grooves but are a little under sized after honing. Just use a regular knurler under the pin hole maybe?? I know it was done with a dedicated machine at one time but a knurl is a knurl huh.? If it goes over sized just knock it back with a file?? Need a special chuck or go with 3/4 jaw?? Been grinding the valves on the lathe using a small router (with the ways covered) fitted into the compound, not as nice as a sioux but the final results are great. Any advice/comments appreciated. DE ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#2
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In article , DE says...
Just use a regular knurler under the pin hole maybe?? I know it was done with a dedicated machine at one time but a knurl is a knurl huh.? If it goes over sized just knock it back with a file?? Need a special chuck or go with 3/4 jaw?? Pistons are tapered, and the skirts are actually pretty fragile. I recall seeing a setup in the SB book how they were held in a fixture that the skirt would sit in, and there was a kind of clamp that went thought the wrist pin hole and pulled it down to the fixture plate. I think they had sort of a live center that went over the crown of the piston to help support it. Jim -- ================================================== please reply to: JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com ================================================== |
#3
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I remember a piston knurling lathe type machine but do not remember exactly
how the skirt was supported. The knurls were formed in several bands around the piston but only on the working sides of the skirts (not on the pin sides). I think you might be able to knurl them if you can support the skirt adequately. It might be feasible to make a squeeze type knurler with one smooth wheel to use up and down the skirt from the bottom or back and forth around the piston between the pin bosses. I recall it did not seem to matter if the knurl was a little high, it just wore down to a reasonable clearance. I remember a machine which peened the skirt from the inside with a long arm while the piston was supported along a V groove and even a tool which expanded the skirt by pressure rolling vertical grooves inside the piston. There also used to be "piston expanders", heavy bow shaped springs to be fitted between the pin bosses and the skirts. So old engines did work with "expanded" pistons of several types. Don Young "DE" wrote in message ... I'm refreshing some lawn & garden small engines, and I am wondering if it is possible/adviseable to knurl the pistons on a lathe. I understand it was common practice at one time but has gone out of favor these days. Some of these small engine parts are obscenely expensive. I mean its just for mowing the lawn. I've been honing out the taper with a rigid hone and the pistons have good grooves but are a little under sized after honing. Just use a regular knurler under the pin hole maybe?? I know it was done with a dedicated machine at one time but a knurl is a knurl huh.? If it goes over sized just knock it back with a file?? Need a special chuck or go with 3/4 jaw?? Been grinding the valves on the lathe using a small router (with the ways covered) fitted into the compound, not as nice as a sioux but the final results are great. Any advice/comments appreciated. DE ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
#4
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I remember a piston knurling lathe type machine but do not remember exactly
how the skirt was supported. The knurls were formed in several bands around the piston but only on the working sides of the skirts (not on the pin sides). I think you might be able to knurl them if you can support the skirt adequately. It might be feasible to make a squeeze type knurler with one smooth wheel to use up and down the skirt from the bottom or back and forth around the piston between the pin bosses. I recall it did not seem to matter if the knurl was a little high, it just wore down to a reasonable clearance. I remember a machine which peened the skirt from the inside with a long arm while the piston was supported along a V groove and even a tool which expanded the skirt by pressure rolling vertical grooves inside the piston. There also used to be "piston expanders", heavy bow shaped springs to be fitted between the pin bosses and the skirts. So old engines did work with "expanded" pistons of several types. Don Young "DE" wrote in message .. . I'm refreshing some lawn & garden small engines, and I am wondering if it is possible/adviseable to knurl the pistons on a lathe. I understand it was common practice at one time but has gone out of favor these days. Some of these small engine parts are obscenely expensive. I mean its just for mowing the lawn. I've been honing out the taper with a rigid hone and the pistons have good grooves but are a little under sized after honing. Just use a regular knurler under the pin hole maybe?? I know it was done with a dedicated machine at one time but a knurl is a knurl huh.? If it goes over sized just knock it back with a file?? Need a special chuck or go with 3/4 jaw?? Been grinding the valves on the lathe using a small router (with the ways covered) fitted into the compound, not as nice as a sioux but the final results are great. Any advice/comments appreciated. DE ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- There also used to be piston expanders which worked like paint can shakers - with some kind of metal BB's inside the piston and the piston would get shaken back and forth in different directions to "hammer" out from the inside...therefore expanding the outside size. Ken. |
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