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Hello all, My name is Drew and I have Patrol Plans #421. I am starting this thread so I have a place to ask questions and share information and progress with the group.
I would like to start this thread by asking a question of the group regarding laser cutting parts. I have been reviewing the plans and drawing parts up in Solidworks. This helps me to visualize assembly processes. I plan on cutting some of the 2024 parts on a CNC and have had a few items laser cut from 4130. I have read elsewhere (and Mark Goldberg advised me) of only using laser cut parts where the laser cut edge would be welded over.
I am not an expert and don't pretend to be one. This is actually something I have been curious about and have asked a few folks I know. It has been difficult to get an answer.
I have no intention of laser cutting any structural parts. So far they have been tabs and components to make the control sticks, torque tube and pedals. Its been many years, but I once took a materials science class and learned about carbon precipitation, pearlite and martinsite in carbon steels (and other topics). I understand that carbon can precipitate out in the thermal zone of the laser cut and that the rapid cooling causes embrittlement. By welding over the cut (assuming something like ER70S), you are using a filler rod with lower carbon content (and lower tensile strength), helping to dilute the carbon concentration and make the weld more ductile.
My thinking was that I would try using these laser cut parts in areas not seeing high loads where carbon embrittlement could play a dangerous role. I don't see any visual indication of a thermally effected zone along the edge of the laser cut (like I do when i use a plasma cutter), but I acknowledge that does not mean that there is no TEZ. I do have a small kiln and could bring these parts up to the transition temperature and stress relieve them before trying to use them. I have also considered over sizing them slightly and sanding away the outer margin to remove some of the heat stressed materials. In the case of brake cylinder tabs and control stick/linkage tabs, I will be welding most (but not all) edges/surfaces and would certainly be getting the whole part up to a solid red-orange glow with my gas torch. I am thinking (perhaps incorrectly) that this will cause the 4130 to normalize as it cools, thereby stress relieving the cut metal. If my logic is flawed, I would love to be pointed in the proper direction before I make too many parts. These are good practice parts if I decide not to use them in the end and I am fine with that.
If anyone has some knowledge to send my way, I do appreciate it.
Best Wishes and Friendly Skies....
Drew
Patrol Plans #421
Scratch Build
Northern California
“When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.â€
I would like to start this thread by asking a question of the group regarding laser cutting parts. I have been reviewing the plans and drawing parts up in Solidworks. This helps me to visualize assembly processes. I plan on cutting some of the 2024 parts on a CNC and have had a few items laser cut from 4130. I have read elsewhere (and Mark Goldberg advised me) of only using laser cut parts where the laser cut edge would be welded over.
I am not an expert and don't pretend to be one. This is actually something I have been curious about and have asked a few folks I know. It has been difficult to get an answer.
I have no intention of laser cutting any structural parts. So far they have been tabs and components to make the control sticks, torque tube and pedals. Its been many years, but I once took a materials science class and learned about carbon precipitation, pearlite and martinsite in carbon steels (and other topics). I understand that carbon can precipitate out in the thermal zone of the laser cut and that the rapid cooling causes embrittlement. By welding over the cut (assuming something like ER70S), you are using a filler rod with lower carbon content (and lower tensile strength), helping to dilute the carbon concentration and make the weld more ductile.
My thinking was that I would try using these laser cut parts in areas not seeing high loads where carbon embrittlement could play a dangerous role. I don't see any visual indication of a thermally effected zone along the edge of the laser cut (like I do when i use a plasma cutter), but I acknowledge that does not mean that there is no TEZ. I do have a small kiln and could bring these parts up to the transition temperature and stress relieve them before trying to use them. I have also considered over sizing them slightly and sanding away the outer margin to remove some of the heat stressed materials. In the case of brake cylinder tabs and control stick/linkage tabs, I will be welding most (but not all) edges/surfaces and would certainly be getting the whole part up to a solid red-orange glow with my gas torch. I am thinking (perhaps incorrectly) that this will cause the 4130 to normalize as it cools, thereby stress relieving the cut metal. If my logic is flawed, I would love to be pointed in the proper direction before I make too many parts. These are good practice parts if I decide not to use them in the end and I am fine with that.
If anyone has some knowledge to send my way, I do appreciate it.
Best Wishes and Friendly Skies....
Drew
Patrol Plans #421
Scratch Build
Northern California
“When once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return.â€
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