larryb Posted June 14, 2020 Report Posted June 14, 2020 I am working on a 3D printed seat rail mount project for a cargo net project. Since the part is made of plastic I would like to do some strength testing to determine if the design is adequate. If anybody has a piece of scrap seat rail lying around the hanger I would greatly appreciate it. Happy to pay for shipping. Quote
carusoam Posted June 14, 2020 Report Posted June 14, 2020 You probably want to define how strong the part needs to be... Printing plastic usually doesn’t lead to very strong parts... How many negative Gs Is a Mooney expected to endure... In an accident... you really want the nets to hold everything back... These are kind of a safety device... steel D-rings attached to the floor, nylon webbing holding stuff in place... (baggage area) Tell us more...? PP thoughts only... Best regards, -a- Quote
larryb Posted June 15, 2020 Author Report Posted June 15, 2020 I’d like it to hold 500 lb each X 4. There are a lot of variations I could test. Different filaments. Different print orientation. Reinforcing aluminum plates, etc. I just need a piece of scrap seat rail to do his testing with. The pictures posted are the first draft. 1 Quote
larryb Posted June 15, 2020 Author Report Posted June 15, 2020 Print the seat rail.... Why didn’t I think of that! Quote
carusoam Posted June 15, 2020 Report Posted June 15, 2020 32 minutes ago, larryb said: Why didn’t I think of that! You did... You put your ideas on MS... for a reason... It isn’t all negativity... Best regards, -a- Quote
larryb Posted June 18, 2020 Author Report Posted June 18, 2020 Well, it holds 300 lb. when my hanging scale and ratchet winch arrive next week I will test it to failure. Quote
bradp Posted June 18, 2020 Report Posted June 18, 2020 Remember that it’s not just static loading, it’s instantaneous velocity / acceleration/ jerk that you are dealing with- dynamic variables will impact durability. Larry if you need a stronger part print a negative split of your draft, use the mold to make probably a forged carbon part of the same design. 1 Quote
Yetti Posted June 19, 2020 Report Posted June 19, 2020 newtons and rock climbing and the gear that go along with it will help you here. 1 Quote
Yetti Posted June 19, 2020 Report Posted June 19, 2020 ten minutes with a milling machine and some alum bar stock would get you in a better place. Probably faster than your printer can dole one out. 1 Quote
Hank Posted June 19, 2020 Report Posted June 19, 2020 1 hour ago, Yetti said: ten minutes with a milling machine and some alum bar stock would get you in a better place. Probably faster than your printer can dole one out. Even an old manual Bridgeport . . . . Quote
231MJ Posted June 19, 2020 Report Posted June 19, 2020 I recall seeing seat rails on ebay a few days ago Quote
Aerodon Posted June 20, 2020 Report Posted June 20, 2020 Macfarlane already make them. I have a set for my Seneca, I'll see if they fit my Mooney. https://www.mcfarlaneaviation.com/products/category/cargo-tie-downs/ Quote
larryb Posted June 20, 2020 Author Report Posted June 20, 2020 The company I got the net from has the rail mounts for Cessna and Piper. I asked if they fit Mooney, the guy tried one on the field but said they didn’t fit. A milling machine would be great, but I don’t have one nor access to one. Quote
larryb Posted June 20, 2020 Author Report Posted June 20, 2020 Tested 3 configurations to 600 lb today. The test fixture started failing before the seat rail mount did. The mount showed no distress. The limit of my scale is 660 lb, so I may just consider this good. The load rating on the stainless steel shackle is also 600lb. The purpose of this project is to keep the baggage in the baggage compartment in case of severe turbulence or a forced landing. There are 4 seat rail mounts, good to a combined 2400+ lb. And the two upper net mounts are the rear shoulder harness attach points. No idea what they would support, but I expect it is a good amount. 1 Quote
carusoam Posted June 20, 2020 Report Posted June 20, 2020 you pulled 600#s on a printed plastic part? What is the empty weight of the M20K, 1800LBs? If you can statically lift/hold the weight of the plane.... know that other things will fail before your cargo straps do.... Now... do a good WnB for everything in the back... PP thoughts only, not a CFI... Best regards, -a- Quote
larryb Posted June 25, 2020 Author Report Posted June 25, 2020 Tested several samples to 700 lb which is the limit of the scale I bought. Two ABS samples failed right at 700 lb. the PETG samples failed somewhere above 700 lb. 1 Quote
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