1 Attachment(s)
Need Assistance on Shoulder Bolt Design
[FONT=Arial]I am developing a pivot point for a recreational wind driven vehicle using an elliptical stride path to generate force. The stride length is approximately 18-26" in length and the max weight could be anywhere up to 300 lbs. [/FONT][FONT=Arial] I would like to be consistent with applicable ISO7379, ANSI B18.3.3M and DIN 9841 specifications as applicable, but I am looking at a design slightly out of those specifications, and I want to get some input on whether I may be setting up for a tensile stress failure.
Ideally the bolt would be [/FONT][FONT=Arial]M20 x 80mm – M14 x 25mm (Overall length 80mm with 25 mm of threads), alloy steel. Additionally, instead of the ten threads, I would have thread one, a flattened surface where threads 2-4 are and threads 5-10 for complete insertion. I was planning on a set screw in the 2-4 thread position to ensure there would be no loosening.[/FONT]
[FONT=Arial]1. Is the shoulder drop form M20 to M14 too great i.e. will it reduce the the tensile strength and create a stress point that would not be there in a M20 to M16 bolt?
[/FONT]2. Is M14, particularly M20 to M14 covered by any ISO or ANSI specifications?
3. Do I gain an advantage using set screws or am I potentially creating another stress point?
4. Would it increase strength to add greater thread length e.g. 35mm
[FONT=Arial]I would like this to use ISO specs, but from what I see, the M20 to M14 transition and thread length may prevent this. Any assistance or personal experience would be appreciated.
[/FONT][ATTACH=CONFIG]625[/ATTACH]