Looking for input on a design of a slip joint

[stezann]

Sorry, i'm late....
Salolan posted the link to the tutorial which explain the basic ratio of the joint. Everything is pretty well covered there and you can use that guideline to adjust your elements.
Another thing (but the tutorial covers that also): when you cut the parts remember to leave a bit of extra meat in the front of the spring (you did right in the cad, you'll adjust it post ht), and in the backs of spring, blade and liners to take into account the spring deflection, post ht, when it will be under tension. Leave room for the final adjustment post-ht and everything will be flush.
As a rough guideline, if everything seems to fit flush before ht, consider that after ht you'll get this:
Blade: the tip will rise a bit, both in the open and closed position
Spring: the tip will rise a bit above the liners and the springy portion between the tip and the cenral pin will dwell down between the liners

Remember also never try the action under tension without oil in the joint, it take just a little to gall badly the contact area without oil, and the only solution then is to sand those galled area again, and this could screw-up your "flushiness" in the 3 position of the blade.

 

[Stevenj369]

Wow alright I have some work to do. This is always the part where I normally just go out into the shop and start making some parts. I am a very hands on type who has taught himself how to be a CAD engineer. But I am also married to my business partner and work 15 ft away, so hiding the fact that I am working on a slip joint fun project when I need to getting some production done is not easy or better stated Smart. So cad it is until I get caught up....

Thank you all for the feed back and the information. I think my move forward to do a redesign and end up with 2 different parts for the spring. I was wondering about the pre-load on the spring and that makes sense to built it over size and adjust in a fixture. Part of me wants to try and pre-design this to see if I can make it work from the get go. I have to figure that some of the larger production companies are not hand fitting each blade/spring. But I think that might be a later exercise.

So the todo List is:

1. Re-work the tang of the blade to have the 1/3 ratio. Right now my blade height at the ricasso is .601" and my spring hight is .108" which is half of what it need to be. Now this seems to be a design cue to improve strength at full open during use. I was planing to make my blade .060" thick and my spring .070" to allow for .005" brass or teflon washers on each side, I wonder if this would allow for less of a ratio? I do like to over build so I think I will stick with the 1/3rd ratio and adjust the tension by grinding a relief.

2. Re-work the tang pivot location and outside profile.

3. Re-work the Spring length and height to match.

4. Create a new parts for the blade and spring that is the same but thicker in the areas of contact and back side of the handle to allow for fitting and finishing.

Thanks again guys for all the input. If you see any issue on my new plan please let me know. I'll be grinding all day again today but am hoping to have some time to do CAD tonight once I get the kids down.