Is aluminum to aluminum a good application

[SmoothCut]

I am in the process of Designing a sharpening jig for knives, dedicated to a certain industry where there is a demand for extremely Sharp Precision Repeatable & Significant smoothie Knife edge.

During the Sharpening & Honing process, We are trying to achieve that one bevel shall be angled 20 degrees from Knife’s center point, and the second bevel shall be angled 45 degrees from Knife’s center point, (See illustration )

The Sharpening & Honing process was used to be done by hand, And I would like to examine doing it with a jig, will it be more Precisely & smoothie Or less, How much easier will it be to achieve the desired edge.

The key factor in the Operation of The Jig is to get The knife in desired angles by adjusting the legs of jig, lock them & make sure That the of the knife Is stationary without any changes, meaning to say That the jig And its components have to stay straight without wiggling or bending, In order to achieve that i need to create custom hinges (See attachment "Custom hinge leaf Drawing").

my Questions is

1. Is aluminum to aluminum (From Pin to leaf) a good application, A) Will it be durable or wear out
quickly B) Will the motion be smooth.​

2. What kind of fit should I choose, LT = Locational transition or LN = Locational interference. I want the motion to be not very Freely, so it shall Keep its position between the stages of Finding the right angle and tightening the legs, but freely enough, So I should be able to make minute angle changes, (Little bit smoother & easier from the motion of a laptop cover)​

3. Taking in account question #1 and #2, How about going with a Sleeve Bearing
(SeeLink https://www.mcmaster.com/#60695k1/=18yus59 ) But I'm curious to know. A) If that Sleeve Bearing will provide only Radial motion or It will allow also a little bit wiggle. B) What type of fit will it provide (See in above link “ Shaft Mount Type Press Fit” )​

 

[mikey]

I'll take a stab at this:
1) No, an aluminum pin rotating in a hole in aluminum will gall quickly and stick or sieze. Bad idea.
2) Can't answer this. I would personally want free movement without any play.
3) Given that the environment will be wet, I would consider a Delrin sleeve and a stainless steel pin. The fit would depend on how you machined the bushing. If you drill it with a twist drill, Delrin typically will ft a bit tight on a nominally sized pin/rod.

 

[whitmore]

Given that the environment will be wet, I would consider a Delrin sleeve and a stainless steel pin. The fit would depend on how you machined the bushing. If you drill it with a twist drill, Delrin typically will ft a bit tight on a nominally sized pin/rod.

Premanufactured polymer (they feel like Delrin/acetal, but what do I know...) bushings/bearings
from Igus (or other suppliers) and matching SS shafts are easy to buy, but machining
a good bearing surface in plastic is ... tricky. I'd favor easy over tricky.

 

[mikey]

Premanufactured polymer (they feel like Delrin/acetal, but what do I know...) bushings/bearings
from Igus (or other suppliers) and matching SS shafts are easy to buy, but machining
a good bearing surface in plastic is ... tricky. I'd favor easy over tricky.

Actually, if you ream Delrin properly it makes for a nice, easy fit. I suggested a twist drill to give some resistance to motion because I thought that he was after that but ...

 

[rzbill]

If the angular motion requirements are small, then consider using a flexible metal sheet as the hinge.
It can be incredibly stiff and accurate in the plane of the sheet but allow easy angular movement normal to the sheet surface. Start around .010" thickness.