I'm working on paper cut mechanism, I use gears to move blade to cut paper. I would like to get knowledge about the technique of seling gear shafts to a metal frame. It would help me in designing elements in fusion 360, the limitations and sizes that I can use. I found information about gears and bending metal sheet fabrications enough but I failed to find any info about gear shift fixing to metal like it was done in my pictures provided below.

UPD: To due to my poor english my question was not clear enough I had to provide more detailed pictures and edit my initial post.

So I'm making case (frame made from metal sheets, bending fabrication) to hold gears, but some places are narrow and tiny, I'm not sure will be possible to seal pins in those places. If I get more info how the shafts are assembled into a metal cases I could design it in right way.

Sealed shafts in real Shafts in Fusion 360

  • $\begingroup$ What exactly are you asking? More information about your circlip? Retaining the pulley on the shaft? $\endgroup$
    – GisMofx
    Feb 6 '16 at 17:56
  • $\begingroup$ I want to know how shafts are assembled to a metal frame. In my AutoCAD schemes I draw it just as a metal pin, and may be later I will discover that the seal methods are very rare or expensive or it impossible to seal shafts as it requires open space I mean free access to it. That is why I like to know more info about the process of seal. $\endgroup$
    – sultan
    Feb 6 '16 at 18:14
  • $\begingroup$ Assuming you have an enclosed gear box, you could use a common shaft seal on the input and output shafts. There are bores machined into the outside of the cases so the seal can be lightly pressed in. Here's a link to a site which describes this type of seal: sealanddesign.com/category/Oil/Rotary-Seals/136.html . Is this what you're asking? Also, where the gearbox is not enclosed or it's a pulley system not needing oil like gears, you could use sealed bearings. $\endgroup$
    – GisMofx
    Feb 7 '16 at 6:19
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    $\begingroup$ Thank you @GisMofx for reply, I appologies that I couldn't reply immediately to clearfy my question because firstly I had to make it in 3D to provide screenshots. I have updated my quesion and pictures above. $\endgroup$
    – sultan
    Feb 23 '16 at 20:01

In that sort of sheet metal assembly the shafts will often be a press fit to their housing with self bearing nylon gears ie the gears rotate on the shaft rather than being fixed to it.

This will usually provide an adequate seal in itself as they will either be self lubricating (nylon or PTFE) or use a fairly viscous grease or a dry lubricant which needs much less sealing than eg pressurised oil.


In addition to chris johns answer of self lubricated plastic gears (nylon, acetal, ptfe, etc) and possibly used with a heavier grease, you won't need a sealed housing... You really need to look at those shorter cantilevered shafts. They need to be secured sufficiently.. Maybe spot welded or press fit, if your housing wall thickness is enough. By looks, it doesn't seem thick enough to be reliable for a press fit. You can locally add a bearing to those locations or possibly design custom shafts that are bolted onto the housing.

Regarding the circlips, you can use those to locate the gears horizontally along the shafts.


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