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Macro Rig Design Enhancements

  • After a bit of use, I found that the camera button servo motor was stressing out the slim bit of wood that was meant to hold it in place.  In the end, I went back out to the shed and redesigned a more robust servo motor holder.  The new mount is easily holding it in place:

New Servo Housing - Finished

  • The other design flaw is a bit harder to fix.  At the time I built the stage shaft holder I knew in the back of my mind that I wouldn't be able to get rid off shaft wobble, is if it was too tight, it wouldn't be easy to move up and down.  Sure enough after quite a bit of use, it's now quite wobbly and the stage servo leaver rotates the stage quite a bit as it's raised up.  My current temporary solution is to just hold it in one place with my fingers, but this sort of defeats the purpose of the 'automated' part of the rig. I really need a totally different approach.  A nice linear servo would be nice, but that's off the table for the moment. 

I woke one morning realising I could use a piece of model R/C airplane plastic tubing to connect the servo motor to the stage:

R/C Plane Push Rods 

I spent  another afternoon out in the shed rebuilding the stage holder.  Luckily I had foreseen this, and had designed a removable mount, so I could easily try different stage mounts as needed.  Just as a recap, here is the old stage assembly:

Old Stage Assembly 

The beauty of this mod, is that the stage servo will now be integrated onto the Macro Rig, thus making it easier to move the assembly around.  Here is the new server holder, complete with a removable lid, so that I can easily swap out the 9gm servo:

New Stage Servo Holder 

I knew the plastic push rod was flexible, so I glued together some scrap wood to act as a shaft support.  As before, this assembly is designed to be removable:

New Stage Shaft Holder 

Here it is underneath the rig, mounted in place, just before the red plastic shaft holder is glued into place:

New Shaft Holder in Place 

I seemd to have missed taking a photo of the finished rig, but here it is just before the last lot of glue and screws go in:

New Stage Servo Holder up on the Blocks 

So, 24 hours pass, while the various glued bits sets. I reconnected the battery and did a quick 'does it work' run - yes it works!:

New Stage Working Platform

Hang on, did that just rotate a bit?  Back in the computer room, I held my breath and ran a few tests with some graph paper on top.  Blast, looks like there is quite a bit of play with the white plastic servo arm to shaft coupling.  This causes the stage platform to rotate quite a bit as it rises up.  I have compiled a few jpegs into a gif so that you can easily see the problem:

New Stage - Problem with Stage Rotation 

Sometimes, it pays to take your mind off the subject and go and do something else.  It's then that you might have a revelation on how to fix a problem.  Mine was to carefully drill two extra guide shafts and glue some 2mm steel rods onto the platform.  Hopefully this will alleviated or at least minimise the rotation issue.  Here is a close up shot of the platform, with the guide shafts being glued into place.  Tomorrow night once it's all dry I will try the graph paper test again:

New Stage Platform - Guide Shafts 

 

  • During an intensive 880 photo shoot session the other night, I realised that the camera has a power socket.  I could have added in a 3V DC power source that would have saved on camera batteries.  Oh well.  I don't think I will add one in for this project, but I definitely will on the next camera project that I build.