Sunday, March 18, 2012

RapMan Reel Holder Using MOI 3D

Moment of Inspiration, or MOI 3D, is an absolutely wonderful application.  I installed it two days ago and was immediately able to design some things that will be not only useful to me; but, other RapMan and RepRap users as well.

One of the things that became immediately apparent when my RapMan was completed was that unless I baby sat the printer, the filament would not feed well.  As soon as enough filament had been used that more should be unreeled, the drag simply was too much for my extruder.  That may or may not be the fault of my extruder roller pressure.   But, if so, with my lack of experience, I couldn't trust I would set it right.

So, I determined that roller bearings would probably solve the problem.  And, it did!  I cab now leave the printer unattended for hours on end without a failure to feed.  That was a MAJOR breakthrough!

So, I want to show you how MOI 3D enabled me to go from having absolutely NO experience with the program to creating hubs permitting me to use bearings to support my RapMan filament reel,  My first hub probably took an hour to an hour and a half.  All the subsequent designs took well under an hour and most less than a half hour.  This is remarkable since (1) I am NOT an artist; (2) I am NOT an engineer or draftsperson and (3) I'd not even seen this program before installing it.

I not only created one roller bearing hub.  I refined the design a number of times with different goals in mind,  MOI 3D allowed me the freedom to do this in very easy fashion.  Here is my first design.

First MOI 3D project.  A filament reel hub with roller bearing
As you can see, this is a relatively simple design.  But, it has some features that might not be apparent.  One feature is that it accommodates two different 8mm Inside Diameter bearing sizes, 16mm and 22mm.  This nested design was easy using MOI's Boolean operations that make it easy to remove material.  The lofted shape was accomplished using MOI's scaling.

I then felt I wanted a lighter weight hub.

Attempt at lighter hub using MOI 3D

This design definitely created a lighter version of the hub.  And, it retained the design allowing for a choice be two different sized bearings.  But, it did not allow me to use the 8mm bolt that came with the RapMan reel holder kit.  The bolt wasn't long enough.  So, I used a 5/16" threaded rod to see how it worked.

It worked BEAUTIFULLY.  What a difference!  The bearing allows the filament to be played out with no intervention by me at all.

But, if a hub was to be useful to a wider audience, it should probably be designed to be used with the bolt the user already has.  So, back to the drawing board.

Hub designed to work with the original reel holder bolt

 This design accomplished several goals.  First, it was light.  Secondly, it was designed so that the 8mm x 7mm x 22mm bearing I found at a hobby store would mount flush to the top of the hub.  This meant dropping the ability to also use a 8mm x 5mm x 16mm bearing.  But, the flush mounting was critical to being able to be used with the 8mm x 120mm bolt used with the RapMan Reel Holder.

Here is the above design being used to print the final design.  Note, too, that MOI 3D allowed me to design a base for the filament reel holder that keeps it locked into place.

Test Hub in use with original bolt

While the above design worked beautifully, I still felt that I could lighten the hub even further.  So, I came up with one more design.

Final RapMan Filament Reel hub Design

As you can see, this final design is very, very light.  Yet, it has turned out to be as effective as all the other designs.  Here is an image of the final product.

Final RapMan Filament Hub Printed

While I am very grateful that I was able to come up with something that allows my RapMan to run for hour on end with attention, I am even MORE grateful to have found MOI 3D.

Here is the final version of the reel hub being used with the RapMan filament reel holder, including the original bolt.

Final RapMan Filament Reel hub Design in the Reel holder

I will be putting up all these designs onto various sites.  The last design will be uploaded to 3D Systems' Cubify site that is now in beta.

I'm loving this software and printer combination.  And, I look forward to the new Cube when it arrives.

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