In this tutorial I will be making a small part on the MakerBot 2. This is a piece that frequently breaks inside the doors of the XJ40 Jaguar cars and renders the doors useless. Since this lever is an integral part of the whole door lock mechanism and is also riveted in place, any breakage renders the whole door unusable.
I made it at TechShop Chandler, techshop.ws.
I took the broken piece out of the door mechanism by grinding the rivet end off. I glued the two halves together so I can have a working model.
The original piece is probably made out of molded nylon and after about 20 years inside a hot door they had become brittle. The original design was rather thin in the critical areas and had no radius to reinforce the webs. I had originally drawn the part as designed and later added thickness and radiuses to the critical areas where stress is concentrated. I saved the part as a *.stl, so it can be interpreted by the majority of 3D printers on the market. The TechShop Chandler has three brand new MakerBot 2 machines and they have proprietary software for maneuvering the part to suit the working environment and the user. On fine resolution the part takes 80 minutes to make on the low end it is only 60 minutes.
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The part was originally drawn in Solidworks exactly as the original then manipulated to get a sturdier design but with the same external critical dimensions. The end result was saved as a SLT file and then imported in the Maker Bot Software. The same results can be had by drawing the part in Inventor.
For some reason when I imported the file it appeared on its side. Using the "Rotation" tools on the left side of the screen it was rotated 90 degrees and put flat and in contact with the plate. At this step it can be made to move around the plate closer to the other corners as some areas of the tape may be damaged in the center where everybody puts their parts. Also it is very important that the part is in contact with the plate and not suspended in the "air"
The next step is to set the parameters for the actual making of the part. The original first "issue" part was set for 2 Shells and 10% fill just to get an idea if the part is what I want. The final part should be done with 1 Shell and 100% fill. More than 1 shell actually creates a separation between shells and the fill and in this case that is not desirable as all the strength possible is needed for this part. Supports and rafts are also added and the fine resolution is checked. By checking the preview you can get an estimate of how long it will take for the part to be made. This part had 147 layers and will take 80 minutes. Click EXPORT and after a brief computation the file is ready for the SD card that goes in the Makerbot.
SD cards that will work in the Makerbot are limited to 2 GB in size and need to be formatted for FAT 16, otherwise they are not readable by the Makerbot.
Here are the parts side by side. The original weighs 8 grams and the copy is 7.4 grams probably due to the different plastic composition. It is difficult to find a way to stress the part properly other than installing it in the original door mechanism, but I tried to break it with my hands (I'm 6'4) every which way and was not successful.
This is my first instructable an I am not sure if it will create much interest, however if you are a XJ40 owner you are probably all ears by now. The door locks from a salvage yard are hard to find intact and even so, the parts are so well "cooked" that they will probably break again while in your door :(
This is a new part and should last many years of service
The same technique can be used to make any number of small car parts as long as they fit on the Makerbot building Plate.
The filament used is PLS and the color was "natural".
Hope this helps somebody