Oftentimes, we have tools that serve multiple purposes. A weak link of the design could failed and we have to dispose of that tool. Each year, we have to buy a brand new scrapper. In the case of the ice scraper, oftentimes, it has 3 parts: the brush, the rubber windshield scrubber and the ice scraper. In my case, the ice scraper broke off. I believe that I found the probable root cause.
I would use this opportunity to polish my problem solving skills, design skills and TechShop CAD and shop skills.
Repair broken Ice Scraper. Find probable root cause. Eliminate or minimize effect of the propable root cause.
Probable Root Cause and Design Change Idea:
I hypothesized that the edge of the tube could create stress concentration on the former plastic ice scraper connector due to its sharp edge at the end. I would find a simple tool that to round this edge. Then I would give my replacement plastic part ample of radius to minimize stress concentration.
I removed the leftover plastic part on the tube.
I used Autodesk inventor to make the parts of the replacement.
I used 1/4" polycarbonate sheet to replace the ice scraper. This plastics are not laserable so I am likely to use combination of bandsaw, sander and mill. The reasons why I attempt to use Polycarbonate scrap in my first attempt are the following: They are soft and safer to use. They are easier to obtain than acrylic scraps. They are not brittle and likely could stand to the ice cold temperature.
I flared the end of the tube so that the sharp edge won't directly cut through the plastic part. I position the small ball point hammer on the open end. I hit it about a dozen times with the large hammer. The tube started to split so I stop.
For safety and to reduce stress concentration further, I ground the edge so there are not any sharp edges.
TechShop DC (Dream Consultant) helped me imported the ice scrapper profile to Autodesk Drawing. Then I could print
the it 1:! scale. I put my plastic sheet on top of the drawing and used a marker to draw the edge lines.
I use the belt saw and cut off the rectangular piece to separate my piece for the main stock. Then I cut along the straight edges and remove the excess material one at a time. On the concave edges, I cut lines and remove more excess plastic material.
I clamped the part and manually smoothed the concave edge with curved metal filer. I used a round filer to create the small fillet radius.
For assembly, I inserted the center piece by tapping with a mallet gently about a dozen times. The tightness is just about right.
I inserted the two wedges and tap it slowly with a wooden mallet. Final assembly picture will be added when I have a chance to finish it off at TechShop.
I have chosen not to put any glue just to see if I really it.
Thank You Note:
Thanks to my shop intructor Bob who chimed it with suggestion to use simple and basic hand filers. Thank you to Head DC Shawn, DCs Erika and Erica. Thank you to all my TechShop colleagues for all your encouragement.
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