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--- projects:crokinole_board:work_logs:work_log_4 [2019/07/09 01:36] – tjhowse
+++ projects:crokinole_board:work_logs:work_log_4 [2022/01/23 00:23] (current) – tjhowse
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-{{indexmenu_n>5}}
+{{indexmenu_n>4}}
+[<6>]
 ====== What I want to accomplish ======
-  * Cut the lines in the main board.
+  * Determine how to mark the lines on the board.
 ====== What I've done ======
-=== Aaarrgh! Scary! ===
+=== Experiments ===
+Other people have used V-shaped router bits to gouge the circles and lines into the board, then filled them with paint. I did a few experiments with that technique and found it hard to get reliable results. If it goes wrong the entire top board is a write-off, so I was very nervous. If the pivot point moves by a tiny amount the circle won't meet up at the end of the sweep, and that would be unfixable. The specification calls for the lines to be between 1/16" and 1/8". It didn't take much slop in the system for the depth and cleanliness of the cut to be significantly affected.
+{{:projects:crokinole_board:work_logs:pasted:20190710-121328.png}}
+I attached a bolt to the side of a router dremel attachment, thinking the smaller tool would give me more control, but I didn't have good success here either. Though I got nice clean grooves cut in scrap wood when freehanding, I couldn't get reliable results when drawing big circles. It was too easy for the pivot to jam slightly, or the dremel to tip, and ruin the groove.
+Instead I decided to go with a black permanent marker. I can easily build a lightweight circle-drawing jig. If it goes bad I can simply wipe off the ink with a solvent. I ran some trials and got some good data.
+{{:projects:crokinole_board:work_logs:pasted:20190710-123018.png}}
+The marker I used.
+I had gone through five varnish -> light sand cycles to this piece of scrap ply before drawing on it with the marker. I drew some straight-ish lines, a black patch and a big squiggle then let the ink dry for half an hour. I then drew some fresh lines as a comparison a few minutes before varnishing. I noticed that some of the ink had wicked out slightly from the lines. I suspect this would be wicking along the scratch lines from the sanding.
+The ink did not streak or bleed during or after the varnishing! Great success!
+{{:projects:crokinole_board:work_logs:pasted:20190710-122131.png}}
+{{:projects:crokinole_board:work_logs:pasted:20190710-122326.png}}
+{{:projects:crokinole_board:work_logs:pasted:20190710-122333.png}}
+After that coat of varnish had dried I gave it a light sand in preparation for another coat. I think I sanded a bit too hard because I broke through the previous layer of varnish and erased some of my lines, though many were unaffected.
+{{:projects:crokinole_board:work_logs:pasted:20190710-122939.png}}
+{{:projects:crokinole_board:work_logs:pasted:20190710-122958.png}}
+These photos show two coats of varnish atop the ink.
+I think my solution to this will be ensuring my varnish sandings are sufficiently gentle, and perhaps re-marking lines if they start to fade during the subsequent varnish layers. Overall I think this technique looks great and it's likely the one I'll be using on the final board.
-Use a bolt or some threaded rod to securely clamp the axle in the centre rather than resting the shaft in the hole. if the axle moves by a millimetre the lines will be bad.
 ====== What I want to accomplish next time ======
-  * Varnish a piece of scrap ply and sand it, then varnish it, then sand it...
+  * Cut out the top,
-  * Work out how to mark the lines on the board.
+  * Glue the offcuts and cut out the base,
+  * Drill the hole in the centre of the top,
+  * Attach the bands to the base.
+[<6>]