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cferrell's blog
Posted by cferrell | Sep 27, 2007 @ 12:24 PM | 2,375 Views
Here is how I drilled out my hdx 300 sx tail case for 3x6x2.5 mm bearings (non-flanged).

I took the plates and screwed them down onto an extra block of wood (mdf wood, but any solid wood will do). The wood has a hole in in that's ~1/3" across so the bearing protrusion on the tail case will fit down into it.

Then secure the plate to the wood with 3 small servo screws (pilot holes drilled in the mdf). I also screwed the wood to the workbench to prevent it from twisting while I was drilling.

Once that's all screwed together, I used 2 long quick clamps to act as guides for my handheld drill. I used it to help control the left/right movement of the drill and I gripped around one of them w/ my fingers to help keep it from moving fore and aft. The drill also has a bubble level on the back to help out.

I used a little bit of thick oil on the plates to help lubricate the 15/64" drill bit. Drilled the plate carefully, but not too slowly, as you want to keep the bit cutting. I stopped a few times once I was moving to check how deep I was going. I stopped once I couldn't see any blue anodization on the inside of the tail plate. I also measured the depth and it was 2.5mm at the most shallow (neared the edge) - enough for a 3x6x2.5mm bearing to sit flush.

A little mini file to help open up the shaft hole a little (just ran it around 3-4 times to clean it out) and little careful tapping with a small hammer to press in the bearings and they sit perfectly flush.

Next up: Rear tail pulley. I've got an extra HDX450 / TRexfront belt pulley that I'm planning on using. I'll only have to file down one side, as the other side is already thin enough (or needs just a very little work). It's also a 10 tooth pulley, which will help w/ tail speed with a 40 tooth main pulley.