Hi everyone, Does anyone know why the above blocks are counterbored at the back ? (Not the hex nut side). A 9mm diameter "counterbore" clamped on top of a 10mm diameter precision shim (or spacer) seems odd to me - only a half mm of plastic effectively bearing the clamping load. Thanks guys.
There were some applications in the past where the screw head was recessed into the counterbore. Your question though does raise the issue of whether the counterbore is relevant going forward as it hasn't been used in quite some time and could be a detriment as you note.
Hi Rick, thanks for that! I did press a low profile screw into the counterbore and found it to be a perfect fit - but to what purpose? I really do think its poor engineering to mount something in the manner it's intended. In fact, I cannot see myself mounting the blocks at all (when I start my build) without some sort of spacing washer to fill the void or a full size 1mm plate across the back of the block.
I was curious about the c'bore as well. I'm getting mine put together now, and I noticed that the acme block was cattywampus... it turns out that that things weren't lined up perfectly, and the precision shim got cocked in the c'bore. Now the block has a permanent indent, and I'm dead in the water for the time being. I think my best solution is to make my own shim plate to larger than a standard shim.
The counter bore for the heads helps with clearance in some builds and the hex on the other side helps retain nuts which makes installation easy if you need the nuts.. As for a spacer, I agree I made a hdpe (had a bunch) plate the size and thickness i needed and it works much better than washers..
That's what I did - made some 4mm plastic spacers on the 3D printer which work very well. That eliminates the existing 3mm aluminium spacer and precision shim.
