Countersink follow-up
I made a comment in my Show-and-Tell post, that Steve replied to.
I have more info, but the discussion makes more sense here.
> I wrote:
> One minor hiccup was that the heads of the #6 screws
> on the ratchet (clicks) were running into the spokes of the
> ratchet wheel...
> Steve replied:
> That is the first time hearing anything about the click screws
> rubbing. Flat head screws should sit nearly flush and have
> enough clearance.
Yeah, I wondered about that too. I thought maybe I had weird screws or something... Here's what I found:
Mine are 'Everbilt' brand, which is the brand sold at Home Depot, so that's probably where I got them.
Just eyeballing, it's clear that their countersink angle is less than 90°. I imagine it's 82°, which seems to be the standard for US, flat head, Phillips wood screws.
https://en.wikipedia.org/wiki/Countersink#Types
https://boltdepot.com/Product-Details?product=16354
https://www.finepowertools.com/drills/countersink-angles/
The countersinks in the click STL files appear to be about 100°, measured by examining the STL file in Fusion 360. |
In a freshly printed click (printed countersink-side up), my screws do not sit flush; but are proud of the top by about 1.04mm.
I printed a cut-down version of the click, just to see if it revealed anything.
Though this photo is not entirely clear, I think my screw hits the lower edge of the countersink before the top of the screw sits flush in the part. It was very close, mind you; just had to bore down by 1/2 mm or so to make it clear the spokes.
I make no conclusions here; just offer food for thought.
What do you think?
-Matt
That is interesting. I have purchased those screws in the past and don't remember the heads being oversized so much. There is a lot of variability between brands though. An 82 degree countersink is a quick solution. This trick should get added to the assembly guides.
I order screws for the parts kits from McMaster-Carr, product number 90048A151. They are specified to have a head diameter of 0.262" and usually measure close to 0.25". I keep using them because they are extremely consistent across many orders.