I find myself overbuilding drawers for my CNC cart (I need to practice for a product box). I am not sure what the joint is called, but it’s a variant of a box joint—let’s call it a mostly blind box joint. I am just trying to guess the best tolerance between the fingers. I am thinking a minimum of 0.1 mm on the pins.
Some screenshots
I’m not sure if it’s possible for anyone to give a blanket tolerance - it’s going to be factor of the kind of timber you are using and to a lesser extent the kind of glue.
When making them by hand (with a table saw) I like them to be “a firm tap”, which more often than not is not achievable with my lack of patience and modest skills. It’s a feel thing - using pva wood glue you get a slight lubricating effect but you really don’t want much gap. 0.1 is what I’d use if I was printing something - so I suspect in a good ply or mdf that will be OK, but if it’s MDF watch out for expansion when the water based glue hits.
If you are using epoxy - make it almost sloppy so you can get a decent glue line.
If you are using CA glue (don’t) it needs to be a whack!
The best thing is to cut some samples before you start the real job, and get a feel for the material.
The shop drawers will be plywood, and the product box will be hardwood. I hate MDF with a passion and only use it when it’s the best for the application. the plan was standard wood glue.
“It Depends.”
Your best bet is to experiment on some scrap.
Most opf my joints the tolerance is the difference between the real kerf size of my bits and what’s defined in CAM. I cut parts using the exact same lines, and with how my machine and CAM is set up, I get a tight fit.
Obviously this doesn’t apply to 3D printing. 3D printed stuff, part tolerance is different with each of my printers, so if I want a tight fit, I have to tgailor the fit to the specific printer that I plan to use, and to a lesser extent, the type of filament that I plan to use.
I would call it a half blind dovetail dogbone joint.
You should make a test piece. I can imagine needing more tolerance than you think.
Yes I think you are right and I wonder if this is one of those jobs you set up from the bed surface and not the top of the stock. My thinking is the from run to run the stock will be a bit different, but as long as the stock for a run is the same I should be OK. But as I type this I am not sure it matters at all as long as the stock is ± 1mm or so
