Fingerjointed boxes

I’m having fun with fingerjoints atm! This parametric model is super easy to adjust: https://www.thingiverse.com/thing:2839125 The joints are looser than I would expect, I think it’s caused by a tiny runout. How can I compensate for this? Setting the endmill a little bigger in estlcam?

The box for sewing stuff is from a nice board of pine, no branches and very smooth. I’ve used cold pressed and boiled linseed oil, I reaally like the smell and the impression it gives. Shiny and smooth.

16 Likes

nice work!

Cant tell from the photos, but how are you dealing with the internal corner radii in the finger spaces?

2 Likes

On the crate I did different things, a chisel, dremel, sanding and overcutting the corners. Honestly, overcutting is super convenient, and it doesn’t show much. (At least when glued)

On the small box I used a 1/16" (1.6mm) mill, so the overcut corners doesn’t show much at all.

I’ve thought about adding a little bit of 3d surfacing to the edges of the fingers. It would require a ball nose tool, extra cycle time, a perfectly level and flat workpiece and spoilboard…and it may still need some sanding after.

1 Like

I’m trying Tung oil on the guitar I’ve been working on, it’s a heck of a lot slower to dry than BLO, but gives a nice light honey finish that really brings out the grain:

3 Likes

Very nice guitar! Did you use the cnc for it?

When using BLO, it’s common to add some turpentine to make it flow and being more easily absorbed . Can you do the same with Tung oil?

Nope, it started life as a kit. I’m definitely not ready to CNC a hollow body. :slight_smile: I just used alcohol to cut the first couple of coats of tung oil, gradually decreasing the percentage until the last few coats were full strength. My guess is BLO could be cut the same way, allowing you to steer clear of the hazards in petroleum products. I’m going to spray a clear coat at the end though, so I’ll have plenty of opportunities to verify my mask is good…

1 Like

The boxes look great! I’ve never done it, but I can’t think of a reason why increasing the cutter dia wouldn’t work to compensate for runout.

1 Like

I’ll try it, and see how it goes:) I’ll let you know!

1 Like

Does estlcam have a “stock to leave” setting? If so, you could try increasing that a bit to help make the joint tighter.

1 Like

I think the finishing allowance does that, but I’m not sure how best to make it not also do a finishing pass.

But making estlcam think the bit is a little bigger will make it move a bit further away, at least for simple shapes.

2 Likes

That makes sense. Fusion360 has the stock to leave setting that I’ve used to fine-tune a joint that was similar.

1 Like

Estlcam will skip the finishing pass (but leave the finishing allowance) if the finishing tool is left blank. I did that by accident not too long ago.

4 Likes

Added 0.05mm finishing pass that I left out, because I was afraid that too big of a runout compensation would make them difficult to fit. Go figure I’m a coward!! Still too loose. Still a fun try. Amazing how gluing and sanding can smooth things out. Next try I’ll just use a few planks.

Edit: silly me. Now I know what to do! I just run some simple shapes with the mill and in the same wood, and then I measure the cut - and voila!

11 Likes

Is that the very hungry caterpillar?

Nice dice!

1 Like

Indeed it is! He’s very fond of food, like myself. It still remains to see when I’m supposed to develop into a butterfly…

Oh man, that’s an understatement!
I can’t seem to find shellac anywhere lately, so I bought tung oil… it never dries! :smiley:

Well, sure it dries… You just have to patient and not put it on too thick. :slight_smile: