Miter-Fold Techniques

A few tips and tricks for effective miter-folding. April 17, 2009

We recently purchased a cutter for our Busellato to run miter folds. We will be folding 3/4" MDF with wood veneer. How deep do you run the tool and what are your methods of folding and clamping after machining? Will miter folding work on particleboard melamine?

Forum Responses
(CNC Forum)
From contributor K:
.005"-.010" from the face is good. We pre-tape most of the parts. If you want to do melamine, you should go to MDF, but particleboard is okay for veneer or hpl. No clamping needed, just tape.

From contributor R:
I recently helped one of my clients get up and running with miterfolding. We found that cutting all the way through gave the best results with veneer panels. Taping first is doable, but they are producing hotel furniture so there were often a lot of small parts such as table legs. They also are mitering ends as well as sides. They now lay the parts out face up and tape the joints in assembly, then add glue and fold. Works very well, even using pre-finished stock. Just another way to do it. You need to tailor the process to meet your needs.

From contributor O:
I do about the same as contributor R. Cut through, hand flip the pieces and tape, flip back over, glue and fold. The pieces fit very well. I do pocket screw blocks on the inside to hold things together till the glue dries, then remove them. Depending on the veneer wood type, you may want to finish after assembly. We did some cherry pre-finished and it was not bad, but oak didn't work as well pre-finished.

From contributor M:
To the original questioner: Did you mount this to your saw? What tool did you get?

From the original questioner:
We are using a 45*, 2.25" diameter router bit with an insert knife. We are cutting at 18000 RPM and 180 IPM speed. Thanks to all who have replied.

From contributor R:
A 90 degree tool will work for miterfolding, but Leuco and some others make a 91 degree bit specifically for miterfolding. The small extra space left by the bit allows for glue and the fuzz that can be present when making this cut. If you find it difficult to close the joints (especially on long joints), try diluting your glue a bit and spreading it evenly to minimize squeeze out.

From contributor W:
We recently built a wall facade that incorporated almost 4,500 five-sided miter folded boxes from 3/4" Medex with mahogany veneer. Because of the intricacies of finishing each box individually, we pre-finished the sheet stock, then laminated the finish side with a low tack vinyl. The material was 18.6mm thick, so the tool path depth was 18.4mm, which relieved enough of the veneer to fold, and the vinyl prevented the joint from blowing out on the outside. We used a 3M hot glue for assembly, then peeled the vinyl and applied the box to the panel.

From contributor B:
That is a very interesting technique! Did you apply the low tack yourself or have the material brought in that way? What thickness for the vinyl and do you have a source? I would seriously like to give this a try, and I can imagine that it would go a long way toward minimizing part movement too. Also, were any of the bends across the grain, and if so, did they fare as well as the ones along the grain?

From contributor W:
The vinyl we used was a simple low tack paint mask; lots of manufacturers make it, namely Mac Tac. We're a large shop, and we have a roll laminator in house we used to apply it. The cross-grain cuts were the main reason for using the vinyl, and we had about an 85% success rate on folding those seams. A little sanding and touch up needed there, but we managed to get it done.

From contributor C:
Most of the responses are correct. A 91 degree bit is the best way that we have found. Even though ours says 90 degree, it is actually closer to the 91 degree. This helps if you have any runout anywhere.