Cajone Questions and files


#1

So I’m finally getting ready to tackle making a Cajone Drum on the laser! Here is the one major problem, the dimensions of the Cajone are larger than the engraving bed, but smaller than the interior of the Basic (16.5 x 18 inches for the largest piece).

My question is, How would you tackle this? We can’t rely on the overhead camera because when we rotate the material within the laser, it needs to be close to laser kerf precision, up to 1/4" off is not going to work here. We’ll only be cutting the exterior edges of the cajone out of the material, so we’ll have the maximum bed size allowable.

My current idea is to load up each “side” of the Cajone into Inkscape, put it on a 20x12 storyboard, and precisely place the edge to be cut along the bottom of the storyboard 1 inch up from the bottom and 1 inch in from the left side. I’d then put a plus sign “+” on that bottom corner where the edge will be. I’ll then run the + first with the lightest score I can to make sure I’m all aligned, then ignore the Plus and run the cut.

Before I spend hours trying to work this out, does this at least make sense to all of you? Have you been able to accurately connect cuts that had to be done in two different jobs where the material HAS to be picked up and moved?

Here are the svg files for anyone interested in taking a look at them. This is a Cajone with a 30 degree slanted front. Should be a little easier for people with achy backs to play.

CajoneFiles.zip (6.0 KB)

Thanks everyone! (Also, let me know if this topic should be moved, I wasn’t quite sure where to put it. But there are free laser designs that work when I make the Cajone in my woodshop, just not sure how to translate them into the laser)


Cajon made with a Glowforge
#2

I think your idea is a good one. Not sure if you’re planning on masking it so your registration marks are only on your masking? That’s what I did a coupe weeks ago when the camera distortion screwed me.


#3

Yep, planning on masking the piece and hoping that a low power and high speed won’t go through the masking tape. Haven’t experimented with that yet.


#4

Unfortunately all I can add is good luck and let us know how it goes. I’m going to have a very similar issue once I get mine trying to engrave a 20" wine barrel top that I can break into two pieces, but they’ll need to line up exactly after.


#5

On my CNC I would drill some symmetrical placed tooling holes in the work piece in places that don’t matter (e.g. bits that cut off or cut out). I would also drill them in my waste board that goes underneath. Then I would place metal dowels cut from 4mm rod in them.

That way I can precisely locate the work piece in two orientations.


#6

interesting…I’d have to do 4 of them on at least some of the pieces, cause I’ll have to shift it around 4 times. I’d also have to figure out how to secure the dowels, or wasteboard with dowels to the tray, or remove the tray entirely to stay within the acceptable height requirements.

I’ll have to think on this suggestion a bit more to see how it might help me keep things aligned.


#7

Honestly? I would either scale down the drum, or cut it and run a decorative panel of contrasting color down the middle, so that the two sides fit on the bed individually.

If you glue the panel to the pieces afterwards, it should be strong enough, and you might get a different sound.


#8

I can almost guarantee you you’ll find the right setting to mark your particular masking. At 240 LPI I think you’ll find that somewhere between 11 and 20 power. Obviously you’ll want to find the exact sweet spot, and the level of granularity we have with power adjustment certainly gives you that freedom.


#9

I think a jig with some kind of registration marks/holes would be the way to go for sure. It’ll take some real thought to get it right, but it might work. I cut small holes in the corners of the wood and used a strong round magnets in each corner for registration. You have to really make sure the magnets don’t move though so I placed magnets on the underside as well to beef up their hold and I was very careful when moving the wood. Good luck and share your solution and results!

(Oh, and I bust out laughing at the titleof your post. In California ‘cajone’ is more often used in a very different context and couldn’t figure out why someone would consider lasering them! :rofl::laughing: )


#10

I was actually a little bit afraid to open this topic!


#11

O my, not spelled with an “a” and always plural.


#12

It would take some very serious ones to attempt that feat.


#13

Testing is underway and I’m finding all sorts of weird things. A 1" by 1" square is about 1.71" from the Left side of the tray and .991" from the front door. The same 1x1 inch square is about .85" from the right side of the tray and 1.03" from the front door. Since I’m going to need all the space I can get, I’m cutting out spacers for the left and right sides to get my usable material closer to the edge so I can use a .5x.5 inch square and waste less material.

alignment testing continues!


#14

That is a very spherical statement!


#15

Well…it looks like this one is a fail guys. I set up spacers on the left side to get it in the area I wanted. Made a score. Flipped it to the right front area and fiddled with spacers to get it just perfect (several hours worth of effort just dialing it in. Then once I FINALLY got it, I took a fresh piece, stuck it in the left spacer area and…it was off, like VERY off (.2 off with my calipers, so within the 1/4" off that they promised). I checked the spacer I had used and it was the same as before. So something else must be going on.

If I can’t duplicate cuts like this, I can’t rely on this machine to do this job, I’ll waste too much material.

HOWEVER, all is not lost. I cut out the longest side and I’ll be using that as a template to draw out the box joints that I wanted for this. I’ll just be transferring them to the wood and then using my saw blade to take out the waste. The Laser would have been MUCH quicker, but I need more accuracy that I’m getting with it right now.

So the plans I posted at the beginning are still good, but you’ll have to make it using something other than the laser, or GF will tighten up the accuracy. This is something that mechanical positioning would have been most appropriate for.