Beginner's DIY laser guide for hollowing

[John Rander]

Thanks to the forum’s recent discussion of replacement lasers for the Monster system, I realized that I could easily build a simple laser guide for my EWT hollowers using a $5 cat laser (Didn’t find the Ron Brown laser guide here in France). After timidly turning a few hollow forms with tape on the gouge for depth, continuously checking the thickness with bent wire loops, this is a cool alternative. There may be other beginners in the same situation, so here’s a photo of my prototype version made out of scraps on a rainy Sunday afternoon (tape marks on the horizontal shaft are for the #1 and #3 hollower positions). Admittedly the prototype elbows aren't very elegant, but they clamp well.

 

[John Rander]

Since the laser guide is perhaps not that obvious to use I have added below two photomontages which should help. First the laser spot distance from the cutting edge needs to be adjusted to your desired wall thickness. Then when the gouge is far from the wall, you will see the spot on the upper surface of your piece (first photo). As you reach the desired wall thickness, the spot drops to the horizontal plane and elongates as seen in the next photo. If the elongated "spot" disappears you have gone too far!

 

[Bill Boehme]

Great work on creating a very clear depiction of how the laser dot works to give the desired wall thickness.

 

[Steve Chu]

Mine is less robust but also cheaper than $5

 

[John Rander]

Mine is less robust but also cheaper than $5

Looks like it does the job. I know the laser diodes are cheaper, did you add a current limiting resistor in your setup? If not the diodes usually don't last long and the beam power can go over 5mW (pointers and cat toys usually have them).

 

[Steve Chu]

Looks like it does the job. I know the laser diodes are cheaper, did you add a current limiting resistor in your setup? If not the diodes usually don't last long and the beam power can go over 5mW (pointers and cat toys usually have them).

The website says it’s a 4.5V laser, 20mA, 51 resistance(?). I have two 1.5V batteries in series plugged in. I figured I’d be safe that way but I’m no expert.

 

[John Rander]

The website says it’s a 4.5V laser, 20mA, 51 resistance(?). I have two 1.5V batteries in series plugged in. I figured I’d be safe that way but I’m no expert.

Steve, from what you say, there is a 51 ohm resistor in series with the diode (its internal resistance is probably around 20 ohms). So assuming even a 4.5V battery and a 2V drop at the diode when it’s lasing that’s 35mA (recall V=IR). Since the batteries also have some internal resistance, you’re safe. If yours works with only a 3V battery there's even some margin, though you may need to go to three cells for longer period use. However, I wouldn’t connect it up to a non regulated power supply (check around on the web for a regulator circuit if you want to go that way).

 

[Steve Chu]

Thanks for the reassurance!