[HOWTO] – Cutting OpenBeam – Small Power Tools

For the crew at Metrix:Create Space, we really wanted to find a tool that is in between a hacksaw and a full blown miter-saw. For this, we scoured the internet for a miniature chop saw and came across the Proxxion micro chop saw:

Before we proceed, I’d like to remind folks that this is a tool where eye protection is a MUST. No project is worth losing your eyesight over, and this is a saw that can toss hot aluminum chips a good distance. I cannot be held responsible for any injury arising from the use of this saw. Wear eye protection, clamp everything down, etc.

To be honest, I am a bit disappointed with Proxxon on this saw. Proxxon markets itself as a “German” tool company – a good portion of their Youtube video features an accented male talking through the tool’s operation and a prominent link back to Proxxon.de – but the saw’s Taiwanese origin and possibly Taiwanese design influences are quite apparent. There are a few major design issues with this saw, and the build quality, as received, was awful. For one, the chop saw that I received was furnished without Loctite on the pulley’s set screw. It’s probably a bit of a bad design to be using a single set screw to tighten the power transmission pulleys on a saw like this (instead of a key joint). However, the design is completely unusable without LocTite on the screw. When we first got the saw, we followed the manufacturer’s recommendation and put on a silicon carbide abrasive cut off wheel (specifically for aluminum – Proxxon No 28729)

Blade on the right was what the manufacturer recommended for cutting aluminum. Problem was, it made an awful racket and we were breaking one wheel per cut made. Upon disassembly, it turned out the set screws had backed out from the vibration from the cut and the pulleys were slipping on the shaft. As the pulley slipped, the shock load to the cut off wheel would just shatter the wheel at the attachment point to the saw. So I pulled the entire saw apart, hand filed down all the burrs left by the set screw spinning loose on the shaft, reassembled it and then Loctited the set screw in place with some Loctite 242 (Blue Loctite) and cranked the set screws down as hard as I can.

Shopping around online a little bit more, I found a carbide tipped 36 teeth saw blade for a micro table saw that Proxxon also makes. (Proxxon No 28732).

Here’s a comparison between the carbide blade that we ended up using and the carbide blade that shipped with the saw. You want a fine teeth (i.e., lots of teeth) on the blade to make for a smooth cut.

We also picked up some liquid BoeLube. Boelube is a cutting fluid that Boeing came up with. Those guys know a thing or two about cutting aluminum.

With the pulleys properly secured, blade securely installed, and the extrusions clamped, we are able to achieve cuts like these:

So what are the other issues with the saw?

Well, for one, the saw comes with the ability to tune the position of the head relative to the clamped piece. I think the designer envisioned people using this feature to fine tune the position of the cut. The only problem is that you really can’t see what you’re cutting with the polycarbonate blade guard in place. (And, under no condition should you defeat the safety guard on the saw!).

And unfortunately for me, the saw was adjusted when it came from the factory in such a way that the blade would cut right through the vise jaws when the saw is pivoted to cut a 45 degree miter:

Oh, did I mention that the vise jaws are hard anodized? As in, destroy your single-source carbide blade as sparks fly sort of hard anodized?

Finally, the placement of the on-off switch is in a HORRIBLE place. In every saw I’ve used, the on-off switch is tucked into the handle to make accidental activation really difficult. Here, the on-off switch is located on the front of the machine. I’ve actually tripped it a few times putting my hands onto the handle, and it scares the crap out of me to think that the saw can be activated accidentally, when I’m making adjustments. To make things worse – this is the ONLY chop saw I’ve used that locks the blade in the UP position. Most chop saws locks the blade down, with a spring loaded guide to protect you from touching the blade accidentally. (To get around the accidental activation, we are wiring a “Dead man’s switch” to this saw station to make sure fingers are completely out of the way.)

Despite all these drawbacks, the saw does cut well once you’ve put some TLC into it. And unfortunately there just aren’t that many manufacturers of micro-sized chop saws. In the next blog post in this series, I will go over in detail the modifications and refinements that we’ve made to this saw to make it a very versatile and useful addition to the Metrix tool library.

In closing, if you treated this saw as a cheap Chinese import tool – i.e., a partially assembled machine tool kit, that you have to disassemble, clean and reassemble, the saw will eventually do good work. That said, this saw definitely didn’t have a cheap Chinese import price tag to match.

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Full Disclosure: I’ve signed up as an Amazon.com affiliates, and if you’re so inclined, you may order items that I’ve recommended / reviewed / mentioned in my blog through the links provided below. I receive a small commission from Amazon.com when you do so and it helps with defraying my R&D costs. Thanks!

Proxxon 37160 KGS 80 MICRO Chop Saw

Proxxon 28732 3-9/64-Inch 80mm Carbide Tipped Saw Blade 36-Teeth

Aircraft Tool Supply Boelube Liquid, 4Oz.

Henkel 01-24200 Loctite 6-ml Threadlocker 242

Loctite 37643 Blue Medium Strength Threadlocker Stick – 9 g