Gladius - month of June recap!
Updated: Sep 15, 2020
This month, I've been put a bunch of work into my new beetleweight, Gladius. In this post I'll discuss some more details of the design, and the story so far with the build!
Here's an extra picture of the CAD, this time without the shield lids so you can see what's going on a bit more easily. It should be noted that this is the first machine I've built in which the baseplate is not structurally integral to the chassis. In fact, I'd argue that Gladius doesn't even really have a baseplate - it's more of a "bottom lid" that covers over all the electrical gubbins.
The structure of the machine is therefore entirely maintained by the side panels and the horizontal "ribs", which not only prevent the chassis warping in strong impacts, but also mount the battery and electronics. This is also the first time I've built a robot without a designated battery mount, which in theory will free up some weight to beef up the chassis.
All of these unusual design characteristics are a byproducts of the shield-like design, as mounting chassis parts or electronics to a curved baseplate would be very difficult without 3D printing or machining parts. Employing expensive processes would go against the goal of Gladius, which is to make use of my excess or leftover materials in a creative way.
How will this unconventional design hold up in the arena? Guess we'll just have to find out!
The chassis parts have mostly all been cut and drilled, but not yet assembled. This includes using my trusty surform plane to fillet the side bulkheads - a highly underrated and favourite tool of mine which is excellent for working with HDPE. It is much more precise at cutting chamfers and angles into HDPE than an angle grinder or jigsaw as there is significantly more control over how much material is removed. Granted it is a longer process, but it always gives an excellent finish and accurate result! I've never heard of other robot builders using surform planes for this purpose, but I highly recommend it.
The side spikes, which have been made from 3mm thick aluminium angle, were really tricky to cut. I've just started to realise how difficult it is to manufacture parts that are significantly smaller than the drill and jigsaw being used! Finding sufficient surface area to clamp parts can be impossible if cuts aren't properly planned out. The barrel nuts and shaft collars, which are also really small, have been modified in a similarly fiddly manner. I've had to use an angle grinder to remove several millimetres from both so that they fit correctly in the chassis. The four motor mounts, which are only about 55mm across and 30mm tall, have six holes each which all had to be countersunk!
In total I'd say I've spent about 10 days/afternoons worth of working getting all these small aluminium parts right - I'm definitely looking forward to getting back to HDPE after all that!
Which brings me onto the to do list! The 3mm HDPE shield lids have been cut but have not been mounted. I'm thinking just some wood screws and a blast with the heat gun will secure them in place, with that distinctive curve that Roman shields are known for!
The rest of the decoration has to be done as well. The leather pads (and yes, it is real leather) have arrived, and I've ordered some wood vinyl sticker sheets to give it that authentic Roman look - they definitely didn't have HDPE 2000 years ago!
Hopefully Gladius will be "Rome-ing" it's way into the arena soon!