reduce friction between sled and material to reduce drag while moving (especially along the sides)
Strategy:
After reading this forum topic (Vacuum Sled Experiment) I was inspired into experimenting with a hover add-on for the sled. The concept is very similar to the basic function of an air hockey table, a quick search on youtube revealed multiple diy build videos so the following design was made:
*this is actually the second design. The first design had an even spread of holes and no slots, but I quickly realised that the most weight will be on the bottom of the sled where the bricks are, so I re-positioned the holes and added the slots to optimize flow
I’ve attached it to the sled so far and tried feeding the blow air from the shop-vac through the top existing hole. It works, BUT, the pressure struggles as-is even without weights
the fundmental problem with this approach is that the air layer is going to be a
different thickness based on what cut the sled is over, and that will change
your cutting depth.
That is true, however we’re talking very small numbers.
A puck on an air hockey table requires a 0.2mm lift to be considered playable, and personally I feel that is an acceptable loss of Z accuracy for better X and Y calibration.
In the video, with the airflow off and no weights, a small rubber band can’t move the sled.
Friction is greatly reduced after the airflow is turned on, allowing the sled and an extra 5Kg weights to be dragged by the same small rubber band.
I am now re-designing the add-on to optimize air-flow and pressure, So far the new design looks something like the image below. More testing will follow
Also I have updated to a “bouncy castle” blower, reason being that the small handheld would stay on for only 10 minutes before overheating and smelling like burnt plastic, but this new blower can stay on all day and moves a lot more volume of air (and makes WAY less noise too).
A quick test shows how the airflow improves greatly the sled movement (Apologies for the rough “video production”, but I was in a bit of a hurry).
Vertical movement in the video with airflow off is quite jumpy and jerky in certain spots. Once the airflow is on, the sled movement smooths out. Calibration tests all result to max 1mm accuracy.
Time to test accuracy with a light pendant project I’ve had in store for a while. Updates to follow
@AlexLikesPizza are you still using this design or abandoned it? How do you handle sawdust and how does the sled act when sliding over pockets and other cuts?
@AlexLikesPizza Bumping this as I’d love to hear how this is working for you these days. Have you run into any issues or made modifications since you last posted about it?
