OMTech 60 W Laser: MDF Honeycomb Pins

Contrary to what I thought, the OMTech 60 W laser’s honeycomb platform gridwork isn’t spot-welded. Instead, it’s many corrugated strips aligned with rods inserted parallel to the Y axis through the strips:

OMTech 60 W Laser - Honeycomb platform structure
OMTech 60 W Laser – Honeycomb platform structure

The silvery rod over on the right passes through holes punched in the grid strips. The black thing in the middle is one of the knife edge bars below the platform; it supports the honeycomb grid and can also hold chunky objects.

Because the grid isn’t a rigid structure in the XY plane, you simply jam a solid spike into one of the openings and have the grid realign itself just enough to grip it firmly:

OMTech 60 W Laser - MDF Honeycomb spike - detail
OMTech 60 W Laser – MDF Honeycomb spike – detail

The shape is inspired by the spikes in AC Wright’s kit of laser workholding widgets, greatly simplified and resized to fit this honeycomb. In particular, there’s no need for a compression slit in the stem, because the grid resizes itself around the solid stem.

Eventually, the corners wear off the stem and it won’t fit securely in the grid, whereupon you throw it out. They’re easy enough to cut from whatever MDF scraps you have lying around, so you won’t form a deep emotional bond.

Likewise, after only a few uses, the sharp point vanishes; a blunt tip would make more sense.

The bottom of the arms locate the top point a fixed distance over the honeycomb, which seems to be sufficiently flat and well-aligned for most (well, my current) purposes. The slanted top of the arms feels more comfortable to push than a hard right angle, at least to my fingers.

These work well when the fumes from cutting MDF / plastic / whatever would blowtorch a cardboard sheet holding metal spikes:

OMTech 60 W Laser - MDF Honeycomb spikes
OMTech 60 W Laser – MDF Honeycomb spikes

The cardboard sheets surrounding the victim maintain airflow from the front opening over the platform surface to where it’s needed, rather than letting it vanish through the honeycomb.

Update: Obligatory Sadler video.

The SVG image as a GitHub Gist:

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3 thoughts on “OMTech 60 W Laser: MDF Honeycomb Pins

  1. I’m super confused about this whole workholding story. I thought the entire point of they honeycomb bed was to provide a flat surface to support the work, take the laser edge-on so as to suffer no damage, and provide a downdraft air flow for smoke evacuation into a plenum below the honeycomb and out the back. Why all this extra stuff and lateral airflow? Or am I just crazy?

    1. AFAICT, the gotcha with honeycomb supports is not having any actual airflow underneath, because there’s no way for enough air to get through the cut line, so the underside of the victim collects soot / smog / gunk and the topside accumulates residue blown down by the air assist jet.

      Raising the victim off the honeycomb with the airflow organized into a horizontal stream across both sides blows the smog away before it can deposit on either surface. This looks like it works pretty well, although the front passthrough hatch must stay open all the time to direct the air across the platform; covering the front of the honeycomb with cardboard (or whatever) prevents the air from falling through the holes before it does anything useful.

      Russ Sadler replaced the honeycomb with a flat sheet of cold-rolled steel and a drilled acrylic plate filled with dowel pins, but I think the honeycomb will be sufficiently flat until I get to some really fussy engraving. Soooo I’ve been fiddling with simpleminded spacers to see what’s least awful.

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