Hey CD,
I was wondering if your team uses anything special other than MDF for workholding on a CNC. We have a Shopbot PRSalpha with an MDF wasteboard, so we currently can’t really run coolant. I was thinking about using something like HDPE or delrin on top of the MDF because we can’t just get rid of it. How does your team deal with coolant on a router?
Are you talking mist coolant or flood coolant?
Most likely mist, although flood cooling would definitely be nice, but the PRSalpha doesn’t have any provisions for flood so it would be “manual”
Our current plan is to use an HDPE spoil board instead of MDF because we have a plastics supplier giving us 50% off. The students have said that they talked to people and heard it should work, but we’ve yet to actually try it.
We do this on our Omio and it works fine.
You could use Extiraboard. It’s an exterior grade MDF and isn’t affected by moisture. Available in 1/2 and 3/4”.
We have run tons of parts with an MDF wasteboard using coolant. It shows obvious wear after the coolant penetrates the top layer of the MDF but we’ve never noticed an appreciable difference in cut quality or had the MDF fall apart on the table.
If you can get it, Extira is a great option. We have a 4’ x 4’ router table. Half of it is covered with MDF for general stuff like polycarbonate, pressboard, and plywood, while the other half is covered with Extira which as George mentioned is basically a water resistant MDF.
Check out https://miratecextira.com/extira-exterior-panels/
We cut all of our aluminum on the Extira side using a fogbuster coolant system. The Extira is really stable, and does not absorb water. We have used all methods to hold down our plate from screws, clamps, double sided tape, to 3M spray glue. All work well and when the surface gets too ugly, a flycutter does a nice job of resurfacing it just like regular mdf. I highly recommend it.
Having said that, we have also cut aluminum on the MDF side which can work well with the fogbuster as long as it is spraying a small amount and not flooding everything. If drops collect on the mdf. It expands and makes the surface uneven. Once dry though you can flycut it flat so mdf can be used if your a bit careful.
Too bad they stopped selling it in Hawaii. I have a couple of sheets left of the stuff and when we run out, I will have to figure something else out. The good news is that it can last a very long time. We laminated two 1/2" sheets and have gone 4 robotics seasons using it. I think I can do one more before replacing it.
Alan
We’ve tested it with HDPE we have in stock, just note if you plan on using wood screws for fixturing it only works when you have a “guide” (like a drilling guide). Seeing as you usually put the wood screw through holes in the plate, that should act as a guide but i thought it was worth noting.
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