Keeping CNC Tables Clean
CNC owners describe onion-skinning, second passes, and other inventive methods to manage dust in router operations. December 8, 2010
Question
Do you onion skin every part to keep the spoilboard clean? Or do you just blow it off? I hate a dirty working environment.
Forum Responses
(CNC Forum)
From contributor J:
Yes, I do onion skin everything and it helps a lot, but you still need to blow it off. Try it - see if you have the extra run time. I recommend that you have a floor sweep in back of your machine to help clean it.
From contributor A:
I only onion skin parts small enough to need it. I'll pull parts off the table, use a piece of 1/4" scrap to sweep the bulk of the remaining dust into a bin at the end of my table, then shop vac the rest before I load the next sheet. The sweeping and vacuuming takes about one minute per sheet. Beats blowing. The dust from blowing ends up landing everywhere in the shop.
From contributor O:
If you don't mind the extra run time, run the 1/2" compression around the toolpath a second time to just pick up the dust.
From contributor M:
For the vast majority of shops, it is worth the time to second pass whether with an onion skin or just in air next to the part. I use a full upcut for my second pass customized at my tool supplier so that the last 1/4 inch or so is full diameter, the rest is turned back a hundredth or so for clearance at the top of the part to eliminate chipping. For large parts I run the upcut a second pass but do not actually touch the part; it leaves a slightly cleaner edge.
Takes care of 99% of the dust. I supply a commercial 10 man shop with all the parts they need and do all of the programming as well. The machine is idle over 50% of the time even at that. I figure I could easily supply parts to 20 men on the shop floor without changing anything about the tooling strategy. Time is rarely the issue on our machine.
Besides hating dust everywhere as well, I think the air quality in most shops is bad enough without introducing even more dust.
From contributor R:
I've spent nearly 15 years working around CNC machines, running them, installing them, etc. This is the biggest issue yet to be solved. For my current clients, I recommend using two spoilboards and a rolling off-feed table the same height as the router bed. When the program run is finished, the spoilboard and parts are lifted off as a unit, and the second spoilboard is set in place with a new sheet of stock. While the CNC mills the stock, the operator can be cleaning and prepping the next run. This is not always easy to do. Some machines are more amenable than others, but with a bit of creativity it can be done.
From contributor P:
We recently purchased a tool holder that incorporates a dust collector in the housing. It was amazing. The problem we had was that it required a diamond bit and a special tool to change it. These bits are very expensive and if you hit a bit of trash, they are ruined. The concept is unbelievable and works extremely well. After our second bit broke, we went back to the dust filled shop, but I understand they have just developed the technology to utilize carbon bits, so we will be going back to using the tool holder. Fascinating really, how well it works.
The tool is called an Aerotech and is manufactured by CRUING Italy. The tool holder is designed to glide 2-3MM above the surface being cut, and it leaves just a film of dust to deal with. We used to shop vac the table after each cut, but didn't need to after buying the tool. It is apparently distributed through a Canadian company called PS CRUING Corp. Our tooling rep introduced us to the product and, to be frank, it was a hard sell because of the initial expense, but after seeing it work we made the purchase. The tool holder with the diamond bit ran approximately $1700 if I recall correctly. The diamond bits were around $600 - $700 each.
