View Full Version : Dust in the controller

07-18-2003, 09:19 AM
Fired up the shopbot this morning, and the motors were humming loudly but not moving on any of the axis. Too early to phone for help, so after cycling it a couple of times with no improvement, I took the side off the case and blew it out with shop air. It now works perfectly again. Scary.

These things run in a dusty environment, yet the back of the controller box is just about wide open. Anyone keep their controller inside a separate box? I'm thinking of a box with a furnace filter on one side for air flow. Will it overheat?

07-18-2003, 10:49 AM
Phil, I built a plywood table boxed in to house the controller and the computer. Furnace filter on the side and a fan on the inside blowing in to create a positive airflow inside the box. Hasn't overheated yet but if I was to do it over, I would put 2 fans in instead of one to be safe.

Moniter goes on top of the case with fibreglass insullation around the hole where the wires lead in from the monoter and the shopbot. Also had problems with a mouse clogging up and bought a 3x3 touch pad and the whole thing has been trouble free. If you need convincing, look at intake side of the filter in about a week!

07-18-2003, 11:18 AM
I have nearly the same setup as Jim. I bought a $50.00 birch cabinet at Lowe's, put a large top on it and some wheels so I could move it. I then built a box with a strong fan on the outside blowing air IN to the cabinet and used a furnace filter to trap dust. Monitor, again, goes on top. This setup creates higher air pressure inside the cabinet....thus creating a pretty good barrier to dust as air is constantly pushed out of the cabinet. The drawer and door on the cabinet are bonuses for access and storage....costs about 125.00 total to build.....D

07-18-2003, 12:30 PM
re: mice - I've been using an optical mouse since the beginning. No dust problems there.

Building a box for the PC & controller sounds like a good idea then, as long as I get sufficient airflow.

Once I got it running this morning, no further problems, but I did hear a big electrical "snap!" come from the controller box so will need to do further investigation of what's going on in there.

07-18-2003, 02:23 PM
I cut a hole in the side of my case mounted a fan on the inside, put a garden tracker filter on the outside with a board on top covering it. Two bolts with wingnuts hold it. I leave the fan running all the time. Oh, I also blocked (with poster board and tape) all the holes in the case except the one for the powersupply fan. Now all air enters the side through the filter and exits out the powersupply. It cost me about 10.00 since I already had the fan.
I was not so lucky when my shopbot stopped it was toasted.

07-20-2003, 12:19 PM
An interesting site is dirtbag.biz .


07-20-2003, 10:38 PM
I've used material from home depot for keeping sand out of septic drain field pipes. I've used it around my airconditioner and on my shop pc. It works very well at keeping very fine sanding dust from getting into the equipment. It also is extremely economical. You can by it for penny's by the foot. It looks like the dirtbag material probably not as good though. But for its price you could probably have several layers for more effective filtering.

07-21-2003, 07:30 AM
David, Do you remember the name of the filtering product from Home Depot that you used or in which dept you found it. Thanks, Pete

07-21-2003, 08:11 AM
Around here the proper name is non-woven geotextile (http://www.google.com/search?hl=en&lr=&ie=UTF-8&oe=UTF-8&q=geotextile%2Bnonwoven&spell=1)(or geo-synthetic textile, but the guys at the hardware store will laugh if you ask for that. Our popular brand name is Bidem, but I don't know if that applies in your country.

07-21-2003, 11:12 AM
Phil, your ShopBot Control Box and PC will over heat if you don't have enough air flow to remove the heat from the enclosure. I've installed many control boxes into boxes with furnace filters on both sides to allow air to flow freely through the cabinet and make accessing the cables and the front of the control box easier. This arrangement is also nice if you want to fasten the box to the wall and get it out of the way. Getting the PC and controller up off the floor is also a good way to keep the amount of dust that gets into it down.

A DirtBag filtered enclosure or similar material is a good economical way to add some protection to your PC and control box. The DirtBag is just that, a bag that the control box slides into with the opening in the back. Then closed around the bundle of cables. They come with a handy Velcro strap for olding it closed. The manufacturer claims that they will last 6-12 months, but I'm not sure if this is with cleaning or not. We have just gotten one in that we're testing. I'll post more once we have a better idea of how well it works.

I've seen some unique enclosures, some with more advantages than just dust protection. One of those that was fairly simple and effective was built on an old wooden table. They cut holes the diameter of the fan in the top (using their ShopBot of course) and below them mounted the fans and then put a filter over the whole array of fans. There were 4 in all. There was also a hole in the table to pass cables through that they packed with foam once all the cables were in place. On top of the table was a sloped box with a plexiglass panel in the front and filtered holes for the hot air to escape at the top of the back. The top was then placed over the PC, monitor, control box and cleats that were screwed to the table to prevent it from sliding. With the keyboard and optical mouse outside, the plexiglass panel allows them to see the monitor and a power strip to turn the power on from outside. It was very effective at keeping the dust out and if you had someone to help you lift it off made it very easy to access all of the units inside. The biggest advantage to a system like this is that they used positive pressure to keep the dust out. The only problem they would have had if they didn't transfer all of their files over a network would have been access to the floppy drive, but with a positive pressure system you can put in a door for access to the floppy or CD-rom drives with out compromising the system.

Why use a positive pressure system? The biggest advantage is that it forces cooler air into the enclosure that contains your PC and control box and in some cases the monitor, not relying on natural convection to move the hot air out. They are also a lot more forgiving on the how tight you have to construct your enclosure. Because they use positive pressure to force air into the enclosure any doors or holes that are in it allow air to escape and push dust away from them as opposed to a negative pressure system that would suck dust into the enclosure should there be any unfiltered openings. The disadvantage to positive pressure systems is that they're more complicated and costly than a simple filtered box.

For those ShopBotters that have the luxury of a room next their ShopBots the ultimate in simple and effective dust protection is to put the control box and PC in a room away from the dust. The mouse, keyboard and monitor can be brought out to the tool with extension cables or the monitor can be placed behind a window and just the mouse and keyboard brought out to the shop next to the tool.

Which ever method you use to keep the dust out of your PC and control box make sure that it doesn't get too hot inside.

07-21-2003, 12:05 PM
Or, you could run a duct from a clean area, and blow clean air into the box that houses your electronics - no filters at all.

07-21-2003, 02:42 PM
Pete, I don't know the name, but it is in the same department that has septic pipe. I quess it was plumbing. I hadn't seen it in any stores until I moved to Florida. The soil here is 99.9% sand so filtering it out is a necessity. They may not have in all parts of the country. I'm sure you could find it with Geralds link though.
I don't get into town too often so it might be a long wait until I could get you the name. Let me know if you find though.
Gerald, Even a clean room(non wood shop air) has a lot of dust that will be sucked into the box. Seems like filtered air from a cleaner room would be the best.

07-22-2003, 12:17 PM
Hi Gordon,

What would be the "ball park" maximum temperature for the cabinet be?

07-22-2003, 01:37 PM
Sheldon, my guess is that it would be around 40 centigrade (a high room temperature for a standard PC).

07-24-2003, 08:12 AM
I just built an enclosure for my computer and controller box last night. I used a bathroom exhaust fan from HD that cost 13.00 and moves 50 cfm. I used a 12x12 filter attached to the intake of the fan and it moves enough air to blow the door open a little bit. I have taken hands full of dust and tested the box and it works great.

Thanks to all for the warnings about this serious issue.