Shop-vac heat issue

I’m concerned with how much heat is generated by my shop-vac while running continuously. I have it located under my build table, and even though it’s in a walled area with over 6" of space on each side with the top open allowing 4" of breathing space to exhaust, it still gets very hot. I tried running it last night with its enclosure door open, and it still got very warm, just as quickly.

I thought the air being vacuumed up the hose cooled the motor (for an ever-changing air volume), but evidently, vacuumed air is exhausted out the back… and the motor is only cooled by air circulated under the hood/top… which appears to be inadequate for long, continuous duty.

I hate to leave this thing running more than 10-15 minutes, but I’m planning on cutting some big jobs, and I need it running during the duration to keep dust and chips down.

I’d hate to abandon my dust collection system and custom dust shoe, because the vacuum can’t handle it. :frowning:

Shop-vac’s are not designed to run all of the time. They will die, so look at investing in a dust-collection system. Sorry for the news. :wink:

There’s a bit of discussion about Dust Collectors in the Glowforge thread in the laser section.

Well, boo. :frowning:
I guess I just need to build some guards to keep chips off my Y-axis and just count on cleaning up after each process.

I wonder if I could get a VFD control and cut my shop-vac speed down to a slower speed to reduce heating… but I’d reduce it’s vacuum power, too. I may not win this one.

Dust Collectors require much larger diameter hose than 1-1/4", right? They’re about “flow” and not as much about sucking power, right?

Yes, they seem weak compared to a shop vac, but they move a lot more air and make a lot less noise !

Here’s a good description of the difference between dust collectors and vacuum cleaners from Highland Woodworking:

Shop Vacs vs. Dust Collectors

When I hooked my dust collector up to my sander, the built-in dust extraction system hardly worked at all. Is there something wrong with my dust collector, or is the problem in the sander’s dust pick-up design?

The problem is that your dust collector simply can’t pull a useful amount of air through the sander’s 1" port. Starved for air, the impeller cavitates and lets the sander blow dust as usual. Movement of air through vacuum sources is measured two ways: cubic feet per minute and static pressure. Static pressure is a measure of how forcibly the vacuum source operates. Dust collectors typically move a great deal of air, generating the high-speed draft needed to grab large amounts of waste from relatively diffuse sources. They don’t develop much static pressure, however. By contrast, shop vacs generate very high static pressure, but they usually don’t move a lot of CFM. Hook your shop vac to your sander, and you’ll see the kind of performance we’ve enjoyed here. The vac has the static pressure to pull a high-speed stream of dust-laden air through the sander base; its modest CFM rating is quite adequate for the small source area through the perforated paper. The only drawback is having to listen to a screaming shop vac.

Of course, they went into a short commercial for very quiet shop vacuums that start at $500 and go UP.

I have a 3hp dust collector for my woodworking tools but it’s worthless on a 1.25" hose for my CNC. The noise of a shop vac can be mitigated with an insulated enclosure. How long a shop vac will last under continuous duty is anybody’s guess.

Yes, you’ll need to get some type of dust collector or shop-vac with a higher duty cycle (the percentage of time it’s designed to run for).

I’ve also found a pre-cleaner to be useful. The “Dust Deputy” I use collects that vast majority of dirt & dust before it gets to the filter in my Shop-vac. I’ve had to clean the stocking I have over the paper filter in my shop-vac only once in the last 6 months - even though I’ve emptied three or so buckets of sawdust from the pre-cleaner.

If nothing else, it’s easier to empty & clean than the vacuum and I also have full suction 99% of the time, even when making dust by cutting MDF.

Bill, that is interesting. I have noticed that my dust shoe works better when I leave the second 4 inch port open. Common sense made me think that only having the port connected to the X-Carve would be best, but when I leave the second (unused) port open the amount of air (and chips) being pulled through the dust shoe increases dramatically.

I had not considered cavitation in the impeller but that may have been the cause.

I have an idea to use a high-volume dust collector solution with my table/enclosure. My biggest concern is keeping my ways clear of dust/chips… particularly the Y-axis.
I’m thinking that maybe if I add spacers to my enclosure (lifting it up off the work surface) to allow air to be drawn in all around my machine toward a dust collector hose at the back of the enclosure, it may keep the enclosure more dust free… sweeping inward constantly with a stream of air and drawing everything airborne toward the dust collector inlet.

@coryalex - I found a pretty good solution. Before, i would buy a new shop vac every year at around Christmas time from a True Value Hardware store - they were $39. NOW I have a Rigid shop vac. It is quieter, way more powerful and has an exhaust muffler that can extend outside of your cabinet. It also has a lifetime warranty. Mine has been plugging away for more than a year and doesn’t get TOO hot even on impossibly long jobs. The good filter, good filter bags and muffler have really, really cut down on dust.

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I thought a similar thing, I have several of these in different sizes . My thought was several holes along the front of the cabinet just above waste board height, maybe 1" diameter spread evenly across the width. to create a air current front to back.

I also read in one thread, possible in the cutting aluminium thread, about some a cabinet that had air suction at the back of the cabinet, and then the air entry was hosed down to the bit using lockline. In effect creating an air jet at the bit blowing the waste towards the back of the cabinet. My idea above was a thought to recreate that idea without having to use hoses :wink:

I don’t have my X-Carve enclosed, but from my experience with just a dust shoe, dust and small chips really stick to the belts (static charge?) if they touch them. So having a high air flow moving through the enclosure may stir up the dust and allow more of it to contact and stick to the belts.

Wow! $99 bucks. I payed about $50 for mine through Amazon.

I’ve seen what you described happen at my router table. I have a 4" dust collection hose below the table and 2" at the fence. The fence hose does little unless the lower gate is open also.

Although I have a 4" DC gate at my CNC, I don’t plan to use my 3hp DC for the CNC - it’s just too much power consumption and heat buildup. I could run it all day long without concern for its health, but a smaller shop vac will be better. I have a shop vac assigned already but haven’t built a dust shoe yet; one more element and I’ll get that done. I also have the parts to build a control box to trigger the shop vac on and off with the spindle control logic.

@ScottWillis, didn’t check price, just posted the first link Google provided.

Nonetheless, Aussie pricing for everything is usually significantly higher. Dunno why, look on the map; if you travel to Australia, it’s downhill nearly all the way!

I’m thinking of giving one of these Router Speed Control modules a shot.
The shop-vac produces a LOT of suction, and with the dust shoe, I can definitely get away with less.
Router Speed Control Dial
It’s worth $20 to give it a shot, right?

I wouldn’t waste your time personally. You can get $99 dust collectors that have a 4" snout and sit on 4 little casters. That’s what I have. It’s something like 1/2hp. It sucks up wayyyy more dust than my shop vacs and takes less space. The hose is a pain though cause it’s so big. But it’s worth it. I have 20ft of hose (a joint at 10ft) and quick fit connector on the end. I just pop it onto my table saw or bandsaw or what ever I’m gonna use. I couldn’t justify spending lots of money on a big DC unit and was scared to buy one of these. But it exceeded my expectations despite being a runt compared to a real DC.

I really can’t explain how much better it is. Can run all day and quite.

ETA- mine is like this, but smaller yet. And it’s a King brand from Canada. I’m pretty sure you can find them cheaper than this:

The cheapest thing I can find is a 3/4 HP one for $139 (+$23 shipping to the US)… there are also some 1HP ones in the $175 range. Definitely want something like this myself - I can currently just holding my shop vac hose and running it occasionally during the job while I work on some dust shields and a shoe.

Not sure how common it is, but my vac has an outlet on the front. Plug the vac into the mains, and plug the Router into the vac. When I turn the router on, the vac starts. Turn the router off and 10 seconds later, the vac shuts down.

Not a biggie, but it’s a handy feature…