ShopVac and DW ROS

[jpaup]

I picked up a DW 5" ROS (D26453) at Lowes on sale over the President's day weekend. One of the features I was looking forward to was the ability to attach my ShopVac directly to the ROS. My 16 Gal. ShopVac (90PN575A) had to use a 2.5" to 1.25" adaptor to connect to the DW. I was surprised that within 15 seconds of connecting to the ROS that the ShopVac motor stopped. When I disconneced the ROS and pushed the vac on button the vac works fine. Connect it back to the ROS and 15 seconds later it stops again. Filter and filter bag were both fine.

I have an older 16 Gal ShopVac (90L650A) so I tried the same setup with the adaptor and the ROS and it worked fine. My newer vac (neither are new, say 3 years for one and 5 years for the other) is the model with the water pumping feature. My older vac just had a filter when I tested it with the ROS, so for apples to apples I will need to add a filter bag to test it. Have any of you had similar issues using ShopVacs with small power tools that require a 1.25" adaptor?

Thanks,
JP

 

[CarvedTones]

Yes. You need to let it have more airflow. You have to add a purposeful leak into the system on some models to keep them from overheating.

EDIT - the longer story...

They don't pump air, they move air to create suction. If too little air is allowed to move through, they create too much suction and the pressure drops in the unit where the fan is, which means there are less air molecules impacted by the fan blades, so less resistance. With the lower resistance, the motors spins faster, gets hotter and has less air cooling it. That's not good. So they put in sensors to shut down instead of burning up the motor (and/or your house).

 

[jpaup]

Thanks Andy,

I can remember an old Hoover vac that had a slide away opening at the end of the hose handle that was probably just for this kind of purpose. Unfortunately, the ShopVac does not have this. I tested again just with the reducer/adaptor and though it ran longer, it eventually tripped the motor off. Both my vacs are wet/dry models so they have a drain cap that I can loosen up to allow air to flow. That or maybe just loosen the hose fitting on the vac to let air in there. Any other suggestions that have worked for you (short of punching a hole in the hose)?:gar-Bi

Thanks,
JP

 

[Tarhead]

Here's what I do to decrease suction on my vac for sanding:

Put the tape on for regular vac duty. It's a Fein fitting but any "Y" with a cap would work.

 

[McRabbet]

Before I had a mini-cyclone (once made by ClearVue Cyclones), I used drywall filter bags and a HEPA filter in my 16 Gal ShopVac. My Porter-Cable ROS used a 1-1/2" hose (a standard P-C accessory) and an adapter that fit onto the 2-1/2" hose for the ShopVac -- it drew all of the fines and I did not experience overheating problems. The Dry Wall Bag system captured all of the fine dust and the HEPA filter stayed clean. After I got the Mini-Cyclone, I removed the dry wall bags (they were about $15/pr) and the cyclone was very effective in removing 99% of the dust from any sanding operation. I never experienced any overheating but it was rare that I would sand for more than 1/2 hour uninterrupted.