4" Dust Collector to Bosch 4100 2.5"

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Forum topic by Sunstealer73 posted 353 days ago 842 views 0 times favorited 7 replies Add to Favorites Watch
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42 posts in 717 days

353 days ago

I finally bought a dust collector after using a shop vac for a while. The last straw was a recent project with lots of melamine that made a huge mess in my shop. I went with the Harbor Freight model for $150 with 25% coupon. My shop is multi-purpose car/wood, so I can’t really install permanent lines for now. My planer and joiner both hook up easy with the 4” flex hose. I am running into a problem with the Bosch 4100 table saw though. The built-in dust port is 2.5”, but the adapters I bought are too bulky to fit correctly. They hit the plastic around the port. I modded a shop vac hose that is small enough to fit inside the port, but the suction drop is terrible with that setup.

What type of adapter do I need to go from the saw’s 2.5” port to my 4” hose that is small enough to not hit on the plastic around the dust collection port?

7 replies so far

View Shawn Masterson's profile

Shawn Masterson

1253 posts in 573 days

#1 posted 352 days ago

go to the plumbing section at the local BORG. you will find fernco's They are really great for bastard conections

View josephf's profile


52 posts in 721 days

#2 posted 346 days ago

cut a bigger hole and add a 4” port .

View Splinter12's profile


51 posts in 740 days

#3 posted 346 days ago

I liked that saw but hated the dust collection, good luck.

View fuigb's profile


178 posts in 1582 days

#4 posted 346 days ago

Sun, you might be out of luck. I’m in a similar place, starting with the 4100 Bosch and down to the lack of a dedicated shop. The connection problem can be overcome with one of the universal adapters made of rubber (ten bucks at Menards or Sears) or the Fernco. However the real problem, I’ve found, is that the 4100 is a bugger to close off and thereby get sufficient suction to grab the dust and chips. I run a 1 3/4 horse Powermatic collector that is awesome but cannot gets it’s arms around the 4100’s dust. Best I’ve been able to do is to plug as many of the holes as is possible with rags and pipe insulation, and then I’ve adapted a piece of cardboard to fit across the bottom of the saw. Thus I’ve gone from capturing maybe ten percent of the dust up to 30 or 40’percent. Next gauntlet that I’ll drop is a hose hooked to a hood, but really the best option is to just roll the damn thing out to driveway and then clean up with a broom.

-- - Crud. Go tell your mother that I need a Band-aid.

View Grandpa's profile


3071 posts in 1300 days

#5 posted 331 days ago

Are you sure the problem is a leak or is the vacuum “cavitating”? That is what it is called when a centrifugal pump can’t get enough liquid to pump. When the vac can’t get enough air to move it moves nothing. Try opening more blast gates or allow more air to get into the system.

View jshroyer's profile


3 posts in 283 days

#6 posted 283 days ago

I have added cardboard to the bottom with a small opening at the back. Also for the dust collector i dont have a large shopvac (1 gal, 1hp, fills up in around 15sec) and am waiting on getting one so i have added some super cheap blue HVAC filters to the back of my table saw. It makes the shavings hit it and drop to the ground into two buckets i have sitting there. not very fancy or efficient but works for now. Just really bad when i cut a lot of stuff.

View b2rtch's profile


4309 posts in 1673 days

#7 posted 283 days ago

Cut a bigger hole in the table saw( 4”).
Restricting the air flow to much will just cause the DC to cavitate and to not work at all.
I had the experience going from 6” to 3” with my Clear View, with a 3” restriction it just quite sucking all together.

-- Bert

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