How to connect flex hose to metal duct

[Barry Lyndon]

I am almost finished with my central dust collection system but I'm having an issue with a couple drops. Is there a trick to connecting flex hose to metal duct work? I have my drop going from 6" to 4" using a reducer and I need to go from that to a 4" flex hose. The flex hose doesn't slide onto the 4" side of the reducer without crimping so I crimped it and the hose fits on fine but then I put a wire clamp on the hose and, since the metal duct is kinda cone shaped now, as I tighten the screw on the wire clamp the wire just slides off the metal duct. I've tried taping it first and then wire clamping it which held for a few hours but eventually fell off. What's the trick?

Also, another quick question, most of my drops are next to concrete walls so I can't really anchor anything like the blast gate to the wall...It seems to me like there is an awful lot of weight hanging down from the main line that is essentially held just using tape and wire clamps. Is this how everyone elses drops are? Is that the best way to handle them? Just lots of tape?

[Jim Tobias]

Barry,
I just used some 4" clear flex hose to attached to a 6" to 4" metal reducer on my overhead tablesaw dust collection. It is hard (at least in my experience) to get the flex duct over the meatl duct. I found that if I almost used the spirals in the flex duct like an inside thread and twisted it continuously down onto the metal reducer. It worked it self down into position and then a hose clamp worked great.
Hope I explained this in a way that makes sense.
Jim

[Lee Schierer]

Take a piece of 4" duct and cut it about 4" long. Roll it up so it fits inside the inside of your reducer. It should also fit the inside of your flex ducting. Tape the seam with aluminum foil tape inside and out as you assemble the joint and you should be good to go. This trick also works with 4" pvc and flex ducting.

[Bruce Wrenn]

For fastening the blast gates to the concrete wall, use Rockler's Blast Gate Brackets, mounted with a couple of concrete anchors. Brackets are about $4.00 each. Instead of hose clamps, I use "zip ties", that HF sells hundred for $1.99, when they are on sale.

[Greg Roberts]

I had some 3" long collars made up to a good size for the inside of the 4" flex hose. I had an outside bead molded into on one end so when I slid the hose over the bead and tightened the hose clamp, it couldn't slide back over the bead and fall off.

Greg

[David Hostetler]

I am setting up my Thien Separator to use 5" metal duct between the DC and the separator. I am using those crimpers that give the wrinkle end to the duct to reduce it's size somewhat. I am also heating my flex hose end up slightly with a hair dryer to get it to stretch a little bit. Once the hose is on, hold in place with a self drilling screw, a clamp, and if there are any leaks, a dab of silicone. Once I get out of the separator I go to the OEM 5x4x4 Wye that came from the DC, and all my 4" duct is S&D PVC. My 4" flex line just slips over...

[Barry Lyndon]

Awesome, thanks for all the tips guys. I ordered some of those brackets from Rockler so we'll see how those work out. I have the whole system put together now but I'm sure I'll have some adjustments to make in the near future.

[stephen stidd]

I added heat to the end of the hose via heat gun to make the hose more pliable....seemed to do for me.