With that small of a blower, just use the big box 5" hvac duct. There will be NO issue of collapse. There is a picture of a 10ft+ horizontal run of 6" 30 gauge hvac duct collapsed in a dust collector run using a much larger blower. A lot of reference is made to that picture and the cry for the need to use heavy expensive ducting. Instead the cheap and simple fix was to add a plywood ring every several feet (plywood with a 6" hole slid over the duct). This keeps the duct from collapsing, it adds a mounting bracket (use plywood ring to attach to wall or ceiling) and saves a considerable amount of money. The longer the run and bigger the diameter the more susceptible to collapse. A lot of small shop setups have enough joints and fittings that add enough rigidity to need few if any rings (every joint/connection will add rigidity).
Blast gates and hose are available here 5" Aluminum ~$12 http://www.blastgateco.com/Cast-Alum...last-Gates.php
Whyes here ~$13 http://www.simplyplumbing.com/27013-smoke-flue-wye.html (these are actually longer than pictured ~24")
and here ~$20 http://thesheetmetalkid.com/wye-bran...duct-fittings/
These wyes should come un-crimped allowing you to crimp the correct end for Dust collector flow (worth verifying that is still the case before you order)
Last edited by Carl Kona; 01-25-2018 at 11:55 AM.
Hope this helps. Let Us know what you do.
Carl