My 55 Gallon Top Hat Separator

[timstring]

Here's my attempt at a 2x top hat separator.  I used 3/4" plywood for the top and the baffle, only because I had a sheet of 3/4" laying around the shop.  The walls are two strips of 1/8" tempered Masonite (hard board).  I used that instead of acetate because a 4' x 8' sheet of 1/8" Masonite is $8.77 at Home Depot and enough acetate to do the job would be about 30 clams, and I'd have to contend with a seam somewhere.  The walls are seamless.  They are sitting in a 3/8" dado on the lid.  (So sorry; I didn't even think of taking a picture of the underside of the lid before I put the walls in.)  Jamming the Masonite into the dado on the lid was fun, because even though Masonite is quite flexible, it's also very springy.  I had to clamp the lid to my work bench to keep it from running away from me while I was trying to seat the walls in the dado.  After the glue had a chance to set, I painted the chamber because I'm frequently milling green lumber and I want the inside protected from moisture. (Just call me paranoid.  I am a belt-and-suspenders sort of guy.)  Fitting the walls into the dado on the baffle was also a challenge because the walls had flared out a bit at the top.  I used a ratchet strap, a hammer, and a few choice words to get the walls mated to the baffle.  I used Titebond III, so I had plenty of working time before the glue had a chance to set, and eventually, I prevailed.  I also used polyurethane window sealer around the walls and the input.

The only real technical data I have is that the walls are 2x the diameter of the input.  The baffle is 2" wide, just so if I run some sort of stringy wood through my planer, the slot should be wide enough for the chips to fall through.  I left the center hole open at the bottom of the baffle so if I need to widen the slot, I can use my circle jig on my plunge router to do that.  The slot starts 120 degrees from the tangent point of the input to the side walls, and runs 240 degrees, stopping right under the input.  Since the only 4" flex hose I have is pretty beat up, I dismantled my dust collector and sat it right on top of the cyclone.

My one question is:  How far should the output pipe extend into the chamber?  Currently, mine is 3" from the top, but this is just a number I pulled out of thin air.  Do any of you have any experience to say that one distance works better than another?

[retired2]

I'd put the outlet pipe at a level that is just below the top of the inlet.  Also, if you are milling green lumber I don't like your thick baffle plate.  You may get away with it because your drop slot is so wide, but the end of the drop slot is where plugs start, and the thicker the baffle, the more likely it will happen.

Round the end of your drop slot. The square corners will make it more likely that snags will occur.  Also, the best way to fix the thick baffle is to take a wood rasp and undercut the edge, especially at the end of the drop slot.  Use wood filler if necessary to smooth the results.  Plywood won't take kindly to filing.

[timstring]

Thanks for the tip.  Everything is so-far-so-good, but then I have 33 board feet of rough hardwood laying on my shop floor, just waiting for me to get my planer fixed.  Should I need to thin down the baffle, I have a 3-horsepower router and a bottom-cleaning bit that will make short work of the task.  That's why there still is a hole in the center of the bottom of the baffle, so I can use my circle jig to turn that plywood into sawdust rapidly.  Forget the rasp and wood filler.  Who has time?

[tommitytomtom]

My outlet pipe on my own 55 gallon drum collector is about 3" into the top. the drop slot ends at just be fore the inlet as well. So far, results are promising. I have a 3HP HF collector. I have yet to underscribe or chamfer the drop slot but I feel this is a good idea. I don't mill green lumber but my jointer will be connected to this unit. I'm still up in the air about a permanent mounting location. I used the original platform from the 2 bagger DC so the footprint is the same.