Slot port w/ round corners - ideas?

[bmaupin]

I am making a box for a RSS315HF - 80L w/ 27" long slot port that has a bend at the bottom rear and exits at the top rear. I was wanting to round the corners to reduce turbulence. I was thinking about using 1.5" PVC cut into 90deg sections, but cutting the PVC pipe precisely may be a challenge - haven't tried yet. I was also thinking about using some scrap veneer - press into the corner with pvc pipe to hold it in place until the glue dries.

Any better, easier ideas?

[AMC]

Use your PVC pipe and get some Bondo. Use the pipe to get into reasonable shape, then sand smooth.

[diy speaker guy]

Anything is better than nothing, even if you just round over the edges with your router. Bigger is better though, especially if the ports are undersized to begin with, so I look forward to picures.

[killersoundz]

Why not just get a huge 3/4", 1" or 1.25" radius round over bit? Trying to cut peices of PVC and glue them to make a round over probably won't turn out too well in my opinion and be a large pain in the ****.

[RINNAV]

use a decent thickness cardboard tube (like mailing tube) glue it in place and use a FG resin to strengthen... It works pretty good.:) I would think a bigger radius would be better; would a 2-2.5" tube work?

[biff]

You can get high radius roundovers from Rockler in, 1.5", 2", even 3" radius pieces - that would take care of the inside, which I think would be fine in this instance. If you wanted to use PVC, you can hot glue scrap on either side and run it through a table saw and get good centration and a reasonably safe method that will give you the inside of the turn and the outside. I have just notched out a lip on theflat surface the thickness of the pipe wall with the router and set cut pvc in the lip for a smooth transition making bookcases.A little caulk on the lips of the tube abd you should have a smooth flow with the radius matched to the section of the port.

[daver]

Check out the corner trims in the moulding selection at the lumber yard. Not sure what radius selections are out there, but something like this could be glued or tacked in the corners easily.

[Chris Roemer]

I am making a box for a RSS315HF - 80L w/ 27" long slot port that has a bend at the bottom rear and exits at the top rear. I was wanting to round the corners to reduce turbulence. I was thinking about using 1.5" PVC cut into 90deg sections, but cutting the PVC pipe precisely may be a challenge - haven't tried yet. I was also thinking about using some scrap veneer - press into the corner with pvc pipe to hold it in place until the glue dries.

Any better, easier ideas?

The air will make it around the bends without you helping it, really. Using a roundover at the exit will do the most good for the effort.

[fastbike1]

Are you trying for something like this?

[Bob Brines]

I routinely put round-overs on all interior edges because it looks nice, but the reality is that at low frequencies, the air column could care less. I have demonstrated to my own satisfaction with folded TL's and TQWT's that smooth bends make no difference at all to the bass but allows MORE treble leak out of the port.

Now the OP has a somewhat different situation with a long resistive port, so it could be different. I am willing to bet, though, that there will be no affect in the port FR. Only the builder will know that there is a radius inside.

Bob

[bambino]

Check out the corner trims in the moulding selection at the lumber yard. Not sure what radius selections are out there, but something like this could be glued or tacked in the corners easily.

If your set on doing this then i like davers idea best otherwise i wouldn't even worry about it and just use a roundover bit at the exit.

[davepellegrene]

I used the pvc in a build similar to what you are describing. except I made a 180 degree turn instead of 90. At the time I was told the pvc pipe really made no difference as mentioned above. If you still want to do it you could do it as simple as setting your table saw on a 45 degree angle and ripping a scrap piece of wood triangle shaped to fill the corner.
Dave

[bking]

If you are, then why not line the port with 3/4" x 3/4" solid wood that matches the veneer? Of course the rough opening would have to be 1-1/2" larger in both dimensions to accommodate this. Then veneer the cabinet. Finally using a 1/2" or 3/4" roundover bit, round over the edges of the solid wood that lines the inside of the port opening.

[bmaupin]

Thanks for the replies everyone. I am planning on using my 3/4" roundover bit on the inside corners, I am only concerned about the outside corners, but not so much now after reading responses. I like the idea of putting something in the corner and using veneer over it to make the transition smooth. I'll see what is easy - after I stop by Lowes on the way home.

I may just have the exit come out the top of the rear and avoid the final 90deg bend, but it sounds like worrying about the bends is unwarranted.