Optimum Drop Slot Size for 12" Jointer and 20" Surface Planer

[ORBlackFZ1]

I just finished my Top Hat separator.  It works much better than my previous in-barrel design.  I also created it with 6" ports for both inflow and outflow.  I used a 1-1/4" drop slot.  Over the first week of using the new separator with my 12" jointer, the chips sometimes get stuck in the slot.  I am assuming that once I test the Top Hat separator with the 20" surface planer, I will get the same problem.

Here is my question to those of you that have created a Top Hat separator and are using it with a 12" jointer and/or 20" surface planer.   

What is the optimum drop slot width for using the Top Hat with a 12" jointer and/or 20" surface planer?

Thanks,
Eric

[alan m]

the drop slot width is a compromisse between wide for choips and shavings and a narrow slot for dust,
im guesssing that the shavings build up at the end of the slot where the solid part starts.

what thickness is you baffle plate. i heavily tapered back that area to reduce that happening.
if you are not worried about fine dust  as much then widen the slot by 1/4 " .

[alan m]

i just saw your post in retired 2 s thread.
another thing that could cause issues is that you have a rond pipe entering the  seperater.
if that was a rectangular transition it would spread out the chips more  and not have a big lump of chips hitting that end of the drop slot.

[retired2]

I think Alan has pointed you in the right direction.  Are the hangups starting at the end of you slot?  That is the one place where a very thin baffle(like sheet metal) is more likely to snag stringy chips than a slightly thicker one(like 1/4").  Whatever you are using, make sure the end of the slot has no sharp corners, round it over in ever direction to make it less likely to grab chips.

[ORBlackFZ1]

Alan:

Thanks for the quick response.

the drop slot width is a compromisse between wide for choips and shavings and a narrow slot for dust,

I was afraid that would be the answer......

im guesssing that the shavings build up at the end of the slot where the solid part starts.

Yes, and then the whole slot fills, if I don't stop the jointer and clean it out.

what thickness is you baffle plate. i heavily tapered back that area to reduce that happening.

My baffle plate started as a 1/2" thick piece of plywood.  I put a 45 degree camfer on it and sanded it to 220 grit to smooth it out.  I think that I will work on the end of the slot to make sure that it is as thin as I can get it, since that is where the clog always starts.

if you are not worried about fine dust  as much then widen the slot by 1/4 " .

Fine dust is definitely a priority in my shop!!!  Maybe I will have to create another Top Hat for use with the jointer and planer.

[ORBlackFZ1]

i just saw your post in retired 2 s thread.
another thing that could cause issues is that you have a rond pipe entering the  seperater.
if that was a rectangular transition it would spread out the chips more  and not have a big lump of chips hitting that end of the drop slot.

Here is the link to a better photo.

http://www.jpthien.com/smf/index.php?topic=1094.0 

In the first photo you can see that the 6" round port gets transitioned to a 3.5" x 8" opening inside the separator. 

I determined the rectangular dimensions by using the area of the 6" pipe.  Hopefully, my math calculations where correct.

Pi r squared = 3.14 x 3 x 3 = 28.27 sq inches
3.5 x 8 = 28 sq inches

The transition is over a 14" length and is lined with a very slippery surface to reduce the turbulence.

[ORBlackFZ1]

I think Alan has pointed you in the right direction.  Are the hangups starting at the end of you slot?  That is the one place where a very thin baffle(like sheet metal) is more likely to snag stringy chips than a slightly thicker one(like 1/4").  Whatever you are using, make sure the end of the slot has no sharp corners, round it over in ever direction to make it less likely to grab chips.

Retired2:

I think that you have the answer.  The end of my slot could be thinner and smoother.  I will work on that and let you know.

Thanks for the help.

[retired2]

i just saw your post in retired 2 s thread.
another thing that could cause issues is that you have a rond pipe entering the  seperater.
if that was a rectangular transition it would spread out the chips more  and not have a big lump of chips hitting that end of the drop slot.

Here is the link to a better photo.

http://www.jpthien.com/smf/index.php?topic=1094.0 

In the first photo you can see that the 6" round port gets transitioned to a 3.5" x 8" opening inside the separator. 

I determined the rectangular dimensions by using the area of the 6" pipe.  Hopefully, my math calculations where correct.

Pi r squared = 3.14 x 3 x 3 = 28.27 sq inches
3.5 x 8 = 28 sq inches

The transition is over a 14" length and is lined with a very slippery surface to reduce the turbulence.

I keep looking at your photo's and thinking your transition from round to rectangular looks very abrupt.  However your comment above claims it is 14" long.  The long straight outside leg could be 14", but the short leg which must hold the angled piece of the transition looks like it is far less than 14".  I may be missing something, but if not, this abrupt transition could be causing a lot of undue turbulance that could hurt performance and possibly contribute to the jams.