MachineJunkie Forum Index MachineJunkie
A site for addicts of classic woodworking machinery
 
 FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

New Planer Dust Hood

 
Post new topic   Reply to topic    MachineJunkie Forum Index -> Fabrication
View previous topic :: View next topic  
Author Message
mystry_tour



Joined: 13 Mar 2006
Posts: 357
Location: Greenville Tenn

PostPosted: Wed Jan 31, 2007 2:35 am    Post subject: New Planer Dust Hood Reply with quote

Here you go pete


Thought you might wanna see these
Reg
_________________
I fought to keep the Gov. in power......they keep screwing around I'll fight to get rid of them.
Back to top
View user's profile Send private message
crzypete



Joined: 16 Dec 2004
Posts: 1689
Location: New York State

PostPosted: Wed Jan 31, 2007 9:09 am    Post subject: Reply with quote

Nice job Reg, did you do it yourself or sub it out? Have you run it yet?

I'm a bit worried about the tightness of the sweep. but if you have a monster dust collector it may be able to overcome it.

Pete
Back to top
View user's profile Send private message Visit poster's website
Jeff



Joined: 10 Jun 2005
Posts: 15
Location: Winooski, VT

PostPosted: Wed Jan 31, 2007 9:37 pm    Post subject: Dust collection duct work... Reply with quote

The duct work looks very nice and I suspect that the duct will work well for transporting the chips away from the instrument. I'll be interested to hear how it works.

Given the nice cross-section of practical machine junkies and artists on this forum, I'd like to make a few suggestions using this project as an example that we can talk about.

When I look at this duct I see a few things, I see:
1. A turning section (just short of 90 degrees)
2. A contraction section with a ratio of 5 to 1 (This is a guess based on estimated dimensions of the duct which appears to contract from and area of 6"x24" to pi*3"^2)
3. A turning section (as the angled walls of the contraction, or nozzle, meet the vertical walls to the circular duct)

The suggestions that I would make for a section of duct like this are the following:

1. Increase the interior radius of the turning section and smooth the transition between the turning and the contraction sections. This would allow the boundary layer of the flow within the duct to remain attached to the wall for a little longer, reduce the size of the recirculation region in the contraction section which may improve performance. Please note that this may also reduce the load on your dust collection fan (reduced pressure drop) and the aero-acoustic noise (noise produced as a result of velocity gradient in the flow).

2. If space is at a premium (as it often is) there are a few things that may be done to reduce boundary layer separation. One of the simplest ways to reduce the size of a recirculation bubble, is to add a small series of air inlets just beyond the corner (the size and shape of the inlets - probably a series of very fine holes - would require some experimentation) of the inside curve. This would allow the duct to inject some clean air which would run up along the inside wall of the duct and break up the recirculation bubble a bit.

3. Although it would drastically increase the complexity of the construction, a contraction section that smoothly transitions from rectangular to round and vertical in one plane to vertical in a second plane would also improve efficiency and probably the dust collection performance. I used to have a little piece of code that would compute just such a transition. I'll need to see if I can dig it up and convert it to something for you guys to try out (that may take a while!).

Without having spent much time in a semi-commercial wood shop, I'm unsure how much of the noise that you experience and that the energy that you pay for is tied to the dust collection systems. If any of you are interested in ways to potentially reduce noise and improve dust collection system efficiency I'd be willing to offer a hand.

- Jeff
Back to top
View user's profile Send private message
mystry_tour



Joined: 13 Mar 2006
Posts: 357
Location: Greenville Tenn

PostPosted: Wed Jan 31, 2007 10:31 pm    Post subject: Reply with quote

Hi Pete. It is mine yes. I did some of the work and some ws done at the fab shop at work, I don't have a roller. No I haven't got it running yes as I haven't got the dust system running. Waiting of th the concrete to dry in the extention to move the machine tools in there and put up the cyclone. It is 3 hp and will be very close to the planer so it should work pretty good.
Hi Jeff.....welcome to the place. I am just a hillbilly and not very educated so it seems your thoughts are very consice and well thought out. I only have one question....huh. I read it a few times and sorry its way over my head.
tour
_________________
I fought to keep the Gov. in power......they keep screwing around I'll fight to get rid of them.
Back to top
View user's profile Send private message
crzypete



Joined: 16 Dec 2004
Posts: 1689
Location: New York State

PostPosted: Thu Feb 01, 2007 10:10 am    Post subject: Reply with quote

Jeff, Did you hear my mind blowing up all the way up there in Vermont?

Your wind tunnel science makes us all look like cavepeople. I would however love a consultation before I ever build a dust collecting hood again. I actually could use some advice for the one I made for my oliver planer. here is the thread http://machinejunkie.com/forum/viewtopic.php?t=99 It doesn't suck as fully as needed. It is my current theory that the having the instant square to round change at the top is a major loss of suction. i am jealous of mystry's beautiful transition in that area. My thought is to roll up some more sheet metal and weld it in to create better fillets. I am open to better suggestions.

I would say the noise issue is not a problem- the sound of the planer and collector seem to be the dominant winners in this category.

Pete
Back to top
View user's profile Send private message Visit poster's website
mystry_tour



Joined: 13 Mar 2006
Posts: 357
Location: Greenville Tenn

PostPosted: Sun May 13, 2007 12:28 am    Post subject: Reply with quote

Hi Guys,
Well I fired up the dust collection system today with the new hood on the planer. It worked like a charm. At first my heart sank because when I ran an oak 4X4 through it I was watching the hose......damn no chips. I ran it through again.....same thing. Then It dawned on me to OPEN theblast gate Shocked the chips wen whirling through the clear hose and into the barrel.....I was so excited I bout peeded myself.
So Pete the worry about the tight 90 Deg. turn is not a problem It works great
Tour
_________________
I fought to keep the Gov. in power......they keep screwing around I'll fight to get rid of them.
Back to top
View user's profile Send private message
crzypete



Joined: 16 Dec 2004
Posts: 1689
Location: New York State

PostPosted: Fri Jun 01, 2007 7:55 pm    Post subject: Reply with quote

Hey Mystry, Glad to hear it is sucking properly. Have you run a full width board yet??

Pete
Back to top
View user's profile Send private message Visit poster's website
mystry_tour



Joined: 13 Mar 2006
Posts: 357
Location: Greenville Tenn

PostPosted: Sat Jun 02, 2007 12:31 am    Post subject: Reply with quote

No thats a 22" wide swipe and I haven't done anything that wide just yet.
I'll let you know when I do do something that wide though. The widest so far is 16" and about 1/8" cut.
Tour
_________________
I fought to keep the Gov. in power......they keep screwing around I'll fight to get rid of them.
Back to top
View user's profile Send private message
swparish



Joined: 11 Sep 2007
Posts: 35
Location: Ft. Worth TX

PostPosted: Sun Sep 16, 2007 4:59 pm    Post subject: Reply with quote

Hey guys, just got here.

I know this is an old post, but if someone perusing this forum comes across this, I'd like to add a reference I came across in my surfing.
http://search.sheetmetalworld.com/tutorials.cfm
This is a great website that has easy explanations on how to measere and cut sheet metal forms including; transitioning from square to round and making a cone with a pitch (which I used).


Anyway hope it helps.
Stephen

[/url]
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    MachineJunkie Forum Index -> Fabrication All times are GMT - 4 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum


Powered by phpBB © 2001, 2005 phpBB Group