dust extraction for bandsaws

[Ivor]

Hi,

Having just bought a 1 hp dust collector I have been trying to hook it up to my 14" bandsaw. My bandsaw is a JET that has a 50mm dust exrcator shute. I then put a 50mm flexible pipe from the bandsaw to the dust extractor with a 50 mm to 100 mm reducer on the dust extractor. AND .... I still get dust flying everywhere.

I had a better look at the dust shute from the bandsaw and found that the 50 mm diameter shute goes down to a rectangle opening about 50 mm x 20 mm. No wonder that there was still dust flying around. So, I modified the shute so it was a 50 mm diameter hole and cut away some of the bottom metal door to do this. I then tried the dust extractor again and still get dust flying everywhere.

I reckon that I need to somehow hook up a 100 mm flexible hose to the bandsaw but I have no idea how. Has anybody out there managed to accomplish this, if so I'd love to see diagrams or photos.

Thanks

Ivor

[Wayne Davy]

Ivor, check out this link for some ideas

http://www.bill.pounds.net/woodshop/bandsawdc.html

[Ivor]

Thanks Wayne,

That is exactly what I was after.

Ivor

[soundman]

The link posted above seems interesting.

Just for general information
Reducing from a 4 in hose to any smaller hose will result in substantial loss even a 4 to 3 reduction shows significant loss.

Most 50mm dust ports require high preasure type vacume form a shop vac or the like.
cheers

[kenmil]

Am I missing something here ? (Probably am) I would have thought that reducing the diameter would increase the level of suction, not decrease it. I confess to never having heard of a cyclone until a few weeks ago, and I am still trying to understand how they work, so this bit is confusing me even more.:confused:

[John Saxton]

No Ken,quite the reverse in fact by narrowing down the suction you reduce the 'flow affect' of cfm(cubic feet per minute of flow).

By reducing surface friction under pressure the flow is greater...in other words and in layman terms the wider the pipe the more surface area thus the easier flow.
Putting in sharp 90 degree bends in the pipe has an effect of slowing the flow whereas a 45 degree with a gentler bend has a more beneficial effect for your dust extraction.
If you could have dust extraction in your shed/shop with a straight direct line to all inlet functions then you could arrive at a almost perfect situation but as we know that is not nearly as possible as we would like it to be with small sheds that we use.

Theoretically by keeping the friction /flow rate within bounds may be assisted by implementing blast gates on each piece of machinery and therefore giving you some harmony within your workshop.A blast gate is a means of isolating machinery not being used that uses the same dust extraction line and therefore dedicates the machine being used to have maximum "draw" on the line and a flow necessary to remove the heavier burden of chips/shavings.
For instance I use a 1350 cfm Dust extractor which is capable on my Bandsaw/Combination Machine/Lathe/Belt Sander/and take off for set-up routers for the Leigh jig and the Router lathe.
The Combination Machine has the heaviest draw of about 400cfm on any of it's use's,but next to useless if I have left one of the other blast gates open therefore reducing it's draw power being next to bloody useless and that is with a 2hp dust extractor!
Some thoughts...HTH
Cheers:)

[kenmil]

John,

Thank you for your explanation. What you say makes sense in terms of bends etc in ducting, and the friction they cause, but it just seemed to my untrained mind that "concentrating" the suction into a smaller outlet would actually make it stronger. I understand what you are saying about CFM though.
I am obviously going to have to do something about dust collection in my shop, (the Triton bucket just does not cut it) but I really don't know what to do just yet, and the more I read, the more confused I become.:(

[Wayne Davy]

Ken,

All the info on dust collection is at Bill Pentz's site at http://cnets.net/~eclectic/woodworking/cyclone/Index.html

However, I can understand that it is quite daunting to read and take in all of the info he presents (I have lost count of the number of times I have read the entire site). Anyway, to try and help you understand, I have snipped a few bits from Bills site:

As John mentions, reducing your hose diameter will decrease the actual CFM due to increased resistance, to understand this Bill has a little test you can try:

"To test this for yourself, get a few feet of 1/8" interior diameter clear hose. Now cut off about a 1/2" of this hose. Without choking on that tiny piece, try to breathe through it. Most can but find it difficult. Now try to breathe through the longer piece. Most can not because it has too much resistance."

As for how a cyclone works, I have re-posted the graphic below and here is a textual description from Bill's site:

"A cyclone works by taking a "dirty" stream of air in, forcing it into a circular path which forces the heavier particles against the side, then letting the "clean" center from that whirlpool exit out the top. As the air spins, the dust and particles slide down the cyclone walls and onto a cone. The cone shape has an ever tightening radius designed to force the air speed to increase as it goes down to keep those particles flung tightly to the cyclone sides until they can exit at the bottom of the cone."

The advantages to a well designed/built cyclone are that the nearly all the dust goes in the bin, not in the Filter Bags so they don't clog up. This means that your flow does not reduce due to back pressure created by clogged filters.

So, there you go, clear as mud. :D

[kenmil]

Wayne,

Thanks again for your patience. I have revisited the site you mention, and frankly, I find it information overload. All I wanted was a simple drawing/ instruction on how to make one. How is yours going by the way ? Does it work as you had hoped ?

Never mind, I just looked at the other thread and that answers my question.


PS I think these things should be called a tornado, not a cyclone, given the way they operate.

[Wayne Davy]

Ken,

No worries. As to how to build one, I probably should have taken more pics, especially during the initial cutting/rolling/bending stages. However, Bill's site has links to some other sites (go to the Cyclone Home page and scroll down) that show the most of the building stages.

P.S. You are probably right about the Tornado

[bitingmidge]

It's nice to reopen a vintage thread!

I noticed at the Bris Wood Show, the latest 14" Jet bandsaw has a 4" DC fitting straight out the "back" throught the casting.

I am in the process of connecting permanently to a ducted system, and that means surgery I feel! The existing fitting clips onto the shop vac, but really only collects through a 50mm x 10 mm port.

I have seen a modification somewhere on the web which connected a 4" port to the front (right through the door) and I was contemplating doing the same until I saw the link above (thanks Wayne!).

Has anyone had experience with a 4" connection, if so how successful was it, before I go chopping my lovely white door to bits!

Thanks,

P

[Al Burdon]

I have the Jet 14 inch bandsaw and tried the 4 inch attachement on the side near the blade and it wasn,t all that successfull but I now have a 4 inch galvinised plumbing connection fitted to the centre of the front door and connected to dc unit and it removes most dust a little iis still on the table but you dont have to open it up every other day and unload the dust collected.

[Sturdee]

Has anyone had experience with a 4" connection, if so how successful was it, before I go chopping my lovely white door to bits!


Rather then bolting a connection to the door, which means you might have to disconnect the hose everytime you open the door, why don't you cut an opening in the back and bolt the connection to the back of the unit.
That is what I did to my small bench mounted model and it works okay.

Peter.

[kenmil]

Try this

http://www.tools-for-woodworking.com/library/bandsawdustcontrol.pdf

[bitingmidge]

Thanks for the replies guys,

I can't cut through the back as it is cast in one piece.

Having discarded the "bodgy up the existing hole" option, these are the three that are left I think:

1: What I think is Al's solution - this is now my preferred, particularly after reading the attached document (thanks Ken - I found it about an hour ago too!). Originally I couldn't see the point of letting all that dust go through the wheel, but now don't think it makes much difference.

2: I have searched without success for a site I have seen a few days/weeks ago which had a port cut where the reddish hole is just near the handle. It was my favourite spot, but now I am tending towards the lower one.

3: The radical addadictomy: This may be the best solution (?) but the surgery required is too serious for my limited metal working skills, and there is certainly no turning back from it! Much more cumbersome than the other two as well.

In terms of convenience, I expect to be running 6" pvc with a 4" flex tail about 1500 long so that I can move the machine by it's own width to clean around it. Hopefully that will give enough flexibility to open the door with the duct permanently attached - or should I try for 6" flex?

Thanks again - makes a change from the regular Sunday mystery tool discovery!
Cheers,

P

[bitingmidge]

Well as most know, things don't always move quickly at the Home of the Biting Midge, and so it has come to pass that after almost a year, and with great trepidation, I cut a hole in the front of my band-saw!

I used a standard plastic fitting, trimmed to match the profile of the bottom of the door.

I traced a template of the inner opening on paper and stuck it to the door with normal glue-stick glue so I could get the unwanted bits off later.

Then I drilled, (well actually I had a cup of tea, a lie down, three or seven really big deep breaths, reconsidered whether I should be doing this, then I drilled...) a hole in each of the corners of the template, and started to cut with my jigsaw, initially fitted with a wood cutting blade, because I couldn't find any other and the shops were shut. The first two inches of cut went very smoothly, but then I either hit a knot or the metal got suddenly hard...whatever happened :D my blade had lost it's teeth. :eek:

I rose early the next day, and bought a metal blade, finished the job without further drama, filed off the dags, primed the exposed metal and screwed the thing on over a bed of silicone.

From the outside it looks as though it came from the factory (or will when I get round to touching up the shiny screws!), from the inside it is tidy, but no doubt the next one I do will be better!

Does it work??? Does Jack Newton swim in circles!!

Initially I was pleased, but not all dust was being collected. I removed the standard 2" fitting from the side of the door to allow more airflow under the table, and the results have been impressive indeed! Most if not all sub-table dust is now collected. The attached photos show the modification, and the saw after a session cutting tenons. The scale of the job can be seen by the offcuts on the table and floor, note particularly the black wheel on the stand, which would have been completely covered in sawdust after the first cut! I am sure that most of the other dust on the floor has simply been knocked off the table during the cutting process.

Now do I need an overhead collector as well??? I might sleep on that one, for another 300 or so nights, but let's leave this thread open just in case!!

Cheers,

P :D :D :D

[Sturdee]

Midge,

Did you make a new year resolution to get all your projects finished this year. Sure looks that way to me with more projects finished this year so far than all of last year. :D :D :D

Looks good but you have the paint the connector white to match the saw. Keep it up and you'll have them all finished shortly. :eek:

Peter.

[bitingmidge]

Did you make a new year resolution to get all your projects finished this year. Sure looks that way to me with more projects finished this year so far than all of last year. :D :D :D

I just have to make room for the new ones!!! All those dust collector fittings are getting in the way....that'll be next!!!

I don't think I'll live long enough to finish EVERYTHING though!! :D

P

[Wayne Davy]

I don't think I'll live long enough to finish EVERYTHING though!! :D And if you did, what would be the point in getting up in the morning :D

Well done mate - I was lucky that the H&F BAS300 I have already has the 4" in the base but, I agree, may need to do something above the table. Well done again (bit scary cutting up our tools).

[Ivor]

I wish this thread was around when I first posted my question. I opted for cutting a slot in the lower door and holding a 4" pipe in place just below the lower guides. I haven't got any brillant way of attaching the pipe I just hold it in place with occy straps. Not an ideal solution but it has cut the dust down. I am not sure that I would have wanted to cut a hole in the bottom of the bandsaw though. Bummer that JET now release their bandsaws with proper dust extraction.

[barnsey]

On my bandsaw I cut the hole in the bottom corner directly under the blade and it works well. I move this connection to the jointer and table clean up is no mare than a pass across it. :D