Under Development - Garnham style dropout boxes

[lemonjeff]

Here you go Si,
The links you posted are direct links to the page.

You need to go into "share" where the IMG links are, I think (i use photobucket).

Jeff

 

[SimonB]

Many thanks Jeff - I'll have to figure out why the link Picasa gives doesn't work with the Img tags.

 

[MikeG.]

Simon,

the drop in "suck" that you are finding can be attributed, I reckon, to the different size of tubes you have. If you replaced the one that collects the dust with one of the same calibre as the one that leads to the vaccum cleaner, I don't think you will find any significant drop in "suckage".

Nice looking construction, BTW.....much too robust and high-quality for the job it does!!!

Mike

 

[SimonB]

Thanks for the suggestion Mike, I think you're probably right. Presumably the flow in the 'in' tube is a fraction of that in the 'out' (to Vac) tube and is directly related to cross section size of each tube. The reason for a larger 'in' tube is that the smaller Vac tube was getting blocked when using with the planer or thicknesser. The clear tube is a match for the thicknesser dust port and with various adapters I also have a connectors for the planer and the CS. For the CS the pipe narrows to a similar size to that of the Vac and from using it just now it seems to be as effective. Also no dust is making it into the Vac which is pleasing. Once I finally get the workshop sorted out and move out of the garage I might consider upgrading to a more powerful suction system.

 

[Chris_belgium]

Hello, I'm also looking to make this kind of dust extraction system, do have a couple of questions, if this is regarded as thread highjacking, let me know, i'll delete my post and start a seperate thread. I'm thinking, this way we keep all the info together.

Anyway on to my questions , am I correct that the air flow goes like this?

How does the air pass the last baffle (small one on top just before the exit towards the vacuum), are there small holes drilled in it, or am I missing something?

I'm planning on using this motor.

Originally this was used with two cloth bags attached to the black piece, one on top, one on the bottom. I'm planning on removing the black pieces, then connect the suction side to the 'Garnham' box, and route the exhaust side outside my workshop in open air. My two question is, first off all will this work?
Second question is, how much dust get's past the box, I live in the country so a bit of blowby isn't a big problem, but offcourse don't want piles of mdf dust flying into the cows faces who graze next to my workshop

 

[MikeG.]

Also no dust is making it into the Vac which is pleasing.

That is good news.....as that is the whole point of the excercise. If none gets to the vac, then none goes into the air.

Mike

 

[MikeG.]

Chris,

yes....that is the right route through the box....and yes, there are small holes drilled in that last baffle.

Yes......it will work with your extractor. keep the extractor set up as originally intended (with 2 bags), and have the drop box between the dust and the extractor. However.........

You will have to make a substantially larger box, and you may have to experiment with baffle positions etc, simply because your extractor is so much more powerful. I made both of mine empirically........by intuition........so I have no idea if there is a way of calculating the sizes of the various elements. With an extractor like yours that appears to run on 100mm pipework, you may need to make a box up to about 8 or 9 times the size of my original, otherwise the suction will be so great that it will simply empty the box.

I am planning to do just exactly what you have in mind when I build my next workshop, and I am thinking that a box of about 800x800 by 1500 would be the starting point. I have no maths to back that up, but the bigger the better. There is no reason why this need to be inside the workshop, of course..........you could easily make the box weatherproof and fixed to the outside of the shed.

Mike

 

[DavidE]

Hello, I'm also looking to make this kind of dust extraction system, do have a couple of questions, if this is regarded as thread highjacking, let me know, i'll delete my post and start a seperate thread. I'm thinking, this way we keep all the info together.

Hey Chris - I think it is good if everyone posts here - that way it will be easier to look at all the different designs. If it makes sense I could change the thread title so it is more obvious there are multiple ones?

Simon - yours looks good. Mike is right the wider hose will mean the speed at the outlet is less. In theory you'll get the same volumetric flow rate (minus the losses)

Mike - have you got any idea what the flow rate of your vac is (or just have a look at the motor power rating as it can probably be compared to similar vacs?) That way if you post your dimensions it should be possible to see what the basic flow numbers are. (If you could estimate the baffle areas (closed to open) and pipe sizes that would be good too. When I made mine I worked on the theory that at the baffle plates I should keep the same area as the hose to minimise the losses as the baffle is effectively a throttle. However, this may not be the best approach... I need to try some more stuff out.

I've been away this week so I've not had a chance to try some stuff out. The box definitely needs to scale up with the higher flow rate. Hopefully, then a bit of fun with the baffles to create stagnation in the flow (and gravity) does the rest. As I have only got really fine stuff getting through now the challenge is giving them enough time to settle in the flow. The big stuff falls out that easily I suspect if you took two pipes in and out of a box (at the top) it would be pretty effective.

Cheers
David

 

[Chris_belgium]

Chris,

yes....that is the right route through the box....and yes, there are small holes drilled in that last baffle.

Yes......it will work with your extractor. keep the extractor set up as originally intended (with 2 bags), and have the drop box between the dust and the extractor. However.........

You will have to make a substantially larger box, and you may have to experiment with baffle positions etc, simply because your extractor is so much more powerful. I made both of mine empirically........by intuition........so I have no idea if there is a way of calculating the sizes of the various elements. With an extractor like yours that appears to run on 100mm pipework, you may need to make a box up to about 8 or 9 times the size of my original, otherwise the suction will be so great that it will simply empty the box.

I am planning to do just exactly what you have in mind when I build my next workshop, and I am thinking that a box of about 800x800 by 1500 would be the starting point. I have no maths to back that up, but the bigger the better. There is no reason why this need to be inside the workshop, of course..........you could easily make the box weatherproof and fixed to the outside of the shed.

Mike

Thanks for the reply, what is the reason that I should keep the setup with the bags, I'd rather remove them as they take up quite a bit of space. Without the bags I could put the extractor motor in some 'lost' space in my workshop and use drainage pipes to connect it to the box, if I have to use the bags, this would take up valuable space in an already very crowded workshop.

 

[woodbloke]

I'm making some sort of progress with mine and hope to sort out hoses shortly. Interesting that Mike recommends that both hoses be the same diameter (or as near as damn)...obvious really.

I wonder if it's worth making a 'sticky' for this thread, or even start a new one as a 'sticky' with different designs? - Rob

 

[MikeG.]

what is the reason that I should keep the setup with the bags,

.......the only reason is that I didn't read your original posting correctly! Yep, should work fine without, so long as you are prepared to experiment a bit. One suggestion is to have some sort of vision-panel in the door of your drop box so that you can watch how the dust swirls around, and see what differences any changes make.

Interesting that Mike recommends that both hoses be the same diameter (or as near as damn)...obvious really.

Rob,

not necessarily! In the circumstances where you have a small vauum cleaner working at its limits and you don't want any drop in suckage (I love invented words!!), then yes, it makes sense to stick to the same size hose. You could even have a smaller hose from the dust to the box than you have from the cleaner to the box, and that should concentrate the airflow.

However, if you have bags of power, say from one of the big extractors such as Chris is talking about, or from something like a big old wet 'n dry vacuum cleaner, then there could be lots to gain going from a small outlet hose to a bigger inlet hose. You could effectivley be converting from HVLP to LVHP. Turn this to your advantage by having a valve somewhere, and being able to swap from HVLP to LVHP at will.

Mike

 

[MikeG.]

Mike - have you got any idea what the flow rate of your vac is (or just have a look at the motor power rating as it can probably be compared to similar vacs?) That way if you post your dimensions it should be possible to see what the basic flow numbers are. (If you could estimate the baffle areas (closed to open) and pipe sizes that would be good too.
David

David,

the box internal dimensions are c. 700w x 450h x 250d, and the hoses in and out are 35mm diam. The cleaner has 2 power ratings........800W IEC, and 900W with some writing after it that is worn out and illegible, but it doesn't say anything about volumetric flow rate.

The lower baffle has 50 no. 6.5mm holes, and the upper one has 25 of the same.

The cross sectional area of the hose is therefore in the region of 960 sq.mm, and the open areas of the baffles are c. 1660 sq.mm for the bottom one and 830 sq.mm for the top one.

Mike

 

[CNC Paul]

Not really a drop box but coming soon for the Festoolians

 

[RogerM]

Many thanks Jeff - I'll have to figure out why the link Picasa gives doesn't work with the Img tags.

Not sure why the photos aren't displaying - any tips? Thanks

Simon - you're pasting the link rather than the "embed image" function. To post from Picasa :-

1. On the RHS, click "link to this photo".

2. Select the size of image to be uploaded. I normally use large - 800x. You have to do this first because the link that you will create will include this info.

3. Copy all the text in the "embed image" frame. Within this diatribe you should find 2 http addresses. Normally the 2nd one will start with http and end in .jpg. It is this 2nd address that you want.

4. Delete everything before http and after .jpg and add the before and after this text and you will have a link to your photo.

HTH

 

[DavidE]

Mike - have you got any idea what the flow rate of your vac is (or just have a look at the motor power rating as it can probably be compared to similar vacs?) That way if you post your dimensions it should be possible to see what the basic flow numbers are. (If you could estimate the baffle areas (closed to open) and pipe sizes that would be good too.
David

David,

the box internal dimensions are c. 700w x 450h x 250d, and the hoses in and out are 35mm diam. The cleaner has 2 power ratings........800W IEC, and 900W with some writing after it that is worn out and illegible, but it doesn't say anything about volumetric flow rate.

The lower baffle has 50 no. 6.5mm holes, and the upper one has 25 of the same.

The cross sectional area of the hose is therefore in the region of 960 sq.mm, and the open areas of the baffles are c. 1660 sq.mm for the bottom one and 830 sq.mm for the top one.

Mike

Hi Mike, Okay grand I'll have a look at these numbers when I'm more awake (I'm rather jet lagged at the moment).

Thanks, David

 

[Mike Saville]

Just thought I'd poke my head above the parapet. There's another 'Garnham special' in development in a shed near me 8).

My plan is for something more upright, with vacuum mounted on top and wheels so it can easily be moved.

I've got some leftover castors from another job, got a cheap 2nd hand hoover, some spare exterior ply, plenty of hose - now just need to find some time to make it

 

[BMac]

Mike,

There's a version of what you are going to do on here, I'll try to find it.

Brendan

Edit: Found it:

https://www.ukworkshop.co.uk/forums/view ... highlight=

 

[MikeG.]

Brendan,

do you mean me? If so, you are about 20 years too late, as I made the first of mine back in the 80's. It's still going strong, and is the pattern for most of the current crop on here.

Mike

 

[SimonB]

Mike, I think Brendan meant Mike Saville's idea of vac on top on wheels, as per Niki's that he has linked to.

 

[Mike Saville]

Thanks for the link, I had seen that, though I don't have access to a bin/tub like that. I do have some scrap ply though so will use that.

It's along the same lines though in terms of vac on top and wheels on bottom.

I'll post some pics as I go.