Thread: Let's see what we can do.....

When you get sick of swapping the inner gate panels over you can put vertical sliders where the lines are shown in the goto..

Blastgates3bcf.jpg

Will see how it goes, thought the idea was to get the gate as close to the "y" as possible.....


Sent from my iPhone using Tapatalk

Originally Posted by Cal

Will see how it goes, thought the idea was to get the gate as close to the "y" as possible.....

Yep, but when the take offs/connections are upwards/horizontal like yours, sawdust moving in the other duct will find it harder to get around the corner and up into the other duct. Most of that sawdust will also tend to fall out when you turn off the DC. In this case you can move them to a more convenient place. It's when the connections are heading downwards that you can run into real problems. The the sawdust is dragged into and falls into the duct. When the DC is turn off the sawdust stays there and builds up. If that duct is not used for some time the sawdust can pack in so hard the DC won't clear it when the BG is opened.

Here are a couple of examples - View is from the side with Arm C above Arm A and B.

Being at the lend of the line, Arm A is the least problematic,
The BG could even be located at machine level, except perhaps if it's something that generates a high dust load like a thicknesser, and there is stall in the middle of the job the sawdust in the pipe will fall back down anb bog up that arm. The best place for a BG is up near Blast gate B2.

Blastgatelcoations.jpg

Arm 2 is the problematic arm.
If the BG for arm B is at B1 and arm A is in use , some sawdust passing Arm B will either drop or (by Bernoulli)be dragged into Arm B (blue arrows) and if there is nothing in the way it will fall all the way to the bottom of the duct. If Arm B is not used for some time this may end up packing the whole arm with sawdust. Clearing these blockages are a PITA so the best place for the BG for Arm B is at B2

Sometimes you cannot locate a BG at B2. Then you need to either remember to regularly open B1 and clear any sawdust from that arm. An alternative is to insert what is know as a "clearing Y" which catches the sawdust drawn it Arm B while Arm A is in use - periodically the screw cap is removed (with DC ON) and the will clear the sawdust built up in the tra.

Arm C is the least problematic. No sawdust will fall into it and sawdust dragged upwards will tend to fall back out when the DC is turned off. BG can be pretty well anywhere along this arm.

It is slowly sinking in now Bob! I will look at moving them at a later date, they are in a bit of a problem spot for reach as they both sit over/behind the sander. Moving them another foot or so is not going to improve the reach though, but as you point out changing them over versus sliding adds to the problem. I still need to shuffle some other items around in the shed to allow better access to all machines. The main bugbear at the moment is the bench, at 1500x900mm it takes up a lot of realestate in a small space. I plan on rebuilding it to a more suitable size.

I don't envisage having any solid drop downs in ducting as all that is left is the TS and thicknesser, which will need to run off flexi and be wheeled into position front and centre of the shed. I have now run a duct into position overhead for this. The mitre saw still remains an issue as it is on the opposite wall to the DC and as I have mentioned previously it will be about 10mtrs of duct to get to it so flow is going to suffer. I may have to just lug it outside to use it.


Sent from my iPhone using Tapatalk

Just to add a little more to my progress which has been slow to say the least, I have just changed the intake to my poor excuse for a thicknesser. I ditched the 4 inch outlet and went straight to 6 inch, I have not given it a test run as yet and may have to add a rim to it where it sits on the jointer top to add a bit of space between the cutter head and the entry to the duct (not sure if it’s too close or not)

I have a way to go to get the rest of the machines hooked up, hoping to get those sorted in the next few weeks.

Another bit done, have enclosed the dirty beast that is the mitre saw. Will be glad when it’s hooked up, hope there will be a lot less mess!

One thing you could do to give your setup a bit more flexibility would be to put some hinges - maybe even piano hinges - as show in the photo below.

The first line of hinges would be at the red lines so you could open the two panels like doors either side of the saw - you would need to trim the bottoms of these panels to get the panel bottoms past the work piece backstops.

Then these two movable panels might get in the way of the workpieces so you need a second line of hinges (green line) about half way back on the side pieces which would allow the connected doors to open operate like wings.

The wings could be tucked in as closed as the panels are now - or opened out wide to catch more stuff flying off from teh saws?

BarnDoor.jpg

Thanks Bob, never thought of that, good idea as usual! That will also help in being able to use the saw in anything other than 90degrees too! I have to buy some more ducting and junctions etc before this will be hooked up, hope to get it sorted soon. Cheers Cal

I did a similiar enclosure for my mitre saw, and it was doing absolutely nothing.

Then I realised that half the dust was actually escaping from under the base of the saw, between the metal legs. Under the saw is a very irregular shape so I ended up stuffing it with sponges and that helped a lot. Easy fix.

The other half of the dust was escaping from high up, when the saw is down and cutting. So I cut a few strips of thick PVC film (the type they use for outdoor patio roll down blinds) and hang them from the top of the box on the outside making sure they overlap a little, and cut them short enough so they don't get tangled in the blade. That helped a lot too.

Originally Posted by Spyro

I did a similiar enclosure for my mitre saw, and it was doing absolutely nothing.

What size is your DC and ducting?
How long was the ducting run back to teh DC?

Originally Posted by BobL

What size is your DC and ducting?
How long was the ducting run back to teh DC?

I did all that testing and modifications before I actually connect it to anything, I wanted to make sure the box keeps most of the dust inside.

So how do you confirm it was useless when you did not have a DC hooked up to it? I’m confused [emoji52]

Originally Posted by Cal

So how do you confirm it was useless when you did not have a DC hooked up to it? I’m confused [emoji52]

He's talking about visible dust, and wanted the majority of chips to be contained in the box by the box design alone which seems like an admirable course to take.

I started to write a long reply about fine dust, yada - yada, air flow, Yadda - yadda and then realized I was in broken record mode again.

In summary;
Even though I often use it as a starting point, testing based solely on what chips (visible dust) are doing does not always indicate what the fine dust will do. I see this approach used time and time again on this forum - can't see any dust (ie chips) thing so it must be working.

This is the same principle that most WW machine manufacturers use, ie 4" dust ports and narrow down gaps in machinery cabinets so chips don't escape. This is one of the major reasons why woodies have a fine dust problem in their sheds.

Unfortunately without a fine dust detector we can't say much about what the fine dust is doing. In general chips act like marbles and follow initial high speed ejection/collision trajectories and/or high speed air flows. Being more gas like than chips, fine dust follows air flows including thermal air currents, and general diffusion (high to low concentration regions).

Fine dust behaves like a fart and the only way to deal with it is to use high air flow. This means forced ventilation and/or large area cabinet ports or openings, more powerful DC and large ducts to allow for as high and air flow as possible. Really high/fast air flow can reduce or eliminate chip scatter as well, which is why I asked Spyro my original questions.

Whoops slipping into broken record mode again: Last point
Remember the fine dust is the one to worry about that need to be grabbed at source, the chips can be swept/vacuumed up later.

That’s what I thought Bob, it’s not really a good indication that the box is doing it’s job based only what the chips are doing. I can’t see that this box will even extract all the visible dust, I am hesitant that it will even help with fine particles but willing to try anything, although without a particle counter I may be blowing wind up my own ....
I only hope it helps to some degree??? Will put the hinges on it as you suggested also. I think I mentioned in the thread a while ago that mitre saw will have the longest duct run of any of the machines approx. 6 metres, there is nothing I can do about that as I don’t have space enough to fit it on any other walls closer to the DC, I just have to suck it and see (or not)
I wonder if after it has been used that I open another gate to a bmh that is behind my lathe to help suck out any dust that will still be hanging around the shed? I ask this because I can’t see that the duct in the box of the SCMS won’t do as good a job at removing the fine dust that is not already in the box.