Thread: Making 150mm DC ports for workshop machines

A bit hard to see the smoke, but here it is.

I am moving the source laterally plus or minus about 300 mm from the centreline.
VIDEO0007.mp4

Originally Posted by John Samuel

here is a video of a piece of cedar being sanded on the drill press. Bit of a trick with the cedar in one hand and my phone in the other ... but here it is. I am very happy with this result. Will have one more shot at a smoke video.

Looks good, real good. Plenty of suck there!

Have you though about putting a fine grill across that opening?
Last time I had no grill across something was on my lathe.
The piece I was working on broke and the DC ended up mincing the pieces into sawdust.
The other thing that can make a tangled mess on a impeller is a cloth or a rag.

Yes ... I did think about it.

Then I recalled the video of a bloke feeding his tape measure into the open duct of a ClearVue. It banged around as it raced through the duct, and fell into the bin.

That's another good reason for a klutz like me to get a ClearVue ... very small footprint ... loads of suck ... no filters/filter bags to clean ... easy to empty bin ... and its tough for me to bugger up the impeller.

Nevertheless, probably not a bad idea. A rag in the duct is not a desirable outcome.

Originally Posted by John Samuel

A bit hard to see the smoke, but here it is.

I am moving the source laterally plus or minus about 300 mm from the centreline.
VIDEO0007.mp4

What's the source of the smoke?

Going back to the sanding video, compared to the dust you can see coming off the wood, there will be somewhere between 100 to 1000 times more fine dust particles being made that cannot be seen.
Sanding something like MDF can be 500 to 5000 time more
However, Based on the amount of suck that is visible (hows that for quantitative ) I'd say you have very good chance of grabbing most of them.

Originally Posted by John Samuel

Yes ... I did think about it.

Then I recalled the video of a bloke feeding his tape measure into the open duct of a ClearVue. It banged around as it raced through the duct, and fell into the bin.

That's another good reason for a klutz like me to get a ClearVue ... very small footprint ... loads of suck ... no filters/filter bags to clean ... easy to empty bin ... and its tough for me to bugger up the impeller.

I'm not that worried about my impeller but I am worried about mincing the work I just spent 2 hours working on

Thanks, Bob.

The smoke is a couple of cigarettes ... very high tech.

And I loved your quantitative assessment! Still, we have other data. The smoke test is not definitive, but it does give us a quantitative readout on the size of the effective negative pressure bubble. Even when we allow for the fact that the dust has significant velocity as it comes off the drum, it would be tough for it to do anything other than to follow the air stream. Big chips can develop enough momentum/velocity to move against the air flow, but very fine dust has little momentum, and will flow with the air, like a fluid.

The vertical sander looks very similar. The dust whips into the port in a similar fashion, except for that machine the air stream actually bends around the end of the belt.

All in all, I am a happy chappie. A couple of months ago I was wading through dust and shavings. You could smell the dust when you walked into the shop, and sometimes the old mucus membranes tingled. It was a proper mess, but thanks to people such as you, Chris and Bill Pentz a transformation has taken place. What has been achieved already is way beyond what I thought possible just a few months ago. I started wanting to keep my shop a bit cleaner, and finished making it a LOT cleaner as well as much healthier.

Thanks to Woodwork Forums. Through this site I found you, Chris and Bill's site. In turn these led me to many other sources of information.

Fighter Command regularly remarks on how much cleaner and tidier the shop is these days; so do the remainder of my family. So, the site also led to the accumulation of a few Brownie Points ... never a bad thing.

And here is a video of the vertical sander. This used to be my Dirty Dust-making Devil, but has been tamed.
VIDEO0014.mp4
If you look carefully, you can just see the section of pipe that runs down the back of the belt. I'm pretty sure that works, so I intend to extend it.

This was another dust-maker. First pic shows the back of the shroud. A 100 mm X 250 mm rectangular transition has been converted from 100 mm to 150 mm pipe. I wanted a wide input source so the shroud would better catch dust when cutting at angles.
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The second pic shows the front view. Note the opening to allow the saw to swing through its full range. I could not get really good dust collection with the zero clearance fence, so the original went back on ... bugger!
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The third pic shows the tool rigged for 90 degree cuts ... two pieces of MDF cover the top opening to force the air to be drawn through the front. The fourth pic shows the tool rigged for a mitre cut. Note the hole that allows the motor to fully descend. This hole is covered for straight and opposite mitre cuts.
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Finally, here is a video for one cut. Note how the kerf closes when the blade rises. This is the suction pulling the off-cut back onto the main work piece.
VIDEO0015.mp4

Very happy with the result. Occasionally a very few small chips return with the blade and bounce off the table. This usually happens when cutting resinous pine, which appears to stick to the blade. Can't imagine how I could stop that. Nevertheless, it is a great result.

IMAG0067.jpgIMAG0068.jpg

Decided to run some trials in an attempt to determine where the small amount of dust appearing on and in front of the drop saw table was coming from.

First came 20 cuts through scrap MDF. No pic ... nothing to show.

Then came a repeat using a cedar scrap. Again, no pic ... three tiny fragments were found, but they did not show up in the pic.

Third test was radiata. Very small amount of coarse chips were found. See first pic.

Fourth test was a dense and resinous piece of pine. See second pic.

Very fine invisibles cannot be seen, and I don't have an instrument to measure them with. However, we know that MDF produces fine dust, and 20 cuts produced nothing, not even a very fine film.

The test seems to indicate that the material not being captured is returning with the saw blade to the piece being cut. It is bouncing off with enough velocity to escape the draft. This is particularly true of the wood heavy with resin.

Material that is fine and light (MDF and Cedar) seems to get captured by the draft better, which is only as we would expect.

Any ideas as to how these coarse fragments might be captured are most welcome, but if this is as good as it gets, I'm very happy.

Originally Posted by John Samuel

The test seems to indicate that the material not being captured is returning with the saw blade to the piece being cut. It is bouncing off with enough velocity to escape the draft. This is particularly true of the wood heavy with resin.

Material that is fine and light (MDF and Cedar) seems to get captured by the draft better, which is only as we would expect.

Any ideas as to how these coarse fragments might be captured are most welcome, but if this is as good as it gets, I'm very happy.

What happens with the denser woods when you cut a little slow?

You are certainly on the ball, Bob.

If I cut more slowly, the amount of material on the table reduces. If I cut very slowly, only the very dense (Vic Ash etc) or very resinous wood returns any material at all, but in much reduced quantity.

Certainly, speed of descent of the saw is a significant factor.

Another thing I noticed was the lack of a distribution of particles. Usually, we expect to see a distribution of particles from coarse to just barely visible, but that is not happening. The fine film of just visible dust I expected is missing. The particles all appear fairly coarse.

Originally Posted by John Samuel

Fighter Command regularly remarks on how much cleaner and tidier the shop is these days; so do the remainder of my family. So, the site also led to the accumulation of a few Brownie Points ... never a bad thing.

John,

Make sure that you make it very clear to "Fighter Command" that your new-found interest in cleanliness does not extend beyond the boundaries of the shed, or you might not see the inside of the nice clean shed as often as you want to.

Doug

Doug,

Good Grief! ... had not thought of that. Thanks for the "heads up". I'll be very careful.

Usually, I hide in the shed trying to appear productive when housework is happening. The sign on the door to my shop helps.
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Cheerio!

John

Originally Posted by John Samuel

IMAG0045.jpg

John, is that either 1 or 2 or must both conditions be fulfilled for entry. It needs an "and" or an "or" after the first condition or you may be swamped by naked women without wine.

Doug