Lightweight/flexible dust hose?

CNC Machines Shapeoko
1

In making my dust boot mounted to my bracket, I want to use hose as lightweight and flexible enough that it will provide minimal leverage on the boot and bracket.

I have some clear rubbery stuff with a wire inside, it is actually kind of heavy but fairly flexible.

Woodcraft lists some stuff as lightweight and flexible on their page so I’ll check w/ the local store tomorrow and see if they have anything.

Would there be anything available at my local home centers (Home Depot, Menards, Lowes)? I’d like to stick to the 2.5" fittings because I have a flange with screw holes and my shop is plumbed for 2.25/2.5" collection. But if there is a compelling product that is smaller/adaptable, I’m open to trying it.

2

I believe this post

references a McMaster-Carr part # for a flexible hose which may be of use.

3

Could use a 1.25" hose with a coupling to step down from 2.5". I’m running a 1.25" on mine.

IMG_0885.JPG4032×3024 1.88 MB

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4

Definitely helpful there. The clear stuff I have now has a metal spiral and a heavy clear vinyl jacket and while it is very flexible, it is also quite heavy. But the stuff in that post is available in a smaller D. So I guess if the stuff at Woodcraft isn’t suitable, I’ll drop down to a smaller D and try the McMaster stuff.

I had wanted to keep the 2.5" for airflow (handy with stuff like MDF) but the advantage of a smaller D is that my shoe could be shorter, which would reduce leverage, too.

5

Got it, that makes perfect sense.

Nice shoe BTW. You and WillAdams make some pretty nice stuff.

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6

I’m using a tiny 4.5hp 5gal Shop Vac with the 1.25" hose with great results cutting MDF. Weakest link is probably the “brush” I’m using rather than the airflow from the smaller diameter hose

7

A few vacuum tubing rules:

A) Use the largest diameter tubing one can use.

This reduces vacuum resistance due to “friction” due to the tubing walls (departure from laminar (non-turbulent) flow).

B) Never reduce the tubing diameter and then increase again.

This creates significant turbulence and drastically reduces the effectiveness of the vacuum.

C) It’s OK for the tubing diameter to constantly increase - from the perspective of pick up to the dust collector.

The smallest diameter segment should be as large as practical (usually on the pick up end).

D) Use the largest diameter tubing - from the perspective of dust collector to pick up - for as long as you can.

Let the air flow as unimpeded as possible for as long as possible.

E) Minimize the number of turns, adapters and tubing segments.

Any turns/bends should use the smallest angle possible.

F) Transitions - from one diameter to another - should have smooth internal surfaces whenever possible.

Avoid abrupt transitions.

H) Keep the total length of tubing - from pick up to dust collector - as short as possible.

Less tubing, less resistance, better air flow.

I) Static buildup in CNC vacuum tubing is an issue.

It’s really easy to create conditions that can cause a fire or dust explosion. I’m not kidding! Use (and ground) static dissipative tubing or take the easy way out - run a bare, ground wire through the tubing.

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8

Friable materials (“easily crumbled”) materials (e.g. wood, MDF, FR4, fiberglass, carbon composite) generate particles that are extremely detrimental to your health. Exhausting the air from a shop vac is actually concentrating these particles in the air around you. You’re seriously damaging your health machining MDF without the proper protection. Shop vacs are some of the worst when it comes to CNC particles. No, they are not (saw) dust. The dangerous stuff you cannot see.

It’s not about picking up what you can see - it is that, but it’s also about picking up and removing the particles you can’t see. The “invisible” particles are the ones that can damage your health.

Particles 5 microns and larger are expelled from your lungs, smaller can be as dangerous as asbestos - or worse. Particles can still deposit chemicals and viruses in your lungs, even if they are expelled.

By-the-by, MDF is one of the most dangerous materials to CNC machine. The particles are toxic, carcinogenic, and teratogenic. Some hardwoods (i.e. cherry) are nearly as bad. Exotic hardwoods - those from tropical regions - can expose you to dangerous viruses and diseases contained on/in the particles.

The dust collector (vacuum element) must be air tight and exhaust either outside the house or, if exhausting inside, through a HEPA filter rated for 0.5 microns (or better). Since HEPA filters are relatively expensive, one should have a dust separator (e.g. cyclone) ahead of the the dust collector. The dust separator will removed as much as 99+% of the particles before they enter the dust collector. This dramatically increases the life of the HEPA filter.

If you can exhaust outside, one still needs a cyclone (to meet EPA rules and necessary safety) but no HEPA filter is necessary. Just a 5 micron filter to prevent “snow”. This solution is much cheaper than using a HEPA filter. There is a downside, however… noise. Your neighbors may not appreciate the sound. It is possible to design a muffler but that is getting into some advanced design stuff.

The physics of tubing and the distribution of particles generated by CNC machining require tubing at least 2.5 inches in diameter. Four or five inches is necessary to absolutely ensure pick up - along with a sufficiently powerful dust collector. In the Nomad and SO3, we need to compromise. Do the best you can.

Only step down from 2.5 inches as close to the dust head as possible. See the principals I posted earlier.

P.S.

Since the particles are toxic, carcinogenic, and teratogenic, it’s all about exposure. The risks increase with exposure; your genetics will govern when and how the effects appear. I know several wood workers who have damaged lungs from CNC work.

The nasty stuff mentioned above is only part of the problem; other issues can be allergies, headaches, and other symptoms.

P.P.S.

I’ve posted extensively about air safety; you can search for those postings.

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