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I had a couple thousand slides to digitize and wanted as good as possible results as reasonable. I used a Nikon Coolscan 5000 with a stack loader. The scanning software was Vuescan which I find is...

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Thanks for the responses...but I think I phrased it not clearly.

What type of setup is needed to measure the cfm of shop vacs? No doubt that you need to use a much larger test duct. How big a...

I recently saw a video where a guy tried measuring the flow of shop vacs and extractors by using a vane anemometer at the end of 1.5 and 2.5" hoses. Does look accurate.

What is a reasonable...

An amazing restoration.... Looks great!!

Those are ugly looking welds with stress risers. They are ideal locations for cracks to start and run. I can not believe you have such poor welds on an impeller.

Note: my opinion is based on my...

Thank you BobL for clarifying this issue.

I am curious about the cost to automate the gates in the men's shed. It seems like it is very costly.

Can one make a rectangular bell mouth hood? I thought that it would be great for a lathe.

Thank you BobL!

I know there was some information comparing the SP loss of these two probably by BobL. I have spent a lot of time looking but have failed to find it. It is commonly thought the two 45s are better,...

Great experiment and interesting results.

He almost hurt himself and the unit trying to put it up with a ladder...dumb idea.

I believe they are Grizzly brand 2 hp at 60 hz


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I recently saw a thread in another forum about using two 2 hp Dust collectors hooked up on one duct via two wyes. They reported measuring over 1800 cfm on a 6" duct using I pitot tube. Does this...

Interesting concept. Does a liquid particle act the same as a dust particle.
? I would think there are significant differences in shape and surface tension.

Interesting device and someone will do a 3d print to make them.

Interesting point about effectiveness of BMH and available pressure.

Would a properly sized/shaped BMH on a vacuum with high static pressure work well. I am thinking a 2.5" or 1 .25" hose.

I understand that 6" hose and BMH would be better and an 8" would be even better. The issue for me becomes practically . A 6" inch hose is more expensive and I do not have one. I used what I have...

I finally setup my Shopsmith lathe with a BMH. I can not believe how well it works especially with the fine dust from sanding. A lot of the larger chips fall to the floor but that is OK> The finer...

I can understand that calculating flow from the pressure and a performance curve lacks some level of accuracy. You have pointed out repeatedly how difficult it is to measure flow properly. Based on...

I have a UEi manometer with the proper range. I just want pressure and will use a performance curve to estimate flow rate.

It will be interesting to read how you use the information to understand and improve your system.

I read in another post some comments about measuring pressure in the pipes. What is the best...

I think BobL has said all there needs to be said. The anemometer is not a good way to measure air flow in a duct. Also, measuring airflow at the end of a duct with any instrument is problematic due...

Great idea....always better to collect dust as close to the source as possible.

It is so easy to miss-interpret a post. One may have posted something as a joke but you can not tell what they really meant. Sometimes you can add a sentence or something to indicate that what you...

I understand what BobL is saying and agree he is correct.

However, there is a real downside to this problem. Many people are working on the dust collection and want to improve it. But how do you...

I do not worry about the chips and what does not get sucked up gets swept.

I tried looking for something that showed velocity vectors for a BMH versus a naked pipe but did not find much but...

Have you ever done any testing to see how much deterioration in performance there is with an elbow before the BMH?

I look at your BMH setup with the bandsaw and got me wondering. The BMH has...

BobL --- I have read and re-read your posts on BMH and other topics and it is very interesting and helpful.

I also took note of the tests you did on 90 degree elbows. After the comment about...

I hope you noticed where I live and I quoted prices for me.

There are two 4" ports that I bought. Parts 260-403 for $2.89 and 260-411 for $2.99. Shipping is a flat $6.95. I bought them and that is what I paid. I do not know where you got the 8 times as...

I have no doubt that a BMH changes the flow patterns as I completely understand that. My questions has nothing to do with that. I am asking about the 20% improvement in cfm that was mentioned and...

So, how long does my 4" pipe need to be to reduce turbulence so I can see the 20% improvement. Or what would someone need to do to be able to obtain the benefits of a BMH. It appears that it is not...

I am very confused as earlier in the thread you stated-

"A bell mouth hood (BMH) increases the fine dust collection because they are very efficient increasing the flow by as much as 20% for a 100...

Well, with the prospect of a 20% improvement in flow, I put a BMH on my pipe.

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I checked the static pressure with and without the BMH several times. It went from about 7.90" to 7.70". ...

I must not have had enough coffee this morning but I do not understand your comment. Could you please explain a bit more. Thanks

I measured 6 points across a pipe section at the spots suggested in the literature. These were at 0.032, 0.135, 0.321, 0.679, 0.678, and 0.968 of the duct diameter. I did the test a couple of times...

It is a 5 hp cyclone and measurements were made in a long section of straight duct across the duct in the proper positions using a Dwyer 471. Does this sound adequate?

Should I see a 20%...

I am trying to understand thing.....So BMH on a 100 mm pipe increases flow by as much as 20%. Right now, I get about 800 cfm from the pipe I show in the picture. Are you suggesting that if I put a...

I have read with interest the posts on bell mouthed dust pickups.

I use the following for dust collection from grinding with an die grinder or similar and get it close as possible to my work. A...

Very interesting discussion on rectangular ducts. When trying to calculate or estimate losses, how do you take into account the surface roughness of the ducts. Both PVC and metal ducts are smooth...

Sorry, I do not have the Jet dust collector anymore that I mentioned so can not measure the diameter.

I put the part in my Jet 1.5 HP dust collector with a canister filter. It made it into what was called the Vortex dust collector.
It kept the filter cleaner and didn't effect the performance. ...

I am a reader of this forum but have not contributed much. I live near Chicago in the U.S. and recently purchased the Nova Voyager Drill Press. It is a very solid machine with almost no run out on...

I find it interesting that someone is suggesting cryogenic treatment. What grade of steel are you going to do this to? Does this grade of steel respond at all or are you just doing this for fun and...