PTS Flowbench Forum

Is there a formula for how much cfm loss when adding more motors. 1 motor = 100 com. How much cfm loss for adding another 100 cfm motor. Building a 100" bench with 12 motors (LH2093-240).

Welcome to the forum Ron.

I doubt if you can assume a fixed amount of flow loss for each additional motor added, there are too many factors that can influence the final maximum flow number. The size of each motor is one obvious factor. Adding one extra small motor will not make as much difference as adding one extra monster motor.

But whatever you end up with, trying to force more total air through the bench will inevitably increase internal bench turbulence and internal pressure drops, leading to a slightly lower total available flow.

A one hundred inch bench is a pretty serious ambition.
Just realise that is 520 Lbs of force per square foot, and a square foot of surface is not that large.
Its probably getting rather high for just a bit of glue and a few wood screws, so something totally different will probably be required.

Is the 3/4" MDF not enough for a 100" bench with extra bracing? Thanks for the welcome!

Try cutting a two foot square piece of 3/4 MDF, support the opposite edges between two bricks and drive one wheel your car up onto it.
Decide for yourself if its strong enough.

MSG is expensive. Is that a yes or no? Thanks Ron.

I mean MDF. Phone has spell check and a mind of its own sorry.

The maths is easy.

How brave are you ?

MDF is stronger then most people please do check it out in this link
http://www.ewp.asn.au/node/6 For got to add this link to

https://www.google.com/webhp?ei=28WyVdO ... elasticity

You can see my flow bench build here http://www.flowbenchtech.com/forum/view ... f=19&t=588

Thanks for the info on the MDF. Your bench is fantastic, what are your limitations. With all those motors you could stop the earth from rotating. Lol. Bruce was kind enough to share some bracing info for the large bench. It was the same direction as I was going. Love this site. When I get my computer online I will be able to download some pics from the site. This phone runs out of data plan really fast. Thanks again, Ron!

Tony wrote:Try cutting a two foot square piece of 3/4 MDF, support the opposite edges between two bricks and drive one wheel your car up onto it.
Decide for yourself if its strong enough.

Not just once either, test as many times as you plan to use the bench over 10 or so years.

Don't forget to place your testicles under the board each time too Ron, because that's how close they'll be when your running the bench.

ronm wrote:MSG is expensive. Is that a yes or no? Thanks Ron.

Don't even think about 100" if you think MDF is expensive, it's the least of your worries

Don't even think about 3/4. 100" is some serious pressure on that front area of a bench. I used 24mm MDF for a 60" bench after testing the MDF in a press and measuring the deflection. For 100" daily usage I would probably double the 24mm or use steel.

Jim