1/4" Hole In Plumbing For Lighthouse Motors?

[zandeauto]

Can anybody tell me what they are doing with their lighthouse motors in the way of the manufactures recommendation about cooling the lower bearing by drilling a 1/4" hole in the plumbing for leakage. Is this really needed?

Here is their wording copied from their website:

"You must have at least 1/4"(Drilled Hole in the bottom of your table or plumbing) leakage per motor for proper cooling of the lower bearing. This must be filtered air - possibly using a filter like a ShopVac uses to cover the all holes that you have drilled. This will give you plenty of filtered surface air. If you come up with a better idea please tell us so we can tell others.
If you do not provide leakage air, you will destroy the motor and the warranty will not apply!"

[coryatjohn]

I used a relief valve that only opens when there is no flow through the pumps. It was a bit expensive but seems to be worth the trouble. Leaving a 1/4" hole will certainly rob your system of valuable vacuum, although I don't know if that's a critical amount or not.

[zandeauto]

Would this do the job?

http://www.drillspot.com/products/41675/Control_Devices_VR-25_Vacuum_Pressure_Relief_Valve

[dlcw]

Can anybody tell me what they are doing with their lighthouse motors in the way of the manufactures recommendation about cooling the lower bearing by drilling a 1/4" hole in the plumbing for leakage. Is this really needed?

Here is their wording copied from their website:

"You must have at least 1/4"(Drilled Hole in the bottom of your table or plumbing) leakage per motor for proper cooling of the lower bearing. This must be filtered air - possibly using a filter like a ShopVac uses to cover the all holes that you have drilled. This will give you plenty of filtered surface air. If you come up with a better idea please tell us so we can tell others.
If you do not provide leakage air, you will destroy the motor and the warranty will not apply!"

I use some simple set of butterfly valves for my cooling system. I have the Gary Cambell "Black Box" vacuum box with four motors. Each butterfly valve is attached to a piece of 1/4" flex tubing which is attached into the main vacuum plenum PVC pipe.

Since I always use at least two motors, two of the butterfly valves are open. When I bring the additional two motors online, I simply open the other two butterfly valves. This provides the equivalent of a 1" tube of air flowing to the motors for cooling.

I've never had a dust problem near the butterfly valves so filtering has not been an issue. If you have a ton of dust been shot into the area where the valves are then by all means provide filtering.

[coryatjohn]

"If you have a ton of dust been shot into the area where the valves are then by all means provide filtering."

If you're using a blower type pump, filtering is mandatory!

[zandeauto]

Don

How much vacuum do you lose?

[Brady Watson]

Is this really needed?

Yes. Without some leakage, the lower bearings cannot cool properly.

Yes. You are going to lose some performance. On paper, this would equate to a maximum 100% sealed vacuum pressure of about 9Hg", compared to 1/4" hole in system maxing out at 7.8Hg". These are 'on paper' calculations and your mileage may vary. This is not an unreasonable penalty for longevity's sake. It equates to about a 10-15% reduction in max suction.

Way back in the stone age, before the 'Black Box' was a twinkle in Gary's eye, I was messing around with several of these motors in my own R&D before making this an open source project. These were NEVER designed to be used in real heavy production. In fact, I was going to call this the 'Stepping Stone Open Source Vacuum Project' - because the idea that should be pounded into everyone's head who uses these is that they are NOT production duty. They are a band-aid - a stepping stone - gitcha goin so you can make enough money to afford a proper vacuum system made for production work. I had no idea that so many people would be using these things as long as they have for production type work.

As they say, 'Everything has a price' and 'There is no free lunch'. There are people out there who have been running on the same set of motors for years - while others burn them out in just a few days or weeks. If there is ANY way to reasonably extend the life of these motors, as they do work for lengths of time they were NEVER designed for, then by all means do it - but realize that you may be putting lipstick on a pig & the 'end' is most certainly inevitable. Do the 1/4" hole as recommended by the vacuum motor expert (what this guy does day in & day out!) and prolong the day of reckoning.

-B

[zandeauto]

Thanks Brady. Do you recommend just drilling the 1/4" hole with filter or a relief valve as others use.

I will be holding 4' x 5' sheets of aluminum and doing through cuts. This is tread plate aluminum and I cut it tread face down. which I also assume will lose some suction around the tread. Any advise? My table is 4x8 and I was just going to do 4 zones for simplicity. Plus my table already has four holes in it from the previous owner.

[zandeauto]

Could I just add two of these simple automotive breather filters into the my intake pipes going into the filter box I built? One on each intake pipe to the vacuum motors

http://scootershop.com/catalog/images/breathers_lg.jpg

[Brady Watson]

For the 1/4" bleeder port ONLY - yes, they are fine. For the main vacuum filter? They won't move enough air. At the very least you'd want a cylindrical automotive or shopvac filter with enough surface area to support the full CFM flow of your pump(s).

-B