Vacuum Blower Over-heating issues

[JNathan09]

Hello Shopbotters,
Great forum! First time poster.

We recently replaced the plenum, spoil boards, and vacuum hold down system on our Shopbot.

plenum.jpg

I used a 3/8" endmill to cut the large grooves in the plenum material. This material is a product called Richlite, a GREAT material for this application. The smaller grooves where cut using a 1/4" ball endmill. After machining, we installed new MDF spoil boards, and a new 6 zone plumbing system. Then we started up the vacuum blower...

blower.jpg

and then this happened to the exhaust tube...

exhaust.jpg

The blower is VERY hot to touch. With only one zone open, the vacuum gauge is reading 8.5 "hg. With all 6 ports open the reading is 6 "hg. Before replacing the plenum/MDF etc., there were no heating issues.

Could the problem be:
Not enough cfm of air to keep it cool? Which could be from using a 3/8" instead of a 1/2" endmill to cut the grooves? Could it be from using MDF instead of a low density board?

Thoughts?

Thanks in advance!

[Brady Watson]

8.5 Hg" is about right for that pump. My FPZ runs about 8.5-9 Hg" full tilt.

Note that performance will be greatly affected on this system without the use of ultralight MDF. Your effective vacuum will be 8.5 - 6 = 2 Hg", which is not much. That is your usable vacuum.

I would close off the table ports and open up the '5th valve' to atmosphere (assuming you have 5 risers w/valves and only 4 ported to the table) and let the pump run. It will (or should!) register 0 Hg" free flowing. Check it to make sure it is cool.

-B

[PNast]

I have a Becker VT 4.40 pump and I use 3/8 inch Polyethylene tubing with a gasket plenum system cut into Phenolic plastic. I have to run with a separate zone open to get enough airflow to keep the pump cool. Sometimes I get enough airflow moving through the Pine board but not always. I also had a problem with the voltage, the pump is a European model and runs on 220 +/- 6%. I had between 240 and 250 coming in from the service, this overheated the pump and shut it down. I had to purchase a transformer to regulate the voltage to 220.