Roof Mounted Dust extractor - help

[Barry Burgess]

I have finally mounted the motor and impellor from the dust extractor on the roof beams. Thanks for to the idea from Bean to use balls as dampener . It took lots of hard work to raise the load to the roof but it is finally there.

It looks like this when finally connected

I have just one problem - there is no vibration but there is a resonating noise??? Its not there all the time but I cannot seem to find it.
Any ideas from the group.
Thanks
Barry

 

[Simoli]

How about adding some weight to the blower base. The extra weight should dampen the the vibration/noise (same thing).

 

[engineer one]

looks very good barry, have you tried to isolate the noise?

resonating tends to imply something bouncing up and down, i wonder whether it might be the pipes.

a trick used in the motor trade is to place a screwdriver on various components either to find the path, or shut down the noise, and thus
tell you where it is.

you might have to change the tension on the motor mounting, but i would think because the motor is mounted thus, the noises are further down the
path.
paul :wink:

 

[Mcluma]

No idea about the noise, as there are no real connections between the blower and the rest of the unit.

Maybe an idea is the vibration of the machine, is sending off vibration to something you have laid down on the loft above


BUT

HOW IS IT WORKING. it it worth all the work, it there an improvement

 

[RogerS]

Barry...as the inverted base is the only 'new' item as far as I can see then I suspect it is acting as a sounding board and amplifying vibration from your motor. Try temporarily sticking some weight on it ...on top of a bit of old carpet or bubble wrap...weight like a couple of breeze blocks or bricks.

 

[Barry Burgess]

HOW IS IT WORKING. it it worth all the work, it there an improvement

Yes it takes up less space so I can put more in the workshop

 

[Barry Burgess]

Thanks Paul ,Jim & Roger I will start by tightening up the 6 M12 studs that holds the motor plate in the morning. I suspected that the plate could be moving. I could do my Tarzan trick and hang onto the motor plate - the extra 85kgs might help the vibration!!!! I don't think it will come down - over engineered by a non engineer.
Thanks again
Barry

 

[RogerS]

Thanks Paul ,Jim & Roger I will start by tightening up the 6 M12 studs that holds the motor plate in the morning. I suspected that the plate could be moving. I could do my Tarzan trick and hang onto the motor plate - the extra 85kgs might help the vibration!!!! I don't think it will come down - over engineered by a non engineer.
Thanks again
Barry

It's not weight per se but where you put it that counts...it needs to be in the middle of the board IIRC.

I'd caution against tightening the bolts...floppy is good! If too tight then you could transmit vibration to the beams.

 

[engineer one]

barry, i tend to agree about over tightening the bolts, wonder whether they are in fact the cause of the noise. i note that you have not spaced the two boards apart, except with the beam.

i kind of wonder whether the boards are vibrating around the beam, and
that is the noise you are hearing, since it is the only thing you have changed. have you thought about putting insulation between the boards and the beam, otherwise i would put tubing spacers between the middles of the bolts.

what we all tend to forget is that every revolution of the motor unless an induction one, there is a jolt of torque as it goes over the armature segments, this torque can set up a low density resonance which might well transfer through the beam.

paul :wink:

 

[Barry Burgess]

Sorry SWMBO had organised a number of people for lunch today so my time in the workshop was not to be. At the crack of dawn today I removed the dampers I had between the motor plate and the beam were removed - I slight improvement. I will have to get Engineer One around for a spot of lunch to help me find the problem.

 

[Simoli]

I will have to get Engineer One around for a spot of lunch to help me find the problem.

Pay for my plane ticket I would be happy to visit and set things straight. :lol:

 

[engineer one]

oh hell, not camberley again :lol:

paul :wink:

 

[Barry Burgess]

I tried adding extra weight to the motor plate but it did not help. I talked to Engineer One and all bolts other than the motor bolts had damping so I added damping to these bolts - it did not help.
The resonance appeared to be loudest at the impellor exit and I concluded that is was caused by turning the motor and impellor upside down.
As a last chance I decided to refit the baffle/silencer. - the resonance was gone. What a result as I was running out of ideas and did not want to remove the motor and test it in its upright position.
Thanks for all the help
This is what it looks like now

 

[Mcluma]

but in effect what you have done is hung quite a bit of weight on the actual blower, which should and has taken the resonance out of the unit :!: :!:

 

[Barry Burgess]

but in effect what you have done is hung quite a bit of weight on the actual blower, which should and has taken the resonance out of the unit :!: :!:

I put 6 bricks on the motor plate with no effect. I also pulled down on the plate with me hanging on to it with no effect so I don't know if you are right
I will check by taking the weight of the baffle away.

 

[Barry Burgess]

Mcluma I removed most of the weight of the baffle - no difference. I think its got something to do with the impellor but I am no engineer.