[vroemm]

Hi.

I am considering buying a OPTIMUM BF20L VARIO mill.
It's weight is 115 kilogram and can take a load of 55 kilogram.
Worst case scenario would be 115+55= 170 kilogram weight.

http://www.optimum-machines.com/prod...rio/index.html

I live in a flat, which makes soundproofing very important.

I have material to build a big soundproof box to reduce the sound going through the air.
That part is probably solved.

The problem is the sound moving via direct mechanical contact from the mill to the floor.

Would this do the job?
Thick layer of foam of 12 cm thick, 75 cm wide, 100 cm long, of a matras of a bed.
Thick wooden board on it, possibly re-enforced with steel bars to reduce bending.
Then the 115 kilogram optimum BF20L VARIO on top of the wooden board.

A small test showed the height of the foam will only become a few centimeters less with the 115 kilogram on it.

The mill has a cross table.
When the table with work piece moves to the right the weight will shift.
Which will make the mill lean over to the right side.
Same to the left when the cross table moves to the left.
How bad is this for the mill and milling ?

And during operation the mill will vibrate more, and maybe even start shacking.
Because the mill is not fixed to the ground, but standing on foam.
Will this vibration be bad for the mill and the milling ?

Would appreciate an answer very much.
Because if i can not solve the soundproofing problem there might not be a hobby mill for me :-(

:-)

Thanks.

Vroemm.

[Geof]

On a small mill like that keeping it perfectly level is not really important, it is so small and lightweight it is not going to distort a noticeable amount just due to its own weight or the weight of the job.

Another way you can consider mounting it to reduce the vibration transmitted to the floor and make it more stable is to use maybe three layers of plywood separated by thinner and more rigid foam.

[vroemm]

Another way you can consider mounting it to reduce the vibration transmitted to the floor and make it more stable is to use maybe three layers of plywood separated by thinner and more rigid foam.

Thanks.
It will indeed reduce shacking.
My first thought was rigid foam is expensive, but in fact i have no idea how much it costs.
I will consider it.

And i came up with a variation on your idea.
What if the soft foam is used.
Then pull with rubber wire/rope the sides of the wooden board down.
This will compress the soft foam in to more rigid foam, like you suggested.
Causing a less wobbly mill.

Vroemm.

[Geof]

I think you may tend to transmit vibration through the wire or roap because it is going to be under tension of course; think guitar string.

[vroemm]

I think you may tend to transmit vibration through the wire or rope because it is going to be under tension of course; think guitar string.

Yes, but so does a more rigid foam.
As long as the rubber rope is not stretched to the end of its elasticity there might be something useful in it.
There is a balance with for now unknown characteristics.
But it is a option to look into.

Vroemm.

[vroemm]

I got an other variation on your idea.

What if soft foam is used.
Then put a strong plastic bag around the soft foam.
Then suck air out of the bag :-)))
Then you have sound dampening foam with on the fly adjustable rigidity :-))

It is more a theoretical idea, making it work is something else :-)

Vroemm.

[vroemm]

An other variation on rigid foam.
This one is more practical.

Take soft foam.
Start milling.
If the mill does not shack to much, great, leave it like it is.
If the mill shacks to much, you could do this.

Cut a big hole in the middle of the soft foam.
Lets say for example cut out 50 percent of the total surface.
Then the same weight is carried by less foam.
The foam will compress more.
Making it more rigid.
Less shacking mill.

I think this might be the plan to follow for now.

Vroemm.

[vroemm]

On a small mill like that keeping it perfectly level is not really important, it is so small and lightweight it is not going to distort a noticeable amount just due to its own weight or the weight of the job.

What about vibrating electrical connections and electronics inside the mill ?
Could they break sooner if the mill is on foam ?

Vroemm.

[Geof]

What about vibrating electrical connections and electronics inside the mill ?
Could they break sooner if the mill is on foam ?

Vroemm.

That is a good question but I think the answer is probably no; actually it should be no because even with a machine correctly placed on a firm base it does vibrate.

[brunog]

Vroemm,
You could use the foam and encase it into a styrofoam insulation frame and apply a sheet of plywood over. you could also place the whole assembly over a layer of rug underlay foam.

Best regards

bruno

[XYZADave]

Hi Vroemm

Do a "Google" on vibration isolation mounts and their applications. They are relativly inexpensive and do a good job if selected and installed properly. Several layer can be used if needed. Note* The top board should be rigid approx 0.5m x 0.5m x 12mm minimum thick with the isolation units mounted asymetrically around the perimiter. Any additional layers should just be a frame to support the vib iso mounts, as in, hollow out any additional layers leaving a, say 12cm edge on all 4 sides. The reason being, these boards act as the sound board of a guitar and you want to minimise their surface area.
Ther are many ways of arranging these ingrediants....try some different configurations...see,hear what the difference is. You are essentially trying to make a guitar, violin etc that makes no sound!

Hope that helps
Dave

[BillTodd]

I suggest you mount the mill on vibration dampers inside and also mount the enclosure itself on anti-vibration mounts.

[vroemm]

A problem.

In the dutch manual of the OPTIMUM BF20L it says something like:

You need a rigid connection between the ground and the mill.
Or else you will get resonance frequencies very quickly.
Which leads to bad cutting of the work piece.

If this is true, then putting a mill on foam is bad.

Which one is true ?

Has anyone a mill running on foam ?
How is this going ?

Vroemm.

[Geof]

....You need a rigid connection between the ground and the mill.
Or else you will get resonance frequencies very quickly.
Which leads to bad cutting of the work piece.

If this is true, then putting a mill on foam is bad.

I do not have a mill running on foam but I think it is very likely you will not encounter any problem.

Do a Google search using 'constrained layer damping'. You will get many links and may have to do a lot of reading but I think you will find useful information.

The best possible way to dampen vibration is to have two rigid surfaces separated by a flexible layer.

[vroemm]

In the German optimum catalogue there are sound dampers.
Page 60 Number 338 1012
http://www.optimum-maschinen.de/file...log/index.html

The catalogue says machines (in general not the BF20 specific) do not need to be bolted to a stand.
And the machine works better when it stands on sound dampers.

This confused me for a while.
It looked like it is the opposite of the text in the dutch BF20_NL.pdf manual, which i wrote earlier in this thread.
http://www.vynckier.biz/assets/manuals/nl/BF20_NL.pdf

Might this be the answer:
I translated the Dutch manual wrong.
It says :
A insufficient solid underground leads to excessive vibrations between mill and underground.

Could this simply mean:
Do not put the mill on a wobbly worktable or you get resonance.

Without it saying anything about how the mill is fixed to the worktable ?

Vroemm

[Geof]

I think if you have the mill sitting on a hard surface but not attached rigidly to the hard surface you can expect more vibration because the two surfaces vibrate against each other. This is why you need vibration dampers to avoid having the two hard surfaces in contact.

[vroemm]

Cut a big hole in the middle of the soft foam.
Lets say for example cut out 50 percent of the total surface.
Then the same weight is carried by less foam.
The foam will compress more.
Making it more rigid.
Less shacking mill.

Vroemm

I have now tried something like this.
The result is completely opposite of what i expected.
Here is the result of my experiment.


vroemm

[ImanCarrot]

Wouldn't standing it on a rigid surface on top of sandbags work?

[ihavenofish]

my mill is about 1/2 the weight of yours, but ive just put it on some mdf, then 3 layers of carpet underlay. carpet underlay is designed specifically for damping vibration through floors, and in my case seems to be working well. the cabinet the mill is in vibrates, but it doesnt seem to go through the underlay much. the mills wight is distributed by the mdf board so the setup doesnt wobble or move.

i think this could work for yours perhaps in two sets - mdf - 3 foam - mdf - 3 more foam. its easy to find out if it will work, the underlay i got was an offcut from a carpet store, cost like $8 if i remember.

[bad bearings]

How about the chips? And the oil? Have you talked to your landlord?