spin balance testing

Dave,

Check out the folks here. Don't know if they rent machines, but they may provide a service if you can send the parts to them.

Alternatively, if you have a defined axis on your part can you just set it up on a horizontal shaft and see if one side wants to always rotate down? (1/4" drill rod and a pair of nice vee-blocks with some spray lube should work nicely...) Not sure how critical your application is, but may work if you just want an indication if a gross unbalance exists.

Good Luck!

Usually when filling containers with hi-viscosity fluids, the nozzle should enter the container almost completely, and just above the bottom, to allow free flow of the product whilst retracting to allow for the fluid to fill without obstructing either; the flow, product, and nozzle. Keep in mind that filler-machines are calibrated to specific volumes and are double checked by some flow device, volumetric, or weight somewhere in the process.

K

/:€ ?

If it has no central shaft it will be difficult to spin it.

You allow it to roll across a flat surface and see if it has any tendancy to stop in the same orientation, maybe roll it down a short ramp, mark its circumference so that you can check start and stop points.

This would cost very little except time and patience.

Del

Brilliant.... (yes I did rate it)

I consider your suggestion as very very good with only one remark: the average density has to be less than the density of water= it has to float if not the test cannot be done. Never the less I rated it as "good" since even if in this case it will not work it can be used in an other situation.

Polyurethane is about 5% denser than water so you should be able float your sample easily in brine.

Your concern seems to be uniformity of fill and not dynamic balance. Correct?

I am trying to picture the part and the process but can not.

Is the object to be filled symmetrical?

Is it machined? consistent?

Will it be used to rotate?

How is the part filled?

How do you intend to rectify faulty ones or will it be scraped?

How about a tire balancing machine? Would it be accurate enough for your purpose?They come with cones for various size wheel openings. And if the size you need isn't available any machinist can make you one.

I've used my friends machine for checking some of my self made projects for balance. Some were better balanced than others. One even blew apart. Good thing they have safety covers.

Thank you for the good vibe.

All the urethanes I've worked with were less dense than water,

but they were "blown" urethanes or closed cell foams.

Specific Gravity 1.12 - 1.24

OOpsie:

Assuming that the material is solid urethane (like skateboard wheels),

I will salvage my position by replacing water with

carbon tet.,

Density (20 °C) 1.59 g/ml .

Carbon tet can be found at your local auto supply store as "electrical cleaner", or "non flammable disk brake cleaner" for about $4.00 per 8 oz..

so if the water doesn't float it, this will.

^{don't breathe the fumes.}

^{and, it's a bitch to dispose of responsibly. I'm kinda amazed it's still available.}

Google armature/balancing and see if this type of equipment will work. I used similar machines to balance(dynamically) electric motor armatures for aircraft. Some of the armatures were close to the dimensions you posted.