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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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In Reply to: Isolation bearing bases mounting question posted by Justin Thorpe on March 14, 2003 at 00:14:17:
Barry's advice is good.Consider that a roller bearing is both an isolation device and a coupling device (all isolation devices are coupling devices, but not all coupling deivces are isolation devices). For a roller bearing, isolation is provided in the horizontal plane while coupling is provided in the vertical plane. Within the device itself you definitely want the coupling to be rigid. Something compliant like silicone between the steel cup and its wooden base will end up, as Barry pointed out, compromising the horizontal isolation. The steel cup needs to remain as stationary as possible to be optimally effective. The roller bearings I have built sound like the same design you are building. I used high strength epoxy (slow curing) to bond the steel cups to their wooden bases (3/4" MDF), and the results have been awesome.
If you have access to a Dremmel tool, I highly recommend polishing the center of the steel cups (keep in mind the bearing will hardly move when in use, so only the very center of the cup needs to be polished). Of course, you may choose to polish the entire cup for the sake of looks.
Any vertical isolation that you want to do when using roller bearings should be done between the bearing device and the platform supporting it (this would be tricky to do, however, and I haven't seen any designs to accomplish this), or somewhere below the platform supporting the roller bearings. The most common method of veritcal isolation is to use a small bicycle inner tube between the platform and a sub platform. For example, you first have a rigid shelf on which you place the inner tube. You then place another rigid shelf atop the inner tube (the tube should be the only thing supporting this shelf). The roller bearings go on top of the upper shelf and suppor the equipment.
Also, you may want to play around with placement of the roller bearings under the equipment (much the way cones sound different in different places under a given piece of equipment, so do roller bearings). Barry and I have both had good luck by arranging the bearings in the largest equilateral triangle that will fit under the equipment. Determining the center of gravity of the component in question will help you to determine the proper orientation of the triangle. The edges of the equipment tend to be much stronger than areas closer to the center - you do not want the equipment chassis to offer any compliance. If the bottom of your component chassis is rough, as it is on my B&K amp, you may want to consider polishing the spots where the bearings will make contact. If the bottom of your component chassis is either flimsy or not flat enough to use with the bearings, you may want to consider mounting a thin, rigid plate to the bottom of the chassis to provide a hard, smooth surface for the bearings to work their magic.
Do make sure that your roller bearings sit flat on the shelf and don't have any side to side play. The more stationary the cups remain at all times, the more effective they'll be. Keep in mind that you're dealing with microscopic motion under normal conditions, so factors that you cannot see can have profound effects. Along these lines, also make your wooden bases so that the bottom of the cup ends up being as close to the shelf as possilbe - in other words, make the cup/base combo as short as possible. The taller it is, the less effective it will be (being taller subjects the cup to more torque, and therefore makes the cup less stationary). The bottom of my steel cups actually 'poke thru' the wooden bases and make direct contact with the shelf below - the wood is really only there for stability, and also to damp the cup itself.
You will be experiencing a sonic delight shortly....good luck!
-Pete
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Follow Ups
- Isolation and coupling combined - pburant 05:49:11 03/14/03 (2)
- Re: Isolation and coupling combined - bdiament 09:21:52 03/14/03 (1)
- True - pburant 10:10:30 03/14/03 (0)
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