bolt size????????

[diovol]

hey guys simple but bit of a silly question... im about to mount my compressor and i was reading the manual that came with it. well the holes in the compressor feet are 9/16 but in the damm book they tell you to use a freaking 3/8 bolt... is there any reason why you would need to use such an undersized bolt or should i just use the matching bolt for the hole....

as always thanks....

 

[mrbreezeet1]

7/16" or 1/2" 8 grade, with a washer ought to be enough, what are you mounting it to, down to the concrete?
Thanks,
Tony

 

[sberry]

There is no reason you couldn't use a larger bolt but the 3/8 is sufficient, not like you are hooking a log truck to this comp.

 

[SMLDONZI]

Its probably oversized to ensure alignment of the pattern once all the holes are drilled--accounting for drill bit walk, etc. 3/8" is plenty.

 

[T1320T]

I agree w/ ^^. Although I'd probably use Grade 5 bolts, you'd want it to bend instead of snap (not like it's probably going to do either)

 

[diovol]

7/16" or 1/2" 8 grade, with a washer ought to be enough, what are you mounting it to, down to the concrete?
Thanks,
Tony

gonna leg it to the concrete floor but use hockey pucks as isolators....

 

[BADSIX]

i have a large 80 gal. upright that just sets on a rubber pad it hasn't move in years and no bolts

 

[koditten]

Try to find 9/16 bolts. Not very comon. You can't usually find them in the normal places. Everytime I needed 9/16 bolt I had to go to specialized fastener supplier.

 

[scott37300]

If you are anchoring this to concrete than use the 3/8" anchors. Drilling in concrete always has some drill bit walking, especially if you mark the holes and move the compressor and just try to drill the mark you made.

You don't need huge bolts to hold the compressor in place, they basically just keep it from "walking" due to the vibration. The compressors weight keeps it put, the bolts just need to handle the vibrations that make the compressor "walk". I have my compressor, a rolair 30 gallon 2 stage that weighs over 300 pounds mounted to the wall of my garage on a plateform I made out of 2x4s and plywood supported by steel brackets I made to hold it up. I am eventually going to lag bolt the compressor to the platfrom with some rubber isolators when I have some extra money, but for the time being the compressor stays put just fine not even being bolted down and not having any isolators. And personally I don't like hockey pucks for isolators, yes they are rubber but really stiff rubber that doesn't absorb much vibrations. For concrete they should be fine but I am going to go with a true vibration isolators from mcmaster.

 

[GeorgiaHybrid]

A 3/16" oversized hole is std when using expansion anchors to concrete. It allows you to drop the shield down thru the hole without moving the equipment.

 

[Dale B]

You want some wiggle room to allow for misalignment of the bolts on non critical spots like this... Go with the 3/8.......

 

[larry_g]

I would also forward the opinion that you do not want to ridigly bolt a pressure vessel down. The tank will change size with temperature and pressure and create high stress points where the feet are welded to the tank. Use the recommended bolt size and allow some movement with rubber mounts. Consider rubber above and below the foot to allow motion.

lg
no neat sig line

 

[diovol]

I would also forward the opinion that you do not want to ridigly bolt a pressure vessel down. The tank will change size with temperature and pressure and create high stress points where the feet are welded to the tank. Use the recommended bolt size and allow some movement with rubber mounts. Consider rubber above and below the foot to allow motion.

lg
no neat sig line

so you mean dont leg it to the concrete?

 

[gmwelder86]

If your worried about the holding strength check this out.

http://www.concretefasteners.com/anchors-fasteners/thunderstud-wedge/technical-specifications.aspx

 

[larry_g]

so you mean dont leg it to the concrete?

I did not say not to lag it down; I said do not rigidly mount it down. Emulate what a shock absorber mount would looks like. It will allow some movement but still holds the unit in place.

Lg
No neat sig line

 

[csp]

so you mean dont leg it to the concrete?

]]

No idea what you mean by 'leg it', but the idea is not to bolt it down tight directly to the concrete.

 

[Falcon67]

Mine is not even bolted down. It sits on three 4" square pieces of stall mat. Never moves. If you are worried about it, use 3/8" co9ncrete anchor, all thread, a big fender washer with a rubber washer under it and a nyloc nut on top. Just snug them and that should be good enough.

 

[diovol]

what type of concrete anchor....there are few out there.... shielded or wedge type.......

 

[Steevo]

Unless you are in earthquake country and have an upright compressor, I'd set it on rubber pads and not bolt it. It will be quieter because it won't transfer hammering vibrations through the slab via a solid metal-to-concrete attachment. If in shakey-town, then I'd use isolation mounts to fasten it to keep it from falling over.

 

[diovol]

]]

No idea what you mean by 'leg it', but the idea is not to bolt it down tight directly to the concrete.

how would you mount it... "lag" it to the concrete is what i meant......... as in my first post i said im going to use hockey pucks between the concrete and compressor...... but it will be lagged to the concrete...

 

[tcianci]

I have to chuckle at the nine lives some of the stories around here seem to have. Why in the world would anyone engineer a vibration isolation machine mount when all you need is to bolt your stuff to the floor through with a hockey puck under it? Because it doesn't do a damn thing that's why. Lagging a machine to the floor will transmit vibration through the bolt no matter what's under the machine foot. True vibration isolators have a decoupling mechanisim inside them whether it's springs or simply a bonded rubber core between 2 plates that you can fasten to. Hockey pucks are for hockey. Go to www.mcmaster.com and look up vibration isolators and machine mounts. They typically have quite a bit of design information along with catalog listings. In the case of a typical air compressor you will find that just mounting rubber feet under the machine will suffice. If you are concerned about it tipping over then use a real vibration isolator.