Lots of talk about hockey puck machine mounts...

[jmarkwolf]

...but little analysis.

Yes, I've seen many examples of hockey puck machine mounts, and I've seen the Youtube video of the guy crushing a hockey puck with an 82,000lb hydraulic press.
It would have been useful if he had used slow motion with a force gauge inset in the video!

I'd like to know the compressive load capacity of a hockey puck lying on it's face. The nominal
durometer of a puck is 90 Shore A harness.

I've made and used them before for my band saw and 12in disc sander, much lighter machines. See below.



I want to raise my Series1 Bridgeport milling machine about 3.5 inches off the floor to better accommodate my height, and to allow getting my pallet jack underneath for moving occasionally.

The weight of my Bridgeport, with 12inch knee, vise, work, and tooling is approximately 2400lbs.

If I put a hockey puck at each of the four corners of a frame under the Bridgeport, each puck needs to support better than 600lbs of static compressive force, not to mention dynamic forces.

By my calculation, each puck has 5.6 square inches of surface/contact area when you consider
the counter bore on the underside to accommodate the head of a bolt. This works out to about 108lbs compressive load per square inch.

Multiply this 5.6 square inches by the four pucks, you get 22 square inches total holding up my Bridgeport.

I'm using 5/8-11 nuts and bolts (grade 5 proof load is 19,000 lbs) to assure the threads won't strip, with
3 inch diameter thick washers on the top surface of the puck for good weight distribution.

My reinforced floor is smooth and flat except for a slight run-off slope, and intuitively I think it's all
going to work fine.

But I'd like to get a sense of how much the puck might "squish", due to these compressive forces, and if I might someday find my Bridgeport "copping a lean" due to a hockey puck "blow-out".

Objective insight gratefully received.

 

[Mach89]

Do your own tests if you can't find good info. Raise your Bridgeport up and set 1 under each corner and see how much they squish. Lay one on concrete with a roughly 6x6 piece of plate steel on top of it and see if it will squish under the weight of a car/truck. If have access to a bottle Jack, place the puck under the jack under a car or truck and jack up the front of the vehicle.

I know these methods aren't giving precise data, but should at least tell you if your mill is too much for them or not.

 

[Silverbullet]

Why not use 4 on each side. Mount them to 1/2" x 3" flat stock long enough for each side on the corners use your bolts as levelers . Between the forces downwards and vibration I don't think it would ever squish down baring chemical attacks on the pucks.

 

[Dave Paine]

I think the hockey puck would take the load, but it would compress over time. I have had a puck chip, but I do not know what caused this.

I would consider hockey pucks and the bolts for wood working machines which are lighter.

Since you have a mill, I would use pieces of steel or aluminium. I would not take the risk of the hockey puck failing over time.

 

[Rustrp]

If you make a frame that supports the mill and will accept the floor jack, why use a rubber or composite isolator at all? The type you show are used for vibration isolation or to keep lighter equipment from moving around. Your BP isn't light and it shouldn't be vibrating.

 

[Bob Korves]

I prefer rigid mounts.

 

[Bamban]

I went to local metal supplier and had them make me some 1/4 inch washers from their 3 inch OD round bar

 

[tweinke]

I used hockey pucks under my PM727 mill and loaded that lightly think they have no discernable compression. The real reason I wanted them is they would not slide. I made up a set for the tire machine at work so it would not walk across the floor and that worked well until they tried to slide it over a bit and one of the pucks cracked. Boy they leave black marks on the floor but it took three guys to slide it. In your application with a heavy mill I wonder if they would crush down?

 

[Tozguy]

I have only used hockey pucks for lighter loads than the one you are considering for your mill.
For a heavy load I would consider making the steel part cup shaped. That way the puck could be supported around its circumference and not allow the rubber to deform as much. The recess would be deep enough and tight enough so there is just enough puck sticking out to contact the floor. Sort of like Bamban's style with a short length of pipe welded around it.

Also, try to get all new pucks from the same batch from the same place. Otherwise the rubber could vary.

 

[jmarkwolf]

OP here.

Thanks for the good input everybody.

I considered many options to implement a hockey puck solution, and I still like the idea of DIY hockey puck machine feet, and have used them on lighter machines, but after considering the unknowns for this beefier application, and totalizing the cost, I decided to go with a commercial solution. See below.

Hockey pucks $8 for pkg of 4
1/4in thick, 3in diameter washers, $22 for pkg of 5
Hardware (carriage bolts, nuts and washers), maybe $15
Buying, cutting to length, turning and welding some 3in ID pipe to the big washers to keep the puck "captured", who knows, maybe $15

Total $60 to build.

The cost to build was over half what it is to buy a set of 4 over-kill, heavy duty, American made, task specific swiveling, leveling feet from McMaster Carr, $102.

It's safe to assume questions of loading, aging, UV rubber embrittlement, etc, are all worked out on this product.

Hate to abandon a fun DIY project but I'm happy with the decision.