Custom leveling pads. Circular disks with a center threaded hole and a rubber pad on one end. Shear strength of thread?

[rons]

Tool is square with four corners about 2' x 2'.
Each corner will have 3/8 stud pointing down.
A slim metal disk with a rubber pad will adjust up and down. Diameter 1.5 - 2". Thickness 1/2". Relieved on bottom for rubber disk.
The question? What shear strength calculation is there to compare 3/8-16 to a 3/8-24 with a distance of 1/2"?

 

[mnl]

It’s easy to look up tensile strength for various pitches and grades, varies by factors from crap bolts to good bolts.

 

[sfriedberg]

I don't have a copy in front of me, but I seem to recall Machinery's Handbook has tables for fastener shear strength (design limits).

 

[Cole2534]

I must not be understanding the description, as I don't see anything in shear besides the thread itself?

Regardless, a conservative rule of thumb Ive heard is half of the ultimate tensile strength.

 

[guythatbrews]

Take a look at this proof load table.

US Bolts - Tensile Strength and Proof Loads

Tensile strength and proof loads SAE bolts.

www.engineeringtoolbox.com

Have you ever stripped a nut loading a 3/8 bolt to it's proof strength? And a 3/8 nut is < 1/2" long. Unless your 2x2 machine is very heavy, you should be fine with a coarse or fine thread.

 

[jackalope]

This certainly seems like overkill for something that small in size unless it is several tons. I’d be more concerned with adjustability with coarse Vs fine. Fine thread gives better engagement and adjustability so barring the weight as a non issue, that would drive my decision.

 

[tft1987]

If your worried about the threaded stud stripping and pushing thru the disk into/through the rubber, can you just put a backup nut above the threaded disk to distribute the load over more engaged threads?

 

[Cole2534]

This certainly seems like overkill for something that small in size unless it is several tons. I’d be more concerned with adjustability with coarse Vs fine. Fine thread gives better engagement and adjustability so barring the weight as a non issue, that would drive my decision.

Easier to turn under load with the less aggressive helix angle as well.

 

[strokersix]

boltscience.com
This website has all the info you need.

Pragmatic approach is to go up a size or two in diameter if you are at all concerned.

 

[rons]

Easier to turn under load with the less aggressive helix angle as well.

Didn't think of that.

 

[rons]

This certainly seems like overkill for something that small in size unless it is several tons. I’d be more concerned with adjustability with coarse Vs fine. Fine thread gives better engagement and adjustability so barring the weight as a non issue, that would drive my decision.

The strut has a 3/8 bolt pointing down for the metal disk idea. Which is like on a turn table.
Then there is the appliance feet. I would have to work out a custom fitting female nut inside the strut.


Are there any better feet in the house?

Certainly overkill but I try to learn so that better choices can be made. And not bore the crowd...

This is what the feet are for. Wet cut tile saw with sliding table. Saw detaches for portable cuts.

 

[David Utidjian]

I think you may have a problem with your design. Yes levelling feet could fix it but every time you move the frame you will have to fiddle with readjusting it so that the frame and attached rails stay flat and square. It can work fine if attached to a fairly rigid flat surface (bench top.)
I don't know what your portability requirements are but I imagine most tile work is done on-site. I would make it with a deepish frame; think metal or wood box; and attach your device to it. Then you just level the box.

 

[rons]

It's starting to get heavy now. I think this is going to be a floor model. Agree with you on everything.

The project started out by using scraps and pieces. Everything there was what I already had except the two Al plates. The big plate is backing up the plastic.
There should be a strut on the right side. But I would have to buy another 10'. The current build relies on the right rail for strength.

And another point is the fine adjustment screws and bushings on the Ryobi. I had to replace them with custom fit pieces.
This thing is going to run like a watch

I did some work with tile and there is a lot of wasted time walking back and forth from the tile saw in the driveway and the hallway floor.
I thinking about a way to make this portable because it is past the easy lifting weight.

 

[rons]

I think you may have a problem with your design.

The problem is that I tried to make it work with scrap pieces.
I went to WinSupply to get a 10' long strut.

 

[Bill D]

My lathe has four jacking bolts. Roughly 1/2" diameter. 1750 pounds so about 450 pounds per bolt.
A 3/8 Bolt should do 200 pounds each, easy.
Bill D

 

[rons]

A 3/8 bolt in vertical position would have more shear strength per thread up to a number of threads.

 

[rons]

Now all opposing pieces are equal lengths and are lined up with a caliper.
Table slides smoothly now.

The re-design is the stacking of the long struts onto the shorter struts. A side benefit was less moment arm for the
saw platform to move. A real PIA to line up and tighten bolts down.