What size leveling feet

As I found out, regulation hockey pucks seem to deflect a bit too much for my lathe. I went with four inch steel discs for feet. However, I have used hockey puck feet for my mill. They work great there.
 
Instead of focusing on the feet I would look into the strength of the threads. I am sure that there are engineering tables that give the spec's on what different size threads will support before the threads deform. It may well be that even fairly small diameter threads will support the weight of the typical machines we use.
 
With nothing pressing this afternoon I decided to research how much force is needed to strip the threads on nuts and bolts. . Did not find any tables on the force required to strip threads. One post I read referenced the proof load of nuts as the value at which a given nut size would strip. Didn't seem to matter whether the load on the nut was pushing the nut or pulling the nut. That should be easy to find. Not. After spending more time than I should have on this all I learned is that the calculations are mind boggling to a non engineer and that a standard size nut for a given bolt is stronger than the bolt. Bolts are referenced by tensile strength. There are charts for the tensile strength of bolts. A 1/4-20 has a tensile strength of 1750 lb. A 3/4-10 has a tensile strength of 15,200 lb. This a for a cheapy grade 2 bolt. The clamping force is 75% of the tensile strength.

As best as I can tell the bolts you guys are using are way overkill for the loads applied to the bolts. Now there may be other factors that I am unaware of the require larger bolts and nuts.

I did this because I am thinking of using nuts on threaded rod to level my lathe instead of shims.
 
mickri said:
With nothing pressing this afternoon I decided to research how much force is needed to strip the threads on nuts and bolts. . Did not find any tables on the force required to strip threads. One post I read referenced the proof load of nuts as the value at which a given nut size would strip. Didn't seem to matter whether the load on the nut was pushing the nut or pulling the nut. That should be easy to find. Not. After spending more time than I should have on this all I learned is that the calculations are mind boggling to a non engineer and that a standard size nut for a given bolt is stronger than the bolt. Bolts are referenced by tensile strength. There are charts for the tensile strength of bolts. A 1/4-20 has a tensile strength of 1750 lb. A 3/4-10 has a tensile strength of 15,200 lb. This a for a cheapy grade 2 bolt. The clamping force is 75% of the tensile strength.

As best as I can tell the bolts you guys are using are way overkill for the loads applied to the bolts. Now there may be other factors that I am unaware of the require larger bolts and nuts.

I did this because I am thinking of using nuts on threaded rod to level my lathe instead of shims.
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the bolts needed for my lathe are 10mm x 1.5, seems that would be sufficient
 
Thank you for taking the time on that. I also wish to spread the load on the .250 wall 6 x 6 riser.
 
mickri said:
With nothing pressing this afternoon I decided to research how much force is needed to strip the threads on nuts and bolts. . Did not find any tables on the force required to strip threads. One post I read referenced the proof load of nuts as the value at which a given nut size would strip. Didn't seem to matter whether the load on the nut was pushing the nut or pulling the nut. That should be easy to find. Not. After spending more time than I should have on this all I learned is that the calculations are mind boggling to a non engineer and that a standard size nut for a given bolt is stronger than the bolt. Bolts are referenced by tensile strength. There are charts for the tensile strength of bolts. A 1/4-20 has a tensile strength of 1750 lb. A 3/4-10 has a tensile strength of 15,200 lb. This a for a cheapy grade 2 bolt. The clamping force is 75% of the tensile strength.

As best as I can tell the bolts you guys are using are way overkill for the loads applied to the bolts. Now there may be other factors that I am unaware of the require larger bolts and nuts.

I did this because I am thinking of using nuts on threaded rod to level my lathe instead of shims.
Click to expand...
The bolt sizes are overkill... but the bolts need to somewhat fit the holes in the machine base, also. I ordered the feet with 5/8-11 studs, because the holes in the base of the machine are clearanced for a 5/8 bolt...

Also, while four 1/4" bolts may have enough tensile strength, putting that much weight... especially unbalanced weight... would tend to bend the bolts.

The shear strength is much weaker...

When considering any unbalanced loads, inertia loads, and the overall rigidity of the machine setup, overkill is your friend. I prefer to use the biggest bolts that will fit the holes in the base...

-Bear
 
I'm not sure if my bolt holes in the base were 23/32 or metricI opened them up to 3/4"
 
mickri said:
With nothing pressing this afternoon I decided to research how much force is needed to strip the threads on nuts and bolts. . Did not find any tables on the force required to strip threads. One post I read referenced the proof load of nuts as the value at which a given nut size would strip. Didn't seem to matter whether the load on the nut was pushing the nut or pulling the nut. That should be easy to find. Not. After spending more time than I should have on this all I learned is that the calculations are mind boggling to a non engineer and that a standard size nut for a given bolt is stronger than the bolt. Bolts are referenced by tensile strength. There are charts for the tensile strength of bolts. A 1/4-20 has a tensile strength of 1750 lb. A 3/4-10 has a tensile strength of 15,200 lb. This a for a cheapy grade 2 bolt. The clamping force is 75% of the tensile strength.

As best as I can tell the bolts you guys are using are way overkill for the loads applied to the bolts. Now there may be other factors that I am unaware of the require larger bolts and nuts.

I did this because I am thinking of using nuts on threaded rod to level my lathe instead of shims.
Click to expand...

I have some 12mm studding leveling my drill press stand , the diameter is probably to stop them bending more than taking the load. I made some simple nut and bolt style leveling feet for my lathe , they are 1inch 8tpi but it's only about 550kg.

Stu
 
The manual for my lathe doesn't specify the size of the bolts to mount the lathe on the bed. Just says use supplied screws. My lathe weighs around 350 pounds. The motor and its mounting bracket is separate from the lathe. The lathe by itself probably weighs around 275 pounds. I can pick up either end of the lathe. My current mounting bolts are 7/16. All the bolts do is hold the lathe to the bench. Don't support the weight of the lathe. I think that 1/2 is the largest bolt that will fit through the mounting holes. I plan to make threaded washers (wrong term??) as thick as a standard size nut. Flange nuts would also work. The bolt will come up through the bench top. A threaded washer will be screwed down to hold the bolt in place. Another threaded washer will be screwed onto the bolt. The lathe will sit on this washer. Then there will be a nut that holds the lathe against the threaded washer. Move the threaded washer that the lathe sits on to remove any twist in the bed. Then tighten the nut to hold everything in place. That's the plan so far.
 
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