# How to make sure all the screws are at the same height



## ng80092a (Mar 7, 2021)

*The situation:*
I have 8 bolts attached between 4 columns.. like the picture.
I need to make sure they are all exactly at the same height.

*The problem* is that the bolts are not all at the same height, as when I place a wood slab over them, it slightly rocks.

*What I tried*
I'm thinking of drilling a bigger hole and putting a thicker bolt.
I tried that once, using an expendable wood piece that I'd level to the bottom, make a sample hole on that one, and drill every single hole of the columns trough that one. But the bolt on the back left remained lower than the other ones.


Anyone has an idea of how to do this?


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## kiwi_outdoors (Jan 15, 2020)

do a very precise setout
used center-spur bits to drill the holes, not regular bits

better yet
use under sized holes and tap them for bolt theads
use all-thread bolts (machine bolts)
thread bolts thru the threaded holes
put vinyl tubing over exposed threads

why not just install proper cleats ??


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## shoot summ (Feb 21, 2014)

The issue is likely that you are not drilling 90 degrees to the piece, any variance will tilt the bolt up or down. The only way to insure you are 90 degrees is with a jig, or a drill press.


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## GeorgeC (Jul 30, 2008)

You keep using the word "height." Are you referring to the length of the bolts?

George


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## John Smith_inFL (Jul 4, 2018)

ng80092a said:


> I need to make sure they are all exactly at the same height.
> *The problem:* when I place a wood slab over them, it slightly rocks.


*is this the project you are working on ??*








without additional information of what the project is, and what it does, leaves us in the dark.
if you are using the bolts as a shelf support, they will not be seen. if it rocks, you could use small shims to prevent that issue. (are shims possible ?)
I have used this method before and some slight "bending" of one bolt fixes the problem.
once you put some weight on the shelf, it sort of fixes itself.


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## ducbsa (Jul 6, 2014)

GeorgeC said:


> You keep using the word "height." Are you referring to the length of the bolts?
> 
> George


I think he means the elevation above the base as it affects the shelf resting on them.


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## Mike Stevens (Apr 22, 2021)

Why on earth would you support a shelf this way?


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## B Coll (Nov 2, 2019)

ng80092a said:


> *The situation:*
> I have 8 bolts attached between 4 columns.. like the picture.
> I need to make sure they are all exactly at the same height.
> 
> ...


If you have one available, use a drill press. Set up a fence and stop for repeatability. If you do not have a drill press, make up a template to clamp onto each leg, similar to what you would make for drilling furniture knob and handle holes.


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