Help - set screws backing out !

[Roy Bennett]

My shop made router table works great - except for one problem. The plate leveling screws, which are 8-32 set screws set in tapped holes in the 3/8" lexan plate, back out with the appearance of any vibration.

It's aggrevating to start with a perfectly level plate, flush with the table, and end up snagging a workpiece on the edge where the screws back out.

What can I do to tighten the fit between the plate and set screws. Locktight would work, but I'd loose the adjustability. Help!!!!!!!!:confused:

[Steven Wilson]

use the other locktight (blue IIRC) it allows you some adjustability

[Bruce Page]

Roy, DO NOT use Locktight! Locktight & Lexan (or almost any plastic material) do not play nice together. The threads in the lexan will crumble in a matter of hours. There is a product called Vibra-Tite that is non hardening and will allow you to make adjustments. You can find it by doing a google.

[Bruce Page]

Roy, another option you could try is to flatten one side of the threads on the setscrew by lightly hitting it with a small hammer. You don’t want to hit it hard, just enough to flatten the crest of the thread. If you have some 8-32 screws laying around, it would be a good idea to practice.

[Steve Clardy]

Roy, another option you could try is to flatten one side of the threads on the setscrew by lightly hitting it with a small hammer. You don’t want to hit it hard, just enough to flatten the crest of the thread. If you have some 8-32 screws laying around, it would be a good idea to practice.

Beat me to it. I just did that on my ZC Plate

[Lee Schierer]

Get some set screws with threadlocker pre applied or with nylon locking pellets. Flattenting the threads may work, but will damage the threads in the lexan.

I fully agree with the advice not to use Locktite with plastics. They do not play well together.

[Travis Johnson]

Maybe I am looking at this a little wrong, or maybe it is just the machinist in me, but have you thought about curing the vibration in the first place?

As a machinist, I could go into detail about all the locations and places that vibration can occur such as belts and shafts, but one of the first steps I take in curing vibration is the use of sand. Because you mentioned that this router table is home-made, I suspect the construction is a bit light. (plywood versus cast iron, etec). I am not knocking you for that, in fact I make a lot of my own machinery. It ends up being light, so I often build a bottom shelf, or box low on the unit and add as much sand as possible. I recently did this to a home-made 19 inch bandsaw, and an older craftsman tablesaw.

You should be able to buy bags of sand just about anywhere. Just make sure you use sand, sheer weight like a chunk of rail or piece of casting won't help as much as sand. It's the millions of particles shifting back and forth that counters the vibration you are getting.

Maybe this will help, maybe not, but I thought I would at least offer a different slant on curing your problem for what it is worth.

[Cliff Rohrabacher]

one of the first steps I take in curing vibration is the use of sand. [...] build a bottom shelf, or box low on the unit and add as much sand as possible.

That is a marvelous idea.
I'm thinking of building a heavy drawer with a 3/4" ply reinforced bottom all sealed against leaking sand with a sliding lid to hold three bags of sand for my shop made slot mortiser. It's a better option, I think, than building a wider base cabinet than I need just to get the 110 pounds of mortiser up top to sit stable.

I have considered using epoxied concrete as working surfaces in shop made machines, for exactly the same reason - along with the super rigidity and the perfect humidity/temperature imperviousness it has.
Other than the fact that it more work to get right it beats the hell outta MDF or ply any day.

[Larry Norton]

How about wrapping the set screws with a tiny piece of teflon tape?

[Don Baer]

another thought is to replace the set screws with new one. The end of set screws should be cupped. If the cup has been flatened then they wont hold worth a darn. DAMHIKT

[Ken Fitzgerald]

Roy....one of the things that I see where vibration is an issue is a set screw set in on top of another set screw. ......Kind of like using locknuts but ........If you lexan is 3/8" thick.....you could use a small set screw to level it and then a 2nd smaller set screw to lock the 1st one.

[Travis Johnson]

That is a marvelous idea.
I'm thinking of building a heavy drawer with a 3/4" ply reinforced bottom all sealed against leaking sand with a sliding lid to hold three bags of sand for my shop made slot mortiser. It's a better option, I think, than building a wider base cabinet than I need just to get the 110 pounds of mortiser up top to sit stable.

I have considered using epoxied concrete as working surfaces in shop made machines, for exactly the same reason - along with the super rigidity and the perfect humidity/temperature imperviousness it has.
Other than the fact that it more work to get right it beats the hell outta MDF or ply any day.

Cliff, most of my machines are weighted down with sand. In some ways it is the lazy way out. In reality I should ensure every inch of the machine is vibration free and then add the sand as a last resort. The problem is, this system works so well, sand is often the first things I add.

To get around the mobility problem, I mount some of the machines I want to reposition (tablesaw/ drill press) on tracks. It does not matter how much sand I add to these machines, they both push around the shop the same....with one finger thanks to the age old answer to friction. An added benefit over the problem of casters is that my machines move effortlessly in predictable paths. And yes, to answer another question you are probably wondering, I do in fact work for the railroad!

[Bruce Page]

How about wrapping the set screws with a tiny piece of teflon tape?
Great idea! This might be the easiest and best solution.