Straight edge ideas

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proppastie

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you can see even minor perturbances
over 100 years ago roller bearings were being made using sight gauges to check the contours of the roller and race......sometime in the 80's working for SKF Specialty Bearings, we were still using sight gauges against a "neutral" light......I was told one could see 1/2 wavelength of light gap.......


"The modern, self-aligning design of ball bearing is attributed to Sven Wingquist of the SKF ball-bearing manufacturer in 1907, when he was awarded Swedish patent No. 25406 on its design.

Henry Timken, a 19th-century visionary and innovator in carriage manufacturing, patented the tapered roller bearing in 1898. The following year he formed a company to produce his innovation. Over a century the company grew to make bearings of all types, including specialty steel and an array of related products and services."
 
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Little Scrapper

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Snap a chalk line on a table. Hook one end and hold the entire length in the air over the table. With your other hand snap the line in mid air so the extra chalk flicks off the line. Now the string is ready. Pull tight and because you knocked 50% of the chalk off the line the one you snap on the table will be extremely clean and thin. About a 1/6” wide it will give you. Now take a fine liner pen and put reading glasses on. Every 3 feet or so carefully put a pen dot smack dab in the middle of the blue chalk line. It may seem crude but this process will get you a straight edge + or - about .020” of a inch. That’s darn accurate for what we are doing. Now put some blocks on.

For a table the best budget will be manufactured exterior trim which is made from thick slabs of OSB and comes in 12,14,16,18’ lengths. They are about 7/8” x 6”. Put them on edge and plywood both sides. Shim the table legs and she’ll be flat, true, plumb and square to the world.
 

Little Scrapper

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Here are some photos. This was cheap and absolutely dead nuts accurate. Checked with a Stabila digital level it was perfect in every direction. It’s so stiff and rigid the key here is to set it on two saw horses and shim the four corners.

This is what I would build.
8833A93A-4852-4808-A3FD-266A5F4F6564.jpeg

BF9D82E0-71F7-4F11-9780-D669F999D97F.jpeg
 

proppastie

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Here are some photos. This was cheap and absolutely dead nuts accurate. Checked with a Stabila digital level it was perfect in every direction. It’s so stiff and rigid the key here is to set it on two saw horses and shim the four corners.

This is what I would build.
beautiful....question...did you rip the boards or use off the shelf from the lumber yard.....I know I would not be able to rip them straight and parrallel but I do not know how well they come from the lumber yard
 

Hot Wings

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Don't use boards. It costs a bit more but use engineered lumber. and design the bench to use off the shelf sizes. Then everything is straight/square and will stay that way.

It's also worth the money when framing door and window openings.
 

Little Scrapper

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These are engineered LP Smart Side trim boards that are pre/cut from the factory. As I explained, they come perfectly cut and ready to use. Easy.

Because they are a OSB type product they are stable, warp free, flawlessly parallel and ideal.

The only prep work I did was use a pocket hole jig to mount one side which isn’t necessary.
 

Little Scrapper

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As a side note on my two photos. The first photo shows it long and on saw horses. The second one shows legs screwed to side. Big difference between the two.

The first photo shows what you want. This allows you to shun the corners for level and flatness.

The second photo is a illusion. Once my fuselage was done I cut my table up and saved a 4’ section as a separate table to weld my control stick on. I didn’t care about flatness in the second photo I just needed it down and dirty and quick to get work done then threw it out.


In the first photo think of a giant box that has to ends that holds it up. It’s incredibly stiff. The first photo shows what you want.

Also. You can store tubing in the table between the plywood sheets.
 

BJC

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Will small (#6) drywall screws work, and should one pre-drill the holes?
When I needed a flat work surface, I bonded the table legs to the floor, used multiple shims to level and flatted the plywood work surface, drilled through the shims, and anchored with countersunk drywall screws. I don’t recall the screw size, but it most likely was bigght than #6.

Edit: Read Hot’s comments about the brittleness of drywall screws, and realized that I disn’t include the fact that I did drill pilot holes.


BJC
 
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Hot Wings

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Drywall screws work - kind of. If you are working with good plywood (or other) then I set one or 2 to fix the part in place and then go back and drill the top sheet. This gives a good clamp rather than lifting the sheet.

Also keep in mind that drywall screws are kind of brittle and tend to snap off when used for structural purposes. Self drilling deck screws, with a flat shank above the threads are a better idea. As for countersinking - depends on the wood. Generally I can get away without, except on hard particle board, Then I use a used countersink bit and my micro-stop tool.
 

Little Scrapper

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There’s nothing wrong with drywall screws. I go through about 20# a year. You’re not building a 50 year table, you’re building a jig to get to your goal.

with steel studs you don’t want to use drywall screws, you want self tapping screws.
This comes from experience using different screws and methods and different table variations.
 

Little Scrapper

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If I were to build a table using steel studs as the main structure here is what I would do based on the prior experiences I’ve had.
33EAA64A-C353-46C3-8F25-C0571D324E1B.jpeg

0E37AF2D-253F-492F-95C8-4601DB62B115.jpeg

Order is critical because a steel stud is like a noodle until it’s sandwiched. So use it to your advantage.

It’s important to understand that the support needs to be on two bases divided in to thirds so you can shim what’s basically 4 corners. So, plywood on one side and studs on the other. Level it, glue it, screw it. Done.

The end result is a rigid structure. Don’t over think it. Glue isn’t entirely necessary but based on my experience it’s a better end product.

A self tapping sheet screw is really nice because bit acts like a drill bit. I would pre-drill the plywood.

If I had my choice I would use LP Smart Side instead of steel studs and glue it. But that’s me.
 

Geraldc

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When we were joining 2 long beams we use a laser to level 3 trestles.
Came back the next day and the middle was low (by eye). Levelled it up again and later that day center was high.
The workshop was on reclaimed harbour and the floor was moving with the tide.
 

BBerson

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Where do you buy steel studs? I haven't ever seen studs for sale anywhere. I suppose contractors get them somehow from Sheetrock wholesalers or something.
 

robertl

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Where do you buy steel studs? I haven't ever seen studs for sale anywhere. I suppose contractors get them somehow from Sheetrock wholesalers or something.
I think you can get them at Home Depot or other big box stores. You could always ask your local hardware store if they can order them. Also, an internet search should show up something.
Bob
 

Hot Wings

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Where do you buy steel studs?
All of the lumber stores here stock them. Get the 20 ga. if you can find them. I think they are much easier to work with than the thinner ones.

They are the standard for interior framing in most office spaces. Fire proof and straight....something framing lumber isn't.
 

Little Scrapper

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Menards has them.
Where do you buy steel studs? I haven't ever seen studs for sale anywhere. I suppose contractors get them somehow from Sheetrock wholesalers or something.
Menards has them. If that’s not available I would call a commercial contractor and ask them. They are readily available to contractors. I get it from ABC Supply but that’s local for me. Drywall distributors and truss companies tend to have them.
 

cheapracer

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Yup, overthinking it. The most accurate way is to have a tolerance there already. In this case, make sure your spar is bending up a little, say 3/8". If it's straight to begin with, it's sure as hell going to be bending down in very short time, if not immediately, after it settles under it's own weight and bounces up and down a few hundred times.
 
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