building streight,what a pain!!!!

[steve pagano]

Ok,I have a work bench,its 11foot long and 32 inches wide doesany body know what i can top it with like glass,pressboard ext,ext,ext and if glass is the best thing,what demesions do u recomend?
My bench started out streight but after three years its not as streight but still good enough to build on.I build mostly foam components.and i would like to compete at the nats so i know that building a streight plane is the key.(aside from a good engine run )

[Bill Little]

A glass section about 5 feet long is mandatory!! 

You would want to also have an area covered with replaceable sheet rock pieces, about the same size.

Shim those areas dead flat with string from corner to corner and a gauge block

Also, get a good Lufkin steel 4' sheet metal workers ruler.  It is as straight a ruler as anything made.  Of course, it does cost a bit more than a yerd stick. 

Bill <><

[rob biddle]

      Hi Steve,
   I highly recommend a sheet of glass.
If you are building mostly .60 size planes you probably want to be able to lay out a 60+ inch wing on it, so I'd aim for about 6 feet long.

   Plenty of blokes get by with a sheet about 6'x2', but this doesn't really allow much space for accurately assembling the whole model unless the bench that the glass is on is perfect.
Being able to accurately Jig up the "overhang" can be a real pain.

   I scored a glass outdoor table top a couple of years ago, it is 6'x4'x1/2" and it is absolutely spot on. It was the "smoko" room table at Dads work and the boss was going to throw it out, Dad grabbed it and put it aside. Got it for free!

Cheers, Rob.

[Bill Little]

Hi Rob,

A piece of glass 6 feet long will be nice, but since Steve's bench is 32 inches wide that will limit him as to width.

5 feet long will easily do a 60" plus wingfspan plane since I don't reall know of many planes who wings are in excess of 60" with out the tips.  I have always added tips after all the sheeting, etc., is done on the wing and it's out of what ever jog I was using.  Flaps are the last thing I do to a wing.

Just giving suggestions based on the dimensions Steve gave of available space. 

Bill <><

[Bill Sawyer]

You must be using a different type of glass than I tried. I ws hauling trash to the recycle center and spotted a pair of sliding doors. I sked for them but they were spoken for. A few days later I got a call that they has a door for me. I hauled it home and removed the metal frame. Inside was a pair of glasses held together by some type of material so they weere about 1/4 inch apart. I was about to place this on my bench when I noticed that when I lifted the end the glass bowed - almost an inch over the length of the door. I decided that the glass would assume the curve of my bench if there was any curve and got rid of the glass. SO what kind of thickness of glass do you use?

[Bill Little]

You must be using a different type of glass than I tried. I ws hauling trash to the recycle center and spotted a pair of sliding doors. I sked for them but they were spoken for. A few days later I got a call that they has a door for me. I hauled it home and removed the metal frame. Inside was a pair of glasses held together by some type of material so they weere about 1/4 inch apart. I was about to place this on my bench when I noticed that when I lifted the end the glass bowed - almost an inch over the length of the door. I decided that the glass would assume the curve of my bench if there was any curve and got rid of the glass. SO what kind of thickness of glass do you use?

I have a piece of 3/8ths glass that was cut for a table top and never bought.  I use it on top of an old billiards table that wasn't fit to shoot pool on anymore, but it makes a great building table! 

I would suggest asking around at glass shops for those types of deals.  The 3/8ths isn't going to sag too much!

Bill <><

[Keith Spriggs]

I would suggest asking around at glass shops for those types of deals.  The 3/8ths isn't going to sag too much!

Bill <><

Good suggestion. 3/8 inch would be excellent, but it may be more difficult to find

 A glass shop that does store fronts often have aluminum frame doors that they have removed. They scrap most of them. Many of them are 3 foot by 7 foot including the frame.
The glass is about 2 foot by 6 foot or lightly larger. The glass will probably be 1/4 inch thick and if has been installed in the last 20 years or so it will be tempered.  If the bench is really uneven you might consider coating the bench with something like ceramic tile "thin set" and laying the glass in it. After the "thin set" hardens the glass should stay flat. Insulated glass probably wouldn't work too good as it would only be supported on the edges and might sag. Regular 1/4 inch glass could be cut to size, but you can not cut tempered glass with a regular glass cutter.

[Tom Perry]

Glass, no matter how thick will sag.  In most cases the sag will be so imperceptible it is not significant enough to matter.  However, I wouldn't recommend supporting it just on the ends as it will tend to sag with more weight applied in the middle.

Best to use the flattest surface you can find to support the glass then shim the glass with paper, card stock etc.  Usually a straight edge will suffice but a laser pointer or level can be adapted for checking trueness of the glass surface.

Once you achive a truly flat surface, don't screw it up by gluing or cutting on it.  Use a piece of window glass that can be tossed if you bung it up.  You can also place your plans under the window glass without worrying about reshimming.

                                                                             

[dave siegler]

A tip for shimming, use playng cards or rip long strips of newspaper and use that under the glass. tempered or plate glass is the best, think shower doors, or glass top coffee tables.