Author Topic: Building surfaces (Read 11475 times)

Richard Hutlet · « **on:** January 17, 2015, 03:32:03 PM »

Hello and yes I DID use the search engine first

I read some interesting things and what I got from it is that "glass" seems to be the ultimate
surface to build off. Using CA to secure jigs and taping and weighting parts. Is that the normal for
a lot of you? I've also heard about "building boards". Just looking to

but also really need to
get into the millennium with my knowledge base so when I start building again I'm not wasting my
time

Larry Borden · « **Reply #1 on:** January 17, 2015, 05:16:49 PM »

I have glass on all my benches and use the Great Planes building boards. Has worked out great for me.

Richard Hutlet · « **Reply #2 on:** January 17, 2015, 05:57:42 PM »

GP building boards on the glass or under?? Just a tad confused but thanks

Leester · « **Reply #3 on:** January 17, 2015, 05:58:49 PM »

Glass is usually perfectly flat for building on especially using a jig. BUT if your building off of the plans and want to pin your work to the plans a piece of dry wall will accept pins glass won't. Therefore put the board on top of the glass.

Richard Hutlet · « **Reply #4 on:** January 17, 2015, 06:02:44 PM »

Yep..and my last builds were built on rigid foam insulation. I read that if you build
on the glass you have to tape and weight but I'm a very much "pin" kind of builder
and trying to find out the best way possible. DW sounds ok BUT as it is so
flexible you must need a very straight and level surface under it. same thing as the 1 1/2 or 2" foam
base.

Leester · « **Reply #5 on:** January 17, 2015, 06:11:28 PM »

I made this from Menards wood for about 20.00 USD it is straight and level !!

Richard Hutlet · « **Reply #6 on:** January 17, 2015, 06:14:37 PM »

I'll give you 100 US plus postage

thanks

Bob Hunt · « **Reply #7 on:** January 18, 2015, 07:14:07 AM »

Actually, glass is far from the perfect building surface. Glass is a liquid. I know that some reading this are now sure that ole Bob has gone round the bend, but it's true; look it up (Google it...). When the panes of glass are removed from old houses, and they measure the thickness of the panes, they are always thickest at the bottom. Over time glass sags. When you lay a flat sheet of glass on a table, the edges will tend over time to be thicker than the center of the piece. True it take a awhile, but who's to say that the piece of glass you purchase hasn't been sitting in a warehouse sagging over time?

A much better solution is a piece of milled granite or a piece of slate (Those who rebuild pool tables can hook you up with a piece for a reasonable charge. I just received the promise of a large piece of pool table state from someone who does just that!). Either way - glass, granite, or slate - you will have to put shims between the surface used and your table as required to to insure that under heavy loads it will not bend. Thicker pieces are less susceptible to bending under load (such as weighting down a foam wing during the covering process), but even 3/4 inch thick granite, slate, or glass will bend if not well supported. I use shims made from file folder stock to do this in my shop. It doesn't take too much weight to make the material bend a few thousandths... I also use a piece of Depron foam under the Granite. The foam takes up minor imperfections in the table to granite interface.

I have a very nice piece of 5/8-inch thick glass that is about 20 inches wide by 60 inches long. I no longer use it for anything but a base on which to trim the edges of balsa sheets, and as a board on which to sand the surface of wing skins prior to attaching them to foam cores. That process is always done on granite...

There are other accuracy critical jobs that are also better done on granite or slate. One of the attached photos shows a built-up wing being built around a carbon tube. This is a take-apart system that I've been working on, and it needs to be built with extreme accuracy. Not a job to do over glass...

Later - Bob Hunt

Allan Perret · « **Reply #8 on:** January 18, 2015, 09:19:45 AM »

I think the best bang for the buck on building surfaces is melamine shelf boards you get at HD and Lowes. They are 12 or 16 inches wide, 4, 6, or 8 foot long. They have a smooth white surface, good for drawing reference lines. Instead of dealing with keeping a large bench top flat, you can make smaller building surfaces for just the wing or fuse. To keep them straight, I glue/screw a couple of 2" ribs to the bottom side. Put only 3 rubber feet under to prevent them from conforming to whatever bench or surface you use them on.

Gerald Arana · « **Reply #9 on:** January 18, 2015, 09:55:12 AM »

Quote from: Bob Hunt on January 18, 2015, 07:14:07 AM

Actually, glass is far from the perfect building surface. Glass is a liquid. I know that some reading this are now sure that ole Bob has gone round the bend, but it's true; look it up (Google it...). When the panes of glass are removed from old houses, and they measure the thickness of the panes, they are always thickest at the bottom. Over time glass sags. When you lay a flat sheet of glass on a table, the edges will tend over time to be thicker than the center of the piece. True it take a awhile, but who's to say that the piece of glass you purchase hasn't been sitting in a warehouse sagging over time?

A much better solution is a piece of milled granite or a piece of slate (Those who rebuild pool tables can hook you up with a piece for a reasonable charge. I just received the promise of a large piece of pool table state from someone who does just that!). Either way - glass, granite, or slate - you will have to put shims between the surface used and your table as required to to insure that under heavy loads it will not bend. Thicker pieces are less susceptible to bending under load (such as weighting down a foam wing during the covering process), but even 3/4 inch thick granite, slate, or glass will bend if not well supported. I use shims made from file folder stock to do this in my shop. It doesn't take too much weight to make the material bend a few thousandths... I also use a piece of Depron foam under the Granite. The foam takes up minor imperfections in the table to granite interface.

I have a very nice piece of 5/8-inch thick glass that is about 20 inches wide by 60 inches long. I no longer use it for anything but a base on which to trim the edges of balsa sheets, and as a board on which to sand the surface of wing skins prior to attaching them to foam cores. That process is always done on granite...

There are other accuracy critical jobs that are also better done on granite or slate. One of the attached photos shows a built-up wing being built around a carbon tube. This is a take-apart system that I've been working on, and it needs to be built with extreme accuracy. Not a job to do over glass...

Later - Bob Hunt

Bobby,
That is a great idea when using weights to hold down your work (wing etc.)
Have you ever tried a vacuum system? Once you have the system down it is very easy to do and IMO much stronger that the weight system due to the fact that it will suck resin into all the nooks and crannies.

Cheers, Jerry

rich gorrill · « **Reply #10 on:** January 18, 2015, 12:03:16 PM »

I agree with Allen, the shelf boards are very good and not to costly. For pinning cover it with thin drywall or ceiling tile flipped over.

Rich

Richard Hutlet · « **Reply #11 on:** January 18, 2015, 04:17:02 PM »

I manage a Lumber Yard and Melamine shelving covered with Drywall it is

I have a great source

Thanks fellas

Avaiojet · « **Reply #12 on:** January 18, 2015, 04:22:18 PM »

Bob,

Granite?

I used a granite base, counter top, with weights and a straight edge back in 2012 with the Loser.

No one picked up on it or even comented.

Dan McEntee · « **Reply #13 on:** January 18, 2015, 10:43:49 PM »

Did your wife make you do the dishes first?

Type at you later,
Dan McEntee

Dan McEntee · « **Reply #14 on:** January 18, 2015, 11:07:16 PM »

I have seen guys use reject hollow core doors for building boards/benches. Pins will stick into the luan (sp?) wood that they are skinned with. I think you need a good, heavy and solid base to work on first. I have an old office desk that is quite large and REALLY heavy. Whenever I have moved it, I always check the top with a straight edge. and adjust the feet if necessary. Then I lay on Celotex ceiling tiles. I like the Celotex brand. Pins hold the best in it. I tack it down with a couple of pieces of transfer tape and check with straight edge again. Celotex is also used as a sound proofing or deadening material and can be purchased in 4 by 8 foot sheets. I had a flying buddy in my sailplane days that built a custom table covered with it for building long sail plane wings,so he wouldn't have the seems from ceiling tiles to deal with. You just don't want to cut on it, that will make it shed, chip, and get all pot marked. Use one of those self healing cutting mats for that.
There are now several ways to build models, all of them good actually. With Bob Hunt's Lost Foam Method, you just need ample space on a large smooth surface that is flat, no need for pins. Fuselages are often jig built. Tail surfaces can be built by pinning to a smaller board. Then there are the other jig type methods now. The good old rod or tube method, the Lincoln Log method and others that Tom Morris came up with. And there is good old foam cores also. They all require a large, solid, level and smooth base, so I would start with that.
And Bob is correct about glass. If you use glass, it needs to be the thicker, tempered glass at least. Just picking up a 1/4" thick pane at the hardware store won't cut it. Most would be surprised how much it flexes and will conform to an uneven surface. Years ago I taught an adult education class in welding and had a bunch of guys from the local Glaziers Union. I didn't teach them how to weld glass, just how to weld steel clips to a super structure well enough to hang glass curtain walls from. Anyway, I asked had heard the story about glass actually moving microscopically over time and they confirmed it. They also said glass has a lot of stress internally, and it can evolve and change over time. That is why the tempered glass for a building table.
Type at you later,
Dan McEntee

Rob Killick · « **Reply #15 on:** January 19, 2015, 04:51:16 PM »

Rick ,

Just give me a call ... I won't steer you wrong .

proparc · « **Reply #16 on:** January 27, 2015, 12:46:30 PM »

Granite!

Steve Helmick · « **Reply #17 on:** January 27, 2015, 09:15:47 PM »

Something that has been recommended in a previous thread is Homasote. I've never heard of it, but it may be something carried in your lumber yard? If you do a search for Homasote, it should turn up three threads where it's mentioned...I just did it. I didn't go through the three threads to see which one has the most information on it, but I recall it being used as a building material up in some snow country...maybe NT or Greenland.

Steve

http://www.homasote.com/

Allan Perret · « **Reply #18 on:** January 31, 2015, 07:47:26 AM »

I remember Homasote being mentioned before, so I checked and it is available locally, but they only stock the 1/2" thickness in 4'x8' sheets @ $27. It has sound deadening properties, used in place of plywood sheeting. Will probably pick up a sheet at some point, I like to have a variety of materials available.

john e. holliday · « **Reply #19 on:** January 31, 2015, 10:24:57 AM »

Handle the stuff carefully as the sheet I got was very brittle.

John Eyer · « **Reply #20 on:** February 01, 2015, 09:22:56 AM »

I use Homasote on my pool table. Constant bending over is tough on my back.

Dan McEntee · « **Reply #21 on:** February 02, 2015, 10:49:09 AM »

I had forgotten about Homasote. It's also referred to as "train board" sometimes. It makes a good layer to put on top of a sheet of plywood for building model train layouts, as mentioned already, it has great sound deadening properties. It's sorta similar to Celotex ceiling tiles, and is considered a construction material. Pins push in easy but hold pretty well also. Don't do a lot of knife cutting on it or it will crumble.
Type at you later,
Dan McEntee

proparc · « **Reply #22 on:** April 03, 2015, 07:22:27 AM »

Uba Tuba Granite is the most dense, and also the least expensive granite. We want high density for our purposes-we don't need designer looks, (some of you may lol).

JIM Nordin · « **Reply #23 on:** April 04, 2015, 08:39:44 PM »

This I last table I built all the wood was dried for a month then milled for to be straight for the top,of my benches ill use MDF it's 30x70 . And still to small the next one will be a full 4x8 I use Formica for the top glue does not stick to it .

For my built up stuff I use a foam board put on another peice MDF sub board to that I use 3M spray adhesive and stick the foam to that and set it on my work bench

For my foam I have some marble slabs that were left in one of the houses I bought and I use for weights on top of the foam when I sheet them

Jim

EddyR · « **Reply #24 on:** April 08, 2015, 06:50:55 AM »

A good source for glass for building on is Good Will Stores.
They have a constant supply of old glass top tables in all sizes for cheap. 2x4ft and larger for $5. I got one old table that was 5x3ft. Through the table away and kept the glass. Cost $6.
Ed

Mike Griffin · « **Reply #25 on:** April 22, 2015, 08:07:54 AM »

Glass

Mike

phil c · « **Reply #26 on:** April 22, 2015, 08:49:50 AM »

One thing missing here, if you are going to lay a large, relatively thin sheet of anything horizontal it will generally need at least four support joists underneath on about 16in. centers. At least 6in. wide vertically if they are wood, thin gauge steel, or even that fancy extruded aluminum stuff. Then you can shim the surface as flat as possible all over and adjust later if it does start to sag.

I've been using a 7x3ft old conference table about 1.5in. thick. Over the years it's sagged ~ 3/16in. in the center(legs are about 6 ft apart). I plan to get some light gauge steel beams to stiffen it up and straighten it out.

Dick Pacini · « **Reply #27 on:** April 22, 2015, 09:44:16 AM »

I talked to Bob a couple of years ago and he briefed me on the benefits of granite. Living in NH, the Granite State, and with a granite quarry within 40 miles away and a granite dealer 2 miles away, I thought I could make that step. Unfortunately, the dealer didn't sell to the public. I would have to order through the countertop department at a lumber yard. The price was not acceptable.

This thread is very interesting. It would probably be an eye opener if some top names in P/A posted their choice of building surface.

And, at what point did they feel that, "If only I had a better building bench, I could have won that contest."

Bill Little · « **Reply #28 on:** April 23, 2015, 07:44:39 PM »

For my main building table I started with a well used pool table (the felt was worn out and torn) on top of this is a 5/8th inch piece of glass (surplus table top, less than $10) which I made sure was flat and straight using paper shims. On top of that I can place foam, dry wall or anything else if needed. And I always make sure they are flat using shims if needed. Real lucky as I only have $35 in everything!

BIG Bear
RNMM/AMM

Charles Hofacker · « **Reply #29 on:** June 10, 2015, 05:29:29 PM »

I've been using a steel clad exterior door shimmed to be as flat as I can get it. Put a drafting straight edge across it and shine a light along the edge you will see any warps, dips, etc. Roll a marble or ball bearing across it to find any twist. I use magnets to hold parts in place...

Author Topic: Building surfaces (Read 11475 times)

Mike Griffin