You don't *need* a welder for a frame.

Absolutely not  angle material comes in steel aluminum and fiberglass and maybe some other material  it can be glued bolted and riveted as well. also tube material and t slot extrusions are a viable option. One shop I worked at uses 80-20 for some things as well as welded tube frames. and as we have seen a plywood box made from furniture grade plywood works as well.

IIRC the plastic scribbler uses aluminum angle and plywood gussets. the sd is bent sheet metal pop riveted together.
Like anything else limited by cost , availability of materials skills of the builder and imagination.

I have a welder and I have a place where i can get steel angle 1.5 x 1.5 x .125 in for about $9.00 for a ten foot piece. and I have a way or several ways to cut it.
In no way was I trying to imply that a welded-frame is the only way or even the best way for everyone.
Tin

if you have access to a welder a frame is easy.

You don't *need* a welder for a frame.  OB1.4 uses T-slotted framing. If you are confident enough, you can design ways to anchor the rods and pulleys. This approach would require basic tools up to a Dremel

How hard is it to make a custom enclosure to extend the print bed size of a stock printer......I have access to pretty much every shop tool known to man, so getting custom parts and cutting them is not out of my reach in terms of rods and making a custom frame to build all of this.

A yea I am with you on this. IMHO if you have access to a welder a frame is easy. I have seriously considered welding up a frame from 1.5 in x 1.5 in  x .125 in angle. drill the holes for the Guide rod with a step bit.   But here is the rub for me . if I am going to build a frame and install longer guide rods I am not going to use the junk stock  carriage parts  and while i am at it upgrade to nema 17 motors and why not use a board that can handle an sd card and a led so the thing will run on its own and as you said larger power supply. So now it almost makes more sense to build a scratch machine than rebuild an sd. so  choices.
And I am already being forced to upgrade the carriage anyway.
Tin

1st print one of the Z adjustment screw mounts with offset to let you adjust for glass thickness. on thingaverse for solidoodle printers

Unless someone has posted one for the SD4 yet this won't work. I'm going to design one for the 4 once my printer is running again, the screw holes are further apart on the Sd4 case. I have a design done but I haven't been able to print it yet.

In the meantime get a 20mm M3 screw and flip it upside down In the Z stop. Or design your own.

Edit: actually the stock z stop is usable with glass. Just balance the bed lower. I didn't have to flip the z stop screw until I got the e3d.

Thanks for all the info, you have been very informative over the past week or so that i have been on here.

Yup. Get some aquanet. It's the kinda stuff you'd use to have a beehive cut id never put it in my hair but... My sig says it all.

that it does my friend......

how thick should the glass be? and does the heatbed still need to be on?

The bed is aluminum and warps. It's normal unfortunately. Print on glass attached to the bed with hairspray

Hairspray you say, lol. looks like im glass shopping this weekend.

As soon as i get the bed flat, i will put in the new carage with bearings.

There's also a lot of information on the forums about your original question. First thing I'd do is upgrade those carriages to lawsy's version with linear bearings. You'll have a much better understanding of how this all works (and get a better printer as well). If you have access to all the tools you said then you'll be able to expand without too much trouble, I would imagine!

Can i not have the print bed heating and still print good? i ask because i want a flat bed to print on and if i have to use something else like a piece of metal that is 100% flat, then i will just put that on the existing bed, make it flat, and off set the Z axis.

Not that i am going to jump into this anytime soon. if i do it will be months away from now. I Have some other light upgrades to do first.

If i wanted to take my stock SD4 with a 8x8x8 print size, and make it so that it could print 12x12x8, what would be needed.

at a 50,000 foot view, i know i would need to build a custom cage to hold all the components, extend all the rods and belts. But some other questions i asked myself was, do i need to upgraded the motors to a more powerful one? I already intended on changing out the MOBO and the PSU down the road, and changing to a E3D. Which also brought up the question on voltage and which one of those to get.

I pretty much opened up a large can of worms for myself looking into all of this.

I have access to pretty much every shop tool known to man, so getting custom parts and cutting them is not out of my reach in terms of rods and making a custom frame to build all of this.