Torsion Box Questions

[mcgrath4u]

I understand the basic concepts of making the box, but have a couple of questions:

1) Whats the best way to rip the mdf without having rollers or the board buddies to keep the stock against the fence?

2) Whats a good size for one? I am thinking 3'x4'

Any other help will be appreciated.

Thanks,
John

[Otter]

I understand the basic concepts of making the box, but have a couple of questions:

1) Whats the best way to rip the mdf without having rollers or the board buddies to keep the stock against the fence?

2) Whats a good size for one? I am thinking 3'x4'

Any other help will be appreciated.

Thanks,
John

Having done 3 of these so far, on question 2, if that size will fit your projects, go for it.

On question 1. feather boards on the front side of the blade and the splitter on the back side should be enough. Make sure that you align check your saw and move slow. Everything you do while building it should be very deliberate and double checked.

It will pay 1 billion times on the finished product.

[mcgrath4u]

Not to be rude, but how could I use my feather boards if the half of sheet of 1/2" mdf is going to be covering my miter slots and hanging off the table?

Though I am relatively new to woodworking, I cant seem how I could do this.

Thanks,
John

[drumpriest]

I've built myself an assembly table, you'll love it! I did mine with a 3/4" top and bottom, and 1/2" innards, 3/4" around the outside, then wrapped it all in oak. Mine is 3'x4', because it made a-lot of sense given a 4x8 sheet of 3/4". It has served me well for projects up to 7' so far. I just have to slide the project around sometimes. Most of my projects are 4' or under, or can be broken up into sub 5' elements. (armour, for instance, top is seperate from bottom, then they are screwed together)

I didn't cut the full 4x8 sheet of 3/4 on my bt. I had the BORG rip it into 2 4'x4' pieces, and then I cut those down as needed. my wife was my featherboard, she stayed to the side near the front of the blade to ensure that I was tight to the rip fence, though I think I could have done it without her, you get the hang of it after a while.

When you are done, hit it with poly a bunch, wax it (paste wax), and keep some wood filler around, it'll get scratched from time to time. Overall I'm VERY happy with mine.

[gimpy]

John, not sure if I am picturing this right or not. Otter's use of featherboards is pretty good. Take the smt fence off of the smt table and use it's bolt to bolt down your featherboard to the smt table. You then clamp down the smt table and can adjust the table/featherboard to the blade (move the smt table/featherboard left or right). Also use a small clamp to clamp down the back side of the featherboard (for more stability) to the smt table. I use this procedure when making rips. The featherboard I use is one I made from the instruction manual out of the BT3100. Seems to work pretty good and is easy to make. Took me 10-15 minutes to make, I think. I used an old 1 X 4 (former bedspring slat).

The featherboard is stationed just to the front of the blade and with enough pressure to keep your work piece against the fence but to not inhibit pushing it thru the blade.

Also, rip all the same width boards at the same time so you won't have to readjust the fence (I've not done this in the past and have come up with minor differences in width of slats cut).

hth, Frank

[Tom Miller]

Not to be rude, but how could I use my feather boards if the half of sheet of 1/2" mdf is going to be covering my miter slots and hanging off the table?

Before you start making final cuts with your featherboard, you'll want to cut your stock down further.

For instance, cut into ~12.5" wide pieces, then cut that with a feather board into your 3" or 4" strips.

Regards,
Tom

[Black wallnut]

MDF is real heavy! If you are asking how to safely cut down a full sheet on your BT3 saw without the aid of roller stands, board buddies, etc. I would say don't! Without infeed and outfeed support IMHO it would be dangerous to size full sheets plus your outcome may not be as good as expected.

You would be better off using a saw board and a circ saw. If you don't know what a saw board is I'm pretty sure www.newwoodworker.com has a page or two about them.

With my set up: large outfeed table, wide table kit and saw cart plus a roller stand in front of my saw I size full sheets when ever needed.Even then this is not always the best or safest way. When I resized a full sheet of 3/4" MDF I wished half way through that I had not tried using the table saw!

Before I try that again I will make or buy a long fence and several more infeed roller stands.

[gary]

I used my circular saw when I cut mine. I first ripped off a 3" wide strip and used it later as a guide for my circular saw. Then I cut a 2 spacers so I could cut the same width pieces each time.

I then used the spacers to position the guide and clamp the guide. Run the circular saw down the guide and you have consistent width cutoffs. Easy and accurate.

[mcgrath4u]

Forgot to mention, even though I frequent this website, I do not have a bt.

I apologize for not putting that in there.

John

[gimpy]

John, sorry, I misread the fact that it was a half sheet of mdf. Oooops!

Frank

[mcgrath4u]

I am in college/broke (remember this)

I ended up buying a full sheet of 1/2' mdf and about ready to joint and plane some 2x4's.

After shimming and placing the extra half sheet of mdf on the saw horses and 2x4's, could I get away with using one on the 3/4" mdf (to be used as top or bottom) as a second support on top of the 1/2" mdf? Do you think too much glue would get on it?

Thanks,
John

[Otter]

Not to be rude, but how could I use my feather boards if the half of sheet of 1/2" mdf is going to be covering my miter slots and hanging off the table?

Though I am relatively new to woodworking, I cant seem how I could do this.

Thanks,
John

John

Feather boards are not just for miter slots, they work great on fences to. If you can place downward pressure this aids in the stock control while pushing the stock through.

Also as other mentioned, smaller strips works, if you are doing a 4'x3'x3" then you can rip a 4' sheet 12" wide strips 4'x1' this should get you 5 2" strips with a 3/4" or so strip at the end. 12" wid will allow for both a miter slot and fence feather boards.

And I also don't have a BT anymore

[Otter]

I am in college/broke (remember this)

I ended up buying a full sheet of 1/2' mdf and about ready to joint and plane some 2x4's.

After shimming and placing the extra half sheet of mdf on the saw horses and 2x4's, could I get away with using one on the 3/4" mdf (to be used as top or bottom) as a second support on top of the 1/2" mdf? Do you think too much glue would get on it?

Thanks,
John

Use a heavy coat of Wax, this will prevent the glue from sticking...

[mcgrath4u]

I know the wax will help with the glue, but...

If I use that 3/4" mdf for the top the finish will not soak in because I have a coat of wax there. It wont take glue anymore for the reason it was there in the first place, therefore I cant use it to glue to the grid.

Same reason if its the bottom side too.. it wont adhere to the grid.

AHHH HAAAAA

I can make the side I waxed as the very bottom(side the base will be on).

Thanks for the help.

John

[drumpriest]

I used my 3/4" sheet at a base to build my torsion frame, no worries. The glue will scrape off easily. As for the wax, you can take it off with mineral spirits.

So I setup saw horses. Leveled them with shims. jointed 2x4's, ripped the other side parallel (you could plane them), put them on the horses, and leveled them to each other, sat the 2 half pieces of 3/4" on it, and used a level to ensure that the entire surface was flat (you could use winding sticks), built the frame, then moved the frame while on the top piece, and stacked the bottom piece on top, attached it. Then flip the entire thing over, and use the piece that had glue all over it as the bottom of my top.

does that help?