[cadfish]

Hi everyone I could use some help designing a machine. I am only 16 and just got the basics. My table is going to be made out of 3/4 inch plywood and no clue how to fasen the work peice. If any one wants to see pics of my design I will try to get them on my pics asap.
:wee:

[Cold Fusion]

Try to stay away from Plywoood. MDF will work much better. What I've done in the past is drill a grid of holes all the way through the sheet and then countersink the hole in the back and glue in a nut.

[mxtras]

Yeah - that's what we do here! Welcome aboard!

There's alot involved, but everyone here loves helping out, so -

What in particular do you need help with? The structure? The control stuff?

The biggest questions we have initially are likely going to be what tools do you have at your disposal - do you have a table saw,a jig saw, a circular saw or is all you have a butter knife?

Another question will be your budget. Now, being 16 we realize that cash isn't readily available for the most part, especially if you are trying to get a car or something like that, but how much cash are you thinking this should cost? You are not going to build a machine for $15 or $20, but you might be able to for less than a few hundred. But the cost depends on your expectations and your design and your ability to find some of the parts you may need cheaply or free, which is possible.

Your Thread title says 2'X4'X12' - please clarify. 12' is a lot of Z axis stroke.... It's usually expressed in X,Y,Z - so how big of a machine do you want to build and what do you want to cut with it? Just wood? Aluminum? These things affect the design and the cost.

Just thought I'd get things started. We are all here to help out! Ask away!

Scott

[cadfish]

First of all I build things HEAVY DUTY I would like to do mainly aluminum and cast aluminum. Also I have a car that gets great gas milage. If I take my time and do things right it will get done. I will try to get a cad drawing on my picture page on Saterday. My dad has a shop 25'x25' full of tools listed above except for the butter knife, which I can get from my mom's kitchen if I realy need it. My friend also has a dad that owns a machine shop if I need it.

[cadfish]

(nuts) woops I was tring to get 12" not 12'

[wizard]

Hi everyone I could use some help designing a machine. I am only 16 and just got the basics. My table is going to be made out of 3/4 inch plywood and no clue how to fasen the work peice. If any one wants to see pics of my design I will try to get them on my pics asap.
:wee:

Some one already mentioned T-nuts for use in the table. These are installed from the back side. This is a common method for fixturing in wood shops. Another possibility is to double up the table top thickness and install the extruded T-slots that woodworking stores sell. Realizing of course that these are no where near as good as real T-slots in castiron. You could also fabricate some flanged bushings that end up being a heavy duty version of the T-Nuts. You will probably find that the ideal situation is a combination of all of the above.

You did leave out one important element and that is what you intend to machine with the router. That can have a huge impact on material selection. Someone already mentioned MDF as a more stable material in some situations, but that is not always the case.

Dave

[cadfish]

Some one already mentioned T-nuts for use in the table. These are installed from the back side. This is a common method for fixturing in wood shops. Another possibility is to double up the table top thickness and install the extruded T-slots that woodworking stores sell. Realizing of course that these are no where near as good as real T-slots in castiron. You could also fabricate some flanged bushings that end up being a heavy duty version of the T-Nuts. You will probably find that the ideal situation is a combination of all of the above.

You did leave out one important element and that is what you intend to machine with the router. That can have a huge impact on material selection. Someone already mentioned MDF as a more stable material in some situations, but that is not always the case.

Dave

what if I get a piece of castiorn with the T-slots and mount that on the plywood. Can I get one for cheap that is 2'x4'???

[ViperTX]

Nowhere that I know of.....something that large will most likely weigh 300 to 400 lbs if it's only 1 inch or so thick...thicker.....well you can guess the weight..at a denisty of 8 grams per cubic centimeter......hmmmm...about 37 ounces per cubic inch....I wonder if that's correct......perhaps less wine would help....

[PaulH]

One method that many use to drill a grid of holes for blind-nuts is to build everything else on your machine, then use a drill bit in the collet of your router. Program the computer to drill holes at regular intervals and just let the machine do the work for you.

Your best bet would be to use a replaceable top for this. Then if it wears out or you decide to try a different hold-down system, you can pull it off without disrupting the rest of your machine.

[cadfish]

Pic #1 (this cad drawing is on "Delta CAD")
I got a cad drawing of the machine so far.
the bright green circles are the ready rod type things.
the blue is my rails that 6 bearings will run along.
The yellow is 1.5 inch square tubing.

where should I mount my router?

[wizard]

what if I get a piece of castiorn with the T-slots and mount that on the plywood. Can I get one for cheap that is 2'x4'???

Maybe we miscommunicated here. I was trying to get across the idea that the extruded aluminum T-slots mounted in wood are not as good as T-slot in castiron. That wasn't to imply that you need to go our and get a castiron table.

A castiron table would of course replace the plywood. At the size you are talking about you would need a well equiped machine shop to machine the table. That would also imply building the rest of the machine out of metal. This is NOT the way to go for your first machine!!! :drowning:

What I would suggest you do is to find a store nearby that specializes in materials for serious wood workers. A place like WoodCraft should do fine. They have a large number of products that fit the needs of this sort of machine.

Dave

[OCNC]

Pic #1 (this cad drawing is on "Delta CAD")
I got a cad drawing of the machine so far.
the bright green circles are the ready rod type things.
the blue is my rails that 6 bearings will run along.
The yellow is 1.5 inch square tubing.

where should I mount my router?

I would make the base out of 3/16 x2 x4 steel tubing. Don't bother with all of those diagonals. Set it up as in the attached jpeg. Precision cut the cross pieces using a stop to keep all of the lengths the same. Make sure your cuts are square in both planes of the cut. Clamp the frame together flat and square and stitch weld the vertical edges of the cross pieces where they butt into the longitudinal rails.

Step-by-step, once the frame is securely clamped, tack each corner of each cross piece where it butts into the longitudinal tube. If everything is clamped together tightly it won't matter which order you do this in. Then go back and use two 1" welds per vertical edge ( that's four per tube end and I'm assuming that these will be quality welds). Start from the corner tacks and weld towards the center of the tubes. Don't run the welds all the way through to the opposite tack. You want to minimize heat distortion. When stitch welding the cross pieces start with the center piece. Stitch weld this to both longitudinals and then move on to one of the adjacent pieces. Next weld the one on the other side of center and finally the outer ones. If the cross pieces had been numbered sequentially from one end, 1,2,3,4,5, the welding order would be, 3,2,4,1,5. Don't weld the short horizontal edges of the cross pieces where they butt the longitudinals. Pre-drill any mounting holes for other items before assembling.

[PaulH]

WoodCraft's competition, Rockler, is also an excellent source for T-track and the bolts that fit in it.

[cadfish]

I may have also mentioned that I want to cut Alunimum. Do I Need A coolent system?

[ViperTX]

cadfish.....yes, unless you want to use manually applied lubricant.

[wizard]

Cutting aluminum does imply lubricant.

That however is a problem with a wood machine, depending of course upon what sort of lubricant you choose to use. My suggestion would be to take extensive steps to seal the exposed surfaces.

thanks
dave

I may have also mentioned that I want to cut Alunimum. Do I Need A coolent system?

[cadfish]

The only thing that I want to be wood would be the table. I was also thinking what would happen if I Coated the wood in a epoxy? My dad has some that profesionals use to refinish boats.

[wizard]

A wood table is good. On these sorts of machines the table is often considred an expendable Item. It amy somewhat limit what you can do with Aluminum but I woldn't worry about that.

As to coatings; Epoxy probably would work, I haven't tried it on such an application. Be very carefully about the type and the application instructions. The big concern would be delamination of the epoxy coating. You might want to look into the stuff they use on bar counter tops. You could also try applying "Formica" type materials to the top, they would be slippery though.

Sounds like you are headed in the right direction.

Dave

The only thing that I want to be wood would be the table. I was also thinking what would happen if I Coated the wood in a epoxy? My dad has some that profesionals use to refinish boats.

[2muchstuff]

If you want to use an epoxy to seal the wood up, thin the epoxy with acetone. I generaly use a mixture of 2 part epoxy and 1 part acetone (2:1). This allows the epoxy to penatrate deeper into the wood. Follow this up with another coat or two of unthinned. Auto body paint supply stores usually stock tubes of different color pigments that can be added to the mix, if you want a colored table.

[cadfish]

Check this stuff out http://www.westsystem.com/ my dad uses it on his custom recurve bows and he says you can brush it on and it will be smother than glass.