Will this work???

[Arc Light]

O.k. so I have my new table saw built and running, now I want to make a cross cut jig for it.  My question is I have come across 12"x12"x1" thick polypropylene cutting board (As in kitchen cutting board) and am wondering if this would make a good base for the jig.  It's a white plastic material that I figure would probably resist warping and other effects that wood and MDF suffers from.  What is the groups thought on using this material, and do you think I can cut it safely on a table saw?

Thanks from the table saw newbie 

[Canuck]

There's no reason why it wouldn't work, the only issue I can see is it's small size...but that's just a personal preference thing   
The other thing is attaching fixtures to it...but that'll just mean drilling through it and using nuts and bolts...   That being said I'm not really a 'jig' guy, I hate making them    Scott is really the jig expert 

[Arc Light]

Thanks for the quick answer John.  I realize it would make a workable area somewhere around 8" wide.  Which may be the deciding factor because that's not a lot of room left for hold down clamps etc.,  but I figured the 1" base would be nice and solid and resist movement.  In regards to attaching hold down clamps I was thinking of using counter sunk carage bolts up from the bottom.  I am guessing that if I used MDF I would probably be in the same boat with attaching things to it.

How the heck do you get the tight tolerances in you puzzles without jigs?

I have seen Scott's aluminum cross cut jig, now that's a thing of beauty.

[Canuck]

How the heck do you get the tight tolerances in you puzzles without jigs?

Oh I reluctantly make jigs, probably the most hated thing I do, but I do make them    My choice for base material is 'Finnish/Birch' plywood, the more plies the better, they sell it at all home building stores, in a 24"x48" size, I usually cut it in half so you get two 24"x24" base pieces....I like to have lots of room on them for stacking pieces and such 

[Johan Heyns]

Hi Peter

Personaly I think its too small.  I also think that the 1" is too thick.  Remember, its lying flat on the table with the two runners attached below, so there is no real stress on this piece.  If its wood, and deformation is a problem then the edges that you add should take care of that, plus the backing board you put across somewhere towards the back.  It looks similar to my saw, so you probably only have 80mm saw height.  1" bottom board takes away 25 mm of that.  Sometimes you need it.  I try not to go more than 10mm fot the bottom.  There are enough ways to strengthen and reinforce on top of that.

The stress comes when your workpieces contact the saw and the speed at which you do it.  Then the clamp attach points becomes important.

All the best. 

[STP]

Looks like you're moving right along, Peter!  Glad to see that.

The plastic cutting board is worth a try - although I'm not positively sure it will be flatter and more stable than MDF.  Surprisingly, plastic can move a bit as well, though I think it is more sensitive to temp than moisture (wood is the other way around).  If you get a piece of plastic thick enough, you should be able to put screws into it.  UHMW PE (Ultra-High Molecular Weight Polyethylene) is pretty tough - I haven't had a screw pull out of it.  Keep in mind, a cutting board is probably not made to any tolerances at all - might not be flat from the start.

(side note - we used UHMW PE for the rub surface between container cargo vessels and the steel fender panels on the faces of pier structures - in my former life as a structural engineer.  gives some idea of the abuse UHMW PE will tolerate...)

I have used carriage bolts before for jigs - but I found it is a bit harder to keep everything precisely aligned as laid out on the top when you need to flip the jig over to insert and tighten a bolt.  You can drill holes from above and then insert T-nuts from below too.  Then, when you make the fixture to be bolted onto the top, drill the hole that fits over the T-nut a bit oversized so you have some adjustment possible.  I like socket head cap screws better than carriage bolts too - and then I glue the T-nut into the bottom so I only need to "wrench on it" from above.

MDF is not a bad material at all in my opinion - it's cheap too.  I learned a lot on MDF before I spent the $$ on the MIC-6 aluminum (which I think was important for me).  There was a month of planning and design I put into that jig for future uses and allowance for adjustment that I could think of then...  The drawback with MDF is the durability...

If you don't have a planer, you might think about buying a couple miter sliders from Rockler (or similar - Woodpecker's?).  The "slick strip" UHMW PE tape is a good buy too - it has an adhesive back and I stuck it on the bottom of the aluminum plates I used to make my jig.  These make the jig slide really well on the table top.

Let us know how things are coming along - you're making much faster progress than I did when I got started!  Keep it up!  

[Arc Light]

Fantastic Scott, Thanks for all the great information.  I think I will start with an MDF based jig.  I also like the t-nuts and socket head cap screw ideas.  I spent 20 to 30 minutes rereading your post and using google to see all of the hardware you suggested.  Lots of information to get me started.  Thanks again!!!

[rolly_wood]

if you are going to use MDF for square stick jig, you might consider also to glue, with 2 components epoxy, a L-shaped alluminium profile in the groove. It is precise, easy to clean, has harder surfaces than MDF. It may be left to protrude a bit laterally outside the MDF jig and, in this region, it is simple to clamp stop blocks with usual clamps.
It is an hybrid solution easy to make...
But you know that I work with a chop saw; this is my experience with it, I do not know if it is suitable also for table saw... listen the experts (I am curious too)... I am not.

[Roby]

eventually, you are going to want more than one board.  You have blades with different kerf's and of course will want to use a rabbit blade in the future but you want all of them to be snug against the board to reduce tear out. 

[VisExp]

I love building jigs    My vote would be for 3/4" MDF.  You might want to also check out the following from Rockler.  It is on sale at the moment.  It goes on sale fairly often.  I've brought the kit three or four times.

http://www.rockler.com/product.cfm?page=21276&filter=jig