Straight cuts with a Jig

[ark_ader]

Hi,

My woodworking skills are improving with experience, but my hand saw doesn't cut very straight.  I'm always over and slightly crooked in my cuts, which is getting me down.   

I thought of a saw board and a jig or a clamped planed piece of wood as a guide for the jig, but would this gave me the same grief?

I know I need a circular saw, but the work I have lined up is minimal.

I'll be cutting MDF, please can you give any pointers on how to make my cuts straight with a Jig?

Whats the best saw blades to use on the jig with MDF?

Many thanks

[ScottS]

I'd try making a sawboard for your jigsaw. Unfortunately, if you have a cheap jig saw that doesn't support the blade well there may be nothing you can do to keep the cut entirely straight; jig saw blades are thin enough and long enough that they have a tendency to wander if there is any resistance from the wood. Since jig saw blades are cheap, you might just buy several different types and give them a try. I'd think that a short blade with a low tooth count might give you the straightest cut, but the results might be ragged. More teeth will give a smoother cut, but may tend to wander more. If your saw supports orbital motion, I'd also play around with that setting.

In the end, I probably wouldn't worry about it too much. If you cut so as to leave the line, you can always use a sanding block to get the cut perfect. A bit more work, but that's often the trade-off required if you want to avoid buying new tools...

[patrickl]

Or cut it reasonably close with the jigsaw and smooth it out with a router?

[fjl]

Not sure how well a jigsaw works with a saw board. I would image it wouldn't be too accurate. Well there's this, it might be of some help.

Amazon.Com Link

Otherwise just get yourself a cheap circular saw and a blade with as many teeth as possible. Make a yourself a saw board and you'll be set making straight accurate cuts. I didn't even think about a sawboard till I saw this thread and now I wont even make a any cuts with my circular saw without it. It's a really nifty jig.

http://forum.arcadecontrols.com/index.php?topic=43568.0

[javeryh]

If you have a router you can use a pattern cutting bit and a straight edge to get perfectly straight lines.  I used this method almost exclusively before I got a table saw and even now if it's just a quick cut I'll use the router over setting up the table saw...

[BobA]

Use a router if you have one or a cheap circular saw.  The jig saw blades are not designed for straight cutting of thick material.  They always deflect and cause an bad cut even with a guide.

[TOK]

Use a router if you have one or a cheap circular saw.  The jig saw blades are not designed for straight cutting of thick material.  They always deflect and cause an bad cut even with a guide.

As someone who tried to go the jigsaw route also, just because I loved working with one, I have to say that this info is right on. Even if you're cutting against a straightedge, if you look down at your jigsaw you'll see the blade flexing and moving.

Get a router... If you're anything like me, the time you save in sanding and the price of wasted material will pay for the router in one build.

[Mallen]

Here's how I cut a straight line on a 4X8 ply.  I took a piece a ply and cut one end off the 4 foot side by free hand with circular saw about 6 inches wide (6"X4').  Keep track of the factory side, that will be your straight edge.   Then cut another stip about 12 inches(1'X4').  Neither strip needs to be perfect. The original 6 inch cut with the factory side gets screwed to the 12 inch strip, be sure line up the NON factory edges, they don't need to be perfect either.  Now, take your circular saw and trim the edge of the 12 inch piece using the factory edge as a guide.  DONE.  From now on, all you need to do is pencil mark each side of the piece you want cut and lay this jig on the marks, clamp and cut.  Never need to measure the distance from the blade to the saw edge.  Remember to lay the jig on the correct side or you will be a blade width short.  I always make a cut mark with a little tick on the side the blade needs to cut on so I don't make that mistake.  I made a few costly ones like that. 
 I know I didn't explain this well, If anyone is interested, I can email photos of the two jigs made, one 4 foot and one 8 foot.  I don't like cutting large pieces on the table saw.  And this way is safer and quicker.  I might even work with a jigsaw.

[bfauska]

You mean something like This?

[ARTIFACT]

interesting... I would agree witht he points made about jigsaws

I am almost done with my cab (painting, etc now) and am a total noob with wood - I'm proud of the results though BUT I had to do a LOT of sanding (60 grit) to get acceptable curves and lines.
I do have a router and used it to do a few things (speaker grill slots, T-Molding slot cut, round edges here and there, etc) BUT didn't realize that I could make long straight cuts using that too.

My neighbor has one of those hand circular saws... the blades seem very rigid and with a couple of metal guides clamped to the table it seems like the best method for long straight lines that I've seen so far. Kind of what Mallen describes.

guys, this is SO much fun ... I can't wait to build some stuff for the family/house next... This arcade project really enabled me to learn useful skills.

[patrickl]

You mean something like This?

A sawboard does not rally work with a jigsaw.

[bfauska]

You are right.  But my comment was in response to Mallen, who's comment made it sound as if we had move past the jigsaw. 

If I were to offer advice to the original topic I would say the best way to get a straight cut that is square and smooth with a jigsaw is to let your friend who only owns a circular saw borrow your jigsaw in trade for however long it takes to use their circular saw to make the cuts.

[Mallen]

   bfuska that link was exactly what I did.  I didn't notice that post.  But it's the best and easiest way to slice a full sheet of plywood.  As far as using a jigsaw, it's not really for cutting straight lines, however you could cut a straight line by using a jigsaw by cutting outside the line and use a router with a pattern cutting bit and a straight board for a guide to clean it up.  Makes a nice smooth edge.  It's a lot of steps compared to using a circular saw with a guide.  I'd at least try to find a used circular saw if your on a budget.  I bought mine 23 years ago when I was 15 and I'm still using it; not much but can't live without it.  I bet you could build a great looking CAB with just a router, circular saw, and drill (preferable cordless).