[olielloyd]

Hi I have to make a pc desktop with an internal curve. I have a jigsaw but I have access to a router aswell wat would be the best way to do it I feel a router would be cleaner but dont fancy doing it free hand. Here is a rough drawing with sizes in mm

 

[BigBull]

Jigsaw, unless you can barrow the use of someone's Bandsaw. That's what I would do. If you use the Jigsaw, leave the line and sand to it, should look ok.

 

[Dave Paine]

Nice introduction. :huh:

Since you show metric dimensions I am presuming you are not based in the US.

You need to make a template and use a pattern bit in the router.

Cut a piece if 1/8in (3mm) plywood with the jigsaw based on a line drawn on the plywood. Sand the edge smooth.

Mark out the line on the plywood. Cut off the majority with the jigsaw leaving about 2 or 3 mm to the line.

Clamp the plywood template on the plywood and remove the excess plywood down to the line with the pattern bit in the router.

An example of a pattern bit.

http://www.woodcraft.com/Product/2001862/9049/WoodRiver-Pattern-Cutting-Router-Bit-12-D-x-1-CL.aspx

 

[Bonka]

First off it can't be done free hand. If it were me I would make a plywood pattern. The arc would be drawn on the ply wood, cut close to the line with a jig saw and then sanded to the line to take out the irregularities. I would then trace the arc on the work piece a little "fat" and cut it. The put the two pieces together with the pattern on top with the edge just shy of a match to the line to be cut. Then with a top bearing pattern bit on the router cut the work piece. The top bearing will ride on the pattern and cut the work piece to its edge.
Some folks might be able to make the cut with a jig or band saw close to the work piece line and finish up with a spoke shave or what have you but I do not possess that ability.

 

[olielloyd]

Hi thanks very much for quick reply that helps loads yea im a carpenter based in uk hence the mm haha and new to the forum

 

[bladeburner]

I'd use a router on a long pivot arm. I know a woodworker who cut a stage front (60 foot radius) by coupling lengths of pipe to the router base. I've cut cut a 6 foot radius (deck).

Anchor the workpiece and fashion a pivot for the arm and clear space for you to control the cut.

 

[tonyuno]

I use a roter and homemade trammel for most curve work. A bandsaw would also do it wellbut I don't own one

 

[olielloyd]

Thats good how did u make that how do u keep trammel fixed to floor I would have to do it outside as my garage isnt big enough

 

[bzguy]

You must have a small garage?
If you picture that radius as a complete circle I would guestimate the center at around 600 MM, (about 24").
Either way will work but with a radius jig like Tony's you can make the cut in several passes.
With a pattern bit you need a thick template for the bearing to ride on or you have to hog it all out in one pass.
You never say what the top is made of, one pass with some materials could get messy.

 

[olielloyd]

Well no room lol ill sort sumat the material will be 1/2" mdf

 

[tonyuno]

Sorry I should have put a size in it. It' a maximum 3' trammel and the table is actually 6' . The trammel had a 11/2" x# 8 screw and this particular top was done on a 4' x 8' x 3/4" sheet of ply wood. As My basement workshop is too small all the large work is done outside.

 

[BernieL]

Nice work Tony...

Good advise here on cutting circles - whatever tool you chose to do the job, leave the line intact and sand it down...

 

[Improv]

I would use a length of PEX tubing (1/2" or ~12mm, however you can find it) and screw it to the underside of the desk as the guide for a router. It would allow for non-circle curves to be made.

Regards,
Steve

 

[gus1962]

Use band saw with narrower blade for cutting curves.

 

[tonyuno]

The OP mentioned he has access to a router but didn't say wether he has access to a bandsaw. If he does't then using a bandsaw to cut the curve is a mute point.