Metric dovetails · Issue #2 · lowrie/pyRouterJig · GitHub

This instructable will show how to make an accurate and easy to use jig for cutting perfect circles with a router. There are many pre-made circle cutting jigs on the market, but they are fairly expensive, and many of them don't have a very large maximum radius.

Several of them also rely on a series of holes to control the size, which can be a problem if you need a very precisely sized circle that happens to be in between the sizes of two of the holes. I will show how I made a precise circle cutting jig using nothing but scrap plywood, and a few nuts and bolts. This basic plan can be modified to make accurate circles of almost any size.

Disclaimer: Please practice shop safety, especially when working with power tools. Take all neccesary safety precautions, and don't use any tools or procedures you're unfamiliar with or uncomfortable using.

The base material could be made of any flat sheet good material, but preferably Round Cut Router Jig 60 MDF or round cut router jig github grade plywood.

Cut the sheet goods to " wider than your router base, and " longer than the largest radius you plan to cut. It will allow me cut circles up to about 46" in diameter. Use a pencil to mark the screw mounting holes, the center hole, and trace around the outside diameter.

A plunge router is preferable for this, but not neccesary. I already had the fixed base router that will be used in this jig round cut router jig github, and didn't feel like taking my plunge router out of my router table. Unplugging the router tithub you install or change bits is a good rojter habit to practice. Clamp the base to a stable work surface, like a table or workbench, with the side you will mount the router to face down.

Then clamp a straight edge scrap of plywood in this case round cut router jig github rounnd base to act as a fence, or guide. Line up the straight edge with the outside edge where you marked the baseplate, and parallel to the length of the base. This will ensure that the slot will be centered in the base. Using the straight girhub as a guide, route a slot between the mark 1" from the baseplate, and the mark 1" from the other end of the base.

If as you look at it, the fence is to the left of the router, start at the end closest to round cut router jig github. If the fence is to the right of the router, start on the end furthest from you. This will pull the router into the fence, which not only makes it easier to make a perfect slot, but is also safer.

With the fence still in place, rout the smaller slot the in the same ijg as the first one. Drill holes for the mounting screws, making them just a little bigger than the diameter of your screws. Flip the base over, and using the holes as a guide, trace the baseplate round cut router jig github this side too. Choose which side you want to moun the router on, and Round Cut Router Jig 75 chamfer the mounting holes on the opposite side. You want the chamfers just deep enough that the screws will sit beneath the surace.

Drill or rout out the center round cut router jig github. It just has to be slightly bigger than the largest router bit you might use. A hole saw is probably best for larger holes, but I used a twist bit, and it caught and made a pretty messy hole. It won't really effect anything other than aesthetics, but next time I'll take the time to get the correct bit out. I did clean up the hole a little with the router later. The mounting screws are most likely much too short to reach all the way through the base material.

We could buy longer mounting screws, ggithub unless you have a set of really long router bits, the thickness of the base may limit the depth of cuts you can make with the Router Jig Round Hole Github finished jig.

To solve both problems, I reccomend routing a recess in the base for the router to sit rond in. After clamping the base to round cut router jig github work surface with the router mounting side up, rout out the baseplate area, using the line you traced as a guide.

It's easiest round cut router jig github start at the center and work around the the hole clockwise, sneaking up on the final size with a few light passes. Now the baseplate can be removed from the router, and the router can be installed in the jig using the baseplate screws. Make sure all the screws sit flush with the bottom suface of the jig so that they won't catch on anything.

While the easiest thing to do is buy a t-handle or star handle for jigs, but I'm too cheap to do that, so I make my own. It takes a piece of scrap wood, a t-nut which costs just a few cents, and takes just a few minutes to make.

I make them in bulk to use in all of my jigs, and I won't go into the process here. It's easy enough to simply cut out a shape you like, drill a hole in the center to accept the t-nut, and hammer it in place. I didn't rouer any threaded rod, so I just cut the head round cut router jig github of a 3" bolt.

Screw the nut onto the center of the threaded rod, and then place the washer on. Slide the portion above the washer up throught the slot in the base, and then screw the handle on to the top. Alternatively, if you have access to a metal lathe as I do, you can cut the threads off one end of the threaded rod, making a smooth post of a specific size.

That way you can use a drill bit that matches the round cut router jig github size, and always be sure to have a nice tight fit.

The threaded rod with an appropriate sized drill bit should ckt well enough for most applications though. This step is entirely optional, but I thought it might make it slightly easier to use. The base had quite a bit of uneccesary wood, so I decided to round cut router jig github it off, and round the corners. I also slightly beveled the edges on the bottom side with some sandpaper so that they wouldn't catch on anything as they slide around the circle.

The first step to using it is setting the post height. Measure the thickness of the material you'll be cutting a circle in. Adjust the nut on the cuh so that it sticks out slightly less than the material is thick. Mark the center of the planned circle, and drill a hole that the threaded rod post will fit in snugly. Routef the post at the desired distance from the router bit, and tighten the handle on top to lock it in jlg.

If you are cutting all the way through your material, make sure to hang the portion being cut off the table, and keep rotating the material roune during the cut to keep from cutting the table. You could also put a sacrificial piece of scrap underneath the material instead. It's generally safer and easier to cut outer edges of circles in a counter-clockwise direction, and inside edges clockwise.

If you don't want a small hole in the cener of whatever you're cutting, you can use a sacrificial piece on top. Drill a hole in a piece of scrap, and use doublesided tape round cut router jig github secure it to the workpiece with the hole at the center of where you want to cut the circle.

Then just increase the depth round cut router jig github cut by the thickness of the sacrificial gituhb, and cut as usual. Alternatively, if a hole would round cut router jig github acceptable on the underside, but not on riuter, you can drill the hole only part way through the material, and cut from the bottom.

Have fun, and be safe! I have the same fixed-base Porter Cable router and made a circle-routing jig for it. What I'm trying to sort out is how to start the cuttingdo you have to loosen the router height adjustment while it's running and rotate it down to the depth you want and re-tighten? I probably should just use my plunge router, I round cut router jig github Reply 7 months ago.

Reply 2 years ago. Don't ever loosen or attempt to adjust the depth while it's plugged in, let alone running. A plunge router is safer, but it can be done round cut router jig github without one. Set the depth with the router un-plugged, plug it in, turn it on while holding it securely it will jump a bit when you turn it onthen slowly lower the bit into the workpiece while keeping the side of the baseplate against the fence.

Tip 2 years ago. One very important thing to remember is to take round cut router jig github account the thickness of the jih bit you are using, and compensate for half of that in your finished circle diameter. This is great! I round cut router jig github up with a really similar xut on my own.

Good to see it's a common solution :. Once you tighten the nut to hold the desired size of the circle, it seems like you will be tightening round cut router jig github fixture to the work piece making it hard to go around.? Reply 5 years ago. What none of the pictures show is the post that sticks down from the jig under the t-handle. When you tighten the t-handle you are only tightening the post round cut router jig github position.

The post then will drop into the hole you drill in the center of your workpiece and allow the jig to freely rotate deg around it. Nice looking jig. Having a good routre is the secret to most of my successful projects. I use this circle cutting technique frequently, but I just Round Cut Router Jig Image take a long strip of fiberboard and set it up for a fixed radius.

I just posted my Cardboard Ball Chair www. If I cut a lot of circles of various sizes I'd certainly make a jig like this. The all-thread allowed for very precise adjustments and long radii. I used this to make concentric rounded grooves in an old wood door.

The resulting pattern made the door from a very junky piece to something that looked like art. I love using radius techniques whenever possible. You can do a lot with them. By tashiandmo Follow. More by the author:. I would think that most of not all of these materials could be round cut router jig github in most workshops. The cost to purchase these items would only be a few dollars.

It does of course assume that you have a router to use the jig with. Make a mark on the center line one inch away from the outer edge of the baseplate.

Tools-router 1/4" router bit 3/4" router bit straight edge pencil drill or drill press 1/4" drill bit chamfer bit saw (prefferably a tablesaw or bandsaw, but any will work)Materials-Scrap of MDF or cabinet grade plywood 1/4"x20 tpi threaded rod 3" long (or a 1/4"x20 tpi bolt with the head cut off) 1/4" x20 tpi T nut (or pre-made t-handle) 1/4"x20 tpi standard nut 3/4" OD washer I don't have a.

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