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I have wood that is about 1 3/4" thick, but I need to cut a circle out of it. I only have a jigsaw and a drill to work with (I only do light woodworking). Is there anyway to do this. Unfortunately, I don't have a band saw.

Edit: The circle is roughly 26 cm in diameter. It has to be a perfect cut because I am actually attaching a motor to the center and it is going to be spinning fast (so I need it to be balanced), so I am not sure if a coping saw would work here. I have a compass-like stick that came with the jigsaw to cut perfect circles, which is what I was planning.

  • There are larger blades you can get the for the jigsaw but the bigger they get the harder it can be for tighter turns as the spines can be larger. Are you cutting a circle out of the middle or cutting it into a circle just so I am clear? How big will the circle be? Coping saw might be a good fit here – Matt Jun 18 '15 at 0:45
  • I want the inner circle, the outside is scrap – electricviolin Jun 18 '15 at 2:21
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    Note that when you can do so, it's often easier to make some rough cuts to remove most of the waste before doing a final pass to trim exactly to the line. That's true with almost all cutting techniques. Downside is that it tends to waste more wood by not leaving you with pieces large enough to cut something else out of... but that's often a cost worth paying to simplify a task. – keshlam Jun 30 '15 at 0:02
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First of all, most jigsaw blades can easily cut 1 3/4". A regular 4" blade will usually have a cutting capacity of 3", which is more than enough. Naturally you should go slow, letting the saw do the work instead of pushing it hard.

Secondly, since you are planning on using the wooden circle as a wheel powered by a motor, you can actually get away with an imperfect cut. After finishing the rough circle, hook it to the motor and let it spin. With a chisel (or even sandpaper) you can shave of the parts that are sticking out. This is the same as what a lathe does, but you don't need anything more than what you already have.

Matthias at woodgears.ca uses this technique for his bandsaw wheels.

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    The only bit of advice I'd add to your suggestion of smoothing out the circles on the motor spindle is to make sure the spindle shaft is well supported enough to handle an unbalanced load for a short period of time. – Doresoom Jun 18 '15 at 13:27
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    I would suggest that @Doresoom's suggestion of making sure the shaft is well supported is critical at all stages of the build and use of this project. A 10" (approx 26cm) circle of balsa wood will not be too heavy, but anything else will have some significant mass to it. Also, be sure you're using some very clear stock - I'm not sure how fast this will be spinning, but you don't want a crack developing and having a split of wood come flying off your axle. – FreeMan Jun 18 '15 at 14:09
  • Ironically, I was just watching one of Matthias's videos while I reading this. I have seen larger jigsaw blades, but none that are made for cutting curves. I don't think I should, but could I use a straight cutting blade to cut a curve (considering the large size of the circle). As for the weight, I am going to cut sections symmetrically around the circle. In the end, I will probably attach it to a drill and sand it before trying to connect it to my motor (as it is a smaller DC motor, but has a lot of torque and speed). – electricviolin Jun 18 '15 at 17:58
  • @electricviolin Given the size of your circle a jigsaw is by no means a stretch to consider as a tool to use. – Matt Jun 18 '15 at 18:37
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Like with a lot of things you can do this but there are some variables here. Namely we don't know how big your circle is and where it is in reference to the rest of the piece.

Cutting Large Stock

Your wood is sufficient for most standard jigsaw blades, that come stock with tools that I see, but they do come larger. Here is a picture of a Bosch 10" blade.

blades of all kinds

You can even see a tool review using the blade on 5" stock. I don't know the dimensions of your circle but if the diameter was wide I'm certain you could cut with larger blades if you managed to acquire one. I would suggest getting a smaller blade than 10" for your case since you don't need that extra blade flying under the wood you are cutting (Would not make for a clean cut if the tool is running at a high RPM). The 10" is shown here to illustrate your options.

Cutting Your Stock

You should aim to get a blade at roughly an inch longer than what you are cutting. So, if you can find a minimum 3 inch blade, that is designed to cut wood, that should cover it just fine. You want to be sure the sawdust clears the path to stop the blade from overheating and possibly snapping. The blade material, carbide, hss etc. might come into play but I don't have specific advice for that unfortunately.

A coping saw would be a good fit here as well if the circle was not to far inside the piece. You could drill a hole and assemble the coping blade into the hole so you don't have to have a cut line outside the circle. Coping saw are rather cheap. Never did use one on this thick of wood and they are generally used for more delicate cuts (Which is why the blades are so thin).

Since you are using a compass attachment I don't see any potential issue as long as the blade is not too wide to prevent nice arc movement. Go slow.

Edit for the coping saw

In a general sense it is still a tool to consider. In your particular case that a rather large hole and a coping saw would not work.

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Use a super simple jig like this, 1 3/4" shouldn't be a problem at all with a decent blade.

circle jig

http://www.wwgoa.com/content/uploads/2015/01/circle-template.jpg

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