How to cut 24" circles out of 1/2" thick maple plywood in LARGE quantities?

I don’t know how else to post it, but it is simply a piece of plywood with a plane ol’ Screw at the pivot point. One issue is it won’t be perfectly smooth, so you would need to sand it. A CNC would cut a smooth edge, but if you don’t have a CNC, then that’s a huge cost, and big floor space. The slower you go, and the sharper your bandsaw blade, the smoother the cut will be with a bandsaw. Use double stick tape to keep the stacked pieces together. It shouldn’t take much force with a decent bandsaw, so the tape doesn’t have to be much- just enough to prevent the pieces from slipping.

Another option is to cut slightly larger and then use a straight cut router bit to trim to a smooth edge with a circle template or a circle jig on a router table- basically the same jig as on the bandsaw.

All CNC's are not created equally. Hire someone with an industrial machine if that is the route you want. A real machine will cut in a single pass if they have enough vacuum, which a pro should have. If hold down is a problem, they will use an onion skin pass (final pass 0.03" or so). The key to this will be finding 49" wide sheets in the species you want or using BB. At this scale you will find industrial guys are interested. They could crank out a couple of months of pieces in short order and you stack on a rack. A pro machine should result in zero clean-up, but smaller machines like the one you posted could suffer from chatter that will lead to 5 - 10min per piece sanding.

Here is a video of high speed production if you have a spare $200-300k+ to spend. https://www.youtube.com/watch?v=uffr3lLlRV4

Key thing to look at in original post: 50 - 100 pieces per month.

Thanks for the link. That is very fascinating to watch. I do not have that kind of cash or plan though.

My monthly rounds for exact now are 100 pcs of 23.5" rounds and 70 pcs of 17.7" out of 4x8' 1/2" maple plywood sheets.

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Originally Posted by Brad Shipton

All CNC's are not created equally. Hire someone with an industrial machine if that is the route you want. A real machine will cut in a single pass if they have enough vacuum, which a pro should have. If hold down is a problem, they will use an onion skin pass (final pass 0.03" or so). The key to this will be finding 49" wide sheets in the species you want or using BB. At this scale you will find industrial guys are interested. They could crank out a couple of months of pieces in short order and you stack on a rack. A pro machine should result in zero clean-up, but smaller machines like the one you posted could suffer from chatter that will lead to 5 - 10min per piece sanding.

Here is a video of high speed production if you have a spare $200-300k+ to spend. https://www.youtube.com/watch?v=uffr3lLlRV4

Key thing to look at in original post: 50 - 100 pieces per month.

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You are correct: nominal 24" circle, actually 23.5". So yes 8 circles per sheet currently.

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Originally Posted by Bill Space

Since the OP really only needs 23.5” the point is moot, as he likely can get 8 pieces from a 4x8 sheet.

But it if he really needed 24” or slightly larger circles, couldn’t he get six of them out of a 4x8 sheet by offsetting the center points of the circles somewhat? Wouldn’t work for rectangles or squares, but with circles it would probably even be possible to get six circles larger than 24” diameter. This is what my minds eye was telling me...

Apologies to the OP as this really is a tangent to his question.

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Thank you so your excellent suggestion about the edge sander setup. I know I have a very primitive approach to the sanding part and it IS tiring mentally and physically!
Your point of not spending top dollars to just cut circles is well taken!
I will contact a few cabinet shops tomorrow to see how much it cost to sub it out.

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Originally Posted by Marc Jeske

OP said - "I am using a belt sander by holding the circle vertically and rotate as I sand."

If nothing else... Like I said above - Strap that sander down horizontally, secure a 2x2 table against it to make the most basic edge sander.

Stop vertically holding and balancing your workpiece... VERY inaccurate in ALL directions, let alone mentally and physically tiring compared to just doing above.

Marc

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Originally Posted by Byron Lu

You are correct: nominal 24" circle, actually 23.5". So yes 8 circles per sheet currently.

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Missed that. I had 24” on the brain. :o

Byron, if you want to see the pictures others have posted, toss in $6 to become a SMC contributor.

You could also get by with a 24x24 cnc and just cut your blanks as you would for the laser. Once setup and a small vacuum pump with a dedicated fixture you would be able to knock them out in no time. Something like this would get you going pretty quick. As Keith said you could use tabs But I would get an Amama 3/16 flush cut and a small trim router to remove the tabs I do this sometimes and the 3/16 bit fits in the 1/4 slot

https://www.automationtechnologiesin...relay-control/

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Originally Posted by Bill Space

I could be wrong, but my gut is telling me a 4x8 sheet should be good for six pieces 24” in diameter.

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bill, You have to allow for the kerf. The operative question is whether the circles must be a FULL 24”. If so, any kerf at all pushes them over and the yield is 3/sheet.

correction. I see where you were going. I stand corrected and concur on 6/sheet.

Actually 8 per sheet for 4 x 8 sheet for the 23.5" size specified with 1/4" bit.

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Originally Posted by James Morgan

Byron, if you want to see the pictures others have posted, toss in $6 to become a SMC contributor.

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Thank you. I did not know this trick.

Hi Byron,
What other kinds of parts do you make from wood, and would any of your other parts lend themselves to manufacture on a cnc router? It would be nice to get a new cnc machine to start paying for itself as soon as possible. With your experience running your cnc laser cutter, it would not be too much of a learning curve to start running the cnc router.
David

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Originally Posted by Matt Day

I’d make a jig to cut on the bandsaw, then a jig at a sander to clean the edges. Both using a 1/4 deep peg in the center. Might be able to freehand the sanding at a disc or edge sander.

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That would be my choice as well, if you even need the jig at the sander. If you get a clean enough cut at the band saw running a ROS quickly over the edge may be enough and if the sanding is light enough freehand may be fine. The sanding might be done on a stack of disks at once.

Pete,
It's very hard to get the accurate cut that may be needed for this with a band saw. It can be very hard to follow a line, even with a circle attachment. Depending on the tolerance of the part, for repeatable results the cnc is the way to go. Either cnc laser or cnc router.
David

If you end up sanding the edges, I would look at an oscillating edge sander. Laying the pieces flat on a table against an oscillating belt would be night and day improvement over your current sanding method.