Circle cutting advice

[Jerome Hanby]

I purchased a wing cutter from Woodcraft for my drill press. Set it up this Weekend to cut some 5-1/16" circles out of 3/4" MDF. The First circle cut fairly well (but slow!) and I had to flip the blank to finish the cut. I tried cutting a second one and it didn't cut well at all. I'm assuming the MDF is hard on the steel cutter. Since I need to make 30 or so if these things, I'm thinking this wing cutter is not going to get the job done.

My first thought was to use one of the wheels I cut as a template, attach it to a roughed out blank and cut it on the router table. Thinking about guiding the blank is making me nervous. Is there a safe technique for this type of routing.

I've used a homemade router trammel to cut arcs in the past, but is seems like a lot of tedious work to use that method for 30 small disks.

Would I be better off putting together a bandsaw circle cutting jig?

Possibly I'm not thinking about this form the right direction at all and there is some better method.

Any suggestions would be appreciated.

[Matt Benton]

I'm planning to do the same thing to build a drum sander. From all the ideas I've seen, I think the bandsaw jig is the best way to go.

[Jerome Hanby]

Same thing I'm building! Guess needing 30 disk about 5 inches in diameter was a dead giveaway

[Ken Fitzgerald]

Is this the drum sander that was in a magazine recently? I talked with a friend last week who is an accomplished woodworker. He'd just made one and said it worked extemely well!

[Jerome Hanby]

I'm combining the ShopNotes design with Nick Engler's modem that mounts on and gets power from the Shopsmith. I may look at replacing the hand crank on the Shopnote feed belt with a motor... Just for good measure, I'm using the hook and loop paper system that is used on the V-Drum sander kits.

[Jim O'Dell]

What about using a pattern cutting bit on the router. Use the one you already have cut out for the pattern that the bearing rides on. Should cut copies that way. Or use a circle cutting jig on a router. Be sure to anchor down what "will be" both pieces of the material you are cutting, so after the cut is complete, the circle you need to keep doesn't go wobbling around and get back into the blade. Jim.

[Travis Gauger]

I built one of the shopnotes drum sanders with a lot of modifications to it. I used the MDF pucks for my first drum made with a circle cutting jig on my bandsaw. The sander I built worked great with the MDF drum but through time it started to show wear. Maybe took a year of a lot of use to get the drum to start to show wear. When it came time to replace the drum, I was too busy to give up shop time to make the MDF Pucks needed for the drum and was looking for alternatives. Got a quote for a balanced steel roller made to my specs for less than $50 from a local roller manufacturer. Can't beat that. Check out RSCI.com and get them to quote you. May be worth it. I have been gathering parts for my next DS Build. It will be 48" wide, built out of extruded aluminum, 6 HP, double drum, etc. etc. Good luck. It is worth the time investment for the DS project. Mine gets used daily with little problems. You'll love it.

[Lee Schierer]

I'd probably use the circle cutting jig on my bandsaw and cut them slightly oversized and then us a circle cutting jig on my spindle sander to true them up to the final dimensions.

[Jerome Hanby]

That's what I was thinking about doing, was just a little worried over guiding it. Any helpful hints?

What about using a pattern cutting bit on the router. Use the one you already have cut out for the pattern that the bearing rides on. Should cut copies that way.

[Cary Swoveland]

...Got a quote for a balanced steel roller made to my specs for less than $50 from a local roller manufacturer. Can't beat that. Check out RSCI.com and get them to quote you.

You certainly can't beat that, Travis. I think some of us would like to know how the roller is attached, and how the paper is attached to the roller.

Cary

[Eddie Darby]

http://www.sawmillcreek.org/showthre...circle+cutting

Nice post on a very effective way to cut circles with a router.

[Jerome Hanby]

I saw that post. At the moment, my router table is cast iron and the only way I could see to mount the pivot was on an "auxiliary" table top that I could clamp to the table. The way my router adapter mounts to my Craftsman CI extension, I loose a little height and I wasn't sure I would have enough to clear the aux table and the 3/4" mdf I'm cutting. Sounds like a good excuse to buy a long, guided spiral bit!

http://www.sawmillcreek.org/showthre...circle+cutting

Nice post on a very effective way to cut circles with a router.

[Doug Shepard]

I'd probably use the circle cutting jig on my bandsaw and cut them slightly oversized and then us a circle cutting jig on my spindle sandet to true them up to the final dimensions.

Other than using a disc sander to true them up I'd probably go that way too.

[Travis Gauger]

You certainly can't beat that, Travis. I think some of us would like to know how the roller is attached, and how the paper is attached to the roller.

Cary

My roller was ordered with a 3/4" shaft going through it. The shaft extends out past the roller 4" on one side (Bearing) and 6" on the other (Bearing then belt pulley). The roller is attached to the shaft with two keyways, keys, and set screws. I used pillow block bearings to mount my drum to the frame. When I said, I built the shopnotes version with some modifications, I should have said I was inspired by...
My sander got out of control really fast with seperate drive motors, 6 pt table mounting, all the gears and chain to drive to table adjustments, etc. I honestly could have bought a drum sander from the store for what I ended up putting into it. But given a little more restraint, this could easily be avoided. We built a friends in a weekend with a $100 budget. I think it ended up coming in at $108 or something. Works well and is just what he wanted.
I wind my paper on from the left to right and start it in a slot I cut into the side of the roller with a hack saw blade. The slot is just wider than the paper is thick. I slip the start of the roll into that slot which holds it as I roll it down the drum. On the other end I use a band style hose clamp to hold the paper from unraveling. I've tried a few ways. On the old drum I just used a flat topped metal thumb tack pushed into the MDF on each end. That wasn't an option for this one so at first I used velcro. What a mess. Don't do it if you want to use your sander for thicknessing or want to maintain crisp edges. the velcro takes up space and gives the drum a squishy feel. The velcro backed paper is pricey too. I buy 250' rolls of norton's 3X paper that are 3" wide. They are cheap, come in a nice little box that has a dispenser built in, and works great. I have to admit that I haven't tried many different papers as the norton's was the last one I tried. That's cause it works.
The really nice thing about buying a pre balanced drum is that you don't have to true up the MDF one. That is a pain. Extremely dusty. And time consuming! I built another sander for a friend who wanted one. For that drum we used a piece of 4" PVC pipe for the drum and only had to do 3 MDF pucks. One on each end and then a third in the middle. The three pucks were trued to the table before the PVC was added. It works great for him as he will never truely task the machine. The problem I had with it was that after a few minutes of use, the PVC starts to get soft from the heat being made. That would be enough for me to recommend against that.
One thing to be carefull with is drum speed. When you put a bigger drum on it the surface speed increases. And Vice Versa. Nothing that can't be fixed through pulleys, but be aware. We powered my friends off his tablesaw and he has to work from the back of the saw as the drum spins the wrong way to feed it from the front. It costed a garage door to figure that one out. It was his sander, his garage door, and his wood that went through the garage door though so it was a cheap lesson for me to learn.

[Jim O'Dell]

Jerome, if you use the bit with the bearing at the end of the bit, not toward the shank, (actually a flush trim bit) and use it in a router table, the bearing will be on top, as is the pattern piece, and easy to see. If you were using the router hand held, I would want the true pattern bit with the bearing on the shank end of the cutter. Both ways makes the cutter further away from you. Jim.