# Looking for a jig to make flat curved pieces out of 1/8” plywood



## JohnnyB60 (Jun 15, 2009)

Hi guys, it’s been awhile since I’ve used my router, so I haven’t been on for awhile.

I need help to cut 28 curved pieces of 1/8” thick plywood and I thought I could just use my RotoZip Saw with and extension to the RotoZip Circle Cutter attachment to quickly make them. Well that turned out to be a disaster there is so much play in the Circle Cutter attachment that it takes too much to get a perfect radius.










So now this idea is going in the garbage and I’m thinking of using my RIDGID R2401 - Trim Router with a 1/8 Single Flute Straight Bit and a wide piece of plywood for the Circle Cutter attachment so that it will not rock.

I took the base off the Trim Router with the 4 screws which are too short to attach to a piece of ½” plywood and after looking through my screw assortment I realize that I don’t have one that fits and I don’t even know what size it is. Anyway I need to go to the store to buy a bit and I’ll see if I can pick up the correct screws.

So now I’m wondering if there is a better way to do this. I thought about making a jig to run a router around inside, but it would be gigantic and hard to handle. I don’t want to use a jig saw because it tears up the 1/8" plywood too much.

Any ideas?

Each piece is a 1 ½” wide ¼ circle with 15” inside radius and there is a 7” straight leg extending out from one end of the circle.


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## jlord (Nov 16, 2009)

Hi Johnny.
You can make a quick trammel for your router. Use 1/4" mdf & you can use the same screws to hold your base plate on. Here is some pictures of one I made for a PC router. This jig is set up to use a 1/2" straight bit. You can use a smaller bit if you wish. 

I rip the width to the same size as the router for easy alignment. The base plate can be a used as template to line up mounting of the router. Ripping the mdf to the width of the base allows lining up between the 3 sides of one end to center on trammel. After trammel is ripped to width I like to draw a center line down the middle for measurements. Also draw a cross line at center to drill for bit. I also draw a line on both sides of bit to measure for inside & outside radius before I drill center hole. A 1/2" bit these lines will be 1/4" of each side of center line. 

For a pivot pin I use anything from a finish nail to a 8p double head. Marking the lines ahead of time helps with setup. It's hard to mark for your cuts after you drill center hole. By doing this before you drill for bit you can measure much more accurately as your layout lines are already there to measure off of. The far side of the bit is for inside radius & the near side is for outside radius. You can see how this is marked on my trammel. Using your 1/8" bit your lines off center of the bit will be 1/16" each side of center. I prefer a 1/2" bit but would use at least a 1/4" bit, but don't go to fast or you will snap that 1/8" bit.


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## jlord (Nov 16, 2009)

You can also make one as a template out of 1/4" mdf then double stick tape & flush trim them out. Or use template on top & use a pattern bit.


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## JohnnyB60 (Jun 15, 2009)

Thanks James, that’s kind of what I had in mind. I’m not sure I have any ¼” MDF in stock, but maybe I can recess out ¼” out of some ½”. I need to make two cuts for each piece. one for the outside cut and then the inside. 

I took this silly RotoZip Circle Cuter attachment apart and I can see why it’s so flimsy and I was thinking that if I could find a thick gasket or washer that will fit between the pieces, I just might be able to tighten it up. 

I'm a little worried about the template because I have so many to do, I'm might screw some up.


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## jlord (Nov 16, 2009)

1/4" mdf can be bought in quarter sheets at home depot. It should only be a few dollars. Or even some 1/4" bead board made from mdf. Put bead board side down. MDF is good template material as it machines easy & has no grain to cause bits to wander when drilling.


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## waho6o9 (Apr 4, 2010)

+1 for the template idea. Easy peasy.


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## JohnnyB60 (Jun 15, 2009)

The pattern bit would probably be the best idea because I can do the entire piece in one shot. Right now I have to cut the outside curve, stop to change pivot points for cutting the inside curve then I have use a straight edge to cut the straight sections. I’m going to look into the pattern idea, but I want to have the pattern above the plywood.

The only reason I started with RotoZip tool was the 1/8” cutting bit. The smallest Pattern bit I have is ½” and I don’t want to remove that much material. I wonder what the smallest pattern bit is available. If I can find a 1/8” bit with a ¼” shank, that would be great. I also have a ¼” Flush Trim Bit without a bearing, but I would have to fasten the plywood to the top of my pattern and run bit through except that I don’t like how it heats up and burns the pattern.


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## bobj3 (Jan 17, 2006)

Hi


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## JohnnyB60 (Jun 15, 2009)

bobj3 said:


> Hi
> 
> Your RotoZip will do a fine job, you can make a base plate for it or just use your 1/2" thick stock and put in a pocket for it to sit in, your RotoZip should take on 1/4" router bits, so you can pickup a pattern bit or trim skew bit and it will do the job you want to just fine..
> 
> ...


Now that’s an Idea. I actually looked on line earlier to see if I could buy an extra base so I could super glue it onto something.

You gave me an idea though. I wonder if I take the sheet metal part off and fasten the rest with the round locknut to a piece of Plexiglas.


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## jlord (Nov 16, 2009)

You can get a pattern bit with the bearing on the shank at Home Depot. You would have a larger selection at a Rockler or a place similar. If you intend on using An 1/8" bit you will have to make the template narrower to compensate for the difference in a bearing or template guide. The easiest would be a 1/2" bit & bearing so you can make template exact size. But it does use a little more material.


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## JohnnyB60 (Jun 15, 2009)

I found a 5/16” Pattern/Overhang bit, but I don’t know what that is and I’m looking for a photo. I keep thinking about how nice it would be to cut each piece in one cut, so I’m still thinking about the template. I would have to make two templates because I have two different sizes, but I’m thinking making at least one and giving it a try with the ½” bit. 


It just dawned on me that by using a ½” bit it will take 2 ½” for each 1 ½” piece and since it is curves of the same radius, I can’t use the same cut for two pieces.


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## MEBCWD (Jan 14, 2012)

*Collars*

If you have a set of router collars for your router you can make an template that you can use with a collar and an 1/8" bit. 
Make your template a curved hole in the template material the size you need (1 1/2") plus the measurement from the edge of the collar to the bit x2 plus the thickness of the bit x2.
If you have a 1/2" collar and an 1/8" bit the width of you hole would be:1 1/2 + (3/16 x 2) + (1/8 x 2) = 1 1/2 + 3/8 + 1/4 = 2 1/8" Wide.
You do have to stay against the inside of the template or you will damage the work piece.
You could add a little bit of width to the hole and use that to cut blanks and then use a template the size of the piece with a pattern or flush trim bit for the finish cut. 

Hope this helps!


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## MEBCWD (Jan 14, 2012)

*Add to the ends !!*



MEBCWD said:


> If you have a set of router collars for your router you can make an template that you can use with a collar and an 1/8" bit.
> Make your template a curved hole in the template material the size you need (1 1/2") plus the measurement from the edge of the collar to the bit x2 plus the thickness of the bit x2.
> If you have a 1/2" collar and an 1/8" bit the width of you hole would be:1 1/2 + (3/16 x 2) + (1/8 x 2) = 1 1/2 + 3/8 + 1/4 = 2 1/8" Wide.
> You do have to stay against the inside of the template or you will damage the work piece.
> ...


I forgot to tell you to add the collar to bit measurement and bit diameter to the ends of the hole to make it the right length!


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## allthunbs (Jun 22, 2008)

JohnnyB60 said:


> The pattern bit would probably be the best idea because I can do the entire piece in one shot. Right now I have to cut the outside curve, stop to change pivot points for cutting the inside curve then I have use a straight edge to cut the straight sections. I’m going to look into the pattern idea, but I want to have the pattern above the plywood.
> 
> The only reason I started with RotoZip tool was the 1/8” cutting bit. The smallest Pattern bit I have is ½” and I don’t want to remove that much material. I wonder what the smallest pattern bit is available. If I can find a 1/8” bit with a ¼” shank, that would be great. I also have a ¼” Flush Trim Bit without a bearing, but I would have to fasten the plywood to the top of my pattern and run bit through except that I don’t like how it heats up and burns the pattern.


Johnny:

Don't go too small a pattern bit. A 1/2" bit really honks out material. A 1/4" bit still provides a serviceable amount of material removal but slows down quite a bit. An 1/8" bit takes only a slight "bite" at a time. You could be spending hours trying to finish a single piece with the 1/8" bit.

Next, I'm not in favour of the rotozip nor the trim router. If you can, use a standard router. Much more stable and easier to control for longer periods.

Your project will have holding issues, even when you leave it in the sheet and cut it out later. You might consider using skis to stabilize the router while you're following your template.

Hold your pattern to the workpieces with screws or small nails. Some use double-stick tape but I've never been able to get the [email protected]#$%^%^& stuff off.

If you can make one perfect example, use that as the pattern to make all of your others.


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## NoChatter (Dec 4, 2010)

Why not cut them with a jigsaw and then flush trim them with your template. Error free.


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## JohnnyB60 (Jun 15, 2009)

NoChatter said:


> Why not cut them with a jigsaw and then flush trim them with your template. Error free.


This is another option that I was thinking about. I was going to mention it yesterday, but didn't quite know how to put it in words. They only thing is that I will be handling each piece twice and I may have to do this.

So this morning I found a scrap piece of Particle Board from an old shelf I disassembled and decided I want to give the RotoZip one more try before making a template. I’m embarrassed to admit this but my Ridgid r2401 trim router scares the heck out of me. I’ve only used it about 5 or 6 times and each time I’ve had problems of it jumping and tearing up my piece. I also have Porter Cable 890 router and a couple of Craftsman routers, but they are too big I think.

Anyway after removing the metal ram of the Cutter attachment I have a little less than ¼” between the base and the nut. I was going to recess the Particle Board to fit the RotoZip base and screw on the nut to hold it, but I don’t think the Particle Board cut to 1/8” will be strong enough to hold it. I’m now thinking of inlaying a piece of 1/8 plywood to rest the base on to screw on the nut.


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## jlord (Nov 16, 2009)

JohnnyB60 said:


> I’m embarrassed to admit this but my Ridgid r2401 trim router scares the heck out of me. I’ve only used it about 5 or 6 times and each time I’ve had problems of it jumping and tearing up my piece. I also have Porter Cable 890 router and a couple of Craftsman routers, but they are too big I think.


On your Ridgid were you going in the right direction? With your Ridgid on top of your material you should be going from left to right & using a bit with a bearing. The bearing needs to ride on the edge of the material. Just asking because you never know.


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## JohnnyB60 (Jun 15, 2009)

jlord said:


> On your Ridgid were you going in the right direction? With your Ridgid on top of your material you should be going from left to right & using a bit with a bearing. The bearing needs to ride on the edge of the material. Just asking because you never know.


Yes, but when it jumped I got confused and tried going the other way only for it to be worst. I’m not sure what’s going on but it’s a brand new router and bit. I’ve never had this problem on my big routers and I think that it might be the small base. I’m not sure if maybe I may be tilting it. 

I haven’t actually been using it as a trim router with the bearings. The few times I used it was when I needed something small to fit into a tight space like inside a cabinet to recess a hinge and another time I tried to use it for a quick dado cut just because it was handy at the time.


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## jlord (Nov 16, 2009)

When you got confused & went the other way (right to left) you were going in the direction of a climb cut. Because of bit rotation it wants to come away from work & ride on top of it & want to take off. In general you should be going the other way, but there are times when a climb cut is beneficial. But they should be light cuts. I do this when mortising for hinges just to break the edge, or grain direction might be a factor, & half-blind dovetails just to break the edge before machining for the tails & pins. Trim routers are the same as your other router just in smaller scale.


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## JohnnyB60 (Jun 15, 2009)

Well I made another Circle Cutter Attachment using particle board. I decide to use a spline in the edge because I didn’t think it would hold up as thin at it ended up. I under estimated the hole size for the nut. Also, there was some scrap pieces of ¾” wood laying on my table saw that was just the right size so I glued them on to the sides just for extra support. 

The base is now pretty firm and I don’t think I’ll have any problems with the RotorZip moving.


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## JohnnyB60 (Jun 15, 2009)

CORRECTION! I spoke too soon. I should have put the RotoZip in the base before posting. The base is firmly attached to the particle board, but the RotoZip is not firmly attached to the base. The base has a weak spot in the height adjustment. 

So now I’m getting tired of fooling with this, so now I’m either going make a completely new base out of steel pipe and weld it to a flat metel base 

-- OR -- 

I’m going to buy another sheet of plywood, cut out oversized pieces and then cut a stack of them with my Band Saw. 

The funny thing is that I own 5 routers besides the RotoZip and I’m always ending up using another method to get the job done. My oldest router is maybe 30 years old and it has probably only 6 - 12 hours on it. My two newest router are about 1 yr old and I might only have an hour on them.


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## bobj3 (Jan 17, 2006)

HI John

Don't give up ,like they no pain no gain. 




===



JohnnyB60 said:


> CORRECTION! I spoke too soon. I should have put the RotoZip in the base before posting. The base is firmly attached to the particle board, but the RotoZip is not firmly attached to the base. The base has a weak spot in the height adjustment.
> 
> So now I’m getting tired of fooling with this, so now I’m either going make a completely new base out of steel pipe and weld it to a flat metel base
> 
> ...


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## jlord (Nov 16, 2009)

After this at least you will know what doesn't work.


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## JohnnyB60 (Jun 15, 2009)

bobj3 said:


> HI John
> 
> Don't give up ,like they no pain no gain.
> 
> ...


Wow, that’s interesting. What are you using for a spacer, is that wood? I have a variety of hole saws, but I’m going to have to check the large size. I know I have a 3.5” and a 4” hole saw among all the smaller sizes.

The Rigid was real close but no cigar, My Porter Cable is probably my best choice.


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## bobj3 (Jan 17, 2006)

Hi John

I used 3/4" thick MDF, 
===



JohnnyB60 said:


> Wow, that’s interesting. What are you using for a spacer, is that wood? I have a variety of hole saws, but I’m going to have to check the large size. I know I have a 3.5” and a 4” hole saw among all the smaller sizes.
> 
> The Rigid was real close but no cigar, My Porter Cable is probably my best choice.


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## JohnnyB60 (Jun 15, 2009)

bobj3 said:


> Hi John
> 
> I used 3/4" thick MDF, no wood grain to split out so to speak.
> 
> ===


I just measured the Porter Cable base and its 3 ½” so I have a hole saw for the OD, but I might have to get creative with the inside hole. The RotoZip mounting surface is only ¾” high and the rest of the case is not perfectly round or even. I wonder if I even need to worry about having it centered since I will be fastening the base and just use shims on one side of the router base. 

It too bad that the Rigid Trim router didn’t have a 1/8” collet and then I wouldn’t have to do this at all


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## JohnnyB60 (Jun 15, 2009)

bobj3 said:


> Hi John
> 
> I used 3/4" thick MDF, no wood grain to split out so to speak.
> 
> ===


Ok I just realized how you did that with the 3/4” MDF and I think I could do that but use different size holes above the initial mounting surface to fit the RotoZip Case


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## bobj3 (Jan 17, 2006)

HI John

You should have got a Adapter for 1/8" bits (1/4" OD ) 




JohnnyB60 said:


> I just measured the Porter Cable base and its 3 ½” so I have a hole saw for the OD, but I might have to get creative with the inside hole. The RotoZip mounting surface is only ¾” high and the rest of the case is not perfectly round or even. I wonder if I even need to worry about having it centered since I will be fastening the base and just use shims on one side of the router base.
> 
> It too bad that the Rigid Trim router didn’t have a 1/8” collet and then I wouldn’t have to do this at all


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## jlord (Nov 16, 2009)

You can get accessories for the roto zip at a local home depot & not wait for something to be shipped.


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## JohnnyB60 (Jun 15, 2009)

bobj3 said:


> HI John
> 
> You should have got a Adapter for 1/8" bits (1/4" OD ) with your Rotozip you may want to check inside the box for a plastic bag if not you can get one from below or Amazon
> 
> ...


Oh I have everything for the RotoZip. 

I was talking about the Rigid Trim Router, I Google searched the internet for an 1/8" adapter for the Trim Router and can't find one


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## bobj3 (Jan 17, 2006)

Hi John




JohnnyB60 said:


> Oh I have everything for the RotoZip.
> 
> I was talking about the Rigid Trim Router, I Google searched the internet for an 1/8" adapter for the Trim Router and can't find one


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## JohnnyB60 (Jun 15, 2009)

I just saw the 1/4” OD to 1/8”ID Steel Adaptor Bushings at MLCS. I never heard of those before. Umm I think that will work. I wonder if I can get that at the Homedepot. If I can use my 1/8” RotoZip Cutter in the Rigid Trim router I be back in business because I can easily mount it to my jig now.


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## bobj3 (Jan 17, 2006)

HI John


===



JohnnyB60 said:


> I just saw the 1/4” OD to 1/8”ID Steel Adaptor Bushings at MLCS. I never heard of those before. Umm I think that will work. I wonder if I can get that at the Homedepot. If I can use my 1/8” RotoZip Cutter in the Rigid Trim router I be back in business because I can easily mount it to my jig now.


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## jlord (Nov 16, 2009)

Bob 
The home depot near me has quite a bit of accessories for the dremel & roto zip.


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## JohnnyB60 (Jun 15, 2009)

bobj3 said:


> HI John
> 
> HD I don't think so, they are not to big in parts for routers but you may find one at Rockler/WoodCraft long shot..
> 
> ...


I’m way out in the desert and I don’t have much to pick from in the way of Tool Stores. Besides HomeDepot, We have a Kmart that sells craftsman tools, but I’ve never been able to find anything there. They even shut down the Ace hardware, so I’m going to have to order it on line. 

I really was hoping to finish this project this weekend and the only way to accomplish this is to make the router base adapter or go with the band saw idea.


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## bobj3 (Jan 17, 2006)

HI James






===



jlord said:


> Bob
> The home depot near me has quite a bit of accessories for the dremel & roto zip.


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## jlord (Nov 16, 2009)

Johnny
Does your home depot carry accessories for the roto zip? You could just check before you order. Online source would not ship till monday at the earliest anyway.


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## JohnnyB60 (Jun 15, 2009)

jlord said:


> Johnny
> Does your home depot carry accessories for the roto zip? You could just check before you order. Online source would not ship till monday at the earliest anyway.


Yes they do and Monday is a holiday so I don’t think anything will be shipped then.

Well I’m going to take a drive over to the HomeDepot just to see what they have and I’m going to pick up another sheet of plywood just in case I decide to go with the band saw method.


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## jlord (Nov 16, 2009)

Can't hurt to check.


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## JohnnyB60 (Jun 15, 2009)

I went to HD and they didn’t have much of anything, but I did order the 1/8-1/4 adapter and some extra bits. So I completely wasted a couple of days trying to cut my plywood pieces with the silly RotoZip. The tool has its uses, but the circle cutting attachment has a lot say about it. Someday I’ll make a new circle cutter attachment out of steel with a solid mount instead of the stamped sheet metal they used. 

Anyway I’m scraping that whole router idea and cutting up the plywood in 16.5” wide pieces, so this way I can stack them on top of each other and use the band saw to cut 5 at a time. Well I tried, but the Bandsaw seems like the best way to go. maybe some day I get to make something with a router


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## jlord (Nov 16, 2009)

JohnnyB60 said:


> I went to HD and they didn’t have much of anything, but I did order the 1/8-1/4 adapter and some extra bits. So I completely wasted a couple of days trying to cut my plywood pieces with the silly RotoZip. The tool has its uses, but the circle cutting attachment has a lot say about it. Someday I’ll make a new circle cutter attachment out of steel with a solid mount instead of the stamped sheet metal they used.


Well it was worth a look. I know not all home depots carry the same inventory. I have 3 close to me & I can find different things in stock at one or the other that the others don't carry on a regular basis. Two of them have a rental center & one of them does not. The one I use the most has a big selection of dremel & roto zip accessories.


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