# How do you duplicate a very thin piece?



## Stokestack (Jan 28, 2009)

Hi all.

I'm cutting 1/8" acrylic into a curved triangular shape. I don't have a band saw or scroll saw, so I cut the original piece with a coping saw and then smoothed the curves a bit with sandpaper. It turned out surprisingly good.

I now want to use this as a pattern for identical pieces (same size). The problem is that the material's thinner than the gap between the pilot bearing and the cutting edge of the bit.

As far is I can see, the only way to address this is to cut a slightly smaller but similarly shaped piece out of fiberboard or something and sandwich it between the master and the acrylic that I want to cut. Does that sound right?

Also, I don't have a table, so I'll be doing this hand-held. Feasible?

And finally, if I did have a table, how would I secure all these pieces together? You obviously can't have C-clamps all around the piece and still lay it on a table and maneuver it.

Thanks!

Gavin


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## derek willis (Jan 21, 2009)

Stoke stack,
You must make an identical shape out of mdf, rough cutyour piece and glue to mdf pattern with hot melt glue, you will find small pieces very difficult ro trim freehand, although it is worth a try, but just hold it against a bearing guided cutter on a table and simplicity itself.
A few years ago, my wife marketed, with my work, acrylic shapes for the cake decorating buisness, I must have cut at least a thousand of these this way, I stacked them about 8 or 10 at a time to cut, they were all less than an eigth thick.
Derek.


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## harrysin (Jan 15, 2007)

I basically agree with Derek but differ in as much as I would go with double sided adhesive tape, it's faster and cleaner than hot melt glue and I would NOT attempt to rout small pieces hand held in spite of the fact that most of my routing IS with the plunge router.


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## dovetail_65 (Jan 22, 2008)

I find both way a pain and have used the tape and glue method for years until I got my Grex pin nailer(any 23 gauge should work). 

I have gone to using the 23 gauge pin nails exclusively to hold the piece down. It's quick, stable, easy to remove and the holes are invisible. I have found these little nails do not crack most plastic, but verify with a scrap piece if using plastic.


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## derek willis (Jan 21, 2009)

Use of hot melt glue. in this instance is not messy at all, as the plastic is covered by a film rather like domestic cling film, so does not need to be cleaned from the finished surface.
Derek.


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## Stokestack (Jan 28, 2009)

Thanks for the suggestions, guys. It's clear that I need some MDF and a table.

I may just make a crude table by drilling through some MDF, screwing the router under it, and plopping it down on my WorkMate with the center section out (as someone suggested).


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## AxlMyk (Jun 13, 2006)

You can make a spacer piece. It doesn't need to be exact to the plastic template, as long as the bearing will ride on the template. Use double sided carpet tape. Pin nails won't work since you have a plastic template.
You can turn your router upside down, clamp it securely in a vice, and you have a small router table. Crude, but usable.


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## bobj3 (Jan 17, 2006)

I agree with Mike and Harry 

use double sided carpet tape .make a sandwich template/pattern and you should be just fine..

If you have a router bit made just for plastic and use it with a brass guide in the router table... your part will come out just like you use a laser cutter.

http://woodworkersworld.net/plastic_straight_router_bit_bits.shtml
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AxlMyk said:


> You can make a spacer piece. It doesn't need to be exact to the plastic template, as long as the bearing will ride on the template. Use double sided carpet tape. Pin nails won't work since you have a plastic template.
> You can turn your router upside down, clamp it securely in a vice, and you have a small router table. Crude, but usable.


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## Stokestack (Jan 28, 2009)

Thanks guys. The clamping of the router in a vise is a sensible suggestion that might just work, since my piece is only about 6" x 5".

As far as bits go, which direction is optimal for the spiral ones, if I have the router upside-down? I would guess "up". I do have a 1/8" single-flute straight bit already; do you think that's good enough?


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## bobj3 (Jan 17, 2006)

hi Stokestack

It may give it a shot, by chance do you a Roto-Zip bit..the one that looks a like drill bit...use to cut tile..

if so give that a shot..

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Stokestack said:


> Thanks guys. The clamping of the router in a vise is a sensible suggestion that might just work, since my piece is only about 6" x 5".
> 
> As far as bits go, which direction is optimal for the spiral ones, if I have the router upside-down? I would guess "up". I do have a 1/8" single-flute straight bit already; do you think that's good enough?


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## dovetail_65 (Jan 22, 2008)

AxlMyk I'll post a picture of a 23 gauge pin nail through plastic after the game or tomorrow after noon.


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## template tom (Sep 18, 2004)

Stokestack

I have not been posting though I do call in to see what is going on everyday. It might have been better if you had posted the actual shape of the project you are about to produce, to give others a better chance of submitting a solution. Enclosed is a drawing of what I was assuming to be the problem other than the material in use. This is only going on your description of what you are trying to do or I may have it wrong. The size may not be what you want or the curves may be going the wrong way. So let us make it clear as to what you are trying to do.

Is this the shape and if it is what are the dimensions you require. Once the details have been confirmed I maybe able to offer a solution to the problem. 
Tom


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## Stokestack (Jan 28, 2009)

Thanks a lot, Tom.

I attached the graphic I traced to cut the piece of acrylic. The thin interior lines are just guides that represent the hole in my dashboard. I bought some hardboard (Home Depot "handyboard") that I'm planning to cut into a rough shape slightly smaller than the master piece, and then sandwich it between the master piece and the second piece of acrylic so I can cut the second piece with a flush-trim bit.

Gavin


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## bobj3 (Jan 17, 2006)

Hi Gavin

http://cgi.ebay.com/ebaymotors/_Car....c0.m245&_trkparms=72:543|65:12|39:1|240:1318

http://cgi.ebay.com/ebaymotors/_Car....c0.m245&_trkparms=72:543|65:12|39:1|240:1318

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## Stokestack (Jan 28, 2009)

Ha, thanks Bob. I'm planning something different, though, which calls for a flat piece on which I will build a couple of device mounts and install power jacks. The flat, curved triangle will sit in the recess on the dashboard.

I'll snap a couple of pics when I get the chance.


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## AxlMyk (Jun 13, 2006)

Bob;
How the heck do you find this stuff?


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## bobj3 (Jan 17, 2006)

HI Stokestack

You're Welcome 

You may not need the one on ebay but it would sure make a great template but it's a bit high in price for just a template but like they say if it's worth doing it's worth doing right  and the dashboard is the one thing you look at all the time... 

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Stokestack said:


> Ha, thanks Bob. I'm planning something different, though, which calls for a flat piece on which I will build a couple of device mounts and install power jacks. The flat, curved triangle will sit in the recess on the dashboard.
> 
> I'll snap a couple of pics when I get the chance.


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## harrysin (Jan 15, 2007)

AxlMyk said:


> Bob;
> How the heck do you find this stuff?


Mike, I've asked Bob this very same question on numerous occasions, he puts it down to a good memory plus the knack of knowing just how to search the web to best advantage


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## harrysin (Jan 15, 2007)

I may be missing something here but as I see it, the method would be:

Cut an exact size template from at least 3/8" MDF, chipboard, wood or whatever, rough cut the acrylic slightly over size with jig saw, band saw or whatever is available, stick the acrylic to the template with double sided carpet tape and, using a straight bearing cutter using a fence or starting pin, go around the piece in an anti-clockwise direction.
If you were going to make several of these, I would make a female template by drawing around your pattern, deciding what size cutter and template guide is going to be used which enables the offset to be calculated. If for instance the offset is 3/8", set a compass to 3/8" and, with the point of the compass touching the edge of the template go all the way round so that you have a pencilled line 3/8" distant from the template. All that is necessary now is to cut out the centre with a jig saw, file/sand the surface smooth and you can now make as many identical copies as you wish.
If the latter method appeals but you don't fully understand, let me know and I'll rig up a demo for you.


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## Bogydave (Nov 14, 2008)

Hi Harry
Your way sounds easy & logical.

All but the "anti-clockwise" 
north of equator folks say "counter clock-ways" (CCW)


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## template tom (Sep 18, 2004)

harrysin said:


> I may be missing something here but as I see it, the method would be:
> 
> Cut an exact size template from at least 3/8" MDF, chipboard, wood or whatever, rough cut the acrylic slightly over size with jig saw, band saw or whatever is available, stick the acrylic to the template with double sided carpet tape and, using a straight bearing cutter using a fence or starting pin, go around the piece in an anti-clockwise direction.
> If you were going to make several of these, I would make a female template by drawing around your pattern, deciding what size cutter and template guide is going to be used which enables the offset to be calculated. If for instance the offset is 3/8", set a compass to 3/8" and, with the point of the compass touching the edge of the template go all the way round so that you have a pencilled line 3/8" distant from the template. All that is necessary now is to cut out the centre with a jig saw, file/sand the surface smooth and you can now make as many identical copies as you wish.
> If the latter method appeals but you don't fully understand, let me know and I'll rig up a demo for you.


Harry 
You have forgotten to mention the template guide and cutter that will be used to rout the shape once you have made the template.
Tom


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## harrysin (Jan 15, 2007)

template tom said:


> Harry
> You have forgotten to mention the template guide and cutter that will be used to rout the shape once you have made the template.
> Tom


"deciding what size cutter and template guide is going to be used which enables the offset to be calculated"

The above was intended to indicate that the member could decide what cutters and guides he has, select one of each then calculate the offset.


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## bobj3 (Jan 17, 2006)

HI Dave

I looks just right if you stand on your head  a down under thing  LOL 

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Bogydave said:


> Hi Harry
> Your way sounds easy & logical.
> 
> All but the "anti-clockwise"
> north of equator folks say "counter clock-ways" (CCW)


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## Stokestack (Jan 28, 2009)

So I finally got around to making my acrylic pieces. I took the original, the hardboard, and plastic to be cut and sandwiched them with double-sided tape as discussed. I turned my router upside down and squeezed it in my WorkMate bench, and covered the holes in the fixed base with packing tape to prevent plastic shavings from falling into the motor.

With the flush-trim bit I got perfect results. So easy! It was almost like cutting wax.

I'll definitely make a router-table top for the WorkMate. Damn, that thing is useful. I even used the flip-up end of the table as a fence and clamp, to rout some wells in smallish pieces of wood using only the flat edge of the plunge base.

Thanks for all the advice, everybody.


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