# Jig I made caused some issues



## scaff (Mar 15, 2010)

Hi Guy's,

Well it's been a few years since I posted here ( must be in trouble )

I made a sorta jig to cut ply on top of a small wall I built, started ok with Jig saw and the outside cut was reasonable ( could have been tidied with a sander )

But when it came to the inside the Jig didn't work as there were slabs in the way so I decided to guide off the side I just cut and it went horribly wrong, at one point it cut in directly with the wall ( was suppose to have an inch over hang ether side )

So I've replaced the wood and looking for advice before I start again !

I can't see why my router with a similar jig won't work again on the outside and give a better cut.......but the inside ????


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## Semipro (Mar 22, 2013)

Can you show a picture of what you are trying to do?


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## bryansong (Mar 4, 2015)

Are you using a router bit with a roller bearing on it or are you using a collar ring on your router to follow the profile of your jig?

A better idea of what you're trying to explain might help.


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## MT Stringer (Aug 15, 2012)

Yes, pics and/or drawings, please.

We can help you figure it out or spend your money! >


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## jw2170 (Jan 24, 2008)

Semipro said:


> Can you show a picture of what you are trying to do?


And the jig you are using.....

This may help us to help you....


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## woodknots (Mar 7, 2012)

scaff said:


> Hi Guy's,
> 
> Well it's been a few years since I posted here ( must be in trouble )
> 
> ...


Just a guess, but were you feeding in the correct direction? Sound like the feed pulled the cutter into the work.


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## scaff (Mar 15, 2010)

Sorry guy's the pics didn't upload 

I was using a jigsaw first time round


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## scaff (Mar 15, 2010)

let's try again


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## jw2170 (Jan 24, 2008)

The wall seems to be made up of opening and closing radii.

Hard to make just one jig for that.

Can you use a long radius circle jig?


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## DaninVan (Jan 1, 2012)

Scaff; a wee bit off topic, but why are you using plywood on top of a concrete wall, outdoors?
Bad idea, just saying. I
I'm paying the penalty as we speak for a similar but even less obvious bad decision in materials.
Instead of using torch on membrane with a concrete or mortar coping over it, on top of a stuccoed walled enclosure, I ran the stucco over the top. Moisture got into the stucco through the relatively absorbent top, migrated down into the sidewalls and froze a couple of times over the Winter, the acrylic paint separated from the textured stucco and now I have to strip it off.
So now I'm doing what I should have done in the first place. :crying:


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## scaff (Mar 15, 2010)

I know it's a bad idea but it's not my idea !

Was supposed to be marine ply at least but I didn't source the wood


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## mgmine (Jan 16, 2012)

It's hard to see what kind of a jig you are using or how you are using it. What you should be using is a flush trim bit and a thin 1/4" template. Here is a link 
MLCS Flush Trim and Shear Angle Flush Trim Router Bits


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## mbar57 (Apr 20, 2015)

I'm still not sure what's going on here, but would something like this http://www.amazon.com/WoodRiver-Cur...r=8-1-fkmr1&keywords=flexible+router+template work, if you wrapped it around the stone and then used the flush trim bit?


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## scaff (Mar 15, 2010)

Well mbar57 that link looks perfect, we need to leave about an inch overhang either side, the jig I made runs underneath and scrapes along the wall to follow the curve and the saw was set to allow for the overhang. When it came to the inside some of the slabs were too close to pass so I just used the saw guide in the normal way it just didn't work.
The idea was to finish of with a belt sander !


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## DaninVan (Jan 1, 2012)

How about just using a pencil with a 1" spacer to scribe the profile on the undersides, then jigsaw it to shape...off the wall and inverted of course.


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## Herb Stoops (Aug 28, 2012)

You definitely need a 1" spacer against the cement on both sides for the router bit to guide on if you are routing both sides. A guide on the router that guides off the opposite side will not work because there is nothing to keep the router from cutting back to the cement wall . The idea of scribing a cut line with a 1" spacer is good too as then a router operation would not be needed.

As far as the plywood material being used on top of the wall, Dan is correct if you are in a climate that gets below freezing for very long, presuming stucco is being used to cap the wall. My guess is that some other material is being used for a cap.

Herb


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## DaninVan (Jan 1, 2012)

Herb; plywood's still a risky choice, especially if something like stone or tile is going over it. A far better product would be something like 1/2" cement board. Routing _that_, however, might be an issue...


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## Herb Stoops (Aug 28, 2012)

DaninVan said:


> Herb; plywood's still a risky choice, especially if something like stone or tile is going over it. A far better product would be something like 1/2" cement board. Routing _that_, however, might be an issue...


You are correct,Dan, I was of the mind that it might be a wood cap and the plywood backer was to screw or fasten the wood cap down. But there are alternative ways to do that too, concrete anchors work well for that. The plywood is clearly to give support to the 1" overhang for what ever is going on top.

Herb


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## DaninVan (Jan 1, 2012)

If anyone is faced with a similar project (underlay for a topping of some sort, consider laying sheets of heavy wt. hot galvanized expanded metal lath on your 'wall' or whatever, you can see right through it. Layout your curves and either cut it with metal snips or a grinder with a thin metal cutting disc. Then make up a batch of modified thinset...thick consistency...and trowel that out over the lath.it'll bond to the concrete below and be in effect a reinforced concrete matrix by the next day. 

It'll take the shape in any plane of whatever you want to cover; perfect base for stone or tile facing


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## Herb Stoops (Aug 28, 2012)

DaninVan said:


> If anyone is faced with a similar project (underlay for a topping of some sort, consider laying sheets of heavy wt. hot galvanized expanded metal lath on your 'wall' or whatever, you can see right through it. Layout your curves and either cut it with metal snips or a grinder with a thin metal cutting disc. Then make up a batch of modified thinset...thick consistency...and trowel that out over the lath.it'll bond to the concrete below and be in effect a reinforced concrete matrix by the next day.
> 
> It'll take the shape in any plane of whatever you want to cover; perfect base for stone or tile facing


You must have been a Lather in an earlier life. :laugh2:

Herb


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## DaninVan (Jan 1, 2012)

Yup; I'm a lath a minute... 

I lied; I just love using the stuff! Best invention since peanut butter.


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## Herb Stoops (Aug 28, 2012)

DaninVan said:


> Yup; I'm a lath a minute...
> 
> I lied; I just love using the stuff! Best invention since peanut butter.


You have to wear gloves,that stuff is like razor blades and eats long sleeve shirts as fast as you can feed them.:laugh2:
Herb:


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## jw2170 (Jan 24, 2008)

mbar57 said:


> I'm still not sure what's going on here, but would something like this http://www.amazon.com/WoodRiver-Cur...r=8-1-fkmr1&keywords=flexible+router+template work, if you wrapped it around the stone and then used the flush trim bit?


Good find, Mike.

I forgot about that template.

CMT Flexible Template for Curved & Arched Routing : CARBA-TEC


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