# Tabs neeed?



## honesttjohn (Feb 17, 2015)

I'm cutting 4" circles in 3/8" Baltic Birch ply for LED lights to fit in. 
Can I just cut them out straight thru or should I throw a couple tabs in there and slice them out. Gonna throw the cutout part away.

HJ


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## Stick486 (Jan 4, 2013)

honesttjohn said:


> I'm cutting 4" circles in 3/8" Baltic Birch ply for LED lights to fit in.
> Can I just cut them out straight thru or should I throw a couple tabs in there and slice them out. Gonna throw the cutout part away.
> 
> HJ


don't know what you mean by tabs but wouldn't a 4'' hole saw be easier???...


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## Mike (Nov 22, 2004)

John, you can cut these with a router but a hole saw would be the easiest method. No tabs.


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## subtleaccents (Nov 5, 2011)

Since you are using your CNC to cut the holes and scraping the core you really don't need to use tabs. Generally I will take 1 rough cut leaving the tool down and have the program take a .020 finish cut just to keep the wood as clean and smooth as possible.


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## Crosetti (Mar 21, 2013)

When I have to cut circles (or any piece) on CNC I always put tabs. I've had small pieces that had no tabs move up just enough to get wedged between the router & the workpiece causing the machine to jam. So, yes put tabs ... any piece that can fly out can cause problems & eventually will.


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## Stick486 (Jan 4, 2013)

okay...
where was CNC introduced into the original question???


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## Cherryville Chuck (Sep 28, 2010)

If you were doing it with handheld router and circle cutter you would want to attach the workpiece to a sacrificial substrate and either put the pin on the circle cutter right through or pin the waste down so that it stays put when cut out. I agree with the statement that having that piece free floating in the cutout is a dangerous practice.


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## Stick486 (Jan 4, 2013)

thanks Charles...
now I understand the tabs...


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## honesttjohn (Feb 17, 2015)

Sorry Stick,

Being posted in the CNC Routing thread, I just assumed (I know, I know) that a CNC was automatically implied.

HJ


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## Stick486 (Jan 4, 2013)

For some reason I never seem to notice thread placement...
my bad...


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## Cherryville Chuck (Sep 28, 2010)

I didn't get it either until I read JT and John's posts. They figured it out. I'm also bad about about not looking to see what subforum something is posted in.


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## chessnut2 (Sep 15, 2011)

Charles.....I looked on the Home Depot site and can't find sacrificial substrate. Just kidding. I'm going to be cutting some large circles, and this is an issue I hadn't thought about. Thanks for the warning.


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## RÖENTGEEP (Feb 18, 2014)

Stick486 said:


> For some reason I never seem to notice thread placement...
> my bad...


Same here.


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## MEBCWD (Jan 14, 2012)

Crosetti said:


> When I have to cut circles (or any piece) on CNC I always put tabs. I've had small pieces that had no tabs move up just enough to get wedged between the router & the workpiece causing the machine to jam. So, yes put tabs ... any piece that can fly out can cause problems & eventually will.


I always use tabs for loose parts because they could cause a lot of problems. If they are thrown from the machine they could hit anyone in the shop and if they don't hit a person they will usually hit a project and dent or break something. If you have a lot of cutouts in a toolpath one might get caught when cut loose and force the X or Y axis to jump, then everything cut from that point on will be in the wrong place and the part will have to be re-cut, wasting material and time.


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## Cherryville Chuck (Sep 28, 2010)

chessnut2 said:


> Charles.....I looked on the Home Depot site and can't find sacrificial substrate. Just kidding. I'm going to be cutting some large circles, and this is an issue I hadn't thought about. Thanks for the warning.


Thank Harry Sinclair Jim. Harry is the one that promotes using a sacrificial top on the workbench you rout on (or drill on, or saw on, etc.). When it's too far gone you put another one on. That way you don't mind routing it, drilling holes in it, sawing into it, or any of the other things you don't want happening to your good work bench.


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## cjskelton (Feb 27, 2015)

HJ, you could put a piece of double sided tape under each of the circles. Worked for me. No tabs to cut and sand.


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