First try at router finger cutting - plyboard exploded

[jaffab]

Hi all,

I recently got my hands on a batch of power tools, and decided to try and make some storage boxes for them from plyboard. As one of the powertools was a router, I thought this was the ideal time to make an upside down router jig thing (technical term) as per a youtube video, for cutting finger joints.

The jig device turned out very well - except the results were... disappointing.

I tried it on a test piece of plyboard and the plyboard pretty much exploded around the cut finger joints as per the pictures below - need suggestions to get tidy cuts in the future (note, this was on a test piece of plyboard).

Is it that its on the wrong side of the plyboard (wrong edge/grain)
Is it the wrong router bit (this was a brand new 8mm straight bit that came with the router - still in the original packaging)
Is it too much pressure? Not enough pressure?
Wrong speed on the router?
Wrong wood?
Wrong size fingers?
Do I have to put support wood in front and behind of the main plyboard when cutting?
Etc

Any advice?

 

[MikeG.]

If the ply were tightly squeezed between sacrificial boards in front and behind, you would have a chance..........but fundamentally this is the wrong material for this sort of joint.

Can I seriously suggest that you get used to the router with more orthodox and simple tasks first. It is a dangerous tool.

 

[Trevanion]

Cheap plywood is fairly weak with very few plys (in this case only 3) and isn’t laminated particularly well so it will have a tendency to explode.

Try some better plywood or actual wood.

 

[will1983]

Mike and Trevanion have beaten me to it.

That ply is not the right material, if you really want to achieve the exposed joinery and ply edges look then you need to use good quality cabinet grade Birch plywood and take smaller bites with the router i.e a few passes increasing the bit height gradually to reach the required depth.

Please be careful though, as Mike said the router is one of the most dangerous of power tools, it can make a very messy mess of you very very quickly!

 

[transatlantic]

It doesn't really mater what material you use, it's going to blowout (to some extent) unless you have a backer piece.

It's one of the main reasons the tablesaw is the prefered approach.

 

[Trevanion]

Please be careful though, as Mike said the router is one of the most dangerous of power tools, it can make a very messy mess of you very very quickly!

I suppose he would've completed the task of finger cutting though! :lol:

 

[sunnybob]

https://woodshopbits.com/blogs/resource ... -box-joint

 

[will1983]

Please be careful though, as Mike said the router is one of the most dangerous of power tools, it can make a very messy mess of you very very quickly!

I suppose he would've completed the task of finger cutting though! :lol:

=D> :lol: