Wood tearout

[Gadjet]

Hi,
I'm putting together a jig for cutting finger joints and I've just tried my first test and it was a pile of crap.
Now I'm wondering if it's a problem with the plywood I'm using or maybe the router bit (it's not an expensive one).
I'm getting cracking noises as I cut through and the layers are breaking out from the plywood.

The actual fingers look they are all in the right place just not all there.

I'm currently using a Ryobi palm router attached to a piece of 18mm MDF until I get my Makita installed into the router lift.

Any help or suggestions appreciated.

Thanks

 

[Alli]

You might like to research spiral router cutters. My understanding that they shear cut the wood a bit like a skew plane. I could well be wrong but it might be worth looking further into them

 

[baldkev]

Try putting a blank across the breakout face ( i.e a sacrificial piece to stop the fibres being blown out of the workpiece )

 

[recipio]

The problem is the plywood. It will always break out unless supported by a sacrificial piece. Poor quality ply will often disintegrate and even Baltic ply is tricky to machine. Otherwise , as in the above posts , a spiral bit is pretty much essential.

 

[Gadjet]

I've looked for a 1/4 inch 10mm spiral bit and they don't appear to exist?
I can only find 1/2 inch ones and I can't use them in the router I have.

 

[pgrbff]

There are plenty of 1/4" spirals available but not neccessarily 10mm wide. You will have to take more than one pass.
https://www.wealdentool.com/acatalog/Online_Catalogue_Down_Cut_2_Flute_228.html

 

[Stevekane]

And just for info I bought a HSS spiral cutter from ebay and used it gently on softwood and its still as good as new after lots of deep cuts, not sure if the glue on ply might cause it issues but might be worth a try, Carbide ones cans be very expensive.
Steve

 

[recipio]

I've looked for a 1/4 inch 10mm spiral bit and they don't appear to exist?
I can only find 1/2 inch ones and I can't use them in the router I have.

Spiral bits are solid carbide and cannot be wider than the shank size. I'm afraid if you want 10 mm it will have to be a 1/2" shank. However 8 mm spiral bits are available if your router takes them. They are stiffer than 1/4" and feel more solid in use.

 

[Gadjet]

Spiral bits are solid carbide and cannot be wider than the shank size. I'm afraid if you want 10 mm it will have to be a 1/2" shank. However 8 mm spiral bits are available if your router takes them. They are stiffer than 1/4" and feel more solid in use.

Makes sense I suppose, I've just had a Google and it does look like you can get an 8mm collet for the rt0700cx4

 

[thetyreman]

router bit quality does make a difference, if you get the cheapest one available don't expect it to be great, wealden bits are very good

 

[recipio]

Makes sense I suppose, I've just had a Google and it does look like you can get an 8mm collet for the rt0700cx4

Hogging out finger joints calls for a lot of power. A trimming router like the Ryobi will struggle a bit and you don't really want to have to make multiple passes. I use the Incra finger joint jig and find it excellent. You can adjust the tightness of the fit to avoid hairline gaps. I'd imagine home made jigs need to be very well made for that reason.

 

[Gadjet]

router bit quality does make a difference, if you get the cheapest one available don't expect it to be great, wealden bits are very good

I have ordered a Trend one that will be a lot better that the one I tried, hopefully.

 

[Gadjet]

Hogging out finger joints calls for a lot of power. A trimming router like the Ryobi will struggle a bit and you don't really want to have to make multiple passes. I use the Incra finger joint jig and find it excellent. You can adjust the tightness of the fit to avoid hairline gaps. I'd imagine home made jigs need to be very well made for that reason.

I was thinking along similar lines (and it's probably not as stable as it should be), I have the Makita rt0700CX4 and a router lift, I think I'll get that set up first and try again with a better quality bit.

 

[recipio]

Have a look at the' Superjig ' by Ola c , a Swedish maker posted here last February. Admittedly designed for a table saw he manages to get superb results.

 

[Gadjet]

Have a look at the' Superjig ' by Ola c , a Swedish maker posted here last February. Admittedly designed for a table saw he manages to get superb results.

I will do, I looked at the rockler jig but thought I could make one out of the off cuts off wood I already have.

 

[ola c]

Spiral bits are solid carbide and cannot be wider than the shank size. I'm afraid if you want 10 mm it will have to be a 1/2" shank. However 8 mm spiral bits are available if your router takes them. They are stiffer than 1/4" and feel more solid in use.

In the old days when I routed my boxjoints I used a 3/8" spiral hss bit, think it was an option for the Leigh dovetail jig. So they are not all super expensive solid carbide.

Here's a link to the one I used, available in 8mm also. Leigh HSS Spiral Upcut Router Cutters

Have a look at the' Superjig ' by Ola c , a Swedish maker posted here last February. Admittedly designed for a table saw he manages to get superb results.

In general I think table saw is superior to router for cutting boxjoints. Much easier to tame tear out using support piece only behind the workpiece. With router you could get tearout also on the entry side and then it starts getting problematic. Large boxjoints are also a quite heavy cut even for a bigger router.

My jig is a beast for overall tablesaw joinery including boxjoints, but maybe not something you put together in an afternoon to just make 10mm boxjoints.

It's here on the first page since I last week released new videos (and deleted the old ones) due to that the jig can do so much more than when first presented last year.

 

[pgrbff]

In the old days when I routed my boxjoints I used a 3/8" spiral hss bit, think it was an option for the Leigh dovetail jig. So they are not all super expensive solid carbide.

Here's a link to the one I used, available in 8mm also. Leigh HSS Spiral Upcut Router Cutters


In general I think table saw is superior to router for cutting boxjoints. Much easier to tame tear out using support piece only behind the workpiece. With router you could get tearout also on the entry side and then it starts getting problematic. Large boxjoints are also a quite heavy cut even for a bigger router.

My jig is a beast for overall tablesaw joinery including boxjoints, but maybe not something you put together in an afternoon to just make 10mm boxjoints.

It's here on the first page since I last week released new videos (and deleted the old ones) due to that the jig can do so much more than when first presented last year.

What blade do you use with your jig? I find it quite difficult to find a blade that gives clean square cuts when cutting box joints on the tablesaw.

 

[ola c]

What blade do you use with your jig? I find it quite difficult to find a blade that gives clean square cuts when cutting box joints on the tablesaw.

I use two blades at the moment, one 250mm Hammer (same brand as makes machines) 3.2mm rip cut with flat tops, and one 200mm 4mm wide rip blade of a swedish brand, also that flat top grind. Both gives excellent baselines without any visible steps at all. The 200mm thicker one is very stable (and expensive, >100£), I made all the videos with the 250 3.2mm though to show that no special blade is required.

It may help that my workpiece is clamped in place and not moved as opposed to a "referencing the latest finger" jig where you manually move the workpice between each cut.

 

[pgrbff]

I use two blades at the moment, one 250mm Hammer (same brand as makes machines) 3.2mm rip cut with flat tops, and one 200mm 4mm wide rip blade of a swedish brand, also that flat top grind. Both gives excellent baselines without any visible steps at all. The 200mm thicker one is very stable (and expensive, >100£), I made all the videos with the 250 3.2mm though to show that no special blade is required.

It may help that my workpiece is clamped in place and not moved as opposed to a "referencing the latest finger" jig where you manually move the workpice between each cut.

Do you mind giving me a reference for the Swedish one? I spend over 100 euro on CMT professional blades anyway.

 

[ola c]

Do you mind giving me a reference for the Swedish one? I spend over 100 euro on CMT professional blades anyway.

It's this one here (picture), comes in different diameters and widths.

Brand is swedex and their blades are sold through different channels though not easily accesable for non company customers. Link below is to one of the stores selling these blades.
https://www.toolmarket.se/produkt/20aa26-200-notsagklinga/