Mastering locking miter router bit use

[NorthernSteve]

Armed with my Trend locking mitre router bit, I embarked upon the task of joining four pieces of Iroko to form the sides of a box this afternoon.
I like mitres, but find them a little finnicky to.glueup.
The locking mitre solution looks a good one, but positioning the bit and fence is a very precise task. Bit height, timber thickness and fence position all need fine tuning to get a good result.
With 11mm thick timber, I ended up with the bit set at 9.8mm high and the fence 7.5mm in front of the mid point of the bit (for both the horizontal amd vertical cuts. This yielded a good result, but took an amount of fiddling to achieve.
Has anyone got a reliable, structured method of doing this, maybe based on a data set showing the relationships between the variables? Trend do not appear to publish such data, yet underlying the processs, must exist a set of quantifiable data.
Anyone had success with tbis type of mitre bit? Thrown the towel in? Found a better way?
Cheers

 

[Phil Pascoe]

Experiment on scrap and get a perfect fit, then mark the pieces that are perfect and keep them so that next time you need it use them to set the router.

 

[recipio]

They are incredibly difficult to set up.i used to rout scrap pieces on the long axis of a rectangle and use my fingertips to adjust the cut. Tedious but it works.
I have an American DeWalt tablesaw with a 5/8 arbour so I took the plunge and bought the brilliant miter fold blade sold by Rockler in the US. Cuts a dead accurate locking miter every time. Worth buying a new saw just for that.!

 

[NorthernSteve]

They are incredibly difficult to set up.i used to rout scrap pieces on the long axis of a rectangle and use my fingertips to adjust the cut. Tedious but it works.
I have an American DeWalt tablesaw with a 5/8 arbour so I took the plunge and bought the brilliant miter fold blade sold by Rockler in the US. Cuts a dead accurate locking miter every time. Worth buying a new saw just for that.!

Recipio, I didn't know they even existed - thanks for the Heads up. I have a Laguna Fusion 3 Tablesaw which takes a Dado stack, so may well take this too. Thats me going to do some rsearch.

 

[Spectric]

All you need is a jig, these make the setup really simple.

https://www.infinitytools.co.uk/accessories/lock-mitre-jig/

some extra info

 

[NorthernSteve]

All you need is a jig, these make the setup really simple.

https://www.infinitytools.co.uk/accessories/lock-mitre-jig/

some extra info

Wasnt aware of these either, curious that Trend dont supply /offer one with theirs. I guess the price is based on relieving the frustration factor.. thanks

 

[NorthernSteve]

All you need is a jig, these make the setup really simple.

https://www.infinitytools.co.uk/accessories/lock-mitre-jig/

some extra info

Thanks, I have just spotted that Rutlands also do a jig for £10.

 

[Spectric]

Does it have the magnets ?

 

[NorthernSteve]

Does it have the magnets ?

Appears not to have,.suspect not as useful then. Will have a better look when at pc tomorrow.

 

[Chubber]

My 1/2" jobby got put back in the box, lucky not to have gone out of the window, open or not.

Spectacular lack of success/repeatability!

 

[Spectric]

The Infinity jig sits on the actual cutter using the magnets and you have the setup lines for your wood. The video explains much clearer than I can.

 

[Mike Fletcher]

Has anyone seen this setup jig for a non-mitre lock joint? I prefer the non-mitre as the edges are not as delicate and you can extend the front face to eliminate the need for a face plate on the drawer front.

 

[HamsterJam]

As it happens, I was using my lock mitre bit yesterday.

There is great guide to setting up here…
https://www.ukworkshop.co.uk/threads/lock-mitre-router-bit-setup-guide.124161/

 

[Blackswanwood]

Wealden Tools are my “go to” source of help with router operations …

https://www.wealdentool.com/kb/tech...v6jDTN3AS6SBgnkn8NQw-ZYOYawHmCqV4EHUAU6DUlL7G

 

[Ollie78]

I agree that these are very annoying to set up.
I always get it right with trial and error, carefully keep a couple of offcuts as setup blocks for next time.
Then next time I want to use it find the setup blocks have vapourised so trial and error again...

 

[HOJ]

I have the CMT spindle moulder cutter, I drafted up an aid memoir from my previous setting up experiences, whether this solution works for a router bit I don't know, but I would have thought the principals must be close to being the same:

 

[recipio]

Recipio, I didn't know they even existed - thanks for the Heads up. I have a Laguna Fusion 3 Tablesaw which takes a Dado stack, so may well take this too. Thats me going to do some rsearch.

It will work as long as you have have a 5/8" arbour. I see it has dropped by 100$ since I bought it. Originally developed by Andy Klein to mill a box out of one piece of ply it will crosscut a solid board very cleanly. Of the best tools I've ever bought.

 

[Against_The_Grain]

I was taught how to set these up a very long time ago by a gentleman who hand-ground his own cutters to fit in a Whitehill block in a spindle moulder, quite mad really but unbelievably accurate.

The way to do it was to set the height first which involved feeding a short section of scrap that was the exact thickness of the workpiece intended to be machined for about 4", cut 2" off and meet them together so that they lay flat, not at 90-degrees, if they were not flush with each other you would adjust the height and cut again and retry until they were flush. Once the height was perfect, you would do exactly the same for the fence depth until the pieces were flush, then you could make the two cuts and they should be a perfect joint.

Trying to set it up with the test pieces at 90-degrees is very difficult as you have little idea of what needs adjusting to make it correct and often can make it worse and it takes a lot of trial and error, the above method works brilliantly.

 

[HamsterJam]

I have the CMT spindle moulder cutter, I drafted up an aid memoir from my previous setting up experiences, whether this solution works for a router bit I don't know, but I would have thought the principals must be close to being the same:

Thanks @HOJ, I like that. It should work for a router bit, the critical part being the initial 4.3mm offset which is likely to differ depending on the manufacturer/size of bit.
Next time I get my bit dialled in, I’ll take the relevant measurements and derive the initial offset. In theory I should then be able to set up for any thickness although I suspect there will always be a little tweaking to be done.

 

[NorthernSteve]

I have the CMT spindle moulder cutter, I drafted up an aid memoir from my previous setting up experiences, whether this solution works for a router bit I don't know, but I would have thought the principals must be close to being the same:

Thanks...