Incra Loose Box Joints

[warmtone]

After finally receiving the LS17 Wonder Fence which was held up over Christmas, I finally cut made my first Incra Box on the week-end.

To keep thing simple I selected a box joint ..... I wanted to make a couple of draws for the workshop and thought this would be good practice.

The incra LS Positioner has superb accuracy and worked very smoothly in conjunction with the template I selected for my stock which was accurately dimensioned. However, I was surprised to find the box joints I have cut have a very loose fit.:(

I am using the US Whiteside 1/2" Router BIT set (in this case I was using the 1/4" straight bit) The set is specially made for the Incra.

The rig consists of a Triton Router/Proessional Woodworkers Supplies Incra Tabletop on top of the Incra Stand. A Unilift system is used for height adjustment. The system is rock solid and the positioner is ultra precise.

I spent 1/2 a day tuning everything to ensure the fence is properly set up @ 90 degrees to the Router plate/Table surface.

I have watched the video and also read the projects book........ according to Incra a loose fit is due to the router bit being slightly oversize.

I measured the bit and found it to be virtually spot on @ 1/4" - however the routed slots measure 6.54mm - a whisker wider than expected and explain the loose fit.

By loose, I mean the joint falls apart and has no inherent strength!:(

I suspect the following 1) slight eccentricity in the bit or 2) perhaps Router collet run out.

Any thoughts from more experienced/capable Incra users?

Meanwhile I am going to drill a test hole on my drill press using the above Router bit and measure the dia....... I will also measure the run out on the Triton with a dial gauge.:!

I will post some pictures of the above box and Incra system over the next couple of days with a mini review of the whole purchasing/assembly experience.

Despite this teething problem I can say that the Incra LS17 (Super System) is an awesome piece of engineering with huge potential:2tsup:

[powderpost]

I use a shop made finger jointing jig, so I can't blame anyone else for inacuracies. I use Cabra-tec router bits and what I have found however, is that there is a small variation in sizes. After considerable experimenting, I found that the bit that suits softer woods is too firm for harder woods. Now I have a dedicated "softwood" bit, that is the larger of the two and a "hardwood" bit, which is a gnats whisker smaller, for hardwoods. I have also found the twisted router bits cause less "breakout".
Hope this is of some help...
Jim

[martink]

A

I am using the US Whiteside 1/2" Router BIT set (in this case I was using the 1/4" straight bit) The set is specially made for the Incra.



I had that problem, with a 3/8" bit, though it was me. Tried another bit - this time a different brand and it all worked fine. Maybe try a different bit, perhaps a different joint size, using a different size bit you already have first rather than buying a second bit the same size.

Ciao,

M.

[Mike Wingate]

In hardwood and ply, my MLCS 3/8" bit was too tight. My Trend bits cut fine. You have to mix and match.