Lock Miter Setup

crovello

I installed my lock miter knife on my shaper tonight so I could make some post wraps. I could not find any scrap from the last time I set it up so I used my usual technic of trial and error. This always drives me nuts. I think it took me a dozen tries to get it close enough for these PVC post wraps. If I had to set it up for some cabinet fabrication I may still be adjusting it. Is there a proper technic to setting these knifes up?

There has to be a better way than making my two passes and looking at it and saying, hmmmm maybe I will move the fence out an 1/8" and lower the head a smidge.

I do have a second smaller shaper and I wonder if I should just leave it setup with this knife but I don't have a power feed on my small shaper.

Dave

TBFGhost

A lock miter bit works using the principle of equalateral triangles. In other words, you want to set the bit up so that the height above table top and distance in front of the fence equal the thickness of the workpiece. The easiest way I know to do this is to make a jig out of some thin stock, 1/4" or thinner. Make a cut out that is the same height as your workpiece thickness and long enough to fit around the maximum diameter of the bit. Then move the bit vertically and the fence horizontally until the jig just touches the carbide. You should be very close at this point. A sample cut or two and you be should be there. Take your time setting up the first time. When everything is perfect run a scrap piece. This will be your set up gauge the next time you run the same thickness.

Splinter

I'm not sure if there's some special mathematical whiz-bang quickie formula... I'd love to hear it if there is.. I do it the same way as you do.. trial and error... annoying and time consuming, but I dont do enough of any one operation to warrant it's own setup. (Well except the dovetail bit in the router)

Edit: Damn Ghost, that was quick... Thanks!

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- Alex

Long Island Remodeling Contractor

jkfox624

Ive seen some set up blocks before but never tried them. Couldnt you just take a bored sat afternoon in the depths of winter and make some pieces the size you need. Run a couple different thicknesses through and get em fit just right then label them for the next time you use that thickness. Just pull out the pattern that fit and adjust the bit and fence to that piece. I have very little experience with these so correct me if my thinking is skewed.

crovello

I think I get what you are saying. As long as the depth of the cut from the table is the same as the depth of the cut from the fence the miter should work? When you run yours, you don't take any material from the leading edge do you? I had it cutting nice last night but it was taking a 1/16" from the leading edge so I had to adjust my outfeed fence.

I will test this out later in the week when I start running all my stock.

I will be sure to save some scraps so the setup will be quicker next time.

In the past when I had only a few pieces to run, I would run the piece on the flat and then reset the fence and run the stock vertical. This would get the job done but surely not the way it was designed to work.

Thanks for you input.

Dave