Incra - dovetails don't fit

I have an Incra Pro - I know, it's old but at least I have it, lol. I am learning the dovetail cuts but can't get past the test cuts. When I cut two test boards and turn them around to fit them together (to check depth of cut) I can't get them together - the fit is so tight I have to bang the heck out of em to get them together. I've tried both lowering and raising the bit but still the same problem. Anyone have any suggestions??
Thanks
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If cutting Blind DT's I have never used that jig but with the "regular" style DT jig the proper fit is controlled by the depth of cut. Every bit has its own unique sweet spot and once found that depth should always be used for that bit. Remember to make slight adjustments and NEVER try to recut DT's. If the joint is too tight, start with 2 new scraps and cut shallower in both pieces. If the fit is too loose, start with 2 new scraps and cut deeper. DO NOT mix pieces that have been cut at different depths.
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GVJeeper,
I cut some half-blind dovetails a couple of weeks ago and as I was testing the fit on scraps they were loose (so I needed to lower my bit more). I was making minor adjustments a bit at a time, but it wasn't looking like it was making a difference. I was running short on the scrap in the thickness I had already milled so I went for it and lowered the bit quite a bit (almost 1/4" I believe, can't remember now, I only remember thinking that it was quite a bit) and sure enough that's what I needed -- I had started way too shallow and I couldn't tell that I was improving the fit but too slight to notice.
Just a suggestion.
Good luck, Mike
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I guess I just didn't keep tweeking it enough. Thanks for the help - I'll give it another try tomorrow.
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One of the solutions I came up with to solve this problem for future use...
Once you find that "sweet spot" on a particular dovetail bit / dovetail jig combination, take a scrap piece of hardwood about 2" x 12" and run it through a surface planer until the thickness precisely matches how far the bit protrudes from the base of the router. I then drilled a hole to hang it, put a coat of finish on it, and labeled it with a marker so I wouldn't throw it out some day when I had a brain fart.
Now, when I set up to cut a dovetail, I get the router, the bit, and my homemade depth gauge. After putting the bit in the router, I use the gauge to set the depth for the bit and it always gets me VERY close to the exact depth of cut. If it isn't right the first try, I usually nail it after the first adjustment.
just my .02 on what works for me.
Joe aka 10x
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I do the same thing but use any small board. I simply put it on edge and run it into a spinning bit until the wide part of the dovetail bit makes an imprint - the exact height is guaranteed. It hasn't let me down yet.
Don
wrote:

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wrote:

Keep a can of international orange paint around for these things. Label with all the information you think you won't ever need next time, because, odds-on, you will.
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Alternatively, route a hard wood board with the bit profile in it at the correct depth.
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Or,...buy/setup a router in the table such that you can precisely set it to any given height. Consider, once the Incra is zero'ed, you can always return the fence to any given distance. If you're going for the Incra's advantage, why not go for the same with the router? My box of dovetail bits has a height by each bit. I zero the router, then just dial in the height.
Alternatively, I'd use a height guide (as in the board he mentions below) and raise the bit until a flat piece of wood swept across the top just scrapes the bit without catching. I suggest this is more precise than trying to visually match a profile. GerryG
wrote:

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Actually when the bit is clocked so that the bit is at its widest when you slide it into the profile, if it is not the right height, either too high or too shallow it simply will not go into the profile. This is not a new method, it is practiced for set up for raised panel bits to match stile bit cuts and for matching rail and stile cuts to each other. Not having to zero to start with saves a bit of time. With that said, I use a Bosch 1716 evs for cutting DT,s because it is simple to adjust in very small increments but I have never entertained the idea of zeroing the bit first.
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I was thinking of getting a mid-sized router for dovetails, and have narrowed it down to the Bosch or Milwaukee. How do you find the Bosch for backlash?
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Not enough to be concerned about. You turn the knob it moves. That said however then the lock lever is released, the motor can move a slight bit. If you adjust the lock lever tighter a bit the base does not open as much and the motor tends to not wiggle much when releasing the lock knob. Do no over tighten as this may increase backlash. Typically though increments of 1/256" is not a problem at all.
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That's good to know. Thanks.
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10x wrote: [snip]

dovetail
run
Don't forget that the router depth being "reusable" is dependent on the stock being the same thickness as well (e.g. if you thicknessed it to .780 when you set it up the first time, going to .750 will result in a different setup requirement).
I guess that's why most people go to .750 all the time, but sometimes I'm too lazy and can't be bothered to run it through my planer any more (once it's flat and close enough). I just make sure that all the stock is the same thickness and then do the router setup. Probably a pain, but I suppose I save on the life of my equipment that way???
Mike
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Huh? Maybe the Incra is different but for the typical DT jig for blind DT's The stock thickness matters NOT as long as it is thick enough to accept the cut. Thicker pieces of wood do not matter. The particular DT router bit is always used at the same depth regardless of material thickness.. I often mix 3/4" drawer fronts with 1/2" thick sides and NEVER change the bit depth setting.
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