otis Posted July 23, 2013 Report Share Posted July 23, 2013 I'm looking to get some new bits for my dovetail jig and was thinking of replacing my straight bit with a down cut spiral bit. I'm thinking it would give me a cleaner cut with less chance of tear out. Has anyone tried that? Is there any reason that wouldn't work? Quote Link to comment Share on other sites More sharing options...
Tom King Posted July 23, 2013 Report Share Posted July 23, 2013 I use spiral bits when the cleanness of the cut matters. I'm very partial to Whiteside router bits. Quote Link to comment Share on other sites More sharing options...
wdwerker Posted July 24, 2013 Report Share Posted July 24, 2013 + 1 or the Whiteside spiral bits. Make sure you get the same diameter bit and bearing as the original one that cam with the jig, length shouldn't matter. Quote Link to comment Share on other sites More sharing options...
farmbag72 Posted February 22, 2014 Report Share Posted February 22, 2014 Is down cut the better option for spiral bit use in a dovetail jig? How about 1 of the compression bits? I've had my PC 4216 for a week and just tried my up-cut spiral bit today to cut box joints. The tear out was insane. The box I was working on was supposed to be a gift but now will be an under-workbench storage bin. Its ugly but it will hold stuff. Quote Link to comment Share on other sites More sharing options...
Janello Posted February 22, 2014 Report Share Posted February 22, 2014 I don't think your going to see much of a difference between up or down spiral in your application, if anything I would think down spiral would be worse for chip load. To limit tear out with that jig you can climb cut by taking small bites to the right and in a circular motion pull back out on the left. Small bites are key to having control over the bit and also allows for your bit to clear chips and not load up. As mentioned, better bits that match the diameter of the porter-cable bits may also give better results but I use PC bits all the time with my Omni-Jig and don't have problems. Quote Link to comment Share on other sites More sharing options...
Tpt life Posted February 22, 2014 Report Share Posted February 22, 2014 Some guys clamp hard board to the face that is prone to chipping out. 1 Quote Link to comment Share on other sites More sharing options...
farmbag72 Posted February 23, 2014 Report Share Posted February 23, 2014 I don't think your going to see much of a difference between up or down spiral in your application, if anything I would think down spiral would be worse for chip load. To limit tear out with that jig you can climb cut by taking small bites to the right and in a circular motion pull back out on the left. Small bites are key to having control over the bit and also allows for your bit to clear chips and not load up. As mentioned, better bits that match the diameter of the porter-cable bits may also give better results but I use PC bits all the time with my Omni-Jig and don't have problems. I haven't had much issue with tear out when I cut dovetails with the PC bits. I was shocked at how awful the tearout was when I cut the box joints with the spiral bit. Not sure if it really matters much, but I was cutting in 1/2" Baltic Birch ply. FWIW, on another box I build, using the same material, I had a bit tearout issues when I was using a round over bit to soften the top edges unless I made a climb cut on my router table. Running the edge in the normal feed direction just made the edge tear apart. Quote Link to comment Share on other sites More sharing options...
Tom King Posted February 23, 2014 Report Share Posted February 23, 2014 I bought a used Leigh jig, and the straight bit with it was shot. I had a Whiteside 1/4 inch spiral bit that works fine. I don' t remember if it was up or down, but it cut perfectly. Since I had only one of the Leigh bushings, I used one I already had of regular PC bushings. I ended up leaving both routers set up ready to go on 3/4 stuff. I can pull the jig and routers out of their toolboxes, and cut through dovetails in a few minutes. I also left one of the backer boards in the jig. if you only take one board out at the time under any circumstances, it makes it much easier to set the next board perfectly-that goes for any jig that uses two boards, whether one is a backer, or both are to be cut at the same time. Quote Link to comment Share on other sites More sharing options...
PaulMarcel Posted February 24, 2014 Report Share Posted February 24, 2014 I can't remember, but isn't the inside face of the dovetail joint facing out in the D4R? If so, the backer behind it leaves the show sides crisp. The blowout or chipout on the face facing you will be hidden inside the joint. A backer in front of that would help if you want it perfectly clean. Another option is to push in on the right side of the jig's opening, swing around, then stop short of coming all the way through. Then go back in from the right side (a climb cut). If you don't leave a lot there to cut, the climb cut is easy (but don't do it if you aren't comfortable with it). Quote Link to comment Share on other sites More sharing options...
Slick218 Posted February 27, 2014 Report Share Posted February 27, 2014 Whatever brand you chose, ensure it has a shearing motion- and it cuts upwards, you need that motion to remove waste material. By removing waste material as you cut, the knives will not generate extra heat by cutting through waste, thus keeping them sharp longer, and increasing your quality by minimizing machine burn. That is solid carbide for a production environment ($200+-), however I'm sure there are companies that make a router bit with 3 knives -which would yield an increase in quality for a reasonable price ($50) or something. Quote Link to comment Share on other sites More sharing options...
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