Replies

1. 
   oldusty | Feb 03, 2007 08:38am | #1

   pjw ,

                  I have also used a 50 tooth combo blade with good results .

      Over the years I have made many a coves using this method , but have never tilted the blade . Imo for best results take very small bites at a time , if you have a scraper blade or the equivelant to clean it up .

                            good   luck            dusty

                          

2. 
   DonC | Feb 03, 2007 08:42am | #2

   If you have a molding head, install a bull nose cutter and use this instead of saw blade. This really replicates a shaper cutter. You can do the cove in 2 passes rather than numerous with the saw blade.

   I don't think directin of blade tilt is a factor. It's always going to be cutting at an angle.

1. 
   pzaxtl | Feb 03, 2007 06:47pm | #4

   Tilting the blade will produce an elliptical (asymetrical) cove, while not tilting the blade will produce a circular (symetrical) cove -- they look totally different.

   See the following link for a detailed explanation:

   http://www.taunton.com/finewoodworking/SkillsAndTechniques/SkillsAndTechniquesPDF.aspx?id=2899

1. 
   BarryO | Feb 09, 2007 12:46pm | #14

   Actually, I'm pretty sure they both produce elliptical coves.  Not tilting the blade produces a cove that's an arc of an ellipse whose major axis is parallel to the table top.  Tilting the blade produces a cove that's an arc of an ellipse whose major axis is tilted with respect to the table top. 

3. 
   nikkiwood | Feb 03, 2007 09:33am | #3

   As long as you don't use a thin kerf blade, I don't think the type of blade matters much. I've done it with a rip blade, a 60 t ATB, etc.

   I have even run some with ####7 1/4" circular saw blade, to get a slightly different profile.

   If you do have a molding head cutter for your saw, I would try a few experimental cuts. I have heard of this technique before, but haven't tried it myself.

   If you're tilting the blade, I would run the piece toward the blade.

   If you have already done some trial cuts, you have no doubt figured out that it's important to take a very small cut in each pass.

   BTW, do you know the trick re: using auto body filler to make a sanding block to fit the profile of the cove?

   ********************************************************
   "It is what we learn after we think we know it all, that counts."

   John Wooden 1910-

1. 
   philjohnwilliams | Feb 04, 2007 07:10am | #6

   i spent last evening playing around with this, and with my first cut i learned to take many small bites.

    i like the idea of using a smaller circ saw blade for different profiles, i may try this next time i am in the shop.

   the auto body filler trick is one of my favorites for jobs like this, i have even set a block of wood into the putty to use as a handle when it is cured, works like a charm.

   -pjw

1. 
   Biscardi | Feb 04, 2007 06:39pm | #7

   The first time I tried to cut a non-symetric cove I did not realize you couldn't cut it all in one pass. That was quite unpleasant.

   Frank

1. 
   dougmeyer | Feb 05, 2007 02:54am | #8

   I have used both a regular blade and the molding head. The latter was fast and made for less clean up. Plus I had to get the carbide blade from the first one resharpend after making the cut, something the molding head cutter avoided.

   As a side note on this I used neet trick to clean up these cuts. If you put a piece of waxed paper in the cut (after you have finished) and then make a batch of Derhams Water Putty (a yellow very hard plaster like material) and make the batch very thick you put the putty on the waxed paper and it will set to the exact shape of the cut. IF you put a small block of wood into the putty as it sets up you can use the wood for a handle. Once the putty is set (over night) pull the waxed paper out of the wood and off the putty (it will just peel off) then cut off the round ends of the putty and you have a great sanding block. Worked like a charm.

   I have included a phot of one of the coves I have done this way but alas the others did not make it out of the fire as anything more then ash. So I can not show you the other ones.  Do keep in mind that the smaller size of the modling head will have an effect on the shape of the cove and the angle you need to run the wood over it at.

   Doug Meyer

   
2. 
   nikkiwood | Feb 09, 2007 05:58pm | #15

   Here is another FWW article about cutting coves, this from #102 by Frank Klausz' kid:http://tinyurl.com/2fqjrfFor those who may be confused, a symmetrical cove results when you run the work piece flat against the top of the TS with the blade at 90°.By tilting the blade toward 45°, you get an asymmetrical cove.You can achieve interesting, exagerated shapes, by arranging your jig so one edge of the workpiece is elevated from the table -- say with a guide piece that has been rabbeted. ********************************************************
   "It is what we learn after we think we know it all, that counts."

   John Wooden 1910-

1. 
   DaveCohn | Feb 10, 2007 01:14am | #16

   I have read about this method of making coves and have a question. It seems that this process would put stress on both the blade and arbor and have a tendency to make both try to go out of round as you are putting a side load on both. Any feedback on this thought?

1. 
   JohnWW | Feb 10, 2007 01:35am | #17

   Using a conventional saw blade forces you to take very shallow cuts so the side load on the blade is quite small and would be unlikely to do any damage.  The arbors and bearings on all but the smallest table saws are fairly substantial and can easily handle moderate side loading.

   John White, Shop Manager, Fine Woodworking Magazine

2. 
   nikkiwood | Feb 10, 2007 01:47am | #18

   What John said...........Tiny bites and many passes --------- and I have not seen an adverse effect on the blade.********************************************************
   "It is what we learn after we think we know it all, that counts."

   John Wooden 1910-

4. 
   BruceS | Feb 04, 2007 12:39am | #5

   I have done very few of the coving cuts,  But I set up angled fence so that the blade is "pushing" the stock into the fence and not away from it.  Magnetic feather boards wouldn't hurt either.

   Work Safe,  Count to 10 when your done for the day !!

   Bruce S. 

    

5. 
   coolbreeze | Feb 05, 2007 08:06am | #9

   I have cut them with 80 tooth crosscut blades with reasonable success. Of course, there is some considerable scraper or samdpaper work left to do. I also have a CMT bit that came with the Lonnie Bird molding set. It is really smooth and requires much less surface work. It is a big heavy carbide bit and that big old bit spinning in the table saw is something one can't help to be cautious about.

   I have not tried a rip blade but think there would be a lot more machine marks to clean up.

1. 
   dougmeyer | Feb 05, 2007 04:47pm | #10

   Yes that is alwas something that makes me a little nervous the molding head type bits. They are masive and if you have a replaceable bit version thier is alwas the fear that the thing will come about.

   I had one of these eat a 0 clearance insert made of UHMW plastic that I had used before with this bit/blade Not sure what happen but it grabed it and pulled it in. Scariest thing that ever happend to me.

   But i still think the big round blade works better then the standard saw blades.

    

   Doug Meyer

1. 
   timothale | Feb 06, 2007 04:30am | #11

   I bought  power feeders several years ago.  I use it with a  scrap piece  of plywood clamped to the saw table  slowly feed the blade or molding cutter up thru the ply.   then I use the feeder that clamps to the fence.. make a temporary fence out of a 2 x 4 and 3 /4 ply with gusset braces  align it  and screw it to the ply table.  back the saw down reset the feeder height and start feeding in the pieces, ... raise the blade, readjust the feeeder etc until you get what you want

2. 
   miller | Feb 07, 2007 03:31am | #12

   How do you like Lonnie's molding set. I have been contemplating buying one for a while now.

1. 
   coolbreeze | Feb 07, 2007 06:18am | #13

   I really like the set. I bought it when I made the 18th Century Pennsylvania Secretary  featured in FWW 154-6. I used a piece of 12/4 walnut to make the solid crown. It worked wonderfully. If you have not worked much with bits where your work is done under the bit, you have to be careful. Unlike bits that are under the work, there is little forgiveness for those "overs".

   I mostly now use the cove cutter. It really makes a clean cut. That particular "bit" is available from CMT outside of the kit.

6. 
   Eric | Feb 10, 2007 05:40pm | #19

   All,

   I've done this procedure using a 40 tooth carbide crosscut blade and it became REALLY dull REALLY fast.  I've since purchased the Craftsman molding head with replaceable bullnose blades, but have yet to try them out. 

   My questions relates to the replaceable bullnose bits -- how you you sharpen them?  The question relates to both "how do you sharpen the profile" and "how you you make sure they all end up the same length?".

   Looking forward you your answers.

   Cheers,

   Eric

1. 
   KeithNewton | Feb 10, 2007 06:11pm | #20

   Eric, There is a machinist dye that I put on the face of the tool, that when it is dry, a line can be scratched into it. Then you can freehand grind to the mark, unless you have one of those key-cutter type tools that will duplicate each blank from a pattern.I usually make my pattern from some acetate plastic. There has been some discussion about cutting a smooth arc of a circle. If this is what you are after, the blade should be set to 90º and the stock must be fed from straight across 90º from normal.If you tilt over, this will flatten the top of the arc of an ellipse. If you feed from an angle across the TS table, the ellipse will get taller in the middle, and shorter front to back.I like to do both. I like to tilt the molding head over, and feed across at an angle, so that the cutter is cutting with a shearing cut with the top of the blade, rather than the side of it. Feed from the side that the top of the blade tilts to.