# 1/4inch wide round-bottom kerf table saw blade



## jamesyawn (Nov 30, 2013)

Perhaps overly bold of me to start a new topic on my first post... feel free to chastise me if this is the wrong thing to do...

But I'm looking for a table-saw blade that will cut a kerf 1/4th inch wide with a ROUND bottom. That's so a 1/4th inch dowel will fit in snugly and evenly, with a little Titebond and rubber-mallet persuasion.

So far, I've used:
Dado blade (round peg in square hole. Inelegant.)
Three circular blades together (slightly nicer square hole.)
Forstner bit applied tangentially (good result but labor intensive.)
Router table (tricky and labor intensive.)

The table saw is quick and easy for this application, and would be perfect if it would just cut a round-bottomed kerf. Numerous web searches have turned up no blades for this purpose. 

I could have a machinist make me a custom blade, but wonder if there is something already available on the market. 

Suggestions? Ideas? Rude remarks? I'm open!

Jimmy Yawn


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## Steve Neul (Sep 2, 2011)

You might use a router on a router table which may get better results. You could just use a 1/4" bull nose router bits that would do it unless the dowel is swollen from exposure to humidity. To do that on a table saw you might have to get a molding cutter and grind a custom blade to fit your needs.


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## Burb (Nov 30, 2012)

I'd suggest using a Core Box Router Bit, like this

http://www.grizzly.com/products/1-4-R-Core-Box-Bit/C1231

Mark


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## mdntrdr (Dec 22, 2009)

Yep, 1/4" Core Box. :smile:


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## woodnthings (Jan 24, 2009)

*Crfatsman molding head*

This one has a bunch of different cutters . Just grind the most likely one into a 1/4" diameter end. 

http://www.ebay.com/itm/Craftsman-9...559?pt=LH_DefaultDomain_0&hash=item3387b45d0f


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## cabinetman (Jul 5, 2007)

jamesyawn said:


> Perhaps overly bold of me to start a new topic on my first post... feel free to chastise me if this is the wrong thing to do...


 





 
Not really the wrong thing to do, but we have an introduction section where you can say a few words about yourself. If you fill out your profile in your "User Control Panel", you can list any hobbies or other facts. You can also list your general geographical location which would be a help in answering some questions.

I also vote for the core box router bit. That would be the best method IMO. Saw blades don't have the width in their tooth design for ¼" wide profiles. It would likely be very costly to have one made.

Using one of the moulding knives for a table saw moulding head and reshaping it to make the groove would be difficult with DIY home type tooling.

















.


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## knotscott (Nov 8, 2007)

Welcome James. I don't know of any saw blades that exist that will give you a rounded 1/4" profile. A molding head cutter may have a profile that will do it, but I'd think the core box router bit that others have suggested would be the path of least resistance.


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## 4DThinker (Mar 13, 2013)

Split the job. Cut 1/8" deep slot with the table saw, 1/4" wide. Use the core-box router bit set 1/4" deep to run down the same slot. Easiest on a router table with fence, but can be done with a hand-held router and a straight-edge guide.


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## FrankC (Aug 24, 2012)

Not sure of application, can you just glue 1/2 round molding to surface of board:
http://www.superior-dollhouse-miniatures.com/miscellaneous-building-materials/30737-half-round.html

If you are burying it then use a router in a table and an appropriate bit as suggested.


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## woodnthings (Jan 24, 2009)

*This will work*

Just bush it from 3/4" to 5/8' for the table saw. Use or make a wider throat opening for the insert in the saw.
It may not be a large enough diameter at 2 /5/8" but the depth of cut is unknown....

C2046 Shaper Cutter - 1/4" Flute, 3/4" Bore

http://www.grizzly.com/products/Shaper-Cutter-1-4-Flute-3-4-Bore/C2046














*Your Price:****$25.95* In Stock​(Click for showroom pickup)


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## jamesyawn (Nov 30, 2013)

*1/4th inch round-bottomed kerf*

Thanks for the excellent suggestions. I'll get one of those bull-nosed bits next trip to Home Deep Hole. 

I've done the two-pass thing with the table saw then Forstner bit, but it's a pain to get the work aligned perfectly 62 times for rack (cookie/cake/bread-cooling racks.) It took 90 seconds on the table saw to make nicely-spaced square kerfs, 90 minutes at the drill press to make them round. The router bit should be much quicker.

The molding blade looks like what I originally had in mind, and would do it all in one pass. I might impose upon my machinist buddy to make me custom tips, or re-shape an existing tip.

Thanks again! 
Jimmy Yawn
[email protected]


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## jamesyawn (Nov 30, 2013)

*C2046 shaper cutter*

Apologies, I did not see this item before making my last post. (Darned modem connection... pictures load sloooow.)

It would be perfect... if my table saw would raise up that high. Just measured, and the spindle (center) only comes up to within 1.425 inches of the bed. This particular blade would only reach up 1.3125 inches, below the bed of the saw.

So do I need a better table saw? Perhaps better question is...what type of machine is this sort of blade used in? Maybe that's what I need.

Jimmy


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## Alchymist (Jan 2, 2011)

jamesyawn said:


> Apologies, I did not see this item before making my last post. (Darned modem connection... pictures load sloooow.)
> 
> It would be perfect... if my table saw would raise up that high. Just measured, and the spindle (center) only comes up to within 1.425 inches of the bed. This particular blade would only reach up 1.3125 inches, below the bed of the saw.
> 
> ...


Shaper -
http://www.grizzly.com/products/3-4-HP-Shaper/G0510Z

And yes, that would do the job....


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## woodnthings (Jan 24, 2009)

*Yes, it is a shaper cutter*



Alchymist said:


> Shaper -
> http://www.grizzly.com/products/3-4-HP-Shaper/G0510Z
> 
> And yes, that would do the job....


BUT, shapers only work on the edges of panels/boards.
To make the rounded bottom kerfs in the middle of a board on the face or in the middle of a panel, a shaper won't work. :no:
So, we are back to square one.

It's possible you could use a circular saw which will get you more blade out of the base, but that would be an "experiment"considering the bushing and thickness of the cutter and all.

The thing I like about the shaper cutter is the large amount of gullet which allows for easy chip removal and it will be turning a lot slower, less chance of a burn out. But I'm afraid the dang thing is just too small around to work in the table saw. HMMM I wonder about a RAS. which has very little "machinery" below the base of the motor's shaft/arbor.

What's the required depth of the cove? Sounds like about 1/4"...
Maybe it could work, but then you are limited by the cross cut capacity of the RAS. usually about 15" or so.


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## cabinetman (Jul 5, 2007)

With a shaper, the bit cuts horizontally. Depending on the specific machine, how high the bit can be raised would depend on how far off the table the groove could be placed. For some items, the groove could be positioned higher than what would be considered the edge of the board.


















.


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## jschaben (Apr 1, 2010)

jamesyawn said:


> So far, I've used:
> Dado blade (round peg in square hole. Inelegant.)
> Three circular blades together (slightly nicer square hole.)
> Forstner bit applied tangentially (good result but labor intensive.)
> ...


Hi Jimmy - I don't understand what kind of issues you had with this, router table would be my first choice unless the board was to large. :blink:


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## rrich (Jun 24, 2009)

I've seen them at woodworking shows. They are similar to the molding head cutter. 

Spendy! ($300) range. They are purple in color. 

If you have an old dado blade set, you could get the outside blades sharpened to the 1/4" that you need.


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## rrbrown (Feb 15, 2009)

Why all the overthinking guys? 

Routerbit is the best and cheapest solution offered.


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## GeorgeC (Jul 30, 2008)

rrbrown said:


> Why all the overthinking guys?
> 
> Routerbit is the best and cheapest solution offered.


I am with you. A 1/4" cove bit should be all that is needed.

George


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## woodnthings (Jan 24, 2009)

*It's not overthinking*



rrbrown said:


> Why all the overthinking guys?
> 
> Routerbit is the best and cheapest solution offered.





GeorgeC said:


> I am with you. A 1/4" cove bit should be all that is needed.
> 
> George


Of course a router bit will work. It's about alternative methods. If I had 500 grooves to make, spaced 1/2" apart on pieces 3 ft long, I'd be looking at a different method. BUT we don't know what the application is. 

If I could get that shaper cutter to fit my saw, I'd use it and for $26.00 it ain't all that exspensive, maybe less than what the router bit would cost, I donno? Try to find an 1/8" radius cove bit, I couldn't on Amazon or from Amana.... :no: 
Because of the small radius it will probably heat up and dull pretty rapidly, depends on the quality and the length of the run.


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## cabinetman (Jul 5, 2007)

The router bit would be a core box, not a cove bit.








 







.


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## jschaben (Apr 1, 2010)

woodnthings said:


> Try to find an 1/8" radius cove bit, I couldn't on Amazon or from Amana.... :no:
> .


Core bits are typically sold by large diameter, not radius. About $10 on MLCS.:smile:
Cove bit will typically have a bearing which would not be suitable for this application. 
http://www.mlcswoodworking.com/shopsite_sc/store/html/smarthtml/pages/bt_core.html


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## bladeburner (Jun 8, 2013)

Assuming these slots/holes are in the 2 ends of your racks, am I correct in that you are trying to put slots into 2 halves of an end?

If so, I would setup an indexed drill press operation and bore the holes into a full size end. A 17/64 or even a 9/32 bit will work fine since the dowels will swell when glued.

However, if for some reason you want to use an open half on the ends, I'd treat this as a fluting exercise and cut indexed flutes into a wide board and then rip off the end halves. You can buy or make a fluting index jig for a router. See Rockler, Woodcraft, etc.


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## jamesyawn (Nov 30, 2013)

*1/4th inch round-bottomed kerfs*



woodnthings said:


> ... If I had 500 grooves to make, spaced 1/2" apart on pieces 3 ft long, I'd be looking at a different method. BUT we don't know what the application is. ....


Your are pretty close. I'm cutting 35 pairs of grooves spaced 1/2 inch apart on 18 inch dowels.

I made a crude web page including a redundant movie of the project for clarity and general annoyance: 

http://www.jamesyawn.net/cookierack/index.html

I'd like to be able to cut round-bottomed kerfs as quickly and easily as the 3 circular blades cut a square one. 

I think that shaper cutter would be perfect if there were a larger version, or if I had a saw that would accommodate it. Might a radial saw arbor go that low? That's a tool I don't yet have... maybe it's time! 

Jimmy


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## cabinetman (Jul 5, 2007)

jamesyawn said:


> Your are pretty close. I'm cutting 35 pairs of grooves spaced 1/2 inch apart on 18 inch dowels.
> 
> I made a crude web page including a redundant movie of the project for clarity and general annoyance:
> 
> ...


Why couldn't you just make a jig to hold the dowel, and use a ¼" brad point drill bit in a drill press, and drill that partial groove. You could make a spacer/stop to get the holes evenly spaced.








 







.


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## jamesyawn (Nov 30, 2013)

cabinetman said:


> Why couldn't you just make a jig to hold the dowel, and use a ¼" brad point drill bit in a drill press, and drill that partial groove. You could make a spacer/stop to get the holes evenly spaced.



Another good idea...my best result so far was using the Forstner bit alone. It did the job in one pass, too. Downside was measuring and marking all the spots, and re-aligning the work precisely. That took a lot of time, but with a jig, or even a template to mark quickly this might be a winner. 

The suggestion of using an old dado blade made me think about getting 3 carbon-steel circular blades so I could file the outside teeth to make a round total profile. Perhaps even re-set the outside teeth so all of them lean toward the middle, then file. 

I'll try all these this weekend:

1. Make some kind of jig for the drill press
2. Run square-cut kerfs over a bull-nosed router bit
3. Find some carbon steel blades and adjust them to cut a round kerf
4. Try to find a saw that will let me use that beautiful shaper cutter in table-saw fashion.
5. Heat a metal rod red-hot and "melt" the wood : ) 

My desire for efficiency is not so much because I'm a lazy bum (I am!) but that I'm making "kits" for someone else to assemble, so they can produce "made it myself!" Christmas presents.

I'll report back on my outcomes.

Jimmy


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## Alchymist (Jan 2, 2011)

4' length of 2X4 clamped to DP table. 3 pieces perhaps 3" square. Stack and drill a hole through all three pieces that will just clear the dowel. Two get glued to the 2X4 fence. 

The third is cross drilled for a wood screw. Insert the end of the dowel in the block, tighten the wood screw. Insert the dowel through the two blocks glued to the 2X4. Adjust 2X4 to put forstner bit in correct position. Drill, slide to next position, drill, repeat. The block screwed to the dowel will keep the dowel aligned.

Mark the positions on the 2X4 using the block on the end of the dowel as a pointer. Make dowel slightly longer than finished product, cut off end where the block was screwed on. Might have to expand the table with a piece of plywood under the 2X4.


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## woodnthings (Jan 24, 2009)

*OK, I get it now*

Here's what I would do. 
Use a 1/4 Straight flute bit in EITHER a router table, or a hand held router, make the cuts at 90 degrees, vertically with the large dowel horizontal, leaving a nice radius at the rear of the cut. It may be difficult to get the spacing even at 1/2" on center, so a marking system or a jig with an index pin referencing a series of holes 1/2" on center will help.
Or use a finger or box joint template with a guide bushing.

It would look like this:









Mount this above your large dowel in a fixture, considering the required depth, and just rout in until the guide bushing contacts the jig.


Or get one of these:
http://www.harborfreight.com/dovetail-machine-34102.html


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## FrankC (Aug 24, 2012)

Now that I see the end product it looks like a box joint jig could be made with a pin made from half a 1/4" dowel. Core box bit in a router table, and go at it. One thing I might do is to tack a strip of material to top or back of dowel that lines up with circumference, this would prevent the dowel from rotating as the cuts are made along it.


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## jschaben (Apr 1, 2010)

I like woodnthings comb idea. Problem with it would be making a comb with the 1/2" on center spacing. One could, however, make a comb on 1" spacing fairly easily and make the jig holding the dowel to allow the dowel to be indexed 1/2" over for a second pass. :smile:


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## woodnthings (Jan 24, 2009)

*this one should work*

Woodstock D3159 Dovetail Template, 1/4-Inch - Amazon.com


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## Alchymist (Jan 2, 2011)

Here's what I was trying to describe - cheap jig. Not the best artist, but I think it's readable.


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## woodnthings (Jan 24, 2009)

I see an opportunity for lots of tear out pushing the bit down against the long grain. A router bit may have some issues as well, but I think it may be a cleaner solution. Only one way to find out ..... :yes:


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## jamesyawn (Nov 30, 2013)

*Wooden jig for grooving dowels*



Alchymist said:


> Here's what I was trying to describe - cheap jig. Not the best artist, but I think it's readable.


Artwork is good enough to lead me to this:










Dowel is encased in this wooden jig, held in by 4 screws - 2 of which go through the dowel itself to keep it from rotating. The jig slides on the 2x4 rail under the drill head. It worked pretty well on the two I've done with it. 

More at: http://www.jamesyawn.net/cookierack/

I want to pursue the molding knife option too, but have yet to find simple 1/4th inch rounds. 

Jimmy Yawn


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