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Zero Clearance Insert with Blade Set to 45 deg

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Forum topic by Jim Crockett (USN Retired) posted 03-25-2008 02:18 AM 3995 views 0 times favorited 10 replies Add to Favorites Watch
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Jim Crockett (USN Retired)

852 posts in 2457 days


03-25-2008 02:18 AM

Topic tags/keywords: tablesaw

I am edge mitering the sides for a box. Would love to use a zero clearance insert to get cleaner cuts but can’t figure out how to get the insert down over the blade to cut a kerf. At 45 deg., the blade is proud of the table by about 3/8” to 1/2”. I thought of using one side of my dado blade set but that would create a 1/8” kerf and my regular blade is 3/32”. Could set a piece of 3/4” stock atop the open hole and attach the insert to the top of this sacrificial hunk of wood, but it would be difficult to determine where I would need to offset the insert due to the angle.

What do you all think – just use the dado blade and not worry about the slight gap on each side of the blade? Or try to remember my trig from 40+ years ago and determine the offset atop a sacrificial piece (actually that wouldn’t be that difficult with all of the online right triangle calculators that we have access to!).

Jim

-- A veteran is someone who, at one point in his/her life, wrote a blank check made payable to "The United States of America," for an amount of "up to and including his/her life".


10 replies so far

View juniorjock's profile

juniorjock

1930 posts in 2489 days


#1 posted 03-25-2008 02:45 AM

Hi Jim. Do you have enough space to just partially raise the dado blad, not going all the way through the insert? If you can get it close and then but your 3/32 blade on and finish it up. I don’t think that much difference between the dado blad and your reg. blade would make that big of a difference.

View GaryK's profile

GaryK

10262 posts in 2712 days


#2 posted 03-25-2008 03:45 AM

juniorjock has the right idea. If it doesn’t work a slight gap won’t make that much of a difference.

-- Gary - Never pass up the opportunity to make a mistake look like you planned it that way - Tyler, TX

View Jim Crockett (USN Retired)'s profile

Jim Crockett (USN Retired)

852 posts in 2457 days


#3 posted 03-25-2008 05:35 AM

I was wondering if the difference between the blades, 1/32”, would really make any difference. I didn’t think it would be a big deal but thought that I’d get the opinions of some of you with lots more experience than me. I don’t think that I’ll be able to partially cut the kerf since with the blade fully down when set to 45 deg, the blade sits above the tabletop by about 3/8 to 1/2 inch. So, I’ll just plan to cut it with one blade of my dado set – no big deal. Really, it’s 1/64” on each side of the blade – lots better than the original plate with about 1/4” on each side!

Thanks.

Jim

-- A veteran is someone who, at one point in his/her life, wrote a blank check made payable to "The United States of America," for an amount of "up to and including his/her life".

View IowaWoodcrafter's profile

IowaWoodcrafter

280 posts in 2800 days


#4 posted 03-25-2008 05:58 AM

Are there any cheap circular saw, 7 1/4”, blades with a thin kerf?

-- Owen Johnson - aka IowaWoodcrafter

View Harold's profile

Harold

310 posts in 2571 days


#5 posted 03-25-2008 06:20 AM

My blade would bind on the bottom of the insert, so I removed the insert, flipped it over and beveled the bottom with a chisel so that the blade would not bind as it was raised. although not perfect it is very close.

-- If knowledge is not shared, it is forgotten.

View gerrym526's profile

gerrym526

265 posts in 2532 days


#6 posted 03-25-2008 09:00 PM

I remember seeing an article on mitering boxes in Fine Woodworking recently-probably in the last 6mo. Gary Rogowski wrote the article. His solution is to have a dedicated sliding cutoff table with a kerf cut through it at 45 degrees. It’s the kind of cutoff table we probably are already using for panels, etc. instead of the miter guage.

-- Gerry

View Bob #2's profile

Bob #2

3808 posts in 2745 days


#7 posted 03-25-2008 09:27 PM

I do mine with a sled.

If you dont want to do this, just make an insert up, move the fence over to lineup with the insert and rip it part way thru until the blade is buried in the insert.
Fill the back end cut with a piece of wood same size as the kerf.

( photo “mocked” for illustration only)
Bob

-- A mind, like a home, is furnished by its owner

View skozub's profile

skozub

59 posts in 2483 days


#8 posted 03-26-2008 02:27 AM

Check out an earlier post that should offer some good info on this topic – http://lumberjocks.com/topics/2296#reply-24480

Bob #2 had a good recommendation at the bottom that he highlighted above…good video too.

Good luck

View Jim Crockett (USN Retired)'s profile

Jim Crockett (USN Retired)

852 posts in 2457 days


#9 posted 03-26-2008 03:29 AM

Great minds must think alike – I began constructing a dedicated 45 deg miter sled this afternoon with dual runners.

Because of the design of my saw, my original plate is only 3/16” thick (there is a 7/16” piece of round bar stock running the length of the throat, and it doesn’t move as the blade goes up & down). I have been using 1/4” hardboard and still have to cut a 3/32” dado to clear this support. And, when my blade is cranked to 45 deg, it stands proud of the tabletop by about 3/8”. So there was no way I was going to be able to lower the insert over the blade.

My other thought was to use a piece of 1/2” stock atop the throat opening, tape the insert plate to that sacrificial stock, and raise the blade through both pieces; the only problem I foresaw with this was determining the offset for the insert due to the height above the tabletop.

I decided that if I was going to go to all of this effort to create a slot in a zci, I might just as well construct a sled. Also, my miter gauge is flaky, so this will solve both problems. I made it 12” x 24” because all I will use it for is box sides and that will be sufficiently large. Luckily, I had a piece of scrap maple long enough to make the runners which I cut this afternoon and sanded down this evening – they fit the slots real nice now. I’ll post a picture after I finish it – hopefully tomorrow.

Thanks, guys. Appreciate all of the suggestions and discussion. I love this forum!

Jim

-- A veteran is someone who, at one point in his/her life, wrote a blank check made payable to "The United States of America," for an amount of "up to and including his/her life".

View Jim Crockett (USN Retired)'s profile

Jim Crockett (USN Retired)

852 posts in 2457 days


#10 posted 03-28-2008 04:04 AM

I finished the Table Saw Bevel Cut Sled today and got box sides cut for a trial box made of pine. I’m planning to make a better, more permanent sled later, now that I know how and see how well this one works . I used materials I had available to build this one – MDF base, maple runners, 2×4 for the front fence and a good piece of plywood that I found at the landfill for the back fence. I would rather have used a piece of hardwood for the back fence but didn’t have any on hand. Setting the back fence perpendicular to the blade was a challenge – ended up running one blade of my steel square along the blade, careful to miss the teeth, and the other blade against the back fence. Seems to be pretty close.

After I finished the sled, I found this article on making a crosscut sleds on the web and thought some of you might be interested:

http://www.geotekds.com/sled/index.htm

Anyway, I am pretty pleased with the way the box turned out.

Here are some pics of the sled and also some of the box just taped together thus far.
Table Saw Bevel-Cut Sled 01
Table Saw Bevel-Cut Sled 02
Trial Box 01
Trial Box 02

-- A veteran is someone who, at one point in his/her life, wrote a blank check made payable to "The United States of America," for an amount of "up to and including his/her life".

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