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View ohtimberwolf's profile

What table saw blade or bit do you recommend

by ohtimberwolf
posted 02-25-2021 09:16 PM


24 replies so far

View Loren's profile

Loren

11196 posts in 4735 days


#1 posted 02-25-2021 09:29 PM

You can get undersized router bits for plywood. MLCS sells them.

View Fred Hargis's profile

Fred Hargis

6993 posts in 3581 days


#2 posted 02-25-2021 09:49 PM

Those would be rip cuts and since the groove would need to be .2” wide (or something that’s not .25”), I would just use a rip blade and make 2 cuts to get the proper width….or the undersize router bit. I’d probably go with the rip blade, they do cut flat bottom kerfs.

-- Our village hasn't lost it's idiot, he was elected to congress.

View LesB's profile

LesB

2993 posts in 4530 days


#3 posted 02-25-2021 10:04 PM

If you are only cutting a few it is usually not worth investing in a new cutter.
Fred had it right on in his comment above.
Why if a plywood panel is going into the groove and cover it does it need to be flat?

-- Les B, Oregon

View RClark's profile

RClark

128 posts in 3272 days


#4 posted 02-25-2021 10:36 PM



Those would be rip cuts and since the groove would need to be .2” wide (or something that s not .25”), I would just use a rip blade and make 2 cuts to get the proper width….or the undersize router bit. I d probably go with the rip blade, they do cut flat bottom kerfs.

- Fred Hargis

+1.

Not really a fan of undersized bits for plywood. Depending on where you get the plywood, it’s not all uniform thickness, even at the known undersized thickness.

-- Ray

View ohtimberwolf's profile

ohtimberwolf

1082 posts in 3440 days


#5 posted 02-25-2021 10:54 PM

So guys, this blade will work ok?

https://www.amazon.com/CMT-256-050-10-Industrial-Combination-Grindwith/dp/B000P4NTRC/ref=sr_1_15?dchild=1&keywords=flat+bottom+saw+blade&qid=1614285309&sr=8-15

or this one? https://www.cshardware.com/cmt-p10050.html

We only have a Lowes store here and the selction isn’t so good. Is there one in Lowes that you know would meet these needs. The way they have these labled confuses me. Some don’t even have a designation.

I have my whole kitchen to do then no more. larry
P.S. I may run down to Keim Lumber in Charm tomorrow as I am in a bit of a hurry.

-- Just a barn cat, now gone to cat heaven.

View Robert's profile

Robert

4558 posts in 2568 days


#6 posted 02-25-2021 11:22 PM

No thats a combo blade a flat top is a rip blade. Look for a 24 tooth rip.

IMO if you have to do very many of these, your better off with a rail and stile router bit set b/c you have another set up for the tenons. Not a big deal but does save time. You need a router table set up, tho.

-- Everything is a prototype thats why its one of a kind!!

View MikeJ70's profile

MikeJ70

92 posts in 1034 days


#7 posted 02-25-2021 11:28 PM

So it sounds like you only want to build cabinets once so a router bit set is probably not the best way to go. I’d suggest this blade: https://www.amazon.com/Freud-24T-Heavy-Duty-Blade-LM72M010/dp/B00004T78V/ref=sr_1_3_sspa?dchild=1&keywords=freud+heavy+duty+rip&qid=1614295068&sr=8-3-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExOVA3SFBNOEw1VTFBJmVuY3J5cHRlZElkPUEwNzI1OTA2S1NIMjVHSTg4UU45JmVuY3J5cHRlZEFkSWQ9QTA0Njg5NjcxRVRQQTBMSDZYMlExJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ== . It’s the one I have and will produce flat bottoms. Take the time to set your saw up so you just have to make two passes with each board, one pass with each face of the board against the fence. It will center the groove and you don’t have to keep adjusting your fence.

My experience lately with plywood is the thickness varies greatly from sheet to sheet, so even the undersized plywood bits will not give you the proper fit. Some sheets will be too tight and some will be too loose. Same is true for mdf. When I made the doors and drawer fronts for our office upgrade I ended up bring a sample rail to the lumberyard to find a sheet of mdf that fit it properly.

If you can find it, some mdf core plywood comes in full 1/4” thickness. One of my local big box stores (Menards) used to stock it in Cherry, Oak and Maple and you could special order other species. Now what they stock is less than a 1/4” like typical plywood.

-- MikeJ

View Rich's profile (online now)

Rich

6851 posts in 1677 days


#8 posted 02-25-2021 11:29 PM


No thats a combo blade a flat top is a rip blade. Look for a 24 tooth rip.

- Robert

Every fifth tooth is flat, so it will cut a flat bottom kerf. It shows it right on the blade.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

View RClark's profile

RClark

128 posts in 3272 days


#9 posted 02-25-2021 11:38 PM



So guys, this blade will work ok?

https://www.amazon.com/CMT-256-050-10-Industrial-Combination-Grindwith/dp/B000P4NTRC/ref=sr_1_15?dchild=1&keywords=flat+bottom+saw+blade&qid=1614285309&sr=8-15

or this one? https://www.cshardware.com/cmt-p10050.html

We only have a Lowes store here and the selction isn t so good. Is there one in Lowes that you know would meet these needs. The way they have these labled confuses me. Some don t even have a designation.

I have my whole kitchen to do then no more. larry
P.S. I may run down to Keim Lumber in Charm tomorrow as I am in a bit of a hurry.

- ohtimberwolf


Right now, looking at the listings, I would have to say neither one of those blades will cut a flat bottom.

First, other listings for blades that cut flat-bottoms are usually clear about that feature. Neither one of the listings states a flat-bottom cut specifically.

Second, the Amazon listing has a drawing of the grind specifications. That drawing shows a .006” difference between the top of the flat tooth and the top of the beveled tooth AND the beveled tooth is higher than the flat grind tooth. Here’s a snip:

-- Ray

View Rich's profile (online now)

Rich

6851 posts in 1677 days


#10 posted 02-25-2021 11:45 PM


Second, the Amazon listing has a drawing of the grind specifications. That drawing shows a .006” difference between the top of the flat tooth and the top of the beveled tooth AND the beveled tooth is higher than the flat grind tooth. Here s a snip:

- RClark

That’s going to give you clean, sharp corners. It’s still going to be flat. Dado stacks cut the same way.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

View waho6o9's profile

waho6o9

9019 posts in 3664 days


#11 posted 02-25-2021 11:52 PM

I usd a CMT cutter designed for that and it’s about 1/32” bigger than the plywood, it
worked well for my needs.

CMT calls them slot cutters
https://www.cmtorangetools.com/na-en/industrial-router-bits/slot-cutters

View RClark's profile

RClark

128 posts in 3272 days


#12 posted 02-26-2021 12:44 AM


Second, the Amazon listing has a drawing of the grind specifications. That drawing shows a .006” difference between the top of the flat tooth and the top of the beveled tooth AND the beveled tooth is higher than the flat grind tooth. Here s a snip:

- RClark

That s going to give you clean, sharp corners. It s still going to be flat. Dado stacks cut the same way.

- Rich

Well…I don’t own any CMT saw blades, so I went out and looked at my Freud blades that have a similar configuration. I wanted to check the advice I gave; I’d hate to to prompt somebody to act on something that is false. I realize it may not be an apples-to-apples comparison, but I’m going to have to stick with what I said: I don’t think the CMT blades linked will cut flat bottoms.

Here’s what I found on my Freud blades. My standard blades right now are Freud LU83 50T thin-kerf combo blades. They have alternating top bevel grinds. Every fifth tooth is a flat top tooth just like the referenced CMTs. I have three of them.

From Freud’s web site the blade spec is:

The site doesn’t give any information about the difference in height of the flat top tooth compared to the beveled tooth, unlike the info on the CMT. The Freud site also does not claim that the LU83 will cut flat bottoms.

I ran a piece of maple scrap through two of the Freud blades. The bottoms are not flat. Pic:

Full disclosure: My Freud blades are not new; they have been resharpened by the place that does all of my sharpening; they service many industrial customers of all sorts and I trust they did it right. I suppose it’s possible that they modified the grind in some way that “took away” the ability for my blades to cut flat bottoms.

I still can’t say whether or not those CMT will cut flat bottoms. But, based on what I saw in their literature, I don’t THINK they will.

Hopefully somebody who has one of the CMT blades can confirm one way or the other.

-- Ray

View tvrgeek's profile

tvrgeek

1874 posts in 2737 days


#13 posted 02-26-2021 12:59 AM

I use the CMT flat tooth rip. Nice square bottom. Some dado sets the outers are flat.

Not quite sure why you need a flat bottom if it is the inside panel grove.

View ohtimberwolf's profile

ohtimberwolf

1082 posts in 3440 days


#14 posted 02-26-2021 01:07 AM

If i don’t have a flat bottom the top and bottom of the stiles will not close and have to be filled. The wood will be finished not painted. Or am I missing something in all of this. Not sure. larry

-- Just a barn cat, now gone to cat heaven.

View Madmark2's profile (online now)

Madmark2

2684 posts in 1676 days


#15 posted 02-26-2021 01:39 AM

Combo blades are a compromise. They’ll do a decent but not perfect job on both rips and crosscuts.

That Freud LU83 is a favorite of mine. They leave a wavy bottom as you have found.

If an absolutely flat bottom is needed a router is called for.

For best results rough the dado with the saw. Cut it a little narrow and shallow. Perfect the dado with the router. Its more effort but will give a great looking join without chewing up bits. As always I suggest carbide.

I don’t go nuts that sometime the ply can be a little wavy. I cut for the thinnest, test fit & lightly sand the high spots to fit. Since the edge is in the middle of a dado it will never be seen.

FYI:
The diameter of the average human hair is about 0.003”. The 0.006” tooth height difference is literally the width of two hairs.

-- The hump with the stump and the pump!

View MikeJ70's profile

MikeJ70

92 posts in 1034 days


#16 posted 02-26-2021 01:57 AM

This is the blade I linked in my response above and will leave a flat bottom:

-- MikeJ

View ohtimberwolf's profile

ohtimberwolf

1082 posts in 3440 days


#17 posted 02-26-2021 02:28 AM

Thanks Mike, I believe they will have that blade at Keim’s. I may also get the router setup as I do have a router table.

Thanks to all who helped me on this so quickly. larry

-- Just a barn cat, now gone to cat heaven.

View Madmark2's profile (online now)

Madmark2

2684 posts in 1676 days


#18 posted 02-26-2021 02:41 AM

FWIW:
Multiple saw passes tend to leave a minor ridge depending on feed pressure, alignment, etc. Router will leave dead flat bottom without a hint of a ridge.

-- The hump with the stump and the pump!

View MikeJ70's profile

MikeJ70

92 posts in 1034 days


#19 posted 02-26-2021 02:56 AM



Thanks Mike, I believe they will have that blade at Keim s. I may also get the router setup as I do have a router table.

Thanks to all who helped me on this so quickly. larry

- ohtimberwolf

You could always use the router bits for this project and turn around and sell them if you don’t think you will use them again. Even if you only get 1/2 of what you paid it might be worth it in the long run. Whiteside, CMT, Freud are all good.

-- MikeJ

View Fred Hargis's profile

Fred Hargis

6993 posts in 3581 days


#20 posted 02-26-2021 11:32 AM



If i don t have a flat bottom the top and bottom of the stiles will not close and have to be filled. The wood will be finished not painted. Or am I missing something in all of this. Not sure. larry

- ohtimberwolf

No, you got it right. You want the exposed cuts to look good.

-- Our village hasn't lost it's idiot, he was elected to congress.

View ohtimberwolf's profile

ohtimberwolf

1082 posts in 3440 days


#21 posted 02-26-2021 01:39 PM

I sure appreciate every single response to my request!!!
Now off to the lumber yard in Charm…

-- Just a barn cat, now gone to cat heaven.

View Axis39's profile

Axis39

483 posts in 684 days


#22 posted 02-26-2021 02:57 PM

Do you own a dado blade? I’ve used mine for this a lot.

Although, admittedly, I own a couple of rail and style router bit sets and usually go this route.

-- John F. SoCal transplant, chewer uppper of good wood

View 75c's profile

75c

208 posts in 114 days


#23 posted 02-27-2021 02:30 PM

I might get into trouble here but I bought a pair of CMT blades the other day. Other than the very top of the line Freud blades I have never been a fan of them. The CMT blades are better to me. And there are many blades better than both. Just my thoughts don’t be afraid of a CMT blade if you decide to go that way. Regards

View ohtimberwolf's profile

ohtimberwolf

1082 posts in 3440 days


#24 posted 02-28-2021 01:48 AM

Thanks guys. I bought a flat bottom 10” at Keim lumber and i’m going to try it out on my table saw. If that doesn’t work for me then i will buy a router set and go from there. larry

-- Just a barn cat, now gone to cat heaven.

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