Forrest Dado King

[Martin Wasner]

Will a 12" Forrest Dado King give good performance in a 14-18" saw?

I've been using a 8" Forrest Dado King in a Delta Unisaw and have been content. The 12" version has the same tooth count as the 8" version, which causes me concern.

[Ben Rivel]

WOW! I didnt even know they made them that big, nor have I seen 14"-18" saws! Post some pictures of that!

[Martin Wasner]

WOW! I didnt even know they made them that big, nor have I seen 14"-18" saws! Post some pictures of that!


I bought a Northfield #4 and a Tannewitz XJ for the new shop to replace a Delta Unisaw and a Powermatic Model 66. The new saws are sitting in storage at the moment.

[Darcy Warner]

WOW! I didnt even know they made them that big, nor have I seen 14"-18" saws! Post some pictures of that!

I run 16's in my Greenlee and whitney, had a 20" in my old Martin t75.

Had a 20" RAS for a while.

I need a 12" Dado set for my whitney.

Probably be an Everlast or a popular tools though.

[Van Huskey]

Will a 12" Forrest Dado King give good performance in a 14-18" saw?

I've been using a 8" Forrest Dado King in a Delta Unisaw and have been content. The 12" version has the same tooth count as the 8" version, which causes me concern.

24 T on a 12" dado stack is not unusual, FS Tools has 24 as does Everlast. Popular Tools and Royce Ayr both have higher tool count dado sets if you have a real concern. If nothing else the increased diameter will create better geometry as the teeth contact and leave the wood.

[peter gagliardi]

That is exactly the set I run in my Whitney 177, along with a Woodworkers Toolworks and a Systimatic set. It works well, but the Systimatic is best. Everyone said they were out of business about 8-10 years ago, but Hank at Select Machinery got me the Systimatic set about 4-5 years ago as I remember, so there might be hope. If doing plywood, you definitely want at least 4 wing chippers, and 6 wing is even better- you will NOT like a two wing unit for dadoing plywood!

[Larry Edgerton]

I had them make me a 10" bored out to fit my Minimax, and it has been excellent for 20 years. I don't really see the advantage of a 12" for the shallow cuts you would be making with the dado other than teeth speed will be a little slower with a smaller blade. My saw takes the metric equivalent of 12" and I have not found a material where the smaller size was a problem. Calculate you teeth speed and see where you will be at. It was $450 20 years ago.

Which reminds me, I need to send mine in to get it reworked.......

[Martin Wasner]

Rim speed is my concern

Just going off of ratios, 8" is 80% of 10"' 12" is 75% of 16". I think I'd be too slow with a 10" set. Whether or not you can look at it that way, I don't know. Seems right, buy I've been wrong lots of times.

I agree a four wing chipper is much nicer on plywood than a two wing. I've been down that path too

[Martin Wasner]

Darcy brought up Popular Tools. I think I bought a couple of their dado sets and put them in a shaper for my frankendrawernotcher. I'll have to take a peek at those again.

[Jim Becker]

Unless you're going to be cutting extremely deep grooves, etc., the only benefit to the larger diameter dado set (besides the revenue to the vendor) is tip speed. If you are going to be doing typical dado blade work, the 8" will do a fine job and costs less. The slightly slower speed shouldn't be a major issue with this set if it's kept sharp, especially because of the steep angle of the outer blades that tend to slice cleanly at the edge.

[Darcy Warner]

Unless you're going to be cutting extremely deep grooves, etc., the only benefit to the larger diameter dado set (besides the revenue to the vendor) is tip speed. If you are going to be doing typical dado blade work, the 8" will do a fine job and costs less. The slightly slower speed shouldn't be a major issue with this set if it's kept sharp, especially because of the steep angle of the outer blades that tend to slice cleanly at the edge.

The only issue is with the direct drive motors of his saws. An 8" set does not give much depth of cut.

I would barely get a 1/2" with an 8" set on my Whitney.

[Martin Wasner]

Yep, they don't make it out of the table on a direct drive.

[Van Huskey]

The direct drive saws will hide a pretty big blade under the table.

I can see using a 12" stack on a Northfield as the arbor speed is lower than a 66 or Uni IIRC.

[Darcy Warner]

The direct drive saws will hide a pretty big blade under the table.

I can see using a 12" stack on a Northfield as the arbor speed is lower than a 66 or Uni IIRC.

Pm66 runs at 3600 rpm, same as these direct drive saws.

[Larry Edgerton]

My 66 is out in the barn, and it does have a motor speed of 3600, but I don't think the pulley sizes are the same? I know just for giggles and grins I calculated rim speed on all my saws from 15" down to 8, and the rim speeds were all between 100-110 mph. I just got hit with a chunk that blew back and wanted to find out how fast it was going when it hit me.;)

[Darcy Warner]

My 66 is out in the barn, and it does have a motor speed of 3600, but I don't think the pulley sizes are the same? I know just for giggles and grins I calculated rim speed on all my saws from 15" down to 8, and the rim speeds were all between 100-110 mph. I just got hit with a chunk that blew back and wanted to find out how fast it was going when it hit me.;)

Says sfm of 10" blade on pm66 is 10k.

Roughly 4k rpm at arbor then.
Just a bit of speed increase with pulleys then.

[Van Huskey]

Says sfm of 10" blade on pm66 is 10k.

Roughly 4k rpm at arbor then.
Just a bit of speed increase with pulleys then.

I was thinking arbor speed on the 66 and (old) Uni were 4200, but knew it was over 3600. That said I seriously doubt every Uni was the same speed, the 66 was more of the "same saw" throughout its life. Also I don't know if all Northfield #4s were the same speed, that is just based on my limited exposure to them.

[Darcy Warner]

I have never seen any direct drive saw, tanny, NF, Whitney, greenlee, oliver, etc. That was anything other than a 3600 rpm motor.

[Jim Becker]

The only issue is with the direct drive motors of his saws. An 8" set does not give much depth of cut.

I would barely get a 1/2" with an 8" set on my Whitney.
I certainly missed the direct drive fact, so yea...the bigger platters make sense.

[Martin Wasner]

I was incorrect, I thought it was a Tannewitz XJ. Turns out it's a type U. Serial number 10266, if I'm looking in the right chart for serial numbers, that means it was built in either 1947 or 1948. How cool is that! If I'm wrong on that, somebody please correct me.

I had to swing by the place where it was stored today, so I managed to take a picture.


http://scontent.xx.fbcdn.net/v/t1.0-9/16114687_10210166545631347_2237625705056517181_n.j pg?oh=1d0fc3092967f8d3ced6306e8fd01103&oe=5906701E



I don't have any pictures of the Northfield, but I think that was built in 1966. I need to swing by and confirm that though. I think I'm going to use the Northfield for the dado saw, just because I can source a new throat plate and the thinner washer that will be required to put a dado head in it easily.

[Brian Scheffler]

That's some serious coin, but some serious equipment as well!

[Clint Baxter]

Rim speed is my concern

Just going off of ratios, 8" is 80% of 10"' 12" is 75% of 16". I think I'd be too slow with a 10" set. Whether or not you can look at it that way, I don't know. Seems right, buy I've been wrong lots of times.

I agree a four wing chipper is much nicer on plywood than a two wing. I've been down that path too

Doing a few quick calculations, the teeth on your 12" will be traveling at only 75% of what the 16" blade is doing. 10" blade drops to 62.5% and an 8" runs at 49.7%

Might be going a bit slow in my opinion. If the saw is running at 3600 rpm, the teeth on a 16" blade are moving somewhere's over 170 mph. 10" blade is a measly 107 mph.

Clint

[Larry Edgerton]

Well there you go. using Clint's figures a 12" blade in your saw would end up having a rim speed at least as fast as a standard ten inch saw, so you should be in like Flynn. All that is left to do is get out your credit card.:D

[David Kumm]

I run a 12" dado king on my DD saws and finish quality has more to do with keeping the stock tight to the table than anything else. The weight is substantial so it takes a big arbor and large diameter bearings to handle the dado. 12" is the appropriate size for a 16" DD. I have extra chippers and run up to a 1.5" groove. Those old motors seem to handle more than my new ones do. Dave

[Martin Wasner]

My brain just can't grasp the concept of the gaps between teeth being so far apart. I get it, but don't. lol

[Jim Becker]

For folks who haven't thought about this much, the thing about dado blades and tooth setup is that you need to accomplish two things: 1) a sharp, clean edge and 2) efficient chipping out of bulk material between those clean edges. Forrest does this well...the two outer platters have a very high angle which almost acts like a knife edge to sever fibers and the very point of those angles is slightly farther into the wood than the chippers. (sometimes folks don't appreciate that when the end of the groove is visible because you can see that little "knife cut" on either side of the groove) They also use some pretty good precision on the grind of the chippers such that they not only remove material efficiently, but they also leave a nice clean, flat bottom that inexpensive setups tend not to do as well. That's the thing with Forrest...their sharpening prowess shows on the products, too. While it might seem that four tip chippers (or even two tip chippers) is strange, that space is needed to be be able to distribute the tips since they overlap slightly, depending on how you use shims, if any, to fine tune width and they are really acting like "rotary chisels". The fact that it works so well is a kewel thing... :)

[Phillip Gregory]

The only issue is with the direct drive motors of his saws. An 8" set does not give much depth of cut.

I would barely get a 1/2" with an 8" set on my Whitney.

The same is true with the other type of direct drive saw that can swing a 16-20" blade, which is a big RAS. My 7 1/2 hp DeWalt GE would have about 1/2" depth of cut with an 8" diameter blade with the bottom of the motor housing just scraping above the work piece. A 10" diameter dado set is the smallest generally recommended for that size of a saw, and would be equivalent to running a 6" dado head on a saw designed for a 10" blade. Generally people with 10" saws run 8" dado stacks, so a 12" unit would be preferable for a large direct drive cabinet saw or a big RAS.

I'd also recommend something with at least 40 teeth in a 10"-12" dado head if you work with plywood. The typical 24-30 tooth blades will chip out the veneer like crazy even if you tape the cut line- you MUST pre-score the veneer if you use such a blade.

[Van Huskey]

My brain just can't grasp the concept of the gaps between teeth being so far apart. I get it, but don't. lol


Just think about a 4 wing shaper cutter, yes it is running faster but they are still quick a long time between knife marks. With 24t and 3600rpm that is 1,440 teeth per second going through the wood.

[Jim Becker]

Van, that's why folks need to be "more careful" when running dado blades and big shaper setups...the forces that come into play as the "limited" number of cutting surfaces engage the wood are considerably higher than with just a regular saw blade.

[David Kumm]

Here is a 12" Dado King . Cut quality is also dependent on arbor strength to minimize runout. My flanges are 4" and ground true which helps. 352727352728352729352730 Also pictured are the stub arbors and the spindles that carry the load. Dave

[Martin Wasner]

I'd also recommend something with at least 40 teeth in a 10"-12" dado head if you work with plywood. The typical 24-30 tooth blades will chip out the veneer like crazy even if you tape the cut line- you MUST pre-score the veneer if you use such a blade.

I score everything that is across the grain. It doesn't matter how good the dado set is, the material is imperfect and you will always get some tear out. Scoring is the only way to eliminate that almost entirely.

[peter gagliardi]

I just use a zero clearance wood plate in my Whitney. The only time I get tearout is if the sheet lifts off the table, but I use a holddown to remedy that.
Prescoring sounds like a labor eater for a guy who is very sensitive to waste, no?
How do you prescore?

[Joe Calhoon]

I wonder how the euro adjustable groovers sized for a table saw would work on ply? We used a zero clearance plate like Peter and a systematic dado with good results in ply. The other dado sets we had never worked for this.

[Martin Wasner]

How do you prescore?

I knew somebody would ask. If you want to know, I'll pm you. I will loudly be shouted down if I explain it in the open.

[Martin Wasner]

I wonder how the euro adjustable groovers sized for a table saw would work on ply? We used a zero clearance plate like Peter and a systematic dado with good results in ply. The other dado sets we had never worked for this.

I've wondered how a insert head with the knives on edge would work. It'd be an expensive experiment though

[Larry Edgerton]

I have an 8" adjustable groover with the same 1 1/4 bore as my saw, I'll throw it on and check it out. Now that you mention it I am curious.

[Phillip Gregory]

Utility knife run along a straightedge.

[Larry Edgerton]

Early riser, so I grabbed a coffee and went out to the shop and threw one of the groovers in the tablesaw. Works just fine, can't believe I did not think of that before. I have one set up in the shaper right now for drawer grooves and the cut was about the same. The nickers are cutting a hair deeper than the dado blade in the corners but that does not bother me for what I use it for. No tearout on Maple ply. good in solid maple. I do not allow melamine in the house so can not comment on that.

Larry

[Martin Wasner]

Early riser, so I grabbed a coffee and went out to the shop and threw one of the groovers in the tablesaw. Works just fine, can't believe I did not think of that before. I have one set up in the shaper right now for drawer grooves and the cut was about the same. The nickers are cutting a hair deeper than the dado blade in the corners but that does not bother me for what I use it for. No tearout on Maple ply. good in solid maple. I do not allow melamine in the house so can not comment on that.

Larry

Melamine is really where you need a boat load of teeth, and a lot of rake typically. I'd be kinda surprised if it worked well.

[Larry Edgerton]

I was looking at that piece of maple ply I ran with the groover in the tablesaw and I had run with the grain, so as it was still in that saw I tried it across the grain. Not the answer, bad tearout, lifting the veneer. So I guess I still need to send in my Forest.