plywood router bits

[Rob Hough]

I'm building some shop cabinets and have a need to route dado's in the ply. The sheets are 18mm thick and none of my bits are even close. Anyone know of a good 18mm router bit that I can get?

I guess my other option is to build some kind of jig and use a smaller bit. I really want to avoid that if I can though.

[Jerome Hanby]

Rockler has a 23/32" (.71875") bit. 18 mm = .7087", so it looks like that's the correct size. Amazon has a Freud set of 4 "undersized" bits for plywood that contains that size, "Freud 89-650 Four Piece Undersized Plywood Router Bit Set 1/2" Shank Ideal for 1/4" to 3/4" Plywood With TiCo Hi-Density Carbide" for $75.

Click to Amazon through SMC so they get the credit!

[Kevin Arceneaux]

I have this set and it works well

http://www.infinitytools.com/prodinfo.asp?number=00-151

Or here, for this size only

http://www.infinitytools.com/products.asp?dept=1054

[Michael Liechty]

Is infinity the old Jasada? While great bits their customer service leaves something to be desired.

The ply bits are excellent for routing dadoes, just be sure to use a good straightedge.

ML

[Charles Lent]

You should build a jig for this. Start with two straight boards that are longer than the longest dado that you will need. At each end of one of them attach some shorter boards using lap joints to the bottom of the board so that the end result will look like a capital letter E without the center leg. Now you can attach the second long board alongside the first one so that it is parallel with the first long board. The attachment can be with slots and bolts to make the gap between the two long boards adjustable, or you can just set the width of the gap and screw this board to the two short boards. The end result should resemble a tall and narrow letter O. You have now built a jig with an adjustable (or fixed) slot. Using one of your 8mm boards as a spacer, close up the gap between the long boards until it is snug against the 8mm board and then lock the jig width in this position. Now remove the 8mm board and position and clamp this jig in position across the board that you want to make the dado in. Using a router with a top bearing morticing or pattern cutting type bit with a smaller diameter than the width of the dado that you want to cut, set your depth of cut so that it will cut the dado through the fixture slot and into your work at the correct depth, and so that the top bearing of the bit will ride along the straight sides of the gap in your jig. Then make your cut moving first along the left side of the slot in your jig and then back along the right side. The completed dado that you just cut will exactly match the width of your jig and since you had just set this width by the thickness of your 8mm board, this 8mm board will now perfectly fit in the dado that you just made. One router bit will make any width dado, as long as it has a smaller diameter than the dado width that you need.

Charley

[Jim Becker]

Is infinity the old Jasada? While great bits their customer service leaves something to be desired.

No. They are not the same company.

[Don Abele]

Rob, I have the four-piece Freud set that Jerome mentioned. It works great.

The 4x4 multi-ply that I buy is listed as 18mm and the 23/32 bit works fine. It's not a super snug fit, but it's not sloppy loose either.

I just bought 2 sheets of 3/4" A/C plywood and - IT'S 3/4" THICK That was a real shock. It's from Georgia Pacific and is actually stamped 3/4. The 1/2" A/C I bought at the same time is GP as well and is stamped 15/32 (and that's what it measures). Weird.

Be well,

Doc

[Rob Hough]

Thanks for the replies all. I bought the 23/32 Rockler bit but it is just too sloppy loose for my liking. I'm going to build the jig Charlie suggests. That sounds like something I can utilize for quite some time.

Guess I'll need to get another router bit though... Now I see how people end up with 100's of router bits.

[Peter Quinn]

Somewhere on the Creek there is a great pictorial from Glen Bradley for a dado jig which is easy to build following his excellent directions and pictures. It requires a 1/2" plunge bit and a router with a template guide, I used a 3/4" OD template guide.

I had some cases to build using pre-finished plywood that could not be dragged over a TS top, and the thickness varied from .710"-.745" on the edges of horizontal dividers. Humm. Very visible joints with a slight taper that must fit tightly to avoid sight lines...what to do.

Use the Glen Bradly jig of course. I created perfect dados using a jig made from scraps and bits I already owned. Thanks again Glen.

My boss has sent 3/4" plunge bits to a grinder to match plywood thickness for a specific job, probably a spendy approach for shop cabinets. Have you checked Amana and Whiteside? Perhaps Festool? All deal more with European markets and may have an 18MM bit. Also check Onsrud, the kings of all things router bit.

Seriously though, Glen's jig beats the pants off of custom made bits or sloppy dadoes.

[Joe Scharle]

Thanks for the replies all. I bought the 23/32 Rockler bit but it is just too sloppy loose for my liking. I'm going to build the jig Charlie suggests. That sounds like something I can utilize for quite some time.

Guess I'll need to get another router bit though... Now I see how people end up with 100's of router bits.

I set this jig to use a 3/8 spiral bit so I can dado 3/8 to 4". It'll cover 34" for something like bookcase sides. I can't remember which mag I found it in, but will look if you're interested.
Joe

[Greg Sznajdruk]

You may look at the Dadowiz, I find it quick to setup and it will accomdate odd sizes.

http://www.sawmillcreek.org/showthre...d=5960&t=49964

Greg

[Peter Quinn]

Rob, Checked with my Amana dealer. Amana makes metric plywood bits in sizes 10mm-18mm for US routers (1/4" or 1/2" shanks).

Amana part numbers:

1/4" shank 18mm straight 2 flute plunge 45256
1/2" shank " " 45498

Each is around $20, my dealer sells online, of you want the link PM me, I think it might be a violation of service now to post it here. If you search these amana part numbers you may find other dealers on line. First rate bits.

I'm certain Onsrud makes them too, just may cost a bit more. Good luck.

[William OConnell]

I'm building some shop cabinets and have a need to route dado's in the ply. The sheets are 18mm thick and none of my bits are even close. Anyone know of a good 18mm router bit that I can get?

I guess my other option is to build some kind of jig and use a smaller bit. I really want to avoid that if I can though.

I'm curious if you have a tablesaw? Why not just use a tablesaw and a dado blade? Its much faster and for shop cabinets 1/64" isn't going to kill you it might even help with assembly. Once the tolerances get to tight assembly can go from a simple pleasureable task to a oh YIT my glues drying and this slightly warped plywood won't fit in my unbelievably tight dado. Just saying

[Rob Hough]

I have a tablesaw but it really isn't big enough to support the stock. If I thought I could make it work, I'd do it that way instead as it would probably be a whole heck of a lot easier.