Dovetail Jig and Splintering Plywood

Rich Aldrich

Member
Messages
296
Location
Manistique, Michigan
I am making drawers for a sewing center. I was going to use some birch plywood, but when I tried to router the half blind dovetails in the plywood, it splintered. I used several different speeds, which helped some, but it was hit and miss.

I have a PC 4112 dovetail jig and have used it before. All of the drawers I have made to this point with it have been solid wood. There have been no issues with solid wood.

Has anyone had this type of trouble with dovetails in plywood?

The other issue is that the dovetails are very tight. There are two guide bushings with the jig and I am using the larger diameter per the directions. I thought the smaller bushing is suppose to be used for the half blind dovetail.

Then, I tried to make a drawlock joint, but my plastic router insert has such a sag from my Freud FT2000E, that it is difficult to make a decent joint. I just ordered an aluminum plate. I remember arguing with one of the sales people from MLCS about the plastic plate when I bought the table from them, but they kept telling me that it wouldn't sag. The polymer chains creep over time and take a permenant set.
 
I wouldnt think you could do dovetail joints in plywood, but I could be wrong. Since the layers of the plywood go perpendicular to each other when the plywood is made, I would think chip out is going to be a huge problem.
 
Dovetails are so-so in BB ply but I doubt success in others. One method to stop tearout is a first light pass climb cutting. Another method is to sandwich the material between pieces of scrap.
 
I've cut alot of dovetails in 1/2" plywood and have found out that you need a sharp bit, you need to climbcut the dovetails first and then go back in the normal direction to make a fine finish cut and most important don't get in a hurry. The only tearout I get is on the vertical piece that is not supported by the horizontal piece in the jig.

As for the joint being to tight you just need to adjust the depth of your cut. A very small adjustment can make a big difference.
 
Thanks for the help guys. Alan, I was questioning the sharpness of my bit as I ran into the problem. I did notice that the slower I went, there was less tendency for damage. I need to touch up the bit, then try it again.
 
Rich here is a picture of one of the many drawers on my daughters bed.
116-1634_IMG.JPG
Depending on the slides you can hide the blowout with the drawer slide.
 
Thanks for the help guys. Alan, I was questioning the sharpness of my bit as I ran into the problem. I did notice that the slower I went, there was less tendency for damage. I need to touch up the bit, then try it again.

hey i thought them yuppers always moved slow:) and i would say alan has it figured out that pic says it all..
 
hey i thought them yuppers always moved slow:) and i would say alan has it figured out that pic says it all..

It's the normal hurry up and wait for da Yoopers, to, eh? :huh::D:rofl:. Yea, I think Alan is onto something.

This PC jig requires you to buy their special bit because no one else makes the 1/2" 14 degree bit like theirs. It doesnt mean it is the best bit. It isnt like a Freud bit, or CMT bit, or etc, where you move the router and the shavings fly almost effortlessly.
 
I bought a replacement at woodcraft made by whiteside.

The part # is D7-531 but I don't see it on their website anymore.

Found it listed with the pc dovetail jig instead of with the other router bits.
 
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OK, I give up using plywood for drawer sides. I tried using a drawer lock bit and birch plywood, but the inner plys bust out after routering with the drawer lock bit. I didnt try using the Whiteside router bit on the plywood - I figured it was going to be just another exercise of frustration.

I bought some pine to make the sides. The Whiteside bit worked very well in the PC4212 dovetail jig. I dont use it very much so I had to brush up on the tricks with the jig. They are coming out very good. Three are glued together and I am putting formica on the bottoms of the other two. Then, I will finish the other two drawers.

This has been an interesting learning experience.
 
hey i told ya that solide wood was better but yu wouldnt listen.. had to go decide to do it your self in order for it to be right:) there i feel better now and your wife told me to say this:):rofl::rofl::rofl:
 
I wish I knew what to tell you Rich.:dunno: I just used the 1/2" birch plywood from HD. I only had 1 or 2 minor tearouts but nothing the drawer slides wouldn't hide. Here are some pics of the drawers. 13 total here with another 19 in my daughters bedroom set I made her.
HPIM0547.JPGHPIM0550.JPG
 
I wish I knew what to tell you Rich.:dunno: I just used the 1/2" birch plywood from HD. I only had 1 or 2 minor tearouts but nothing the drawer slides wouldn't hide. Here are some pics of the drawers. 13 total here with another 19 in my daughters bedroom set I made her.
View attachment 33045View attachment 33046

I think it is bad plywood. It is supposed to be A-1 and the surface layers may be. However, the interior layers are not hardwood core and has hollows that are not filled in - maybe a litte light on the glue, also. I bought this plywood at Menards, because everyone else up here quite selling hardwood core in 1/2". Most of the 1/2" is beaver puke (MDF) core.

Also, I did not try the new bit on the plywood. I got the bit at Woodcraft in Appleton a couple of weeks ago.
 
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