Anyway to Neville, you mentioned the tightness of the joint and this was a question I asked yesterday on another forum before I glued it, but I had only one reply and I would have liked a few more just to be sure. I’m not sure I was completely satisfied with it but I took the advise and went ahead anyway.John the tightness of the joint is not really going to help that much, in fact if it is very tight then that hinders the correct spreading of the glue as a correctly glued joint has an even and all over coverage and a very tight joint will get glue in the bottom of the trench but up the sides may be a bit thin, IE the reason for the grooves in dowels is to let the glue run up the sides of the dowel hole, a proper join is not overly tight. Screws and nails are not really necessary with a trenched joint as a properly glued join that is clamped up after being set square and left to dry will not come apart. You have used good strong wood to to the clamp up but I would keep the clamps much closer in to the cabinet as out where it is then you can bend the wood. Don't think that I am picking on you as I am not, what you are doing with trenches and clamps is the real deal and I am happy to see it being done, I hope that you did get that unit set square before it dried as however it was when you walked away is how it will be forever. Neville
Thanks Charles, I’ve been thinking about the middle shelf and I thinking I am going to run some screws into the sides it just to be safe.That's going to be a nice unit when you are done. If you put 1/4 ply on the back you shouldn't need to use fasteners on the sides unless you got a poor joint because of what Neville described. I would say use the piece and if the joint should loosen then add screws to hold the joint together. BTW, I would use screws or dowels over nails. Nails resist shear forces but don't hold well where the force is trying to pull the joint apart. The joint would only loosen at the front, the back won't allow it if it is glued and nailed on (the brad nailer is perfect for that job).
The joint is too tight if you have to force it together when dry fitting. I would say that the proper fit is to be able to just get the panel into the groove with no force involved. If it is really close but still tight I usually sneak up on a good fit by either sanding the groove, especially to remove roughness and slivers, or to the end of the panel or both.
Ok, I’m now fully awake and smiling with my cup of coffee and slice of toast. I just realized while making my coffee that I said ‘Good morning’ and its probably good night for those of you downunder
Anyway to Neville, you mentioned the tightness of the joint and this was a question I asked yesterday on another forum before I glued it, but I had only one reply and I would have liked a few more just to be sure. I’m not sure I was completely satisfied with it but I took the advise and went ahead anyway.
This is the first time I have ever used a router to make dados and I did it with the aid of my brand new router guide.
I’ve been using dado saw blades for 30 years and I’ve always felt they might have been a little loose. This time with the use of the jig, I found that the dados were tight and held by themselves. Not so tight that I could not push them in by hand, but tight enough that they don’t fall out although I did have to tap them with my hand to get them in. If I had to use anything else like a mallet, I would have re-cut the dado. So do you think I’m OK with the tightness even though it’s a little late now?
As far as the clamping, I had one heck of a time with that because I was missing some clamps that I lent to my daughter and I also had an obstacle in the back. I decided that since my cabinet was to be in a corner and on wheels, I made the bottom protrude out in back so that it could not tip over when being pushed in to place with all the equipment on it. It will be pretty heavy with all the surround sound equipment and the speakers.
The only way I could find to clamp the top was to extend the surface out with boards and clamp away from the cabinet. If it had been at ground level I would have piled barbells on top.:laugh:
Oh and I did square it up with a small ratcheting tie strap although it was pretty square all by itself. It was only off about a 1/16 inch. I would have attached the plywood to the back at that point, but I forgot that the back was only up to the middle shelf and thought it would be in the way of the clamps. it wasn’t till latter that I looked at my drawing again and realized I could have done that.
Thanks Mike, I used an adjustable dado jig with a ½” straight router bit as shown in Post #10 so I was right on the money.While we're on that... As Neville noted, 3/4" ply is not 3/4"... it's 23/32" but people using a 3/4 dado bit (router) or setting a dado stack to 3/4" will get a loose joint... and wonder why.
Several ways to get around that:
- Use a plywood dado, which is marketed to be smaller, sized to plywood sizes. (I don't do this)
- Use a dado jig that allows for / adjusts to the thickness of stock and use a thinner router bit (like for 3/4", using a 1/2" or 5/8" bit), making one pass for each side of the dado, taking in consideration for the direction of travel. (This is the way I use if doing with a router).
- Use a caliper to get an average for the thickness. I don't assume the thickness of stock. I get too much changes in humidity here to assume that. Set the Dado stack to that thickness. Test with scrap and adjust if needed. That is what dado shims are for... (i use this if doing dado stacks).