How to attach case back?

[LCHIEN]

quote:Originally posted by Les

Loring,

Thanks for the detailed description! Very helpful! I particularly like how rabbeting the case top and sides fixes the rabbets showing from the case back. However, I don't have any big clamps so I was planning to assemble the case using pocket hole screws on plain ol' butt joints. Is it a good idea to run screws through the type of joint you are describing?

And, one more really basic question...how do I make a sacrificial fence? I have seen pictures that show three pieces of ply cut to fit snugly over the rip fence. Does it need to be bolted on? Also, to make the cutout to by able to bury the dado blades, do I just turn on the saw and raise the blade into the sacrificial fence? Seems like I might risk chewing my real fence...

(Clearly not faking that I am a newbie...!)

Les

It would be a bad candidate for pocket joints because the joint will be right where the screw goes into. Pocket holes are just butt joints with a special holding fixture to put the screw in from the inside.
Also a bad candidate because on a bookcase, the pocket screws would be visible since the inside of a bookcase is normally vieweable.

I personally would glue the joint, then clamp it leaving the clamps on for a couple of hours or overnight, or, better,
Glue it clamp it, brad nail it, then remove the clamps.

To clamp the corner joints, miter clamps are nice, or these clamp-its from Rockler:

http://www.rockler.com/ecom7/product_details.cfm?&offerings_id=10112&objectgroup_id=525&catid=80&filter=clampit

they're $10 bucks each but I made my own from 2x2 stock carefully joined and squared. BTW, I hear Rockler has free shipping (see bargain alerts) thru Dec 15 or so.

Re: sacrificial fence. I used T-nuts and a bolt, Countersunk the head of the 2 bolts into a 1x4 x 24", put the t-nuts in the fence.
Very solid and secure.
The bolts at the height of the slot, a few inches from the ends of the rip fence (to keep it well away from the blade). The countersink makes sure the bolts don't interfere with stuff passing by. 1/4-20 bolts if i recall, drill a 1/4" thru hole and a 5/8" concentric hole 3/8" deep for the countersink.

[Black wallnut]

For a newbie it might be best to just raise the blade into the sacrificial fence. The reason for firmly attaching the sac fence to the rip fence is to avoid creating a dangerous kickback. For sacraficial fences I just use a long piece of plywood scrap that is ripped to about the height of the rip fence.

You can make your own case clamps with a few boards of solid wood that are longer than your case is tall or wide. All you have to do is screw or glue and screw blocks near each end and use a wedge between the block and your case. Make sense?

sorry for all the typos![:I]

[Les]

Mark,

Thanks for the suggestion on the sacrificial fence. And the homemade case clamps are a great idea. I know I should get some real clamps but I am saving for more power tools...

Les

[Les]

Hi again,

With all your suggestions, I was able to make the sacrificial fence and cut my very first rabbets. Oooh the Freud dado set sure does make nice square cuts!

One lesson learned though: I raised the blade into the sacrificial fence about an inch thinking more clearance would be better. When I actually went to make the 3/8" rabbets I was wishing I hadn't cut so much out of the fence. More support would have made me less nervous about catching the edge of the fence cutout while moving the stock past the blade on the far side. (Don't know why I didn't think about the zero clearance throat plates...)

Now that I have successfully made regular rabbets, I am wondering is it possible with the table saw to make a rabbet that is stopped on both ends?

As always, thanks for for all your wonderful advice!
Les

[LCHIEN]

quote:Originally posted by Les

Hi again,

...
Now that I have successfully made regular rabbets, I am wondering is it possible with the table saw to make a rabbet that is stopped on both ends?

As always, thanks for for all your wonderful advice!
Les

Not really, they get very, uh, ramped.

[MileHigh]

To Glue or not to Glue? and if not to Glue, how much expansion clearance to allow? I need a sanity check (for how to attach cabinet backings).

I am doing 3/4" Melamine kitchen Island cabinets w/ 5/16" dowels. The first two cabinets I have done have had 3/4 Melamine inset backs for rigidity, again fully doweled. I also route out a thin strip off of the Melamine surfaces between the dowel holes. Most glues don't stick very well to Melamine.

The next set of cabinets don't need the killer rigidity and I want to use 1/4" hard board (BORG) that has one side covered with a Melamine laminate for the cabinets backs. The hard board will be slipped into some router pre-cut slots in the 3/4" cabinet box. Hopefully standard stuff.

The question is do I allow the hard board to float? Tack it in with brads? or can I glue it? I am very concerned about expansion of the hard board. There was a warning installation sticker on the back that talked about leaving extra clearance around the hard board when installing them as wall panels to allow for expansion. These are going into a kitchen island, so it is going to be very difficult to
repair. I plan to seal the unpainted side of the back with a non-breathing paint.

I live in Colorado and run an evaporative house cooler in the summer. In the winter, the humidity is the north side of 0%. I have a pre-primed BORG six panel door that was never installed sitting in a back room that is showing 3/16" contraction on one of the inner panels.....

Concensus so far in this thread seems to be to glue.

Was watching some back episodes of Norm on Yankee Workshop. He didn't glue the Melamine hard board backs into place.

Thanks,

Nick

[JimD]

Les,

You might want to use hidden screws through the face of the top and bottom to build you cabinet. You can use short lengths of 3/8 dowel to plug the hole (you have to recess the screw for the dowel) or get a plug cutting bit for your drill press (I wouldn't use it hand-held) and cut them from a scrap. You will be able to see where the screws are but if you space them evenly and sand them flush I don't think they look too bad. Then you don't need clamps.

Nick,

Glue the back on. The thin back of a kitchen cabinet is what keeps it from racking. You can get melamine glue but it is stronger to cut a shallow rabbett to eliminate the melamine in the joints. For the back I would probably use melamine glue and brads (assuming it doesn't show). The only drawbacks I see to melamine glue are; it sticks to everything (including you) and it has essentially no give before the glue joint breaks - it isn't as strong.

Jim

[MileHigh]

So make a shallow cut in the 1/4 backing with a router to expose the MDF underneath for a normal glue joint.

For grinns, do you have any links, brand names and where to buy Melamine glue?

[LCHIEN]

quote:Originally posted by MileHigh

So make a shallow cut in the 1/4 backing with a router to expose the MDF underneath for a normal glue joint.

For grinns, do you have any links, brand names and where to buy Melamine glue?

Franklin Int'l 4014 Titebond Melamine glue.
Available at Amazon.
But couldn't find in the on-line pages of Lowes of HD - doesn't mean they don't have it.

[mater]

quote:Originally posted by Tom Hintz

I also would rabbet it and set the panel in. Rabbets are quick and easy and the job turns out looking way better and you get the anti-racking strength to boot. I usually glue the panel in and shoot some staples in also. (Just to tick off the anti-staple/brad crowd).

I also do it this way using a stapler. I don't glue mine though. I do add a couple of screws thru the back if I have a stationary shelf.