Glue/Clamp Problem

[IBBugsy]

Well, I'm starting my first "big" project - Wood Magazine's Drop-Leaf Mobile Workbench.

Going over the plans, one step has me puzzled?

Take a look at the picture below. I'll have two side panels with matching dados and grooves for the shelves and dividers. The horizontal shelves are one piece (go from front side to back) while the vertical dividers fit between the shelves.

The instructions say "Glue and clamp the shelves and dividers between the side panels, checking for square."

Frankly, I don't see how I can do this? I'm assuming you put everything together and clamp the entire unit? Should I try to do one piece at a time? I expect whatever I do will be wiggling all over the place!

[LCHIEN]

you have to do it at one time. Your working time for the glue will be about 20 minutes or less. you need to get it glued, fitted, and clamped square in that time.
Dry fit ahead of time. It'' be a little harder to dry fit as they'll be falling all over, the glue will help hold in place better.
You need some squaring clamps or accessoroies at least in a couple of corners to keep the whole thing square. Rockler and other sell some or you can make then yourself.

http://images.rockler.com/rockler/images/29190b-md.jpg

[LarryG]

Adding to what Loring said about dry fitting ... part of this process is checking to make sure eveything fits together properly, but an equally important part of it is to work out your clamping strategy. Sometimes things can only go together by following a specific sequence that may not be readily apparent when all the parts are neatly stacked in a pile, awaiting assembly. All this will become immediately apparent as you do the dry "dress rehearsal" of the glue-up and figure out what pieces have to go together when, what clamp lengths will be needed, where they'll be able to get a purchase, etc.

[cabinetman]

Dave

The drawing didn't show the shelves, and whether they are dadoed for the verticle dividers. In any case, with the info given, assemble the whole shebang at once with glue where it goes, and have it standing on a flat surface. Set the clamps on the ends where the shelves intersect the ends, and at the top, where the divider meets the ends. You may have to bump with your hand or a rubber mallet on the ends to seat the shelves in the dadoes. Once clamped up, check it for square in two directions. If there is movement, tack on a brace on the top of one end over the divider to the other end on an angle, to keep it square. If your dadoes are a snug fit (but good) it should hold its position until dry. Adding brads, nails or screws at this time is up to your discretion.

In the future, when designing your own with this type of multiple pieces, consider making the ends and divider run full, or to the floor of the cabinet, and have the shelves slide in, if it is too large or bulky to glue up all parts at the same time. I prefer to have downweight supported in the middle of the cabinet by panels of one piece.



"I'M NEVER WRONG - BUT I'M NOT ALWAYS RIGHT"

[IBBugsy]

The drawing didn't show the shelves, and whether they are dadoed for the verticle dividers.

They are not dadoed. If I do dado them, that would cut 1/4" above and below for the dividers and the shelf would have 1/4" remaining between the two dados. Is that a problem?

In the future, when designing your own with this type of multiple pieces, consider making the ends and divider run full, or to the floor of the cabinet, and have the shelves slide in, if it is too large or bulky to glue up all parts at the same time. I prefer to have downweight supported in the middle of the cabinet by panels of one piece.

I don't see why I can't change the design and do that now. Have one long vertical divider and cut the shelves to fit into dados in the divider. However, the divider would have only 1/4" thickness between the dados for the shelves. Would that make the vertical divider too fragile??

[IBBugsy]

Thanks for the help!

"Squaring clamps or accessories" - Been mulling this in my mind. Good excuse to get some.

"Dry fitting" - Been definitely planning to do this. I hate having a "time limit" put on me so glueing is something I always worry about.

The other thought I had was, once I dry fit everything and get it all square and clamped, why not just screw the thing in place? I'm trying to resist this urge. I need to "upgrade" my woodworking skills and this would just be a cowards way out. Plus I expect it would not be as sturdy/secure with just screws. Ya gotta "Grow Up" sometime!!

[cabinetman]

Dave

If you dadoe the shelves for the verticle dividers, then you have to add for the depth of the dadoe to the dividers. If you do a sketch of your own (like an explosion drawing) for your worksheet, you might not get screwed up when to add or subtract measurements.

As far as that 1/4" between dadoes, if you have a good seat of both inserted pieces, when dry, its a good glue joint. Handling the sheet before assembly can be a problem if you bump it or drop it. If you have a good clean fitted dadoe, you could go with 3/16" depth, which will increase the middle to 3/8" . If you get glue on the sides of the dadoe, that helps that joint incredibly. The 1/4" dadoe makes for easier figuring of panel sizes for us math impaired, than 3/16".

A little glue tip here. Put a thin coat of glue on the bottom and sides of the dadoe. Put a thin coat on the bottom of the inserted piece. Also put a tiny glue line 1/8" along the side edge of the inserted piece. If it was only on the edges of the dadoe, it would get scraped down as the piece gets inserted. This way as the piece gets inserted the glue gets pushed up the side a bit on the inserted piece.



"I'M NEVER WRONG - BUT I'M NOT ALWAYS RIGHT"

[IBBugsy]

Thanks again for the gluing tips.

I do have a set of bits specifically designed for plywood dadoes so the fit should be great. They are slightly smaller than the nominal sizes.

Part of my mind expects that when I get all the pieces put together, the design itself will keep things in place as long as I have a few clamps strategically placed (and maybe a few of those squaring assists). The dry run will tell me if this is true.

[LCHIEN]

Thanks again for the gluing tips.

I do have a set of bits specifically designed for plywood dadoes so the fit should be great. They are slightly smaller than the nominal sizes.

Part of my mind expects that when I get all the pieces put together, the design itself will keep things in place as long as I have a few clamps strategically placed (and maybe a few of those squaring assists). The dry run will tell me if this is true.

Don't assume that the "plywood bits" match the plywood you actually have. Measure and make sure! Sometimes they don''t make plywood to the expected dimensions even the smaller than expected dimesnions can be off. Better find out now that later.
Again, calipers are the perfect tool for this kind of measure because it has "stops" on both ends, prevents ruler alignment errors on sub-inch measurements.

[jabe]

I would do as cabman suggest, I'm for having a one peice vertical panel go all way to the bottom for better support. If that is not possible cause the vertical panel will not be in line then I would dado the top & bot of the shelves to accept the vertical panels so it can be inserted after the shelves and side panels have been glued, clamped and squared.
Another way would be to use screws and plug the screw holes with a wood plug of the same species of wood or to give it contrast use another type of wood it'll look like a doweled joint. You can eliminate using dados and soo many clamps. I would layout all the screw holes spaced evenly, countersink it with a 3/8" brad pt. drill @ 3/16" deep then drill a 9/32" pilot hole in the center of the countersunk hole that's the reason for using a brad pt. drill frist. Use a 3/8" tapered plug cutter and make your plugs from scrap wood species of your choice. I would still use a thin layer of wood glue between the joints for added strength. I found glueing the plug with clear 5 min. epoxy is best, less of a glue line and it'll cover up any tearout from drilling the countersink hole. Use a plug cutting saw to cut the plugs and sand. Note when drilling the countersink hole it's best to use a DP and go slowly into the wood, give the drill time to cut through the 1st layer of wood to get a clean hole. If you don't have a DP, suggest you use a 3/8" forstner bit instead of a brad pt. drill. It'll give your projects an old craftsman look instead of nail & putty look. I know there is a tapered dowel kit that would eliminate the screw & plug but then you would have to purchase the tapered dowel & tapered drill bit from them exclusively. Don't know the cost comparison? It might be a better alternative.

[IBBugsy]

Thanks again!!

I like the idea of making the vertical divider one piece and cutting the shelves instead. Makes sense to my engineering brain. I also have been contemplating using screws to make the final gluing easier.

I'm not worried about looks for this project since it's my first big project and will be a "working" bench for me. However, I do want to try learning some new things. I've never used a router before so that's part of my new learning. Getting everything fairly square is also new to me (was always sloppy about this in the past). Gluing/Clamping is also new since I would just use nails/screws for everything in the past. Even using a table saw is new to me (rather than a circular saw).

So, once I get my dry fit together, I expect I'll figure out that a few choice screws will be helpful when I do the final gluing.

[Tom Miller]

I used to glue everything at once, but for the last few projects I've been gluing in increments. I really like this approach better, and I think I'm getting better results, but I'm sure it takes a little longer.

The general idea is to glue parts starting from the inside. I use plenty of homemade squaring blocks, leaving one side of the block attached to one of the pieces after the dryfit, so it's in place for the glue up. After applying the glue and fitting, I dry fit the other pieces around the glued piece to make sure they'll be aligned when it's their turn.

I leave these pieces to dry for ~1hr, and then go to the next joint. At this point, the glue is holding well enough, as long as the joint is not stressed.

If you have time for this approach, it's worth thinking about.

Regards,
Tom

[meika123]

I cannot stress too strongly to make sure you have a good, snug fit of the shelves in the dadoes. It will make this job much easier-believe me.
Watch Norm, and how he fits dadoes. It will really make a job easier to glue up when the shelves will stay in place.
HTH

Dave in NC