clamping question

[MarcW]

Hi all,

Gluing up a frame for a bookshelf, the first part of three, I encounter old well known problems. Dividing the gluing process helps surely but this step here is one and only - well I think. This way I already glued the side frames together. Now I will join them to 4 rails.

In order to have it all square, I fix the clamps the way its bar is parallel to the rail. That gives me squareness to all rails in this plane. Measuring the distance at both ends could look like this:

Then I orient the clamp square to the stiles. The bar should be parallel to the rail. I check this with a level, a bit like this:

My problem is how can I do all this four times in twelve minutes gluing included? I'd be very thankful for any relaxing hints. Surely clamps, glue, brush, gluing blocks and so on should be ready. But nonetheless I have this hyteric moments when gluing

Regards, Marc

 

[David C]

Set the clamps by eye first.

Get the joints closed.

Go back and adjust the clamps precisely.

Glue ususlly has a plastic phase before hardening when it is perfectly safe to make adjustments.

The main concern is too fast a grab, making closing impossible, or not getting both surfaces wetted by the glue due to skinning over after spreading. Double coating is good for this reason.

David

 

[woodbloke]

Also helps to have a cooler workshop as this lengthens the open time of the glue....nice collection of trinkets in the second photo - Rob

 

[engineer one]

surely marc it is easier to measure the squareness with a diagonal measure.

as d.c says get the initial bite all around, then check square and then tighten up properly.

the other thing is to use speed clamps, to do the initial clamping,
then having checked, replace one by one with screw clamps to ensure
proper pressure.

paul :wink:

 

[Bernhard]

Marc,

for jobs like this I have prepared some sqare plywood sheets. Three or four of them fixed in the frame should take care that everything is parallel.

I would not trust the measuring from the clamp to the frame as the clamp will be bending during the clamping process.

Nice progress of your work.

Best regards
Bernhard

 

[CONGER]

Marc... cool down the workshop, or take the kit outside (10C here in Munich today)... and use a slower glue... e.g. LV Fish Glue... best I have found so far...

 

[jasonB]

I wouldn't be happy measuring off the clamps even if they were true and level any error in the tennon shoulders will throw the joint out and as has been said the bars will flex and twist as tightened. I also assume the base you are assembling on has been checked for level otherwise the clamps will not be at parallel to the frame rails.

Checking the diagonals is the best way to go especially as the items get larger, I did a 6'x7' shelf unit in the week, got the diagonals were spot on before fixing the back, would have been difficult to do to the same accuracy with a level as the bubbles are not accurate enough.

A slower glue will also help.

Jason

 

[MarcW]

Hi all,

First thank you all for your good advice. I've done the job right after Rob's post, so I took profit above all of David's post.

David, the description of the steps helped very much. I guess I needed a plan.

Rob, workshop temperature was then at 15°C. Thanks for reminding me.

Paul, Jason, I don't measure squareness with these rods for diagonal checks, because looking at one diagonal shorter than the other, I don't know how much and where to move the clamps. I never read in any book and never made any thoughts about. Maybe I should give it a go.

Gerard, thanks for the hint of the glue. I'm looking now since a moment for some long open time glue. It seems I have to place an order, maybe with a router, so my bad conscience will be a little teased. ](*,)

Bernhard, I now know what you meant. BTW I measured distance clamp bar to rail at both ends of the clamp so the bow in the middle didn't bother me much.

Looking forward to gluing part two tomorrow and part three when the new sash cramps will arrive hopefully thursday or friday. Again thanks alot, Marc

 

[engineer one]

marc, i always look for using the longer edge as the reference, and then
move it to the shorter side, mark with a pencil, and then measure the difference. half that is what you need to move the whole unit by to get it square.

so if one diagonal is 2mm longer than the other, a nudge of 1mm will get it all square. the other thing is do a little trigonometry, and decide what the diagonals should be, then make your rods to fit.

so it says here :lol:

paul :wink: