How parallel are the parallel clamps

[woodworkingMK]

I am using pipe clamps for gluing up boards or frames, and they tend to bend the glued piece.

I was wondering, if I invest in Bessey parallel clamps, will this problem be avoided easily?

I was wondering how parallel they really are?

On the video they claim that they stay parallel no matter what or where, is that true? https://www.youtube.com/watch?v=d4NtGGNnANw

 

[Myfordman]

I think you need to improve your technique rather than change clamps. Don't do them up so tight and fit them on alternate sides of the job.

 

[Beau]

All clamps will bend just strong ones less so than weak ones. I use cramp heads on 2x1 wooden bars and yes they bend a bit. To allow for this with small panels once it is lightly clamped up I reset each one so the bar is no longer touching the panel. This allows the bar to bend without influencing the panel. On large wide panels I do much the same but set so the panel will just touch in the middle of the clamp bar but be set a touch up at the heads. Best way is just to put a straight edge over it once clamped to se what is happening and adjust as need be.

 

[memzey]

The bessey parallel cramps are very good and the jaws do, more or less, stay parallel during glue up. I still tend to use bearers and cauls to get a truly flat surface though and imagine you could do the same with your own cramps:

 

[custard]

I am using pipe clamps for gluing up boards or frames, and they tend to bend the glued piece.

I was wondering, if I invest in Bessey parallel clamps, will this problem be avoided easily?

I was wondering how parallel they really are?

I use Bessey's, but I don't trust them, or indeed any other sash cramp, to remain perfectly square and parallel. It's not just the "shoes", it's also that the "spines" of all sash cramps (including pipe based versions) bend upwards once the pressure is increased.

There are lots of solutions, but the ultimate answer for the very best results is to use bearers so that the workpiece never touches the spine, and shaped cramping blocks. You can read more about it here,

how-to-edge-joint-t112936-30.html