Biscuit Jointing

[Bean]

Fellow woodworkers
I need some advice regarding Biscuit Jointing. I have a jointer but the slots appear to be oversize when cut. I have measured the thickness of the slot and compared it to the thickness of the blade, the two seem acceptably close, but as I said the finished slot is I feel too wide as the biscuit is a very sloppy fit. I can only think of two reasons for this:
1. Runout of the blade spindle.
2. Poor technique (most likely)

Any hints tips advice gratefully received Please !


Bean

 

[Adam]

3) UNdersize biscuits?

 

[thomaskennedy]

is the slot too thick?

if it is the width i had the same problem with my Ferm Biscuit Jointer but i found out from james (sawdustalley) that there is a little threaded bolt in which you fidle with untill its right

hope this helps


Cheers

Tom

 

[desmoengine]

if your blade was distorted or the spindle of the machine were bent this would cut an over sized slot. if what you mneasured was acceptably close that would discount this possibility.
if your technique was questionable ie movement vertically or radialyy whist cutting slot the result would be an oversize slot .

aslliech is probaly correct

have you tried dampening of biscuits to swell them slightly.

Dave W

 

[desmoengine]

memo to self must try to use spell checker
dave w

 

[Aragorn]

If the slot is only slightly oversized compared to the cutter, it implies a bit of practice on the old technique front!
Make sure the fence is very firmly held against the board both on the plunge and the release. Make sure you plunge in perfectly horizontallay as any up/down movement of your arm may cause the blade to wobble. I used to find that the withdrawal of the cutter was the easiest time for slight errors as the spring action can make it all wobble a bit.
Biscuits do vary slightly in width even from the same batch. If you get a few loose ones - don't worry! They are really just an alignment guide - the glue is what holds the joint. I don't even bother gluing biscuits any more.
A

 

[Adam]

Have you tried "wobbling" the blade in the joint after you've made the cut and the blade has stopped spinning - this should be a tight fit - if it wobbles, you could blame either technique or equipment. Have you tried removing the blade and putting it on a flat surface - to check it's flat? - If you can remove the covers/blade housing - can you spin the drive shaft and see it wobbling. Have you tried manually rotating the blade and watching for it wobbling?

Adam

 

[Bean]

Thanks All
I am going to check both the run out on the spindle and the flatness of the blade first. Then the thickness of the biscuits and then lots of practice.
Although I have noticed that there is some play in the slide mechanism which I shall endeavor to eliminate.................Fussy things Engineers !! :roll:

Bean