Biscuit Jointing

[Iain]

Well, got my new toy and have succeeded in alignment of the same and I'm ready to go, almost...............
No reference to frequency of biscuits, obviously some of you can help having used these before.
I thought about one every 250mm but I am more than likely wrong, nothing with the instructions to show how often to place them or what size to use.
I thought this would be a fundamental instruction with the contents of the package but once again, wrong http://ubb.ubeaut.com.au/ubb/frown.gif
I intend joining 19mm Tas Oak that is 900mm long, tomorrow.
Any help and I promise I will contribute something I have been working on to the Woodies Jokes that is a personal attack on moderators and politicians as well as other public figures.

[Shane Watson]

Originally posted by Iain:

Any help and I promise I will contribute something I have been working on to the Woodies Jokes that is a personal attack on moderators and politicians as well as other public figures.

Geez, you expect my help & yet you warn me of an upcoming attack on my personality? http://ubb.ubeaut.com.au/ubb/mad.gif Your just lucky I have a sense of humor! sometimes http://ubb.ubeaut.com.au/ubb/wink.gif

Seriously though, I never really thought about distances between biscuits or dowels for that matter. But thinking back to yesterday when I joined up a couple of table tops I would have placed the dowels about 300mm apart on one and about 400mm apart on the other. For 900mm long stock I would probably only use three biscuits, (but four couldn't hurt). One in the middle and the other two about 60-80mm in from the ends. Anything longer I have usually always just spaced them evenly between the end ones and the centre one.

A lot of people that use biscuits only rely on them for lining up the joint, they don't seem to rely on them for adding any structual strength to the joint. Its an argument thats continually thrown around on some of the american boards. Its not something I have ever really thought about. Although I do place 90% of my faith in the adhesive used rather the the jointing method ( dowel, biscuit, nothing, etc )( excluding machining obviously, as without a very close fitting joint ain't much gunna help keep it together ). I use a two part urea formeldehyde (sp?) AV Syntec, and all tests I have performed with this adhesive has resulted in the timber breaking before the adhesive & the biscuits or dowels can only add to that strength in my opinon.... But then like you, I may be totally wrong! http://ubb.ubeaut.com.au/ubb/eek.gif

Cheers & Be nice now Iain!.....



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Shane Watson..

Combine Love & Skill & You Can Expect A Masterpiece!

[John Saxton]

Hi Iain, I remember quite distinctly reading on a recommended placement of biscuits when first using a biscuit jointer with the rule of thumb for 19mm thickness of a No 20 every 100-180mm apart.
I for one in using the above thickness in hardwood place the biscuits at about 180mm apart with No 20's.

With thicker timber 25mm and above and with 20 size biscuits I stagger the joints one up one down but 100 mm between centres.

It really is what you think is necessary in regards to strength in bonding the joint re thickness length and type of glue used.

Everyone will have their own opinion but your own knowledge and experience will be your guide.
One thing though and this I have tested is that with a good adhesive it's a rare occasion that the joint will break at the biscuit as it would on a mated flat surface.
The tests that have been conducted (I cannot remember when or where they were done) but I do remember that a phenomenal amount of pressure was required to actually snap a biscuit once jointed.
Cheers http://ubb.ubeaut.com.au/ubb/smile.gif

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Johnno

[RETIRED]

Gooday.

Freud in their manual suggest what John has said. http://ubb.ubeaut.com.au/ubb/biggrin.gif

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Ian () Robertson
"We do good turns every day"

[Iain]

Thanks for the input, I will try the 100-150 and I will be using Weldbond Yellow glue.....and clamps of course.

[Rod Smith]

G'day all
I can't see why anyone would use biscuits for panels. If you prepare the boards properly I can't see the need. I have done thousands of glue ups for tables, door panels, side panel etc etc, no dowells or biscuits and no failures. I do use splines occassionally for joining mel board or face frames to side panels.
I guess I have now joined 1 cat and one flock of pidgeons.
I look forward to your replies (from a bunker)
Cheers
Rod

[Iain]

I have heard all the stories of creep and decided to use biscuits to avoid the chance of this happening.

[Shane Watson]

Using a waterbased adhesive is the first no no in avoiding glueline creep. Biscuits ain't gunna stop that, not from my experience in the past, thats why I changed from waterbased to urea-formeldyhyde adhesive.

I scanned a section of my manual from my DeWalt. I havn't even read it before http://ubb.ubeaut.com.au/ubb/eek.gif until mentioned about a manual.

http://www.gatherround.com/j/View?File=viewpic.html&u=182500&a=202548&p=1000000000004281277&Sequence=1

That might be of interest to you. Frankly I reakon those distances are over kill. But to many is probably better than not enough.



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Shane Watson..

Combine Love & Skill & You Can Expect A Masterpiece!

[ubeaut]

Goodonya Rod - I also have done many table tops etc. over the years without the aid of biscuits, dowels, etc. In many instances I have not even used clamps but have opted for perfect planed edges and a rubbed joint with hide glue.

Have only ever had 2 tops come apart both were glued from the same glue bottle which contained a contaminated glue. (Manufacturer shall remain nameless but needless to say I have never used their rubbish glue since - matter of fact that particular glue is no longer available. Wonder why?)

To my way of thinking nothing beats a well executed hand planed joint. They take a bit longer to do but are equally as strong, if not stronger than dowel or biscuit joints.

There is nothing quite as satisfying as completing a rubbed joint with hide glue and knowing that the joint will probably still be together in 100 years time, while the machined joints will in many cases be struggling to make it to 20 or 30 years.

Another cat amongst the pidgeons. I hope they all flock off.

Cheers - Neil http://ubb.ubeaut.com.au/ubb/smile.gif

[Dennis Hill]

I just got myself a GMC joiner and did notice that there was a distinct lack of info on placement of biscuits. Thanks for all the info folks.
Cheers, Dennis.

[Marty Lott]

I too have recently purchased a GMC jointer...good for the price. I noticed today that Hardware House are flogging Ryobi jointers for $128.00 !! I notice too that Aldis Food Stores are also flogging powertools for insanely cheap prices.

Is it true that biscuit joints need to be glued up with a water based glue in order to make the bisciuts swell up ?

[Iain]

I have read that the biscuits swell when glue is applied and I noticed today that I had to tap biscuits in after they had been left in my garage. I suspect that this is due to the damp atmosphere at the moment and in future all my biscuits will be stored in an airtight container.
Unfortunately we don't have Aldis yet but I am sure it is only a matter of time.
I am using yellow glue (much to Neils disgust as he wants me to buy his foul smelling hide glue)and using sash clamps to join up boards.
I only wish I had more clamps as I have to wait for each panel to dry before I can progress to the next, I have well over 100 clamps but only 2 sash clamps.
Back to the biscuits, they seem to be a very soft porous wood and I can imagine them swelling when wet, I have no idea what the timber is but I am sure someone will let us know.

[ken yates]

BISCUITS are made of compressed beech wood.
They in fact do swell up and fill the slot from the moisture in the glue. And they will swell from high humidity and will be no good.
So keep them in an airtight container. Experience has spoken. http://ubb.ubeaut.com.au/ubb/biggrin.gif

[Iain]

Thanks Ken, experience has spoken, care to elaborate http://ubb.ubeaut.com.au/ubb/rolleyes.gif

[Marty Lott]

Thanks guys...looks like I've found a use for all my spare plastic feezer containers !

You can never have too many clamps, my favorite sash clamps are the aluminium ones made by Jorgenson,although have since found some Chinese ones that do just as good a job (so far) for nearly half the price.

[John Saxton]

Marty,you have truly whetted my appetite the plastic will know no rest.
With the choice open to you guys over yonder in that there Eastern 'Ol states itsa no bloody wonder 'Er indoors has marchin' orders down the track for us little'ol folk to be a'movin your ways.
Standin' orders decree that henceforth come the big 04 yours truly will have to summarily containerise all said sheoak/jarrah to thereby stand on a place to be appointed on the Eastern Seaboard!
Oh woe is me I'll have to grab the ol plastic even though too hot to handle and store up that there jarrah and sheoak to make the move worthwhile.
Cheers http://ubb.ubeaut.com.au/ubb/smile.gif


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Johnno

[Iain]

Does this mean you glue up old credit card to make airtight containers http://ubb.ubeaut.com.au/ubb/biggrin.gif
O4, will we still be here then? The way GST is affecting the price of everything now we well may be bankrupt by then.
And careful Johnno, (sotto Voce) your age may be showing http://ubb.ubeaut.com.au/ubb/wink.gif

[ken yates]

Originally posted by Iain:
Thanks Ken, experience has spoken, care to elaborate http://ubb.ubeaut.com.au/ubb/rolleyes.gif

[ken yates]

Originally posted by Iain:
Thanks Ken, experience has spoken, care to elaborate http://ubb.ubeaut.com.au/ubb/rolleyes.gif

Yes I lost an open package of 1000 bisciuts because I failed to keep them air tight and humidity got just about all of them.