Advice on using a Postform jig

[ike]

I might need some advice here.

I bought a jig cheap a while ago with the intention of practising on my own kitchen, but that's been put back. Now I've agreed to fit some worktop for a friend but haven't practiced yet and the jig came with little in the way of instructions.

I've got to go and get a 30mm guide this week and I should be ready to have a go. If I run into any problem I hope I can draw on some professional expertise!.

First, several questions - If you use the clamp type joiners, do you still use biscuits to keep the joint flush?. Is the joint glued? If needed, do you apply the coloured filler before you clamp up the joint or after?

I'll keep in touch as I go. Thanks in advance

Ike

 

[Ian Dalziel]

Ike,
re;- biscuits are used to try and keep it level whilst pulling the two sections together sometimes depending if you have larder units etc and are hard up against them you cant get biscuits in you will need to rely on the joining bolts, i sometimes screw on a plate on the underside of the worktop to help level if i cant get a biscuit in.

depending on what type of worktop joining compound you use this should be suffix to seal, trend etc are sealants as well so no need for anything else. Apply the compound on one face the full length slightly in favour of the upper half of the join before you draw your bolts up and have a clean damp cloth ready for clean-up as it goes off quite quick

when cutting the postforms always remember to work the router from left to right;always start from your postformed face, this might mean the you are cutting it the right way up or upside down, the important bit is starting to cut from the postformed edge. take small cuts i normally do it in 4 cuts for a 40mm top.

when you rout out for bolt slots you can adjust the positions to work around akward carcasses

if possible postion your worktops albeit slightly oversize and draw on the underside where you want your postform to be, the fact its oversize it might give you 2 hits at it (male cut)

be careful when working near a sink or hob so as to leave enough meat on the worktop to allow for joining bolts

hope this made sense and was of help

Ian

 

[Neil]

Hi Ike,

You might find the user manual for the Trend jig useful:

http://www.trendmachinery.co.uk/library/Instruction_Manuals/combi66man.pdf

NeilCFD

 

[ike]

Ian,

Thanks for that- no substitute for experience I guess!.

Neil,

I downloaded it and will have a readthrough tonite.

cheers

Ike

 

[Anonymous]

Hi Ike,

Don't know if you read our mag, but I did a walkthrough on using a budget jig on pages 56-58 Good Woodworking issue 148 if it's any help.
The principle is the same for all types of jig though, so the Trend info should see you through it OK if you don't read us!

cheers,

Andy

 

[ike]

Andy,

I 've got a confession - I've never read any of the mags, unless my Dad bungs me the odd back issue!. So I can't lay my hands on your article, but thanks very much anyway.

best regards

Ike

 

[Anonymous]

One thing to be aware of when joining worktops - the corners of rooms are rarely square, so you'll need to take that into consideration when you cut the joint.

With regard to biscuits, my experience has been that sometimes the biscuit doesn't line up perfectly, so when you make the joint make sure the two surfaces are perfectly alighned. If they aren't, break the joint and reassemble. There's usually nothing wrong, but the biscuit may have swollen slightly out of shape after you've applied the glue.

You can't fix this problem once everything is glued up, so it has to be done right whilst the glue is still wet.

Andrew

 

[johnelliott]

I prefer to avoid biscuits altogether. If the slots have been cut absolutely perfectly then OK, but otherwise they force the joint out of line and stop you doing anything about it. Quite often worktops have a slight curve front to back. On a right angle joint this means that the middle of the joint on the male side will be slightly higher than the front and back. If you have not used biscuits it's sometimes possible to push it level.
I think that if you are using good connectors and tighten them properly then biscuits are simply not necessary.
Another thing, make sure you router cutter is sharp, ideally use a brand new one.
John

 

[ike]

I've got a brand new CMT cutter. Perhaps it'd be better if I just use the biscuits dry rather than glue them? That way, if theres a problem with bowing, I can resort to plan B (whatever that is).

Ike

 

[Anonymous]

There's not much point using dry biscuits. They are designed to swell when glue gets at them.

You can glue and clamp up, and if the joint isn't perfect it's easy to unclamp and remove (or reseat - that often works) whilst the glue is still wet.

Andrew

 

[ike]

Andrew wrote:

There's not much point using dry biscuits. They are designed to swell when glue gets at them.

I know, and in other applications the biscuit contributes to physically hold the joint faces together partly by virtue of it swelling. In this application however, it only needs to vertically locate the faces. Dry biscuits are quite a snug fit (at least they are in slots made by my biscuit jointer). The clamps are holding the joint together n'est pas?.

 

[Anonymous]

Not just the clamps - that whole section should be glued with PVA IMHO. Reason being that it stops damp migrating into the worktop.

Same trick in the hole you cut out for a sink - the entire rim of the hole which the sink drops into should be PVA'd to give a barrier against damp.

Andrew

 

[johnelliott]

I've had good results painting the cut edges with water-based paint (Dulux). This has the useful characteristic of sticking to similarly painted surfaces that it comes into contact with but slowly (a few hours). Might be a useful trick if you are working on your own and can't be sure of getting everything just right in the time PVA allows
John

 

[ike]

Andrew,

If I glued the whole face except biscuits, that'll be OK won't it?. If theres a vertical misalignment I can get it apart more easily.