Hi All

Having problems with putting screws into the edge of 18mm MDF.

I've tried correct size pilot holes and special MDF screws from SPAX but I 
still get splitting and a slight bulge where the screw is.

Special MDF screws are best (or least worse) but still noticeable.

Any tips?

Dave

david lang wrote:

> Hi All
>
> Having problems with putting screws into the edge of 18mm MDF.
>
> I've tried correct size pilot holes and special MDF screws from SPAX
> but I still get splitting and a slight bulge where the screw is.
>
> Special MDF screws are best (or least worse) but still noticeable.
>
> Any tips?
>
> Dave


If its possible clamp 2 pieces of wood either side of the MDF where the
screw/s are being inserted.

david lang wrote:

> Having problems with putting screws into the edge of 18mm MDF.
> 
> I've tried correct size pilot holes and special MDF screws from SPAX but I 
> still get splitting and a slight bulge where the screw is.


Either don't, find another way to do it, or use a
tap (which you could make out of a screw), with
clamping as suggested by "ben". I guess
drill'n'fill'n'screw would be fiddly.

On Sun, 18 Sep 2005 19:42:58 GMT, "david lang"
 wrote:


>Having problems with putting screws into the edge of 18mm MDF.


That's because you can't.

If you absolutely must, drill and glue hardwood plugs in there. Ideally
drill the plugs through the face perpendicular and screw across them,
like a wooden knock-down barrel nut.

Don't do anything to MDF that puts a tensile force across the
laminations. It might not delaminate today, but it will do.

Andy Dingley wrote:

> On Sun, 18 Sep 2005 19:42:58 GMT, "david lang"
>  wrote:
>
>> Having problems with putting screws into the edge of 18mm MDF.
>
> That's because you can't.
>
> If you absolutely must, drill and glue hardwood plugs in there.
> Ideally drill the plugs through the face perpendicular and screw
> across them, like a wooden knock-down barrel nut.
>
> Don't do anything to MDF that puts a tensile force across the
> laminations. It might not delaminate today, but it will do.


Heh! MDF does not have laminations, its compressed  fibres.

david lang wrote:

> Hi All
>
> Having problems with putting screws into the edge of 18mm MDF.
>
> I've tried correct size pilot holes and special MDF screws from SPAX but I
> still get splitting and a slight bulge where the screw is.
>
> Special MDF screws are best (or least worse) but still noticeable.
>
> Any tips?
>
> Dave


If youre screwing with MDF youre screwed already. Use something decent

NT

In article <GkkXe.111036$G8.35878@text.news.blueyonder.co.uk>,
   ben  wrote:

> > Don't do anything to MDF that puts a tensile force across the
> > laminations. It might not delaminate today, but it will do.

> Heh! MDF does not have laminations, its compressed  fibres.


Still delaminates, though. ;-)

-- 
*He's not dead -  he's electroencephalographically challenged

    Dave Plowman        dave@davenoise.co.uk           London SW
                  To e-mail, change noise into sound.

ben wrote:

> Andy Dingley wrote:
>>Don't do anything to MDF that puts a tensile force across the
>>laminations. It might not delaminate today, but it will do.
> 
> Heh! MDF does not have laminations, its compressed  fibres.


It splits quite easily into thinner bits. Take, say, a 12"x1"
bit of 1/2" MDF. Flex it severely, and see how it breaks.
You know how your finger-nail sometimes flakes? Same thing.

david lang wrote:

> Hi All
>
> Having problems with putting screws into the edge of 18mm MDF.
> Any tips?


Drill 2mm holes and use panel pins with a smear of glue on them.

In article <GkkXe.111036$G8.35878@text.news.blueyonder.co.uk>, 
allo@h.co.uk says...

> Andy Dingley wrote:
> > On Sun, 18 Sep 2005 19:42:58 GMT, "david lang"
> >  wrote:
> >
> >> Having problems with putting screws into the edge of 18mm MDF.
> >
> > That's because you can't.
> >
> > If you absolutely must, drill and glue hardwood plugs in there.
> > Ideally drill the plugs through the face perpendicular and screw
> > across them, like a wooden knock-down barrel nut.
> >
> > Don't do anything to MDF that puts a tensile force across the
> > laminations. It might not delaminate today, but it will do.
> 
> Heh! MDF does not have laminations, its compressed  fibres.
> 

And those fibres are oriented in such a way that they effectively form 
layers which will easily split apart.

In article <6rjXe.1975$Rv1.1036@fe1.news.blueyonder.co.uk>, 
davidlang@nospamblueyonder.co.uk says...

> Hi All
> 
> Having problems with putting screws into the edge of 18mm MDF.
> 
> I've tried correct size pilot holes and special MDF screws from SPAX but I 
> still get splitting and a slight bulge where the screw is.
> 
> Special MDF screws are best (or least worse) but still noticeable.
> 
> Any tips?
> 

Don't screw into the end grain - either use glue with proper cut joints 
or dowels, or metal plates or wooden battens with screws.

On Sun, 18 Sep 2005 20:44:22 GMT, "ben"  wrote:


>Heh! MDF does not have laminations, its compressed  fibres.


MDF is pressed in sheets, rather than rolled. The pressure is applied in
one axis and so there are two strong tensile directions and one weak
one. You can (pointlessly) argue the semantics of "laminated" and
whether it means that such a material _must_ be formed by laminating
flat sheets together, but the simple upshot is that MDF has inbuilt
planes of weakness and disassembles into laminations, no matter how they
were formed.

Thanks for the input chaps.  No magic bullet then.......

Plan 'B'.

I'll try cutting a 6mm deep dado in the sides & screwing through from the 
outside - hopefully the tight fit of the shelf in the dado will stop the 
splitting.

I'll try that tonight & report back!

Dave

On Sun, 18 Sep 2005 20:44:22 GMT, "ben"  wrote:


>Heh! MDF does not have laminations, its compressed  fibres.


Slightly OT..

It's worth mentioning that it is now thought that dust from some types
of MDF *could* be carcinogenic, due to the glue used to bond the
fibres.

It's therefore very important to wear a face mask and cut it in a well
ventillated area.

sponix

david lang wrote:

> Thanks for the input chaps.  No magic bullet then.......
> 
> Plan 'B'.
> 
> I'll try cutting a 6mm deep dado in the sides & screwing through from the 
> outside - hopefully the tight fit of the shelf in the dado will stop the 
> splitting.
> 
> I'll try that tonight & report back!
> 
> Dave
> 
> 


I've built mdf shelving with Scewfix Powerdrive carcass screws, straight 
into the end grain with no pilot hole. As long as you're dead centre, 
and at least 2" inches from the edge, you should get away without 
bulges. Boxed in 1000s, so not something you can try out easily. Maybe 
B&Q Warehouses would have something similar in smaller packs. I've never 
had much luck with "mdf screws".

On Sun, 18 Sep 2005 19:42:58 GMT, "david lang"
 wrote:


>Hi All
>
>Having problems with putting screws into the edge of 18mm MDF.
>
>I've tried correct size pilot holes and special MDF screws from SPAX but I 
>still get splitting and a slight bulge where the screw is.
>
>Special MDF screws are best (or least worse) but still noticeable.
>
>Any tips?
>
>Dave 
>


Hi,

Have a look at the woodfit site, they have loads of fixings for this
sort of thing, eg:

<http://www.woodfit.com/product_info.php?cPath=16&products_id=1184&Name=Chipboard+Fastener+-+12mm+-+Nylon>
<http://www.woodfit.com/product_info.php?cPath=16&products_id=185&Name=Confirmat+Screw+-+7+x+50mm>
<http://www.woodfit.com/product_info.php?cPath=16&products_id=176&Name=Hi-Lo+Screw+-+8+x+55mm>
<http://www.woodfit.com/product_info.php?cPath=14&products_id=161&Name=Barrel+Nut+-+plastic+-+Beige>
<http://www.woodfit.com/product_info.php?cPath=14&products_id=171&Name=Klix+Cam+for+15+to+17mm+board>

Also some good tips here:

<http://www.canadianhomeworkshop.com/toolbox/toolbox_mdf.shtml>

If just a few holes I'd try giving the screws a good coat of molten
wax then dropping them in oversized pilot holes filled with epoxy.
After the epoxy has set the screw should home out (hopefully!) and
allow the other bit to be fastened on securely. Would need trying on
some scraps first though.

cheers,
Pete.

In article <RPuXe.77594$2n6.28312@fe3.news.blueyonder.co.uk>, 
davidlang@nospamblueyonder.co.uk says...

> Thanks for the input chaps.  No magic bullet then.......
> 
> Plan 'B'.
> 
> I'll try cutting a 6mm deep dado in the sides & screwing through from the 
> outside - hopefully the tight fit of the shelf in the dado will stop the 
> splitting.
> 

Why not just glue it?  I've made bookcases that way that held themselves 
together even without glue, which makes the gluing up pretty easy.

Try drilling and then screwing with 2 inch drywall screws from B &Q with a 
dab of pva glue. Done all cupboard door hinges this way and no bulging or 
splitting

"Pete C"  wrote in message 
news:je5ti1566kch795qd9jmmdsnlc287rtra7@4ax.com...

> On Sun, 18 Sep 2005 19:42:58 GMT, "david lang"
>  wrote:
>
>>Hi All
>>
>>Having problems with putting screws into the edge of 18mm MDF.
>>
>>I've tried correct size pilot holes and special MDF screws from SPAX but I
>>still get splitting and a slight bulge where the screw is.
>>
>>Special MDF screws are best (or least worse) but still noticeable.
>>
>>Any tips?
>>
>>Dave
>>
>
> Hi,
>
> Have a look at the woodfit site, they have loads of fixings for this
> sort of thing, eg:
>
> <http://www.woodfit.com/product_info.php?cPath=16&products_id=1184&Name=Chipboard+Fastener+-+12mm+-+Nylon>
> <http://www.woodfit.com/product_info.php?cPath=16&products_id=185&Name=Confirmat+Screw+-+7+x+50mm>
> <http://www.woodfit.com/product_info.php?cPath=16&products_id=176&Name=Hi-Lo+Screw+-+8+x+55mm>
> <http://www.woodfit.com/product_info.php?cPath=14&products_id=161&Name=Barrel+Nut+-+plastic+-+Beige>
> <http://www.woodfit.com/product_info.php?cPath=14&products_id=171&Name=Klix+Cam+for+15+to+17mm+board>
>
> Also some good tips here:
>
> <http://www.canadianhomeworkshop.com/toolbox/toolbox_mdf.shtml>
>
> If just a few holes I'd try giving the screws a good coat of molten
> wax then dropping them in oversized pilot holes filled with epoxy.
> After the epoxy has set the screw should home out (hopefully!) and
> allow the other bit to be fastened on securely. Would need trying on
> some scraps first though.
>
> cheers,
> Pete. 

Rob Morley wrote:

> Why not just glue it?  I've made bookcases that way that held
> themselves together even without glue, which makes the gluing up
> pretty easy.


It's really an assembly thing, difficult to glue up without screws in my 
somewhat cramped workshop.

Dave

david lang wrote:

> Thanks for the input chaps.  No magic bullet then.......
>
> Plan 'B'.
>
> I'll try cutting a 6mm deep dado in the sides & screwing through from
> the outside - hopefully the tight fit of the shelf in the dado will
> stop the splitting.


Plan 'B' worked a treat!  Applied glue to the dados (Titebond 11) and used 
3.5 x 40 SPAX 'M' MDF screws from B&Q.  No splitting on the trial run and 
virtually no expansion on final assembly.  Straight in no pilot holes at 
all.

SPAX 'M' screws aren't cheap mind, 5:98 for 100 - but they do what they say 
on the tin.

Joints are as tight & strong as they could be - jobs a good un!

Dave

In article <KNGXe.1194$lB4.225@fe3.news.blueyonder.co.uk>, 
davidlang@nospamblueyonder.co.uk says...

> david lang wrote:
> > Thanks for the input chaps.  No magic bullet then.......
> >
> > Plan 'B'.
> >
> > I'll try cutting a 6mm deep dado in the sides & screwing through from
> > the outside - hopefully the tight fit of the shelf in the dado will
> > stop the splitting.
> 
> Plan 'B' worked a treat!  Applied glue to the dados (Titebond 11) and used 
> 3.5 x 40 SPAX 'M' MDF screws from B&Q.  No splitting on the trial run and 
> virtually no expansion on final assembly.  Straight in no pilot holes at 
> all.
> 

I've found that can cause a small bulge where the screw goes through the 
dado which pushes the joint apart slightly.

In uk.d-i-y, Rob Morley wrote:

>In article <KNGXe.1194$lB4.225@fe3.news.blueyonder.co.uk>,
>davidlang@nospamblueyonder.co.uk says...
>> david lang wrote:
>> > Thanks for the input chaps.  No magic bullet then.......
>> >
>> > Plan 'B'.
>> >
>> > I'll try cutting a 6mm deep dado in the sides & screwing through from
>> > the outside - hopefully the tight fit of the shelf in the dado will
>> > stop the splitting.
>>
>> Plan 'B' worked a treat!  Applied glue to the dados (Titebond 11) and used
>> 3.5 x 40 SPAX 'M' MDF screws from B&Q.  No splitting on the trial run and
>> virtually no expansion on final assembly.  Straight in no pilot holes at
>> all.
>>
>I've found that can cause a small bulge where the screw goes through the
>dado which pushes the joint apart slightly.


I don't understand where a dado comes into the picture. Did I miss
something? Just curious.

-- 
Mike Barnes

david lang wrote:


> It's really an assembly thing, difficult to glue up without screws in my
> somewhat cramped workshop.


I thought -all the way through this thread, that you were talking about
putting screws near the end of the face of the MDF.

(You need to pilot drill and countersink screwing through the face of
that stuff. And you need to keep as far from the edge as possible. 3
inches is getting close.)

MDF is a medium density fibre. That means laminations that are not even
tightly bonded. An example of well bonded fibre board is Formica.

OK that is a different medium entirely. I doubt though that you would
get screws into the end "grain" of higher density fibe board.

What you need to do is put some architrave or 2x1 on the uprights where
the shelves are going to sit. Remember when measuring out for them that
you need to keep them the thickness of the shelf down.

You want a 10 inch space from the top of the bottom shelf to the bottom
of the next shelf up for books that are 8 inches high. So with a 3/4
inch board as the shelf the batton needs to be 10 3/4 inches from the
top of the batton for the next shelf up.

(Another point to note is that shelves over 2 feet long need either
extra thickness board or some other sort of extra support. A nice
edging strip will act as a feature and help keep dust out of the shelf
below.)

In article <o8+6PUrYd8LDFwJG@g52lk5g23lkgk3lk345g.invalid>, 
september2005@mikebarnes.fsnet.co.uk says...

> In uk.d-i-y, Rob Morley wrote:
> >In article <KNGXe.1194$lB4.225@fe3.news.blueyonder.co.uk>,
> >davidlang@nospamblueyonder.co.uk says...
> >> david lang wrote:
> >> > Thanks for the input chaps.  No magic bullet then.......
> >> >
> >> > Plan 'B'.
> >> >
> >> > I'll try cutting a 6mm deep dado in the sides & screwing through from
> >> > the outside - hopefully the tight fit of the shelf in the dado will
> >> > stop the splitting.
> >>
> >> Plan 'B' worked a treat!  Applied glue to the dados (Titebond 11) and used
> >> 3.5 x 40 SPAX 'M' MDF screws from B&Q.  No splitting on the trial run and
> >> virtually no expansion on final assembly.  Straight in no pilot holes at
> >> all.
> >>
> >I've found that can cause a small bulge where the screw goes through the
> >dado which pushes the joint apart slightly.
> 
> I don't understand where a dado comes into the picture. Did I miss
> something? Just curious.
> 

Plan 'B' above   :-)