screwing into a glued join gap - Woodworking Talk - Woodworkers Forum
 
Thread Tools Display Modes
post #1 of 11 Old 01-06-2016, 11:25 PM Thread Starter
Member
 
Join Date: Dec 2015
Posts: 51
View Johanx3's Photo Album My Photos
screwing into a glued join gap

Hi, please can anybody tell me how safe or bad is doing what you see in the picture below? I got this circumstance in a project, and I don't know how recommendable is screwing like this. I know that I can use 2 screws and screw into each board. but for aesthetics, I don't want to do that and need to use only 1 screw. I have planed pre drill and then screw, will be the glued join compromised with this action? I can also move a little the screw, in order to take it away from the gap, but I need centered, just for aesthetics.

Wood thick is 0.75", and screw is about 1.5"

Attached Images
 
Johanx3 is offline  
Sponsored Links
Advertisement
 
post #2 of 11 Old 01-07-2016, 02:40 AM
Village Idiot
 
epicfail48's Avatar
 
Join Date: Mar 2014
Location: Springfield MO
Posts: 4,946
View epicfail48's Photo Album My Photos
With a well prepared glue joint, you shouldn't have any problems. I do that all the time, and I've yet to have problems. Just make sure to pre-drill, otherwise you'll split the joint

I need cheaper hobby
etsy.com/shop/projectepicfail
epicfail48 is offline  
post #3 of 11 Old 01-07-2016, 09:31 AM
Senior Member
 
Join Date: Aug 2012
Location: British Columbia, Canada
Posts: 5,666
View FrankC's Photo Album My Photos
Hopefully you don't have a gap, but a line where the glue is, just drill a pilot hole for the screw.

Wise men speak because they have something to say; fools because they have to say something -Plato

FrankC
http://sawdustmaking.com
http://woodworkerglossary.com
FrankC is offline  
Sponsored Links
Advertisement
 
post #4 of 11 Old 03-11-2016, 06:32 PM Thread Starter
Member
 
Join Date: Dec 2015
Posts: 51
View Johanx3's Photo Album My Photos
Hey guys, today had some problems screwing some #8 screws into this MDF configuration. They are splitting and ruining my mdf piece very easily. Excluding the threads, the screw is 3.0mm, and 3" long, then I drilled a hole using a 3.00mm bit, 3" depth, but it ended like this (second picture below, that mdf piece was a test). did this happen because of the mdf sandwich? I notice mdf to be very delicate, I split it even when drilling the hole, so next time I was more careful with the drill bit, but still the mdf was ruined once I screwed the screw. So then whats going here? I tried using a bigger bit, 4mm, but I am loosing screw tightening. In the picture below, the screw looks very forced, I did that once I noticed a light splitting, and it ended like that. Now I am not confident about using screws, but dowels and glue, even machine screws and glue, making a hole of same diameter including threads, I did this before and of course impossible to split the piece. What do you think about this?

Attached Images
  

Last edited by Johanx3; 03-11-2016 at 06:42 PM.
Johanx3 is offline  
post #5 of 11 Old 03-11-2016, 07:28 PM
Senior Member
 
GROOVY's Avatar
 
Join Date: Apr 2008
Posts: 791
View GROOVY's Photo Album My Photos
Could your pilot hole be too small?
What kind of screw is that?
GROOVY is offline  
post #6 of 11 Old 03-11-2016, 08:09 PM
Senior Member
 
Tony B's Avatar
 
Join Date: Jul 2008
Location: Dickinson, Tx.
Posts: 4,165
View Tony B's Photo Album My Photos
I dont recall ever screwing MDF. I always used glue and an air nailer with "T" head nails.
You will also have better luck with just joinery and glue with MDF. Also note that all MDF is not alike, just like all metals are not alike.
The stuff from Home Depot is about the crappiest you will ever find.
If properly laid out, the dado joints, when assembling, would be self aligning.
There are several ways to make identical pieces and mirror images with dados
Attached Thumbnails
Click image for larger version

Name:	Scan0001.jpg
Views:	149
Size:	29.6 KB
ID:	222490  


Tony B Retired woodworker, among other things.


"Strive for excellence and settle for completion" Tony B
Tony B is online now  
The Following User Says Thank You to Tony B For This Useful Post:
Johanx3 (03-11-2016)
post #7 of 11 Old 03-11-2016, 08:51 PM Thread Starter
Member
 
Join Date: Dec 2015
Posts: 51
View Johanx3's Photo Album My Photos
Quote:
Originally Posted by GROOVY View Post
Could your pilot hole be too small?
What kind of screw is that?
The screws are #8 - 3" phosphate power interior wood screws. Their diameter is 3.0mm ignoring threads. But that does not matter, with my little experience in present and past, and after reading internet, have concluded that it's not convenient screwing mdf into the edges, only on its surface (picture below).



In the past I had the same problem, I thought it was because of the 1/4 screws I was using, which were to big, I pre drilled also, but the same thing happened, so I ended drilling with 1/4 bit, and put glue in the hole and on screw, and inserted it as if it was a dowel, I liked this idea, but found more convenient machine screws because their threads are less aggressive and play better with the glue we add. There I used titebond III, don't know how convenient is using regular glue, because we need to consider that are using glue as a filler (very little gap between wood and the screw), titebond did a great job, has good viscosity and strong as hell, even harder than the whole wood.

I will never screw a MDF on its edge, only loosen dowels or box joints and a good wood glue. I was so frustrated to see the thing being splitted.




I see a person recommend this technique (picture above), surely it works, but I still feel like we finish with a fragile structure that will eventually rip, just because the screw is not part of the structure, that's why I recommend gluing the screw or using dowels. When I use a screw as a dowel or a segment of threaded rod, I prepare the rod segment by brushing it with a metal brush, that way the glue will hold with more force, now having three holding factors, the threads of the rod, that they are clean and treated with the brush and a good wood glue.
Attached Images
  

Last edited by Johanx3; 03-11-2016 at 09:24 PM.
Johanx3 is offline  
post #8 of 11 Old 03-19-2016, 09:14 PM
Member
 
Join Date: Feb 2013
Location: Maryland
Posts: 64
View madmantrapper's Photo Album My Photos
We don't use MDF for anything anymore, too many issues.

Jack of All Trades, Master of None
madmantrapper is offline  
post #9 of 11 Old 03-20-2016, 06:28 AM
johnep
 
johnep's Avatar
 
Join Date: Apr 2007
Location: East Anglia UK
Posts: 1,962
View johnep's Photo Album My Photos
Yes, plywood would be a better choice, After all, always drilling into end grain on one layer with plywood.
johnep
johnep is offline  
post #10 of 11 Old 03-20-2016, 06:37 AM
Senior Member
 
ducbsa's Avatar
 
Join Date: Jul 2014
Location: Virginia
Posts: 449
View ducbsa's Photo Album My Photos
You could embed a dowel in the bottom piece of MDF for the screw to bite into.
ducbsa is offline  
post #11 of 11 Old 03-30-2016, 05:41 PM
Junior Member
 
Join Date: Mar 2016
Location: Wales, U.K.
Posts: 21
View Woodyhoots's Photo Album My Photos
Screwing into the face of mdf is OK otherwise biscuit joints and glue. Mdf 's only redeeming feature is it paints well apart from that it's a pain in the ass, mind u I recently made some lovely display cabinets out of oak veneered mdf at a fraction the price of solid oak and once I'd veneered the edges you can't tell its veneer. Mdf knackers your tools and its carsonagenic, why the hell do we use it? oh yeah it's cheap.
Woodyhoots is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Woodworking Talk - Woodworkers Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
How to uncup glued cherry board? dreamiurg General Woodworking Discussion 17 12-27-2015 08:58 PM
Best way to join 4x4 for kitchen table mfran12345 Joinery 4 09-26-2015 04:44 PM
Mechanical Removable Join Catldavis Joinery 3 08-29-2015 08:12 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome