screw distance for speaker box construction

[rajesh srinivas]

Hi everyone,

Need to know the min/max distance between 2 screws on speaker box panels for a nice air tight box,some keep 4in,6inches ect..

I am using this NO# 8 Screw on 19mm mdf (the top portion 3/4th is plain and remaining threaded) this is the most preferred screw to hold
both the panels tight,

Any feed backs will be appreaciated.

thanks
rajesh

 

[sadik]

I usually prefer 120 mm gap between screws. The job of screw is to hold panels together. The bonding & sealing work is done by glue. Use enough glue between joints so as when screw it tightened the excess glue squeezes out from both sides of panel making it an air tight joint.

 

[rajesh srinivas]

Thanks sadiq,
You are an experienced box builds,nice advice,even the length of the panel counts say if u are using a 48in panel I feel 4 to 4.5in gap should be good enough.if using 8in then leaving 1in min gap from the ends ,2.5 to 3in gap should be good.

My question may look silly,but for those involved in diy box build it will be is useful to know.

Drilling a pilot hole and applying adhesive on both in the hole and on screw adds more to the strong building if the box.

What should be the height of the screw I am using 2inch screw for two19mm panel joints together.

 

[sadik]

Thanks sadiq,
You are an experienced box builds,nice advice,even the length of the panel counts say if u are using a 48in panel I feel 4 to 4.5in gap should be good enough.if using 8in then leaving 1in min gap from the ends ,2.5 to 3in gap should be good.

My question may look silly,but for those involved in diy box build it will be is useful to know.

Drilling a pilot hole and applying adhesive on both in the hole and on screw adds more to the strong building if the box.

What should be the height of the screw I am using 2inch screw for two19mm panel joints together.

First of all I will advise you to work in metric units, so instead of "inches" use "mm". Now say for 48 Inch length (Roughly 1220 mm). I would prefer leaving space of 50 mm on both ends then I will measure the center distance of both holes and try to divide it by a number so that i can get a equal space between screws which will be close to 120 mm. So in this case i divided the distance by 9 and got distance of about 124.4 mm. Dividing by 9 will let you to use 8 screws equi-spaced between this distance hence the total count of screws in 1220 mm length will be 11 screws. which i think will be more than enough to hold the wood securely.

Drilling Pilot hole is a must specially while working in mdf and It should be little longer than the total length of screw. so when it is fully tight it will not split the mdf from inside. check the image for details.

I hope the image will give you complete idea on drilling of pilot hole, clearance hole & even chamfering. It is not necessary to stick glue on screws, a glue in pilot hole will be sufficient. For 19 mm PLY or MDF i also use at least 2 inch long screws. I think 2 inch long screw will be sufficient.

 

[rajesh srinivas]

Very well explained sadiq,useful tips for me and also to members who are following this thread,In fact i had already bought the traditional wood screw 1box (100nos) but luckily yet to begin my work of joining panels.

In fact the sheet metal screw you mentioned is available at our place as in pic is it ok,the diameter of the shank is 2.6mm (2in size),with star head design type suitable for power screwdriver i own Bosch 06019F40F0 GSR-1000 Cordless Screwdriver recently bought for this work.

But In this site https://www.diyaudioandvideo.com/Guide/BuildSpeakerBox/
they have mentioned that we can also use the tranditional wood screw as in your first pic with the first 3/4" of the screw having no threads,what do you say about it.



Lastly your preference

I would prefer leaving space of 50 mm on both ends

Dont you feel its too far from corners,say 25mm would be a good choice for
the corners????

thanks
rajesh

 

[sadik]

Very well explained sadiq,useful tips for me and also to members who are following this thread,In fact i had already bought the traditional wood screw 1box (100nos) but luckily yet to begin my work of joining panels.

In fact the sheet metal screw you mentioned is available at our place as in pic is it ok,the diameter of the shank is 2.6mm (2in size),with star head design type suitable for power screwdriver i own Bosch 06019F40F0 GSR-1000 Cordless Screwdriver recently bought for this work.

But In this site https://www.diyaudioandvideo.com/Guide/BuildSpeakerBox/
they have mentioned that we can also use the tranditional wood screw as in your first pic with the first 3/4" of the screw having no threads,what do you say about it.

View attachment 35113

Lastly your preference


Dont you feel its too far from corners,say 25mm would be a good choice for
the corners????

thanks
rajesh

Those screws shown by you are fine to use because they are not taper. In the image shared by me the screws shown are taper. And I refered to leave 50 mm on both sides however its up to you to decide. I leave the corner distance with respect to panel length, if length is less then 500 mm, I will prefer to leave 35 mm from corners, I feel 25 mm will be too close to the corners.

 

[Hiten]

By panels I guess you are talking about back panel. I guess idea is to just hold panel together as there would not be any weight hanging and supporting, so one does not want it to be super strong. (Though at points of bracing and edges where side panels come together to make a box and front panel where heavy drivers are mounted it would be good to have strong rigidity) Because I read somewhere the screws increases chances of amplifying resonances and vibrations*. If cuts are straight and clean use at little amount of screws as possible and it will seal the box with the help of glue. Unless the back panel is detachable. you can use felt type material on edges. No need to go deep with long screws also as slight change in angle and screws come out from side panels. wouldn't 4 to 5 turns of the thread be sufficient ?
Contrary to belief sealed cabinets are hardly completely sealed as some air needs to be leaked out** when speakers is not making any music so as cone settles in the mid position.

* I have passed the age where I can't hear high frequencies. So I dont claim to hear any resonances and vibrations. which are subtle form of hearing but not as important and as the basic frequency range.
** from driver surround ? not sure.
regards

 

[rajesh srinivas]

Those screws shown by you are fine to use because they are not taper. In the image shared by me the screws shown are taper. And I refered to leave 50 mm on both sides however its up to you to decide. I leave the corner distance with respect to panel length, if length is less then 500 mm, I will prefer to leave 35 mm from corners, I feel 25 mm will be too close to the corners.

Ok will go with the fully threaded screw and also while drilling the pivot hole we have to take the diameter of non threaded part of the shaft for getting a nice fit.

25MM before edges i am referring coz dont want the corner edges to have any air leak, any way even 35mm will do,

Thank you very much for all the details,will keep in touch with my progress.

rajesh

 

[Kannan]

lol...that is a funny heading by the way...."Screw the distance"

 

[Kannan]

@sadik very good point to use fully threaded screws.
Tee nuts and bolts are a great option, but the chambering for the nuts should be solid.

 

[rajesh srinivas]

By panels I guess you are talking about back panel. I guess idea is to just hold panel together as there would not be any weight hanging and supporting, so one does not want it to be super strong. (Though at points of bracing and edges where side panels come together to make a box and front panel where heavy drivers are mounted it would be good to have strong rigidity) Because I read somewhere the screws increases chances of amplifying resonances and vibrations*. If cuts are straight and clean use at little amount of screws as possible and it will seal the box with the help of glue. Unless the back panel is detachable. you can use felt type material on edges. No need to go deep with long screws also as slight change in angle and screws come out from side panels. wouldn't 4 to 5 turns of the thread be sufficient ?
Contrary to belief sealed cabinets are hardly completely sealed as some air needs to be leaked out** when speakers is not making any music so as cone settles in the mid position.

* I have passed the age where I can't hear high frequencies. So I dont claim to hear any resonances and vibrations. which are subtle form of hearing but not as important and as the basic frequency range.
** from driver surround ? not sure.
regards

We were discussing all panels in general,adding a wood screw is only to see that the panel joints are firm enough without any air leakage,some use screws till the glue or adhesive dries up and remove them,few dont use screw at all,but to comply both ends we add screws.

No need to go deep with long screws also as slight change in angle and screws come out from side panels. wouldn't 4 to 5 turns of the thread be sufficient ?

A pivot hole solves the problem as shown by sadiq,a straight drill press as i have made one (DIY) as per below pic,keeps the pilot hole 90deg straight,so no question of any screw coming out side.

 

[rajesh srinivas]

lol...that is a funny heading by the way...."Screw the distance"

Its actually screw distance,you have added "the"

 

[Hiten]

We were discussing all panels in general,adding a wood screw is only to see that the panel joints are firm enough without any air leakage,some use screws till the glue or adhesive dries up and remove them,few dont use screw at all,but to comply both ends we add screws.
A pivot hole solves the problem as shown by sadiq,a straight drill press as i have made one (DIY) as per below pic,keeps the pilot hole 90deg straight,so no question of any screw coming out side.

ahh ! you are doing some pro work

. Sorry to comment. Looks like a good build and members would benefit. Please do share complete speaker project.
thanks and regards.