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req. help frugal horn mk3 build

Wharfedale Linton Heritage Speakers

sarathssca

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Hello,

I have started the build of frugal horn mk3 for my ma alpair 7p (paper version). Brought 8*4 sheet of 18mm exterior grade MDF sheet. I have no prior experience with any wood work and this is first time doing such work. my doubts/questions may be very baisc. Got a circular saw for rent for a day and started the basic cuts following the plan from the frugal horn plan pdf page 17 Sheet C-2. But only managed to cut as shown in the attached photos.
Got some idea and info from the threads of Bibin, Balu, Manniraj, but cuts I made were no where as nice as in those theads. cuts were not very uniform and smooth (curve cuts and height/length of the long pieces). Could you please help in clarifying below :

1. now already the pieces are cut, how to make them uniform and smooth so that they couldd fit properly ? do i need to use a sand paper or any other tool ? ( in the photo its looking better than the actual pieces i cut)

2. what tool to use to make the circular hole for the driver and binding post. Also for the flush mount do we need to cut the mdf or add a separate 3-4 mm additional sheet on the front.

3. how to fix the pieces? seems they are fixed by screws in other threads.. what is the size and type of the screws to use? what tool to use to fix them? do i need to drill the holes and then put the screws in them?

4. will the box be completely closed or the one side will be removable with screws? if its removable how will it be air tight?

thanks and regards
S Sarath
 
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Sumanta

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If I were you, I would have requested a carpenter to do the joining.

For true DIY pleasure and sweat, Bibin, Captain, Anthony such names come to my mind whom you can ask.
Search for the Frugal horn make post here in DIY section.
 

bibin3210

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Hello,


1. now already the pieces are cut, how to make them uniform and smooth so that they couldd fit properly ? do i need to use a sand paper or any other tool ? ( in the photo its looking better than the actual pieces i cut)

Use a C-Clamp to clamp together identical pieces and using a hand plane and file you can shape it. This is not going to be an easy task IMO.


2. what tool to use to make the circular hole for the driver and binding post. Also for the flush mount do we need to cut the mdf or add a separate 3-4 mm additional sheet on the front.

You need to use a router with straight bit to cut the flush mounts. For mounting binding post you can use hand drill.

3. how to fix the pieces? seems they are fixed by screws in other threads.. what is the size and type of the screws to use? what tool to use to fix them? do i need to drill the holes and then put the screws in them?

I usually apply Fevicol SH and put together the pieces using screws and F-clamp. Once the glue is dry and everything is set, I remove the screws and apply metal paste to fill the holes.

You need to drill holes before fixing the screws. Use #6x1.5" self tapping screws with counter sink head (CSK).



4. will the box be completely closed or the one side will be removable with screws? if its removable how will it be air tight?

It is completely closed.


Regards,
Bibin
 

sarathssca

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Hi Bibin,

Thanks for the info...
also

1. how to cut the edges of the front piece, which dont seems to be straight cuts as the front piece is slanted by some 5 degrees, and for it to properly fit with the bottom and top pieces, its top and bottom edges should be cut at same 5 degree angle also ?

2. what is metal paste and why are the screws removed after the glue dried up?

3. do we need any additional thing to make the joints air tight?

thanks and regards
S Sarath
 

quad

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Many of the carpentry shops have a planing machine. Take those
pieces there and get them planed. It cost a few tens of rupees only.

https://www.youtube.com/watch?v=OmNp1BddtpU

For the round cuts for the driver, carpentry shops have an power jig saw machine.



Many carving shops have routers too , which are better. They can do the flush mounting inset also.

See Maniraj's build for an alternative way for flush mounting, by gluing a 3mm veneer on top
 
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gcr

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Hello,


1. now already the pieces are cut, how to make them uniform and smooth so that they couldd fit properly ? do i need to use a sand paper or any other tool ? ( in the photo its looking better than the actual pieces i cut)

Use a C-Clamp to clamp together identical pieces and using a hand plane and file you can shape it. This is not going to be an easy task IMO.


2. what tool to use to make the circular hole for the driver and binding post. Also for the flush mount do we need to cut the mdf or add a separate 3-4 mm additional sheet on the front.

You need to use a router with straight bit to cut the flush mounts. For mounting binding post you can use hand drill.

3. how to fix the pieces? seems they are fixed by screws in other threads.. what is the size and type of the screws to use? what tool to use to fix them? do i need to drill the holes and then put the screws in them?

I usually apply Fevicol SH and put together the pieces using screws and F-clamp. Once the glue is dry and everything is set, I remove the screws and apply metal paste to fill the holes.

You need to drill holes before fixing the screws. Use #6x1.5" self tapping screws with counter sink head (CSK).



4. will the box be completely closed or the one side will be removable with screws? if its removable how will it be air tight?

It is completely closed.


Regards,
Bibin
Slight off topic.
wow Bibin, Your helping mind make you unique.
This post is for you / your brother and for those who help others (newbie) without expecting in return.
Also, your replies are so assuring and building confidence ( sub amp board problem,...) . Irony is that, we didn't met though we are from same state. Hats off to you.

regards
girish :)
 

venki7744

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Hello,

1. now already the pieces are cut, how to make them uniform and smooth so that they couldd fit properly ? do i need to use a sand paper or any other tool ? ( in the photo its looking better than the actual pieces i cut)

>> As Bibin suggested invest on a good Router, attach it to a bench (I will post pics once I reach home). using double side tape attach similar pieces so that the its almost close to matching. Using Flush trim bit with bearing running thru the shorter wooden piece (you might have to flip the wood depending on the sides). Since you have a cutter, making a straight cutting jig might help you a lot in minimizing uneven cuts.
2. what tool to use to make the circular hole for the driver and binding post. Also for the flush mount do we need to cut the mdf or add a separate 3-4 mm additional sheet on the front.
>> Already answered by Bibin. Nothing to add other than may be get a variable circle cutter for your drill (if you own one). Again I will post the pics later

3. how to fix the pieces? seems they are fixed by screws in other threads.. what is the size and type of the screws to use? what tool to use to fix them? do i need to drill the holes and then put the screws in them?
>> Again as Bibin suggested, for screw you can also use 1.5" dry wall powder coated screws. Removing the screw is an optional step. This is required if you want to round off the edges. If you plan to carpet it screws can remain screwed on :).

4. will the box be completely closed or the one side will be removable with screws? if its removable how will it be air tight?

>> Depends on how you intend it to be :). Sealed would be better if you just plan to have the driver in the cabinet. If you want to include the amp as well. Better to make a removable panel (construction would be more complex).

thanks and regards
S Sarath
Not an expert here, but still wanted to add some points :). If you plan to make this as a hobby (not one time) its better to invest in a Circular saw, Drill, Router and a Jigsaw.
 

bibin3210

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Hi Bibin,


1. how to cut the edges of the front piece, which dont seems to be straight cuts as the front piece is slanted by some 5 degrees, and for it to properly fit with the bottom and top pieces, its top and bottom edges should be cut at same 5 degree angle also ?

Using a hand plane you can make that angle.


2. what is metal paste and why are the screws removed after the glue dried up?

It is not mandatory to remove the screws. Since I don't have enough clamps I am using screws.

Metal paste is something like M-Seal, you can find it at any paint shop.


3. do we need any additional thing to make the joints air tight?

If the edges are cut perfectly, the glue applied is more than enough to get an air tight joint. Other wise you can use silicone sealant.

Thanks,
Bibin
 

manniraj

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Looking at the pictures it doesn't look like the panels cuts are not accurate especially the curved parts where there is a specific angle for the front baffle. Please look into the same. Coming to the wood cuts if you see my build pictures I used my carpenter to make the cuts but the measurements and drawing were done by me and I forced them to go slow and I was the supervisor. One a first go its very difficult to make even a small cut accurately as per the measurements. I took the help of my carpenter to make the driver cut out using a jigsaw. As usual he didn't do a perfect job and I have to sit down and make use a high grit sandpaper and file it to the exact measurements. Regarding the screws I normally first drill holes at the right spots on the upper panel and do not drill holes on the lower panels (I mean when you put panels one over the other for joining). This way I can adjust the panels while actually hitting the screws and as well as it gives a very tight fit.
 

captrajesh

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If I were you, I would have requested a carpenter to do the joining.
Well said. That's the way to go if you are seeking a well finished cabinet. Finding a competent, willing and a amenable one is not easy though.
For true DIY pleasure and sweat, Bibin, Captain, Anthony such names come to my mind whom you can ask.
If you are referring to me, I'd say 'Whoa where did that come from!' Though I love DIY activities, I hardly have enough time to devote so I usually take the help of professionals, be it carpentry or soldering.

Use a C-Clamp to clamp together identical pieces and using a hand plane and file you can shape it.
My carpenter takes the two pieces, aligns them together and drives in a couple of very thin nails before routing. After finishing, he uses a wedge to separate them and pulls out the nails The same thing can be done here too.
I usually apply Fevicol SH and put together the pieces using screws and F-clamp. Once the glue is dry and everything is set, I remove the screws and apply metal paste to fill the holes.
I discussed the same with my carpenter while making the boxes for the GRR kits. According to him, though the screws are not as good as liquid nails, removing them would seriously compromise the structural strength of the boxes.
 
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venki7744

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As mentioned before:

>> Pic of (mockup) of how you can remove excess wood from larger piece. If you notice the lower piece is little bigger than the upper one (again mockup) so that when the router runs thru the wood the extra wood would be shaved off from the lower piece.

>> Variable holesaw for drill.


Hope helps :).
 

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sarathssca

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I discussed the same with my carpenter while making the boxes for the GRR kits. According to him, though the screws are not as good as liquid nails, removing them would seriously compromise the structural strength of the boxes.
Hi Captain,

which one is not good while removal , screws or liquid nails (does it refer the metal paste)?

thanks and regards
S Sarath
 

captrajesh

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It looks like I've confused you. What I meant was, according to my carpenter, liquid nails are the best. However, since they and the related machinery etc. is not available in India, the next best thing is to have screws. Contrary to the popular perception, my carpenter says that leaving the screws on is the best bet for ensuring structural integrity of the cabinets. He makes lots of pro speakers for theatres and in his experience, not having screws and relying only on the glue in 'Butt joints' could result in the two panels falling apart due to the weakest point of one of the panels giving away though the end points of the panels stuck with the glue are still intact.
 

keith_correa

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What I meant was, according to my carpenter, liquid nails are the best. However, since they and the related machinery etc. is not available in India, the next best thing is to have screws.
What related machinery?

Contrary to the popular perception, my carpenter says that leaving the screws on is the best bet for ensuring structural integrity of the cabinets. He makes lots of pro speakers for theatres and in his experience, not having screws and relying only on the glue in 'Butt joints' could result in the two panels falling apart due to the weakest point of one of the panels giving away though the end points of the panels stuck with the glue are still intact.
So how will leaving the screws in mitigate the problem of the weak points of the panels giving away? :confused:

But I agree that leaving screws in would be better. I don't see how it would hurt in any way unless someone has a very good explanation against them being in AFTER gluing up.
 

venki7744

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So how will leaving the screws in mitigate the problem of the weak points of the panels giving away? :confused:

But I agree that leaving screws in would be better. I don't see how it would hurt in any way unless someone has a very good explanation against them being in AFTER gluing up.
I can give you my(noob) explanation. Removing the screw would mean the that the adhesion is only between the surface of the two pieces (say MDF). MDF has a chance of split which could cause panels separate (with some part of one panel stuck the the other...remember only the surface is glued not the whole structure).

IMO liquid nails are available in India(I have seen this in Trivandrum as well). http://www.snapdeal.com/product/liquid-nails-construction-adhesive/1082585023.

The only big disadvantage of leaving the screws is that it would be difficult to round over the edges.
 

captrajesh

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What related machinery?
I have no personal experience of using them. Apparently the liquid nails are administered with some kind of gun.

So how will leaving the screws in mitigate the problem of the weak points of the panels giving away? :confused:
I'm surprised that a DIY proponent with a bent of mind for all things DIY is asking this. Venki has given a nice explanation. That's what my carpenter said could happen if the nails are removed.

I don't see how it would hurt in any way unless someone has a very good explanation against them being in AFTER gluing up.
DIY forums are replete with arguments on how the nails, voids and the likes would 'pollute' sound with their own resonances. On our own forum, (FM Suri's speaker build thread IIRC) has some mention of this.

IMO liquid nails are available in India(I have seen this in Trivandrum as well). http://www.snapdeal.com/product/liquid-nails-construction-adhesive/1082585023.
Could you share the details? I'll share with my carpenter and may be replace the screws with them?
 

venki7744

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I have no personal experience of using them. Apparently the liquid nails are administered with some kind of gun.

I am not really sure how liquid nail can be better than screw/woodglue as its application is similar to using silicon sealent (cauking gun). I have not used this thing so I cannot comment on comparison between woodglue and liquid nail but from what I have read, its take about 24hrs for liquid glue to set while wood glue sets in probably 30mins to 1 hr.

Could you share the details? I'll share with my carpenter and may be replace the screws with them?
I remember seeing this in one of the plywood shops (near Nalanchira). It should be available in Power House road. Again I am making the assumption that you are from Trivandum itself :). I might go their this weekend and will confirm post that.
My reply inline.
 

keith_correa

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I'm surprised that a DIY proponent with a bent of mind for all things DIY is asking this. Venki has given a nice explanation. That's what my carpenter said could happen if the nails are removed.
Be prepared to be even more surprised. :D
Actually that use case never even crossed my mind. Why? Because to my mind [whatever is left of it] it is implausible that this case can occur.
DIY forums are replete with arguments on how the nails, voids and the likes would 'pollute' sound with their own resonances. On our own forum, (FM Suri's speaker build thread IIRC) has some mention of this.
You have a screw, that is well - screwed in wood. And it will resonate so much as to "pollute" the sound? And people can hear that resonance? Yeah, and some people think that using screws/bolts to mount the drivers made from a material other than copper cause unwanted resonances. To each his own.
 

sarathssca

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For FH3 build what options do we have for the felt layer behind the speaker, woolen felt of 12 mm thickness or a carpet?
I called one store here in chennai for woolen felt, and when i told its for speaker building he is suggesting to use a carpet instead of woolen felt, and also asking why do you need that thick (12mm) woolen felt for speaker build.

Please suggest what to use carpet or woolen felt and of what thickness and if any idea where to get in chennai.
 
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sarathssca

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For Frugal horn build how to put stuffing below the speaker driver? do we need to put any mesh like net for holding the stuffing in place or how do we put stuffing below the driver?
 
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