New BassChat 8"Cab design

[rwillett]

34 minutes ago, Rosie C said:

My old piano teacher used to say in a deadpan style that one missing finger she could help me work around, 2 and my piano playing would be seriously affected! I was never how much she was joking. 

 

Ah, that's my super power, I could lose one, two or even three fingers and my bass, guitar and piano playing wouldn't be any worse at all ....

[Chienmortbb]

3 hours ago, Phil Starr said:

Screw and glue, The whole design of the 'easy build' cab is based upon the ease of forming really strong 90deg joints without needing clamping. The screws hold everything in place and put pressure on the joints until the glue sets. The glue is what gives the cab it's final strength (it's stronger than the wood) and it also seals the joint so it is completely airtight. One option is to assemble the cab 'dry' with just the screws to check everything fits properly. You can teh take it apart and assemble it with the glue. I'll explain the gluing procedure later today. 

When I built my first basschat design, might even have been a prototype, I screwed and glued but if you are using Tuffcab, it does not stick well to metal or same fillers. The second cab I built screwed and glued but once the glue was dry, I removed the screws, drilled out the holes and filled with dowels. Once cut odd and sanded flat, the Tuffcab went on fine. Remember the glue is more than enough on its own, the screws just hold the panels in place while the glue dries.

 

What glues to use? Nothing fancy. There is no difference between the strength of Titebond and any £1.99 glue from Lidl. Titebond and a few others offer faster initial drying. That is to the time that you may unclamp. However, almost all require 24 hours to full achieve fullstrength so why risk it.

[nekomatic]

Apart from the baffle, the screws in the 1x8 and similar designs are on the inside - from the battens into the panels. 

[Stub Mandrel]

1 hour ago, Chienmortbb said:

When I built my first basschat design, might even have been a prototype, I screwed and glued but if you are using Tuffcab, it does not stick well to metal or same fillers. The second cab I built screwed and glued but once the glue was dry, I removed the screws, drilled out the holes and filled with dowels. Once cut odd and sanded flat, the Tuffcab went on fine. Remember the glue is more than enough on its own, the screws just hold the panels in place while the glue dries.

 

What glues to use? Nothing fancy. There is no difference between the strength of Titebond and any £1.99 glue from Lidl. Titebond and a few others offer faster initial drying. That is to the time that you may unclamp. However, almost all require 24 hours to full achieve fullstrength so why risk it.

 

I have a simple dowel jig from Screwfix. Never thought of using it for a cab!

[Chienmortbb]

2 hours ago, nekomatic said:

Apart from the baffle, the screws in the 1x8 and similar designs are on the inside - from the battens into the panels. 

Yes the cabs I built were battenless so a very good point. However, the main point is that the glue is enough if you can keep it clamped supported long enough.

[martin8708]

Great post , I had a few off-cuts of ply from a 1x15 build . 
Other bits are lower grade builders plywood, and raiding the spare parts bin produced corners and a handle and a port ( hope it’s not too big ) 

Speaker is an 8 inch 18Sound 250 watt driver from Lean business.( they were on sale ) 

I work outside ( no workshop ) ,so rain is a constant pain in the rear .

[rwillett]

Some magic seems to have occurred...

 

The observant amongst you will notice the 8" plans.

 

 

This is the home made router jig and it set up for a 68mm hole. This was some tests I did"just-in-case"

 

 

This is the baffle board with what appears to be the right sized hole and a 68mm with my printed port set in. The router jig works really well and cost an hour or two of printing and two M5 bolts.

 

 

As I'm intending to make three boxes, there's an awful lot of batterns....

 

[rwillett]

Now about half way through.

 

Holes and battens done. I've glued two sides and the bottom.

 

 

 

Its now clamped very tightly. These are clamps I use from making the guitars, never thought I'd use them for real wood working.

 

 

The only reason for stopping was the temperature was falling rapidly and the glue was thickening. So took the whole unit inside the house overnight. Not allowed to do things like this inside the house. Somewhat surprisingly most of the panels seem to fit. Not sure what happened there, normally I'd be out by 10mm or more

 

Its pouring with rain here, enough for waterproof trousers, so I can build and glue in the garage (assuming it's above 5C) but that's it.

 

 

 

 

Edited 9 hours ago by rwillett

[3below]

14 minutes ago, rwillett said:

Now about half way through.

 

Holes and battens done. I've glued two sides and the bottom.

 

 

 

Its now clamped very tightly. These are clamps I use from making the guitars, never thought I'd use them for real wood working.

 

 

The only reason for stopping was the temperature was falling rapidly and the glue was thickening. So took the whole unit inside the house overnight. Not allowed to do things like this inside the house. Somewhat surprisingly most of the panels seem to fit. Not sure what happened there, normally I'd be out by 10mm or more

 

Its pouring with rain here, enough for waterproof trousers, so I can build and glue in the garage (assuming it's above 5C) but that's it.

 

Not allowed to do woodwork in the house, good grief, the kitchen table was designed for motorbike repairs.  When the weather is good I will woodwork outside by preference.  The build looks good and always a bonus when parts fit well 👾  

 

 

 

[rwillett]

10 minutes ago, 3below said:

Not allowed to do woodwork in the house, good grief, the kitchen table was designed for motorbike repairs.  When the weather is good I will woodwork outside by preference.  The build looks good and always a bonus when parts fit well.

 

If I brought a motorbike in and dismantled it on the kitchen table, I suspect parts of my anatomy may be dismantled as well and distributed far and wide. 

 

The ply is nice ply (in my limited experience), the two things I've done differently are:

1. Buying a guide rail for the circular saw. Massive change in cutting wood and it's now simple. 
2. Buying an 80 tooth circular saw blade and putting it in the right way. You can actually burn your way through plywood with it the wrong way, so I'm told. I of course didn't do that at all. Nope not me. Also moving the saw blade up so it's only cutting 12.5mm makes it a little friendlier and I can use some old wood as a base rather than my 40 year old Workbench. 

The second cab will be better again. 

 

Also the weather forecast is for six days of constant rain  🌧️🌧️🌧️🌧️🌧️🌧️ so this is likely to be the only can this week 

 

Rob

 

 

 

[rwillett]

Hi

 

The plans for the 8" talk about a port length of 64mm inside diameter and 87mm length.

 

I've printed the port and the flange as one piece. Do I include the flange height in the port length OR is it 87mm from inside the baffle board OR 87mm from the front of the baffle board OR is it 87mm from the front of the flange? 

 

My assumption is that it's 87mm from the front of the flange, so if the flange is 10mm and the plywood is 12mm then the port inside the cabinet is 87-10-12 = 55mm. 

 

Sorry for the dumb question.

 

Thanks

Rob

[Stub Mandrel]

My understanding is it would be 87mm total lenght of the tube so from the front of the flange.

[Phil Starr]

That's correct. Looks like its all going well

 

When the glue thickens I put the container in a bowl of hot water or just stand it on a radiator and the glue softens and flows more easily. I did that in the video.

 

I've got all sorts of woodworking gear including a table saw circular saws, jigsaw etc but last year I bought a plunge saw with an aluminium track. It's a revelation for cutting panels, so much easier than manuvering an 8'x4' sheet of ply through the table saw even with the sliding table on the saw. It's a great tool for cutting speaker panels. It's what I used for the prototype 8.

Edited 7 hours ago by Phil Starr

[rwillett]

So thats this measurement on the right hand side, I would have thought so as well, but always good to check

 

[rwillett]

29 minutes ago, Phil Starr said:

When the glue thickens I put the container in a bowl of hot water or just stand it on a radiator and the glue softens and flows more easily. I did that in the video.

I did see it in the video, but part of the problem as it was getting colder was me slowing down and thickening up. There wasn't a bowl big enough for me to stand in  

[rwillett]

31 minutes ago, Phil Starr said:

I've got all sorts of woodworking gear including a table saw circular saws, jigsaw etc but last year I bought a plunge saw with an aluminium track. It's a revelation for cutting panels, so much easier than manuvering an 8'x4' sheet of ply through the table saw even with the sliding table on the saw. It's a great tool for cutting speaker panels. It's what I used for the prototype 8.

 

I saw a video with a plunge saw and thought wow, that looked the business and then saw the price of it. I think if I was making a dozen or so cabs, I'd invest, but for me, not sure it's worth the effort. Now I know you have one, I'll send future ply cuts to you

[Phil Starr]

To all intents and purposes the air in the port will just 'see' your printed port as a cylinder of air so this is great. the flange will cover any imperfections and give you a potential way of securing the port.

 

For the technical nerds: there are sharp changes of pressure at the ends of the port when the air is moving. This is different at the end of the baffle where there is a 180deg change and the inside end of the port where it is 360deg. WinISD includes an end correction in the calculations and to date I haven't measured anything to suggest it isn't accurate. I've got some printed flanges I'm meaning to try which curve the exit of the port (much bigger radius than Rob's port). These are meant to allow a slower change in pressure and reduce turbulence in the port. Even with a big radius on the end of the port I still wouldn't expect you to need to change the length significantly. Your flange should have no audible effects.

 

[Phil Starr]

1 hour ago, rwillett said:

 

I saw a video with a plunge saw and thought wow, that looked the business and then saw the price of it. I think if I was making a dozen or so cabs, I'd invest, but for me, not sure it's worth the effort. Now I know you have one, I'll send future ply cuts to you

I bought a really cheap one from B&Q and it does the job so much better than my Skill Saw. I've invested in all sorts of clamping and jigs over the years but this little cheapy does the job really well. It's great for trimming doors when you hang them too. 

[rwillett]

Shout if you need any wide ports printed. Easy to change the radius of the outer port, it could be something exponential or a non constant radius.

 

Rob

[Stub Mandrel]

2 hours ago, rwillett said:

 

I saw a video with a plunge saw and thought wow, that looked the business and then saw the price of it. I think if I was making a dozen or so cabs, I'd invest, but for me, not sure it's worth the effort. Now I know you have one, I'll send future ply cuts to you

 

Don't underestimate how fast and accurate a good handsaw is, just a disposable hardpoint will do.

 

Also, a batten clamped in place will guide a cheaper rotary saw or even a router accurately.