60 Degree DIY Mid Hi - AKA PM60

[Max Warasila]

Re: 60 Degree DIY Mid Hi

So I've been doing a lot of modeling in Inventor, and I pretty much have the cabinet done. I won't say anything just yet - first, a quick picture:



Parts haven't come yet, but here are some noteworthy parts of this box:

• First and foremost, I will be creating as many of the parts as possible on a ShopBot 4'x8' machine. Part of this is because Helge said he wanted to use a CNC shop, and I wanted to make sure all of the parts were possible. The other reason is that I just want to.
• Second, the box does not have interchangeable horn baffles. I decided that, although it's possible, I simply did not want to deal with making the parts. Which is ironic, considering...
• I added a maintenance panel to the left side of the box (a la DSL). It will be secured using T-nuts and machine screws, and will have a gasket. This is completely optional, and can be replaced with the same model from the other side.
• The box is wider than other models to allow for a full front grille. It's my box - I'll do what I want! 8)~~

Depending on how this goes and if Peter gives me the green light, I will post a link to the files, as well as just generic drawings for those who aren't as CAD inclined. I haven't added handles, and the internal bracing has not be finalized either. I get the ply in on Wednesday, but I plan to start testing the CNC process with less fantastic wood tomorrow - with any luck it will all fit on one 4'x8' sheet of ply. If not - whatever. I've got extra space when the BB comes along.

One last thing - I've always wanted to do this~!:

 

[Peter Morris]

Re: 60 Degree DIY Mid Hi

So I've been doing a lot of modeling in Inventor, and I pretty much have the cabinet done. I won't say anything just yet - first, a quick picture:

View attachment 12729

Parts haven't come yet, but here are some noteworthy parts of this box:

• First and foremost, I will be creating as many of the parts as possible on a ShopBot 4'x8' machine. Part of this is because Helge said he wanted to use a CNC shop, and I wanted to make sure all of the parts were possible. The other reason is that I just want to.
• Second, the box does not have interchangeable horn baffles. I decided that, although it's possible, I simply did not want to deal with making the parts. Which is ironic, considering...
• I added a maintenance panel to the left side of the box (a la DSL). It will be secured using T-nuts and machine screws, and will have a gasket. This is completely optional, and can be replaced with the same model from the other side.
• The box is wider than other models to allow for a full front grille. It's my box - I'll do what I want! 8)~~

Depending on how this goes and if Peter gives me the green light, I will post a link to the files, as well as just generic drawings for those who aren't as CAD inclined. I haven't added handles, and the internal bracing has not be finalized either. I get the ply in on Wednesday, but I plan to start testing the CNC process with less fantastic wood tomorrow - with any luck it will all fit on one 4'x8' sheet of ply. If not - whatever. I've got extra space when the BB comes along.

One last thing - I've always wanted to do this~!:
View attachment 12730

Hi Max,

I don’t have an issue with you releasing a CAD / CNC file. I’m actually very grateful for the all the help
I have had so far, and that some people have actually been brave enough to build my design.8O~8-O~:shock:~~:smile:

A couple of suggestions –

If you are going down the CNC path you should make the two braces that go from the inner section to top and bottom of the box wider where they connect the top and bottom of the box. Then route some hole(s) in the braces to reduce the weight.

I don’t think you need a side access panel. The two twelve inch drives fit through the horn cut-out and it’s just as easy to remove the horn and do maintenance as it is to remove a side panel. It’s also lighter and stronger without a cut-out.

 

[Don J Davis]

Re: 60 Degree DIY Mid Hi

The box is wider than other models to allow for a full front grille. It's my box - I'll do what I want! 8)~~

Looks great Max! I see by the shape of the baffle cut out you decided to go the 60 deg route. I'd love to see the Cad files when you're done and compare them to what we've done so far. CNC would be sooo nice.
I'm glad I opted for the full front grill as well but it does cause the box to be a little wider and a little heavier.

 

[Don J Davis]

Re: 60 Degree DIY Mid Hi

I don’t have an issue with you releasing a CAD / CNC file. I’m actually very grateful for the all the help
I have had so far, and that some people have actually been brave enough to build my design.8O~8-O~:shock~~:smile:

We never doubted you Peter ;-)

Just got the word I'll be providing for a concert/movie premier outdoors for 600 peeps on July 12. Time to test out the DIYs.

 

[Jeffrey Knorr]

Re: 60 Degree DIY Mid Hi

Max, if you make the CNC files and/or flat packs available, that might be the extra push I need to get back on board with this project!

Jeff

 

[Max Warasila]

Re: 60 Degree DIY Mid Hi

Hi Max,

I don’t have an issue with you releasing a CAD / CNC file. I’m actually very grateful for the all the help
I have had so far, and that some people have actually been brave enough to build my design.8O~8-O~:shock:~~:smile:

A couple of suggestions –

If you are going down the CNC path you should make the two braces that go from the inner section to top and bottom of the box wider where they connect the top and bottom of the box. Then route some hole(s) in the braces to reduce the weight.

I don’t think you need a side access panel. The two twelve inch drives fit through the horn cut-out and it’s just as easy to remove the horn and do maintenance as it is to remove a side panel. It’s also lighter and stronger without a cut-out.

Thanks for all of the positive feedback, everyone. I'm working at my local TechShop, so I'll see if I can get a reservation for the CNC machine today. With that preface, here's some disclaimers about the CNC programs. Because of the physical limitations of the model of the ShopBot and time restrictions at the TechShop, my plan for CNC isn't quite worked out yet. It would be nice to make all of the parts in one pass on a machine (or more realistically, two passes), but that will take a longer than average time to cut, and has the potential to burn the bit prematurely (though I doubt it, since I'm doing 1/8" layers with my bit at the moment through Birch). The other problem is that I simply do not know how to get all my parts into one program - I'm working on that right now. There is a simple way to use a single drawing to cutout the profiles of the part, but the fillets and miter joints present a slight challenge, since the program that makes it easy doesn't appear to support that feature so far. Whatever the case may be, I'm going to shoot for a prototype CNC run this afternoon. With all that said, with proper part drawings, any of you could potentially make the particular CNC programs to fit your needs. I will most likely not give out the final ShopBot programs as a safety precaution - it makes it too easy to screw up if you assume it will work properly with what you are doing.

See, even with CNC there's a certain amount of workaround nonsense! 8)~~

Peter, wouldn't the holes in the brace increase turbulence significantly? I just feel like that particular route (lol) could screw with the box a bit. Then again, we've totally altered the dimensions, so why start caring too much now? As far as the side panel goes... it's more for my own entertainment and fun than practical purpose. I fully expect to hate it going down the line, but it's fun for right now.

All in all, this box would appear to be cheaper, louder, better sounding, and lighter than almost any similar box. Good work, regardless of which style of any part that you choose.

 

[Mark Wilkinson]

Re: 60 Degree DIY Mid Hi

Hey Max, nice work!
I'd get my hands on the XT1464 horn and have a good look at it before i finalized anything...
Its structural ribs, mounting hole locations on its sides, and volume, might effect your baffle design and internal bracing a bit....maybe not...but if you're going CNC.....
Just FWIW, Mark

 

[Phil Graham]

Re: 60 Degree DIY Mid Hi

Max,

Way to dive in on this project, and work on executing!

Because of the physical limitations of the model of the ShopBot and time restrictions at the TechShop, my plan for CNC isn't quite worked out yet. It would be nice to make all of the parts in one pass on a machine (or more realistically, two passes), but that will take a longer than average time to cut, and has the potential to burn the bit prematurely (though I doubt it, since I'm doing 1/8" layers with my bit at the moment through Birch).

In addition to controlling depth of cut, you'll need to make sure your feed rates are compatible with material. What sort of endmill are you using (upcut/downcut/compression)? How many flutes? What is your spindle speed, and have you checked feedrates for proper chipload?

Does your CAM package do things like ramp in and and out, or control toolpath speed around tight corners? If your spindle has the juice, it would be preferable to execute these cuts in a single pass, even it requires a ramp in, and/or modified toolpaths for corners.

There is a simple way to use a single drawing to cutout the profiles of the part, but the fillets and miter joints present a slight challenge, since the program that makes it easy doesn't appear to support that feature so far.

Briefly looking at the Shopbot site, their workhorse machine would appear could either be a 2.5 axis, or perhaps true three axis. Either way, things like miters and fillets are either going to require special cutters, or are going to be secondary operations off machine. It would be my suggestion that you finish your miters and fillets after CNC using a table saw and router/router table with a roundover bit.

Since it appears the Shopbot uses a spoil board, it would be likely they have the tools to make spoil boards, and therefore plenty of tools to execute your secondary operations.

See, even with CNC there's a certain amount of workaround nonsense! 8)~~

Drawing components for CNC, or most other manufacturing processes, is typically trivial to setting up and owning the manufacturing steps to replicate the drawing. See for example.

 

[Helge A. Bentsen]

Re: 60 Degree DIY Mid Hi

Max: Nice work, looks really good. I don't need pre-made cnc-files, as the shop I'm working with insists on programming their own. I "just" need an exact model/drawing. So don't put in too much effort on my behalf

Peter: IIRC you have talked about a few different LF drivers and horns. What do you consider to be the best components for the 60deg in terms of sound quality?

 

[Max Warasila]

Re: 60 Degree DIY Mid Hi

Max: Nice work, looks really good. I don't need pre-made cnc-files, as the shop I'm working with insists on programming their own. I "just" need an exact model/drawing. So don't put in too much effort on my behalf

Peter: IIRC you have talked about a few different LF drivers and horns. What do you consider to be the best components for the 60deg in terms of sound quality?

Lol, Helge, as well they should. Otherwise they can't be sure the cuts are being performed correctly. My particular model is designed to fit perfectly with the B&C NDL1276 basket, so I'll redraw it for you if you choose a different model.

Phil, you're always good at catching the things we wouldn't think of, but to respond to your questions and musings:

• The end mill is your standard, run of the mill (ha) 1/4" double flute downcut. Spindle @ 14000 rpm, and 70ips feed rate. Nothing too fancy, and nothing too boring; really just correcting for the downcut slightly. This is, of course, if I simply cut the pieces out and then do the secondary operations separately, which brings us to...
• Yes, my CAM package is very smart But even if it wasn't, the project is well within the "good enough" range, as my pathing isn't at all aggressive.
• You're absolutely right regarding that I could do it on a table saw and router. In fact it'll probably be faster, create a better cut, and far less expensive (and, if I'm honest, will actually work). However, if I were to do that, I would be using the panel saw to cut out my parts anyway, so why bother? In all honesty, the deciding factor was that I couldn't find a metric ruler or tape measure that I didn't have to order.

It doesn't have to be done all CNC. If I were a master carpenter, I wouldn't even bother touching the thing. However, I'm not, and I don't need to be. At any rate, I will be testing out this particular process tonight, and it will be most interesting to see what becomes of it.

 

[Peter Morris]

Re: 60 Degree DIY Mid Hi

Max: Nice work, looks really good. I don't need pre-made cnc-files, as the shop I'm working with insists on programming their own. I "just" need an exact model/drawing. So don't put in too much effort on my behalf

Peter: IIRC you have talked about a few different LF drivers and horns. What do you consider to be the best components for the 60deg in terms of sound quality?

I think the RCF is probably the best. It’s a very recent design and has flux demodulation rings. B&C recently released a 12NDL88 which looks fantastic, but its cone mass and BL are not suitable for this design. Ciare’s 12NDH-3 also looks OK.

My only concern with RCF is its limited Xmax. The 60 degree has the best sound quality but its pattern is narrow and drops of quickly beyond 60 degrees- BUT at this stage I have not used the 60 degree version in anger.

FWIW The 90 degree box is probably the most useful.

 

[Max Warasila]

Re: 60 Degree DIY Mid Hi

Okay so six hours of fighting with ye olde ShopBot later and I'm here to tell you - find a panel saw instead. It's far easier, it's faster, and - most importantly - cheaper. If you don't have access to one, change that. Just remember to cut on your lines, not the integrated rules.

That said, the handle cutouts, horn baffle, the occasional strange brace and especially the 12" baffle are all good candidates for CNC routing.

I won't say much regarding my experience this evening, but I will say that 14000 and 70 is not the best solution for 18mm ply of any kind and, as it turns out, the spoil board on the machine I was using is not flat. Goodnight (at 7:20 in the morning).

 

[Phil Graham]

Re: 60 Degree DIY Mid Hi

Okay so six hours of fighting with ye olde ShopBot later and I'm here to tell you - find a panel saw instead.

Experience is what you get right after you need it.

 

[Max Warasila]

Re: 60 Degree DIY Mid Hi

Experience is what you get right after you need it.

That got me laughing, Phil.

I did a test run for a reason, haha!

 

[Peter Morris]

Re: 60 Degree DIY Mid Hi

Okay so six hours of fighting with ye olde ShopBot later and I'm here to tell you - find a panel saw instead. It's far easier, it's faster, and - most importantly - cheaper. If you don't have access to one, change that. Just remember to cut on your lines, not the integrated rules.

That said, the handle cutouts, horn baffle, the occasional strange brace and especially the 12" baffle are all good candidates for CNC routing.

I won't say much regarding my experience this evening, but I will say that 14000 and 70 is not the best solution for 18mm ply of any kind and, as it turns out, the spoil board on the machine I was using is not flat. Goodnight (at 7:20 in the morning).

Hi Max,


FWIW I used a NC table saw (for want of a better description) that could automatically set the width and cut angle.

I used a router to cut the handle holes and the recess in the speaker mounting plate etc. Obviously an NC router would have been better than my home made jigs and Parts Express circle cutting guide.

The other advantage of using an NC router is cutting a rebate in the panel ends and the mid-section in the shape of the horn so all the bits fit together like a jig saw puzzle and the panel alignment becomes automatic. https://www.youtube.com/watch?v=xQ9hoTbLGY4

To do this the plans need to be changed a little.

 

[Max Warasila]

Re: 60 Degree DIY Mid Hi

Hi Max,


FWIW I used a NC table saw (for want of a better description) that could automatically set the width and cut angle.

I used a router to cut the handle holes and the recess in the speaker mounting plate etc. Obviously an NC router would have been better than my home made jigs and Parts Express circle cutting guide.

The other advantage of using an NC router is cutting a rebate in the panel ends and the mid-section in the shape of the horn so all the bits fit together like a jig saw puzzle and the panel alignment becomes automatic. https://www.youtube.com/watch?v=xQ9hoTbLGY4

To do this the plans need to be changed a little.

Damnit, Peter. Now I want to do that. :lol:

I'll be honest, I'm getting into the building of the box more than anything else. Part of me says, "just make it a DIY cheap thing - cut it on a table saw or with a circular saw and get it over with. It doesn't have to be perfect. The other part says, "you been given the opportunity to learn how to design a very, very nice manufacturing solution for a very, very nice box.

I'll let you guys know what I decide to do. I have some time until my parts come anyway - though my plywood is here and ready to go.

 

[Peter Morris]

Re: 60 Degree DIY Mid Hi

Hi everyone,
I have done a bit more work on the 60 degree settings – a 600Hz24dB LR crossover between the lows and the HF seems to work well and results ina good off axis response, both horizontal and vertical.
I have the FIR settings sounding absolutely amassing, but I’mnot happy with the IIR settings yet. If it’snot raining tomorrow I will have another go at them.

 

[Max Warasila]

Re: 60 Degree DIY Mid Hi

Okay, everyone - I need help with something I simply don't know how to do, nor know if I need to do. There are two questions that I need answered:

1. Is it worth making this an actual trap box, since they will most often be used two a side? If so, how does that effect the acoustics of the box? How much more insanity am I getting myself into by deciding to do this?
2. If I decide to build the box with angled sides, how do I cut the angled sides to the now trapezoidal pieces? Normally, I'd say use the table saw for miter joints, but I'm basically requiring that I use a circular saw, correct? I can caluclate any angle to cut - but that doesn't mean I'll be able to cut it.

I'm reworking a lot of the parts post Peter's contributions to the design. I'm also considering using 15mm ply instead - if I can find any. I seem to be able to reliably find and purchase 12mm and 18mm (1/2" and 3/4") It reduces the time for CNC too, which would be great. Thanks in advance - it's been a great learning experience so far.

 

[Mark Wilkinson]

Re: 60 Degree DIY Mid Hi

Okay, everyone - I need help with something I simply don't know how to do, nor know if I need to do. There are two questions that I need answered:

1. Is it worth making this an actual trap box, since they will most often be used two a side? If so, how does that effect the acoustics of the box? How much more insanity am I getting myself into by deciding to do this?
2. If I decide to build the box with angled sides, how do I cut the angled sides to the now trapezoidal pieces? Normally, I'd say use the table saw for miter joints, but I'm basically requiring that I use a circular saw, correct? I can caluclate any angle to cut - but that doesn't mean I'll be able to cut it.

I'm reworking a lot of the parts post Peter's contributions to the design. I'm also considering using 15mm ply instead - if I can find any. I seem to be able to reliably find and purchase 12mm and 18mm (1/2" and 3/4") It reduces the time for CNC too, which would be great. Thanks in advance - it's been a great learning experience so far.

1. Trap box? Max, I can't picture how you could make a true trap box out of it. Since the 12" drivers run the width of the box, and are in the rear, doesn't that prohibit a trap? I'm assuming a trap is a 30 degree straight walled taper, front to back....that would make it wide as heck up front...
2. Are you saying cut angle sides onto a trap box, That doesn't seem to make sense...or cut the angles on to the square box? Sorry, don't follow what you mean here....

If I make some more, the "inner shell" (12" baffles, MID horn flare pieces, & horn baffle) will be 15mm, and the outside box will be 12mm. 12mm BB seems to be pretty available, in 5x5 or 4x8. 15mm BB is only 5x5 as far as I can find..

 

[Max Warasila]

Re: 60 Degree DIY Mid Hi

1. Trap box? Max, I can't picture how you could make a true trap box out of it. Since the 12" drivers run the width of the box, and are in the rear, doesn't that prohibit a trap? I'm assuming a trap is a 30 degree straight walled taper, front to back....that would make it wide as heck up front...
2. Are you saying cut angle sides onto a trap box, That doesn't seem to make sense...or cut the angles on to the square box? Sorry, don't follow what you mean here....

If I make some more, the "inner shell" (12" baffles, MID horn flare pieces, & horn baffle) will be 15mm, and the outside box will be 12mm. 12mm BB seems to be pretty available, in 5x5 or 4x8. 15mm BB is only 5x5 as far as I can find..

1. I'm thinking 15 deg? None of the more popular ground stack boxes are more than 22.5 deg on the edge. The front is already 15" with a full length grille. The reason I might not even bother is because of number 2.
2. I meant the internal baffles. The interior angles are very, very strange when the sides of the box are angled, and they are not parallel to the other side of the pieces (because they are trapezoids).

Honestly, I don't see how it would be worth doing, or even possible, without a very, very large amount of effort and complicated parts. However, it would make the product truly beyond anything else currently in production for the weight, form factor, and output.