Minerva Monitor: "Patience my ass, I'm going to go build something!"

[Alaric]

I thought Menlo Park was in New Jersey???

[Steve Manning]

After some clean up on the sides I have glued, I did a test fit of the sides and the cabinet body .......







Also checked the fit of some aluminum. Should be a nice fit.

[JonMarsh]

Looking dang good, Steve! Tell your wife you get a gold star for this week!

Depending on which route you take and how you want to trade off time and distance, it's 46 to 52 miles to the venue from Danville, but in the end, it was a total of about 4-1/2 hours on the road yesterday- only 1-3/4 in the early morning, much more leaving to go back at 4 in the afternoon. But it was actually worth it, good material presented yesterday, and a bucket full of additional collateral to bring home for extra credit and learning. I like it that way...

Just to show you we're getting serious about the Unicorns, these came back out of storage today...

[benthe8track]

After some clean up on the sides I have glued, I did a test fit of the sides and the cabinet body .......


Also checked the fit of some aluminum. Should be a nice fit.

Looks great Steve! Really shows that a CNC helps but only gets you a fraction of the way there.

[Steve Manning]

Looks great Steve! Really shows that a CNC helps but only gets you a fraction of the way there.

Thanks Ben ...... your so right on the cnc part. It lets you do more interesting stuff, but there is still a lot of work to be done after that.

[ergo]

I finally got the cutter into the wood and made some sawdust. After weeks of pondering and redrawing stuff in Rhino I ended up with a different box.... but the driver distances from each other and edges that matter are almost same still.
This box design serves two purposes - my Ikea TV cupboard lineup in listening room is 40cm high. So placing these on the cupboard will raise the coax exactly to right height and I will not need a stand (or at least that the plan).
Secondly, making the boxes 780mm tall uses up the 800x600mm material much more efficiently. So efficiently actually that I had to precut the pieces on table saw as there was not enough room for 6mm cutter and some extra to holds things in place.... So had to make a bit of sawdust out in snow as well as my cellar where CNC lives is not big enough.

To be continued tomorrow....





Some more pics here

[5th element]

Looking dang good, Steve! Tell your wife you get a gold star for this week!

Shouldn't that be a diamond or beryllium star?

[JonMarsh]

Shouldn't that be a diamond or beryllium star?

Always leave a little headroom to recognize truly exceptional performance or progress! :B :W

I have some glimmers of knowledge of what Steve is capable of... It's a lot!

[JonMarsh]

I finally got the cutter into the wood and made some sawdust. After weeks of pondering and redrawing stuff in Rhino I ended up with a different box.... but the driver distances from each other and edges that matter are almost same still.
This box design serves two purposes - my Ikea TV cupboard lineup in listening room is 40cm high. So placing these on the cupboard will raise the coax exactly to right height and I will not need a stand (or at least that the plan).
Secondly, making the boxes 780mm tall uses up the 800x600mm material much more efficiently. So efficiently actually that I had to precut the pieces on table saw as there was not enough room for 6mm cutter and some extra to holds things in place.... So had to make a bit of sawdust out in snow as well as my cellar where CNC lives is not big enough.

To be continued tomorrow....

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Some more pics here

Some good progress! I'm looking forward to tomorrow!

[sdl2112]

I finally got the cutter into the wood and made some sawdust. After weeks of pondering and redrawing stuff in Rhino I ended up with a different box.... but the driver distances from each other and edges that matter are almost same still.
This box design serves two purposes - my Ikea TV cupboard lineup in listening room is 40cm high. So placing these on the cupboard will raise the coax exactly to right height and I will not need a stand (or at least that the plan).
Secondly, making the boxes 780mm tall uses up the 800x600mm material much more efficiently. So efficiently actually that I had to precut the pieces on table saw as there was not enough room for 6mm cutter and some extra to holds things in place.... So had to make a bit of sawdust out in snow as well as my cellar where CNC lives is not big enough.

To be continued tomorrow....

[ATTACH=CONFIG]25314[/ATTACH]
[ATTACH=CONFIG]25315[/ATTACH]
[ATTACH=CONFIG]25316[/ATTACH]

Some more pics here

That picture in the snow shows the ultimate dedication....I don't think I have ever seen that before. ;x(

Looking good and I look forward seeing the build progress. :T

[Steve Manning]

Shouldn't that be a diamond or beryllium star?

If I'm really good what about diamond coated beryllium, just like what they use in the Magico Q7?

[Steve Manning]

That picture in the snow shows the ultimate dedication....I don't think I have ever seen that before. ;x(

Looking good and I look forward seeing the build progress. :T

Your right Scott ...... it was around here 40 yesterday and that was bad enough, with snow Ergo should be getting the star.

[Steve Manning]

I finally got the cutter into the wood and made some sawdust. After weeks of pondering and redrawing stuff in Rhino I ended up with a different box.... but the driver distances from each other and edges that matter are almost same still.
This box design serves two purposes - my Ikea TV cupboard lineup in listening room is 40cm high. So placing these on the cupboard will raise the coax exactly to right height and I will not need a stand (or at least that the plan).
Secondly, making the boxes 780mm tall uses up the 800x600mm material much more efficiently. So efficiently actually that I had to precut the pieces on table saw as there was not enough room for 6mm cutter and some extra to holds things in place.... So had to make a bit of sawdust out in snow as well as my cellar where CNC lives is not big enough.

To be continued tomorrow....

Some more pics here

Interesting changes to the design Ergo ..... looking forward to your update tomorrow.

[ergo]

That picture in the snow shows the ultimate dedication....I don't think I have ever seen that before. ;x(

Looking good and I look forward seeing the build progress. :T

It all depends on whatever is "normal". In our part of the world there is snow for so many months of the year that it's normal to do some work outside. We have had around 30 Fahrenheit (0 Centigrade) this week - thats a very ok weather. One can work without gloves on. It gets tricky when it's below 20, then hands start freezing without gloves and it'll be less fun to do precision work

I think I would have problems with the other extreme. In summer we sometimes get 90F and for us in north thats usually so hot it's hard to work outside.

[ergo]

Todays progress - all parts are cut beside the outer front and back panels. I plan to glue up the frame and then re-measure and cut the panels to get precision.
I did try fit the top/bottom layers and it turned out that 16 * LBL stack was 3mm more than what the 18mm*16 should have been. So the I did still have a chance to cut the inner front and back panels bit wider to compensate.

Some of the pieces cut do have cavities. Some even through the part. So next up will be some experimentation with filling those with glue and sawdust mixture. If that does not work well enough I'd need to cut some new pieces.
Seems that if one would do this in scale and not fill cavities, but just waste the parts not up to scratch - then waste ratio would be something like 15..20%. Not so small for relatively expensive source material.

https://flic.kr/s/aHskump5WP

[JonMarsh]

Looks to me like this is coming along very nicely! :T

I wonder if there are significant differences in vendor quality for this type of bamboo wood product? for the 12" wide "boards" I get, I never see these kinds of issues, and for the 4' x 6' LBL plywood sheets I purchased for the Isiris, I don't recall having the amount of issues you and Steve have described. You're just dry fitting for now and checking how things go together? From here and your pictures, it looks pretty good. Being able to do that right at home is pretty cool... One other member, MEB46 has a CNC setup, a fairly large one, but I don't think he's fired it up yet - we're working on reasons for him to do so in the reasonable future!

[Steve Manning]

I'm seeing a fair number of voids as well, which I'm a bit disappointed about. So with Scott as well as Ergo that's three of us. I wonder about TEK, Bob, and Ron if they had any issues? I'll be interested to see how your epoxy and sawdust combo works Ergo since I'm thinking of going the same route for my voids.

[BobEllis]

I bought the same "boards" that Jon buys and had no issues. They were delivered with edges sharp enough to cut my hands and straight enough to make an invisible joint if glued edge to edge. Of course, they were bought 18 months ago...

[ergo]

This is the type of issues I'm finding. Bauhaus is a Home Depot type of generic building material supplier, so may be this stuff is sold as a more of a hobby use material and is of a lesser grade. Pitty is that I have no other source either. If there were less of these voids I'd be very happy - the bamboo does machine very well otherwise and I get a smoother surface out of the machine than I have with baltic birch ply.

[JonMarsh]

The Bamboo ply used for the Isiris is of the same general configuration as yours, with regards to how the layers are arranged and thickness, but I had essentially NO voids- nothing at all like what you show here, unfortunately.

[Steve Manning]

Wow, I'm not seeing stuff that bad. I am seeing some additional stuff show up with routing but nothing like your seeing. It would be interesting to find out who gets their stuff where here in the states at least, as far as major distributors.

[Steve Manning]

Pulled out the big 45 chamfer bit today and did the final shaping of the stand tops. Yesterday I had drilled the holes for the feet and counter sunk the mounting holes, as well as sanding/scraping of the pieces.





This stuff does like to tear out though ..... got some repair work to do. Luckily I found the major piece that tore out so that should help with the fix. :x



Got about half way through the cabinet sides. Between tear out and things bogging down, I decided to get a nicer bit on order over the MLCS that I have. The MLCS bit works great on softer wood, but not this lbl stuff. Once that gets in I'll finish the chamfer on the cabinet sides.

[BobEllis]

I bought my bamboo from the place where Jon gets his boards, but can't remember the name.

Steve, were you using the standard MLCS or katana bits? Katanas worked great for me without tear out or chipping. Maybe you should let dynamic saw sharpen the bits you have.

[JonMarsh]

I've used the Katana series bits with good results, too- otherwise I'm usually a Freud or Whiteside kind of guy. But you're right, the long fibers due tend to lead to tear out, have to be careful about that, IME.

It's getting there, though- you're making good progress. I just spent most of the morning learning on my Audio Precision- posted a bench review of the AURALiC Taurus Pre in Audio Hideout. Next step is moidifying a balanced cable for signal pick up with clip leads, then I try the first amplifier with this rig.

[Steve Manning]

I bought my bamboo from the place where Jon gets his boards, but can't remember the name.

Steve, were you using the standard MLCS or katana bits? Katanas worked great for me without tear out or chipping. Maybe you should let dynamic saw sharpen the bits you have.

Hey Bob ....it is a standard bit, MLCS does not carry the Katanas in that size, I have ordered the Katanas when I have the option. I have a diamond hone that I touched up the edges with and it helped a little. I went ahead and ordered a Whiteside bit that is solid carbide. I think if I had a larger router as well it would help. I'm using a Milwaukee that is 1.75 hp as I recall, a 3 hp is on the wish list, along with a lift for the router table. With most stuff that I have done it's not too much of an issue, but this lbl puts up a good fight. I'll Dynamic Saw in mind though .... thanks.

[Steve Manning]

I've used the Katana series bits with good results, too- otherwise I'm usually a Freud or Whiteside kind of guy. But you're right, the long fibers due tend to lead to tear out, have to be careful about that, IME.

It's getting there, though- you're making good progress. I just spent most of the morning learning on my Audio Precision- posted a bench review of the AURALiC Taurus Pre in Audio Hideout. Next step is moidifying a balanced cable for signal pick up with clip leads, then I try the first amplifier with this rig.

I imagine with all the rain you've been getting that was a good choice of activities for the day.

[JonMarsh]

That's has been a bit of a problem this weekend... :W

We did have a dry sunny patch for a little while this Sunday morning. But not something one could get much done in...

Anyway, I learned a lot, and am getting comfortable with how to do things.

[ergo]

As if the design is not complex enough I'm pondering on one more option. On computer screen the models looks very good if all the edges of LBL are slightly chamfered. I did try this on some test pieces - routing of the chamfer works ok. BUT what I'm afraid of is glue up phase and what happens after that. If many of the chamfer's get glue in them it might mean hours and hours of sanding and cleanup. Has anyone attempted something like that and can say right off that it's a bad idea? Or could it work if I'd use the glue moderately or pre cover the edges with a tape or some such trick?

[BobEllis]

Maybe make up a guide that wraps around the radius and use a trim router with a veining bit to clean/make the grooves?

I like the look in gray/solid color, it adds interest. If you are going to leave the LBL natural or stained, not as much (Probably because I know that's an old woodworking trick to hide less than perfect joints)

[Steve Manning]

I agree with Bob ....glue it up and then cut the grooves after, you'd be there forever trying to clean those grooves out with glue in them.

[IslandHydro]

As if the design is not complex enough I'm pondering on one more option. On computer screen the models looks very good if all the edges of LBL are slightly chamfered.

My opinion: not worth the effort. It'll make for a surface that's really hard to keep clean, and finishing might get more complex too. I think the highly varied grain patterns, with a nice finish will be very complex and interesting. Any additional complexity (imo) will be distracting.

[ergo]

Thanks guys for good feedback. Indeed as it is not a solid color material (as opposed to the model) it will probably not show up as well plus is a pain to do. So I'll check the final outer front panels . if the fit is not super snug I'll consider chamfering only those a bit.

I did find one solution thats available here for wood filling. This one allows mixing in the original sawdust as opposed to just sorta matching the color.

http://www.pallmann.us/products/product-search/details/pall-x-kitt-filler-6508/

So I'll buy this and try it out.

The ones that are pre made are only available for wood types that we have around here - ie birch, pine, oak and nothing of bamboo.

[TEK]

Are you talking about filling the imperfections in the bamboo?
First, if you are looking for something like that to fill it with, would it not be just ad good to mx white wood glue with sanding dust? That's what I usually do.
However, in this case I'm a bit worried that it might be hard to get a really good result. Your bamboo is laminated in a given pattern. You must consider how the filled areas will look compared to the laminated pattern after you fill it in.
What you might do is to fill it with quite light sanddust and then use stain or coloring to try to match up the patterns.
Or it might not be a problem at all, easier for you too see that have it all up close.

About the chamfering, I agree with what was stated before
- you will probably need a solid color for ut to look good
- you should chamfer after gluing up

[ergo]

I've just counted that there are 10 out of 56 top/bottom pieces that have holes through that are wider than 2mm. And then from big chamfered side pieces 3 out of 4 are pretty bad. So my plan A is actually to go back to Bauhaus with the pieces and just ask for replacing those. These are clear quality flaws after all... not sure if I get replacement boards free, but at least I'll ask a considerable discount. Then I'll just rerun these pieces. That will leave me with much smaller crack and voids and I can choose the top/bottom pieces so that the best ones are on top.

I did learn to look for issues pre-purhase better too. If one looks at the "row of squares" pattern on side, then it must be very even squares. The worst side panel with most voids also looks different from the side - the square pattern is very uneven and not even squares - so that's an indication that it's been assembled from crappy grains. I did not know to look for that plus the boards are wrapped in plastic, so not so easy to check, but possible. So with next ones I know what to look for and scrap the obvious bad ones before purchase already.

[JonMarsh]

That makes a lot of sense and I think you're on the right path to get this sorted out in a better fashion. I've never seen pieces myself with those kinds of voids- something is not right with their manufacturing or quality control.

[TEK]

Not so usual when working with factory made material like this or plywood - but when working with "real" wood it is an art to carefully select the right pices that is suited for the work you are going to do.
Think about the old woodsmen with ave as you continue your life as a woodworker ;-)

[Steve Manning]

Ergo ...... with that many voids you could opt to paint those areas of the cabinet (Bob's idea) after filling those voids with epoxy and leave good areas natural wood.

I did a repair of the chipped out area that I posted earlier using CA glue, larger wood slivers and some shavings/sawdust, with pretty good results.





I think you could do something similar, though it will take a while given the amount of imperfections your going to have to fill. I think this would give you a better match than using a wood filler if your going to leave the finish natural. Just my opinion, there are certainly guys on here that are far better at finishing than I am.

[BobEllis]

That's a great looking repair, Steve. Once finished I doubt anyone will notice even if you challenge them to find it.

[Steve Manning]

That's a great looking repair, Steve. Once finished I doubt anyone will notice even if you challenge them to find it.

Thanks Bob ...... your weather warming up any up there, looking forward to seeing you get your cabinets finished.

[BobEllis]

So am I! It's a bit warmer this week. I probably would be working on them if I wasn't attending to a sick father. He's on the mend and I should be heading home soon. I considered bringing them with me to NC, but I really wouldn't have had much chance to do anything with them.

[Steve Manning]

So am I! It's a bit warmer this week. I probably would be working on them if I wasn't attending to a sick father. He's on the mend and I should be heading home soon. I considered bringing them with me to NC, but I really wouldn't have had much chance to do anything with them.

Sorry to hear about your dad, glad he's doing better though. Since your a little south of me at the moment, you should be getting some decent weather, we're in the 70's and sunny today.

[BobEllis]

Thanks. I just told Dad I have to go for a bicycle ride at 75 degrees and will be back later. Only the second time outside this year.

[hyperducky]

When I look at the response graphs for all of the seas coaxial drivers they seem to drop off 6-8 db around 10khz. Is this an issue? Even the L12re/xfc has it but in ergo's measurements the drop is less only about 4 db. I am wondering if the measurements for the magnesium driver is better or if there is going to be some Jon marsh magic being worked in this area to smooth out the response


Sent from my iPad using Tapatalk

[JonMarsh]

When I look at the response graphs for all of the seas coaxial drivers they seem to drop off 6-8 db around 10khz. Is this an issue? Even the L12re/xfc has it but in ergo's measurements the drop is less only about 4 db. I am wondering if the measurements for the magnesium driver is better or if there is going to be some Jon marsh magic being worked in this area to smooth out the response


Sent from my iPad using Tapatalk

That is probably the waveguide loading you're looking at. It's not that 10kHz is down particularly, but also that the lower frequncies down to 2-3 kHz are up. Also, the waveguide effect should be improving the off axis power response of the tweeter, so though it might look down compared with a direct dome, the off axis energy should be better. I haven't measured any of these other than the C18, so I can't comment as much about the others.

BTW, after examining VituixCAD a bit, and looking at my AP stuff, I'm probably going to do a full new set of measurements with more detail off axis than I have usually done in the past, and then re-evaluate the crossover. It may not change at all, but who knows... Should be an interesting experience.

Sent from my iPad Pro using Safari.... :W

[JonMarsh]

BTW, the initial measurements and crossover development using test cabinets was described in sections 3,4 of "Fundamentals of a stand mounted loudspeaker". That was using two separate test cabinets, as a proof of concept evaluation.