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

[JonMarsh]

Well, here I go, on the dark side again. I'd intended to hold off posting more about this or starting an "official development and build thread" until we had more film in the can, but as this paraphrase of a quote Steve Manning used in a recent email goes, I'm itching to get going and have a thread with a more clearly and narrowly defined focus than the thread I started kicking around these ideas for, which originally was just going to be focused on the low frequency design.

Everything is subject to change at this point, yet I think we've got a pretty good grip on things as they stand.

And that patience quote relates to the fact that their are two main build efforts going on- the official Translam design which has been briefly discussed, and my earlier "by hand" design, which will still get built and likely finished earlier. (our CNC vendor is having some teething pains getting his setup sorted out- this may still be a few weeks).

Part of my lack of patience is also due to some more listening checks on the one acoustic prototype, including with a Naim album I just came across that is really lovely, (if you like latin influenced female jazz singers- MadMac, you better listen up!)

You can get this in CD version, which is probably pretty nice, but I have the direct from Naim 24/192 download, sort of like getting the master tape. well, actually, a LOT like getting the master tape! Recommended, in fact, Highly Recommended. (some really nice subtle percussion, and excellent bass guitar work)






So- back to the Minerva Monitor.

This is a TAD inspired design (think Compact Evolution One) "stand mount" design using the Seas C18EN001 concentric Midrange/tweeter driver, with low frequencies handled by the combination of Wavecor SW223BD02 and ScanSpeak Discovery 26W/0-00 10" Passive Radiator. yeah, it's not hardly fair putting that LF combo up against the 6-1/2" ported woofer used in the Compact Evolution One, but then it wasn't fair putting the SW223BD01/2 up against the Eton 7" woofers used in the Indra either. Some would say, if you're not cheating, you're not trying hard enough.









Next, I'll recap the table saw design and a quick overview of the Translam version of the design Steve Manning has been working up, then summarize the state of crossover development and the reasoning behind where that stands.

I should mention Seas has their own stand mount design using the C18EN001 and the RO4Y 10" subwoofer; it's even smaller, and uses DSP in the Hypex plate amp for the LF to mid crossover and equalizing out the upper range response after the relatively simple passive crossover.



It's very compact, no question!



And if the electronics in the Hypex plate amp (A/D; DSP; D/A, UcD modules) are up to the quality standard you want, this might be a system to take a close look at. OTOH, for me, I can't bear the thought of running any of my DAC's into this for music. It might be really killer for HT, though- think a 2.1 system without the 0.1!

[sdl2112]

I'm looking forward seeing these come together :T. Among the many interesting aspects of this design will be your take on the sealed vs passive radiator loading of the SW223 driver compared to the Ardent. That begs the question...why did you go the passive radiator route vs sealed?

[csmielke]

Just gotta love it, can't wait for the ending.
Chris

[JonMarsh]

Just gotta love it, can't wait for the ending.
Chris

Yeah, this is probably going to be too much like one of those movie serial shows back in the days of yore- "What will happen to our intrepid heros Steve and Jon in the next Episode of "Minerva Monitor"!"

[JonMarsh]

I'm looking forward seeing these come together :T. Among the many interesting aspects of this design will be your take on the sealed vs passive radiator loading of the SW223 driver compared to the Ardent. That begs the question...why did you go the passive radiator route vs sealed?

Well, you know what they say- it's all about trade-offs. In this case, I wondered how close I could come to making a stand mounted box that would do something close to 20-20K. Originally I was thinking in terms of the PR223BD02, and I have a couple of those on hand, but the SS PR in the bone stock configuration just models better.




Initial testing confirmed the validity of this approach, at least at a first cut.

Near field output of SW223BD02




"summed" output (mic directly to the side, half way between woofer and PR)




Also, for this design, being a bit of a b@ll-buster for load impedance was not deemed so much of an issue, because one of the original intents was to make a challenging load for testing Class D amplifiers, both things I'm working on an the IR Class D stuff developed by the "new" Infineon Americas since we bought International Rectifier. So, in this case a nominal 4 ohm load that looks a bit like 3 ohms at times wasn't going to scare me off. OTOH, the impedance of the SW223BD02 reveals a well designed motor with lots of copper in the gap, and a very easy impedance curve to work with for a three way. Notice the impedance curve shows the box tuning on the money from prediction, just a bit over 20Hz.

[JonMarsh]

Any one remember this post from Steve?

Sounds like you need to clone yourself or pick up some Minions Jon . Wish I were closer, being off work at the moment I could play the role of a Minion.

Well, Steve IS the official Minion on this project, though only his wife can say if his appearance is even vaguely like this picture he linked to...

I prefer to think of him as my key collaborator and right hand man, and so far this is working remarkably well considering we're on opposite sides of the country. Has a lot to do with his major contributions and very strong organizational skills.

He's also a real wizard with SketchUp, and what he's done with it hasn't exactly convinced me to abandon Shark, I have popped for a license for SketchUP Pro. SketchUp has a very curious history, it's doing quite a bit better now that it's with Trimble, I think. But it has some of that quirkiness in it's genes, enough that guidance from an experience person and a few good books are mandatory. As it is, I've learned enough to know that I need to go back and reset and create my table saw version with crossover integrated in the cabinet from scratch again, for a number of reasons. Live and learn, that's what works.

[JonMarsh]

Table Saw Minerva Monitor concept

OK- for quick reference for the new thread- the table saw concept version of the Minerva Monitor, with built in crossover, maple stools for speaker stands are optional extras.

This is included so folks won't have to go bouncing around between threads to pick up the key points.





Most of the material is a LBL, with some BB ply on some inner walls.

[Steve Manning]

Well, Steve IS the official Minion on this project, though only his wife can say if his appearance is even vaguely like this picture he linked to...

I prefer to think of him as my key collaborator and right hand man, and so far this is working remarkably well considering we're on opposite sides of the country. Has a lot to do with his major contributions and very strong organizational skills.

He's also a real wizard with SketchUp, and what he's done with it hasn't exactly convinced me to abandon Shark, I have popped for a license for SketchUP Pro. SketchUp has a very curious history, it's doing quite a bit better now that it's with Trimble, I think. But it has some of that quirkiness in it's genes, enough that guidance from an experience person and a few good books are mandatory. As it is, I've learned enough to know that I need to go back and reset and create my table saw version with crossover integrated in the cabinet from scratch again, for a number of reasons. Live and learn, that's what works.

She's sworn to secrecy ........ though these days I would say there might be a strong resemblance. and thank you for the kind compliments .....

I don't know about be a wizard with Sketchup, especially looking at this guy today, https://www.youtube.com/watch?v=uTtB...8aATrh&index=1. Though I'm certainly happy that Sketchup is relatively easy to learn and that vendors supplying CAM software for CNC machines are allowing for direct importing of Sketchup files for tool path creation. That way you can even use the free version of Sketchup and get machining down at the other end.

[JonMarsh]

Translam version

Now, a view to some of the work Steve has been doing, planning out the translate version of the cabinet and stands. This is an experiment, trying Flickr as the image library source- otherwise I'm going to load up the HT Guide server!

The primary work Steve has been doing is to prepare part pieces in the form from which they can be cut out using a vendor's CNC setup. These pieces will be further worked on to produce the final design.

So, in this case, while the pieces for the main cabinet, if arrayed as they will be built, show the outline of the basic pieces that will be cut out.




With the holes cut, all the bevels and other work done, including finishing, the final result is intended to be something like this:



Getting to that point will be a lot of work- note the different pieces required for each section, and how many- that's why there's 1300 lb of LBL sitting in the vendor's warehouse that Steve picked.



It's a very similar if somewhat less arduous process for the stands:










We even did a 3D evaluation of whether the crossover could actually fit in the base- Steve made the component part models, and I did my best to put the puzzle together....

Something to always keep in mind, as Willie the Shake would say, there's many a slip twixt the cup and the lip, so I expect we may have some "interesting" challenges and perhaps some unpleasant surprises ahead.

But I've got a feeling about this... and it's not that something wrong with the earth's gravitational pull!

[---k---]

Very cool. Should be a special speaker. Would love to see people's face react to the bass from such a small package.

[JonMarsh]

Well, it's a bit sneaky, K, because it is so neutral in that area, you don't really notice anything unless something comes along in the program material that get's down there. That, and one notices a bit more weight behind drums and other low frequency percussion.

One last post this evening, at Steve's suggestion, to show an X-RAY view of the stand so you can appreciate the way this will be going together if all goes according to plan:



The X-RAY view in SketcUp does work rather nicely. Note how dowling is used in the stand (as well as the main cabinet) to locate the components precisely for gluing operations.

BTW, this moderate size PNG file is fairly high resolution- the larger you can stretch you window, the more fine detail you'll see. Download for the best effect, unless you're already running a 4K or 5K monitor.

[CADman_ks]

...
I don't know about be a wizard with Sketchup, especially looking at this guy today, https://www.youtube.com/watch?v=uTtB...8aATrh&index=1. ....

WOW!!!

That dude is off the chain!!

That's incredible what he's doing with the software!

Having spent my whole professional career in the CAD field, it's easy for me to appreciate what he's doing there. He's actually leveraging the model to do all of his work, and if you're good, that's the end game. While that sounds simple, and makes logical sense, it's not necessarily the easiest thing to do. It takes a LOT of planning and forethought to get everything to work together. He's obviously developed a powerful system that works well. The trick would be teaching that system to others. I've been there done that, and most of the time it's hard to get your system out of your head, and into someone else's...

[dar47]

Steve, will be fun assembling these and hopefully your around for the machining process? As the xovers are in the bottom of the stand and I see a hole on the back of the stand at the top and 4 holes on the top plate of the the stand, are you planning a quick disconnect to separate the speak for moving purpose as I would think these would be a bear to slide around together? Only asking as I park my monitors against a wall and move them out some times.

[csmielke]

Guys,
If this one is named Minerva does the floor standing version with dual woofers and quad PRs become Jupiter, from Roman history the father of Minerva?
Chris

[Steve Manning]

Steve, will be fun assembling these and hopefully your around for the machining process? As the xovers are in the bottom of the stand and I see a hole on the back of the stand at the top and 4 holes on the top plate of the the stand, are you planning a quick disconnect to separate the speak for moving purpose as I would think these would be a bear to slide around together? Only asking as I park my monitors against a wall and move them out some times.

I'm very much looking forward to the build ...... I will be present for the machining process and will have pictures for posting as things progress.

There will be connection points at the bottom of the speaker stand around back and then there will be connections at the back of the speaker cabinet. So yes, you can easily move them around separately. Of course "easily" is all relative since the cabinets with the drivers will be pushing 100 lbs all on their own.8O

[Steve Manning]

WOW!!!

That dude is off the chain!!

That's incredible what he's doing with the software!

Having spent my whole professional career in the CAD field, it's easy for me to appreciate what he's doing there. He's actually leveraging the model to do all of his work, and if you're good, that's the end game. While that sounds simple, and makes logical sense, it's not necessarily the easiest thing to do. It takes a LOT of planning and forethought to get everything to work together. He's obviously developed a powerful system that works well. The trick would be teaching that system to others. I've been there done that, and most of the time it's hard to get your system out of your head, and into someone else's...

I think this guy has been at this for awhile with Sketchup and your right he is VERY organized and detail oriented ....... it just shows what can be done with the software and some planning.

[Steve Manning]

Guys,
If this one is named Minerva does the floor standing version with dual woofers and quad PRs become Jupiter, from Roman history the father of Minerva?
Chris

We'll put it on the list. Of course that will depend if the boss man intends on pursuing that build.

[JonMarsh]

Guys,
If this one is named Minerva does the floor standing version with dual woofers and quad PRs become Jupiter, from Roman history the father of Minerva?
Chris

A very apt suggestion- but realistically, at this point a proposal for another calendar year I expect! At least I've got some of the drivers- but will have to pick up two more of the CSS woofers.

[JonMarsh]

WOW!!!

That dude is off the chain!!

That's incredible what he's doing with the software!

Having spent my whole professional career in the CAD field, it's easy for me to appreciate what he's doing there. He's actually leveraging the model to do all of his work, and if you're good, that's the end game. While that sounds simple, and makes logical sense, it's not necessarily the easiest thing to do. It takes a LOT of planning and forethought to get everything to work together. He's obviously developed a powerful system that works well. The trick would be teaching that system to others. I've been there done that, and most of the time it's hard to get your system out of your head, and into someone else's...

This series is on my list to download with iTubeStudio and review in detail- though when I can find the time to do it justice is another matter!

[csmielke]

Jon,
FYI, CSS has the SDX10s on sale for $100 off a pair right now. Might want to strike while the iron is hot.
Chris

[ergo]

I am planning to follow this design with CNC methods on EU side as well.
I have VCarve Pro as a CAM for my CNC and even though it should import *.skp as well it does not seem to go too fluently from this project. I don't have the SketchUp Pro with DXF export, but going Sketchup skp file -> Rhino3D -> DXF -> Vcarve works well.

Due to the machine bed size I will have to cut 1 piece at a time. But I will be attempting to also produce the 45 deg chamfer for the two sides.

Toolpath trials look like this.

[JonMarsh]

That's one thing about being "vertically integrated" that's going to give you a bit of an advantage! Looking nice, Ergo! :T

[JonMarsh]

Jon,
FYI, CSS has the SDX10s on sale for $100 off a pair right now. Might want to strike while the iron is hot.
Chris

Hey, this is all a conspiracy to get me to spend more money! But thanks for the heads up...


==============================

The iron has struck, and is cooling off... good price. Thanks!

[sdl2112]

Looks like the SW223BD02 is on sale too.

http://solen.ca/products/speakers/home-speakers/subwoofers/sw223bd02/

[JonMarsh]

Yeah, that's what I paid for the four I ordered just before XMAS. I was happy to see that pricing, believe me!

[dar47]

Yeah and you US buggers, are getting another 0.35 on your dollar, make my want to sweater you guys, haha.

[JonMarsh]

Yeah, it's funny (not in a ha ha sense) how the dollar has rebounded over the last year or two against the Euro and other currencies. And still China is trying to play games de-valuing their currency for economic advantage, even though they pushed so hard to get accepted into the IMF major currency basket, where that sort of behavior is not kosher.

I'd be stupid not to take advantage of it, and make hay while the sun shines. You never know what the next 12 months will bring.

I've also started putting together a slightly more upscale BOM for the crossover, and ordering parts- some MR caps on the way from Madisound, and another pair of C18EN001. Stolen has those listed at a nice price, but is back ordered. Need to get some more PR's on order, too- only have about 3 in the box lying around here!

[ergo]

On the topic of SketchUp a bit more...
I did buy this one

SketchUp® Guide for Woodworkers - The Basics (Video Download)

Well worth the 13 dollars asked. Found many neat tricks in there that would help speaker box builds too

[JonMarsh]

Thanks Ergo! I've bought a couple of books, too, but I'm going to give this a try also, as anything that speeds up my learning curve for the price of a nice lunch is probably worthwhile.

[TEK]

Jon, have you had the oppertunity to listen to the SW223BD02?
I'm a bit curious on how it sound/performs compared to SW223BD01. Is it a upgrade or mostly the same/same?

[TEK]

Jon, have you had the oppertunity to listen to the SW223BD02?
I'm a bit curious on how it sound/performs compared to SW223BD01. Is it a upgrade or mostly the same/same?

[JonMarsh]

The SW223BD02 is what's in this project. But making a comparison between the Minerva acoustic demonstrator and built/finished Ardents with the SW223BD01 is sort of an Apples and Oranges thing, especially as I've only got one acoustic demonstrator setup, and the LF is just in an MDF test enclosure.

The SW223BD02 seems to have about the same small signal distortion, but it has a somewhat longer throw (by about 2mm) due to redesigned VC and changes in the driver suspension. This results in about 2 dB less sensitivity, too. All of these changes seem focused on making it more of a sub driver, yet because it uses the same very stiff cone and plenty of copper in the gap and has a nice flat impedance curve, doing the Wavecor Ardents with it shouldn't be a problem, just requires reducing the mid and tweeter level by about 2 dB. I need to do a crossover check and update on that, but I don't know of a set in progress right now using the BD02, so this hasn't been a scalding hot priority.

[BobEllis]

My Ardents will use the -02s, but no rush, it's too cold here to get the veneer applied. There's a good chance mine will at least start as active at the low crossover, so I'll be starting with the relative level of mid and tweet for my padding.

[ergo]

I did some progress today. As I had not cut anything from bamboo ply before on CNC I did some feed and speed tests to see what works for this material.
ZigZags were all cut with each one getting a bit more feed rate to find whats optimum.
18000RPM and approx 95 inch per minute with 6mm 2 flute upcut cutter was what I settled on for now.

I did cut out 4 corner holders that will be the holding raw panels when I start to cut all the 40 layers of box

[JonMarsh]

Well, you're making some progress! how much does the LBL panel cost you in Estonia? Just curious...

[ergo]

It does not come cheap unfortunately.

https://www.bauhaus.info/suche/produkte?q=Leimholzplatten+bambus

and in Estonia it's even a bit more
600 x 800mm (23.6 x 31.5 inch) 21.8EUR per piece - so some 870 EUR per 2 boxes
400 x 800mm (15.7 x 31.5 inch) 15.7EUR per piece - so some 650 EUR if I use these for inner layers and 600x800 only for sides

So I'm contemplating an idea to do this kind of 'tweak' - would save me some 250EUR as from 600x800mm board I can still get only 1 cutout per piece.


Sad news I found out today was that some company had bought up basically all of the stock of the Bamboo ply the shop had (some end of December budjet remains that they decided to spend). So I'm also now on a forced few weeks idle time before they restock I have not found alternate places for this material this far. But I guess it's good from a point of view that I can play this stuff out in CAD in all variations and get a better use of material/money later on.

[Steve Manning]

I feel your pain in the waiting department ......

[Norm]

Steve M & Jon, do you want to continue to discuss CNC machining for speaker boxes in this thread or start one dedicated to the topic? I have been there, done it, and doing it and would love to compare notes.

As a start in the 'Fundamentals' thread Steve wrote: "This machine is new and unfortunately the factory installed some parts made from the wrong material which has prevented the vacuum table from working, which has caused some delays (weeks) in getting parts cut. The machine is supposed to be fixed as of yesterday and I'm hopping sawdust will fly this week. I'll make notes on things like feeds and speeds once we get underway and of course post some pictures." Beware that vacuum table, I much prefer clamping and screwing the material to a sacrificial base board. My first attempts a CNCing speaker boxes was with a shop that used a vacuum table and they ultimately decided making signs is way easier and told me to get lost. Look at your parts and consider as material is removed is enough left to maintain clamping? My vendor's frustration started when scrap rates went up as almost finished parts came unstuck from the vacuum table during machining. The Vcarve screen shots you posted look on the right track in that you seem to be planning to keep the parts and scrap attached with tabs so lots of solid area remains for the vacuum to work on.

[TEK]

It does not come cheap unfortunately.

https://www.bauhaus.info/suche/produkte?q=Leimholzplatten+bambus

and in Estonia it's even a bit more
600 x 800mm (23.6 x 31.5 inch) 21.8EUR per piece - so some 870 EUR per 2 boxes
400 x 800mm (15.7 x 31.5 inch) 15.7EUR per piece - so some 650 EUR if I use these for inner layers and 600x800 only for sides

So I'm contemplating an idea to do this kind of 'tweak' - would save me some 250EUR as from 600x800mm board I can still get only 1 cutout per piece.
[ATTACH=CONFIG]25046[/ATTACH]

Sad news I found out today was that some company had bought up basically all of the stock of the Bamboo ply the shop had (some end of December budjet remains that they decided to spend). So I'm also now on a forced few weeks idle time before they restock I have not found alternate places for this material this far. But I guess it's good from a point of view that I can play this stuff out in CAD in all variations and get a better use of material/money later on.

Are you sure you cannot make them a little bit closer, so that you get less than 300mm height? That would let you have 4 pieces on a 600 x 800 board. If you make the taps on the lower one just a tiny bit lower that might work.
Or if you make the speaker 1 cm lower you could raise them up on a 600 x 800 shett and then easly get 4 on a 800 wide sheet. Maybe more for all I know...

[ergo]

Thanks TEK.
Those are the options I'm thinking of yes. I also thought about making the middle separation wall as a separate piece and have some sort of interlock type dadoes on it. Might help keep things better together at glue-up phase and give more freedom to get parts placed for better material use. Have to continue learning the CAD and drawing the options up as I go along.

[JonMarsh]

Steve M & Jon, do you want to continue to discuss CNC machining for speaker boxes in this thread or start one dedicated to the topic? I have been there, done it, and doing it and would love to compare notes.

As a start in the 'Fundamentals' thread Steve wrote: "This machine is new and unfortunately the factory installed some parts made from the wrong material which has prevented the vacuum table from working, which has caused some delays (weeks) in getting parts cut. The machine is supposed to be fixed as of yesterday and I'm hopping sawdust will fly this week. I'll make notes on things like feeds and speeds once we get underway and of course post some pictures." Beware that vacuum table, I much prefer clamping and screwing the material to a sacrificial base board. My first attempts a CNCing speaker boxes was with a shop that used a vacuum table and they ultimately decided making signs is way easier and told me to get lost. Look at your parts and consider as material is removed is enough left to maintain clamping? My vendor's frustration started when scrap rates went up as almost finished parts came unstuck from the vacuum table during machining. The Vcarve screen shots you posted look on the right track in that you seem to be planning to keep the parts and scrap attached with tabs so lots of solid area remains for the vacuum to work on.

Probably best to keep it with this thread, as that is a major focus of this build.

[Steve Manning]

Steve M & Jon, do you want to continue to discuss CNC machining for speaker boxes in this thread or start one dedicated to the topic? I have been there, done it, and doing it and would love to compare notes.

As a start in the 'Fundamentals' thread Steve wrote: "This machine is new and unfortunately the factory installed some parts made from the wrong material which has prevented the vacuum table from working, which has caused some delays (weeks) in getting parts cut. The machine is supposed to be fixed as of yesterday and I'm hopping sawdust will fly this week. I'll make notes on things like feeds and speeds once we get underway and of course post some pictures." Beware that vacuum table, I much prefer clamping and screwing the material to a sacrificial base board. My first attempts a CNCing speaker boxes was with a shop that used a vacuum table and they ultimately decided making signs is way easier and told me to get lost. Look at your parts and consider as material is removed is enough left to maintain clamping? My vendor's frustration started when scrap rates went up as almost finished parts came unstuck from the vacuum table during machining. The Vcarve screen shots you posted look on the right track in that you seem to be planning to keep the parts and scrap attached with tabs so lots of solid area remains for the vacuum to work on.

Hey Norm,

I've been going through a bit of a self induced crash course on vacuum tables for CNC Routers of late, just trying to get a feel for the process. I find the whole process less than optimal in terms of it being called "vacuum". I've worked in and around vacuum systems all the way down to 10 to the minus 12 torr range and this just seems like a kluge. So I'm also a little concerned with parts coming loose during the process as well. The vendors typical SOP is to onion skin the cuts (not go all the through until the very end) which I guess is common to keep the vacuum pressure up. We are going to perform some test cuts prior to the real parts being machined and will make modifications from there. It could turn out that I don't get invited back at the end of this, I'm a bit of a stickler when it comes to details, but I hope that's not the case. It could be that we have to use a combination of clamping and vacuum to get through this. I'm visiting the shop tomorrow to get some CAD to CAM details tweaked and we hope to do some test cuts then. Thanks for the heads up though.

[bbcmp1979]

subscribed...

[dar47]

A few things I have learned, programming and tool path can be time consuming. Test your path on junk first, it my look nice on the screen but does it work as planned? Once that is down actual machine run time is not long and taking extra care with this expensive material should be the top priority. If it's a single sheet and flat the vacuum should work well. If your doing small pieces don't rely on vacuum. If your not cutting right through the material vacuum is nice, example driver recesses. If you are it's okay to take a couple passes and the onion skin thing on Bamboo works well, we did this with the Ardent baffles, Ben had this thin like paper. If your cutting glued up sheets and the sheet is not completely flat just put a sacrificial sheet under and level it with the machine using a big bit, then screw the material that's being cut down. Takes longer but then there will be no issues. It can be nerve racking handing this over to someone who is just learning their machine so if he not going to replace what he screws up I would watch the process and yes Steve be tough and go straight to screw down before you muck any Bamboo. Start cutting slow then increase speed it's time but it goes pretty fast. We cut full sheets in 12 to 15mins. With 2 sets of hands with 2 drills at work changing sheets that were screwed down goes fast too. You get a couple sheets cut right then you will be flying.

[Steve Manning]

A few things I have learned, programming and tool path can be time consuming. Test your path on junk first, it my look nice on the screen but does it work as planned? Once that is down actual machine run time is not long and taking extra care with this expensive material should be the top priority. If it's a single sheet and flat the vacuum should work well. If your doing small pieces don't rely on vacuum. If your not cutting right through the material vacuum is nice, example driver recesses. If you are it's okay to take a couple passes and the onion skin thing on Bamboo works well, we did this with the Ardent baffles, Ben had this thin like paper. If your cutting glued up sheets and the sheet is not completely flat just put a sacrificial sheet under and level it with the machine using a big bit, then screw the material that's being cut down. Takes longer but then there will be no issues. It can be nerve racking handing this over to someone who is just learning their machine so if he not going to replace what he screws up I would watch the process and yes Steve be tough and go straight to screw down before you muck any Bamboo. Start cutting slow then increase speed it's time but it goes pretty fast. We cut full sheets in 12 to 15mins. With 2 sets of hands with 2 drills at work changing sheets that were screwed down goes fast too. You get a couple sheets cut right then you will be flying.

Thanks Darrell .... all very good advise. This has already become a bit nerve racking and we have not even started cutting wood yet. I would certainly feel better if it were just me doing all the work on a machine of my own, it would take 5 times longer but it would just be me to worry about. The biggest issue for the guy doing this is that the bigger machine start up, has has not gone smoothly as was the case with his smaller machine.

Fortunately we won't be cutting pieces that are small and no glued up pieces. Driver cutouts will be done by hand later on once the cabinets are glued up. Screw down will be an easy option with most of the parts as well since they have a bunch of alignment holes being cut for dowels later on.

We are also going to cut some test samples of each different piece with some other plywood to verify files and what not prior to using the bamboo.

You are certainly right about not blindly trusting the vacuum, the whole process is like trying to make a sail boat out of a kitchen colander. As I said earlier, if you got a few good vacuum tech's, (not engineers) together, they could come up with a system that worked considerably better.

Steve