Deep Grooves Mastering - Project Bladerunner

[opcode66]

I decided to start a new thread. I'm now way beyond a simple transducer and into stereo cutterhead territory. My work has progressed very quickly. I've learned so much. And, I think I'm really close to having a very good cutterhead. Below is a link to my latest video.

And, here are some pictures

IMG_5015.JPG

IMG_5020.JPG

IMG_5024.JPG

IMG_5026.JPG

[opcode66]

After some tinkering, a few issues that were causing resonance have been resolved. One issue was as I suspected. The enameled wire form the bobbin was loose and rattling around causing buzzing. The second issue was pointed out by my friend Chris (K-rAd). My washers were a bit shorter than they should be. That was also causing rattling. With these issues resolved, the head is sounding much better. I still have some resonance. But, I feel with some processing of the audio, this will decrease significantly. So far, so good!

[EpicenterBryan]

I still have some resonance. But, I feel with some processing of the audio, this will decrease significantly.

Quick question. What material are you using on your print? The head I'm working is printed with ABS, 100% rectilinear infill at 45 degrees, 6 perimeters. Not sure if ABS is the right material choice on my project, because if I take my finger nail and tap the housing I can hear it resonate even on the opposite side. I'm thinking I may need to find something different to print it with.

Have you used any of these materials from Taulman 3D? http://taulman3d.com/
I've got some Nylon "Bridge" I might try but wonder if you have any thoughts on the best material choice.

Bryan

[opcode66]

I'm currently printing with 10% fill 2 shells and 0.2 mm per z layer. I'm not sure what effect printing with more fill will have. When I have time to print another cutterhead body, I'll try more fill. I'm printing in black PLA.

The resonation I'm having is not due to the body like I though. I'm tweaking the springs in the transducer some more. I'm now getting better results overall. Also, some of the resonance is due to the resonant frequency of the device itself. I'm not doing any compensation for 1K which is definitely my RF.

I've not printed in anything but PLA. Also, I've made a number tweaks to my printer. These upgrades have allowed by to get really accurate prints. Even for small parts. Did you notice how nicely aligned each of my Z layers are?

[opcode66]

I'm starting to wonder if feedback could be accomplished using 2 small laser distance sensors. Wouldn't that make things nice and simple! Thoughts?

[ROLANDJAYS]

if you print solid instead of hollow or cored it will help

[opcode66]

Understood. I've been making changes to the design a number of times. As it stands now, the cutterhead body takes 3 hours to print with 10% fill. I don't even want to think about how long it would take to print solid...

Until I finalize the design, I'm not willing to waste the print time or plastic on a more solid print for that particular part. I'll get there though.

[EpicenterBryan]

As it stands now, the cutterhead body takes 3 hours to print with 10% fill. I don't even want to think about how long it would take to print solid...

Mine was printed in ABS with 0.25 layers solid infill and it took over 5 hours at 50mm/s. So today I tried the Taulman Nylon "Bridge" product... got about 6 layers before it hopelessly contaminated my supply tube and print head. Oh, and some people said I needed to run it at 2/3 normal print speed so I started it at 1/2 speed (figure 10 hours print time). OK, I've been using ABS on this same printer but I ran miles of the "Bridge" through there ahead of time so I was sure there was no debris from the ABS. But it plugged my nozzle and supply tube.

Then after several hours of rebuilding my print head with virgin parts (thanks "Bridge") I tried again.... using all the recommended settings (like I did before) and got rotten, but better results. Now I read I may need to "Bake" the material ahead of time like it's some old Ampex 456 or something - 8 hours ahead of time - even thought it is new, and sealed in a bag with a descant. And to make matter worse, it's 1.75mm filament, that is really 1.75 in one direction and 1.87 in the other. It's elliptical! So what in the hell do you tell your slicer software about the diameter of the filament? Not a happy camper with this stuff but I bought 2 rolls of it so I have to figure out how to make it work (for something).

Bryan

[Stevie342000]

What about sorbothane damping? Would mean you could still print hollow and save time and cure the issue of the body acting like a bell? Or some other damping type of material.

Just an idea, it might work and it is a relatively cheap option.

[opcode66]

I would return it to the vendor and state your case. That is some bullshit right there. I like PLA. I'm getting great results. With the mods I printed for my 3d printer, I'm getting better results than I did out of the box. You see how straight and parallel my layers are right? Really nice and shiny! I'd be willing to print parts for you if you like.

When I think that the cutterhead body design is more or less finalized, I will print it solid or close to solid. But, until then, it is a non-problem. Though it may have some effect, it is minimal. I've re-egineered some of the parts of my transducers and my resonance issue is gone. I have zero audible resonance now.

I do, of course, have a resonant frequency which seems to be a bit above 1K. But, no amount of tweaking the print setting will resolve that. All objects have an RF.

I am focusing on the bigger issues for now. How to print the head falls very low on the list. At this point, I'm more concerned with getting a higher wattage amplifier for testing. When driving the head hard, I am getting distortions caused by the lack of power in my amplifier.

It should be noted that I am getting some help from the oddest of sources. Our beloved JP has been emailing me almost everyday. And, actually making a good suggestion or two. The world never ceases to amaze me....

I hope you all are as excited as I am about this project. It is coming together much quicker than I expected and with good solid results. I never predicted I would have a working head after only 3.5 weeks. Especially because all I set out to do was make a transducer.

[EpicenterBryan]

I would return it to the vendor and state your case. That is some bullshit right there.

So here is what I got back from taulman3d.com about this, and my original (very detailed) email to them. I'm done with them... I recommend no one buy their product based on their BS response to very specific questions. Oh and the link, you should check out. No specific details but I guess I'm to use kitty litter to dry their filament? WTF?


" Hi Bryan... Yes, it's sees like steam. There is no way to even ship it so it won't get some humidity. We've tried...!
Here is how ppl are drying it.....you can also just use a small lamp overnight as well..
http://taulman3d.com/specifications.html

This works so well, we use it when it's 60% from 2 days of rain and it gets the line down to 30% RH

Let me know..
Tom"


And my detailed E-mail to them about the problem:
----------------------------

Comment
I'm having real troubles with my Bridge product. It seams to have a bunch of moisture in it. I took it straight from the sealed bag and put it right on my machine. My other roll is still sealed and unopened. I wonder if there is a phone number I can call to get some tips on settings and how I can dry the open roll, and if I can exchange the other roll for a different product.

So here are some of the issues and some background - I'm running a MK8 extruder with updated drive gear and roller tension, with 0.4 nozzle. I normally run ABS and never have the problems I am running into with Bridge. While testing with Bridge the print speeds tried were 40-50mm. Temps tried 240-254. Layer height tried: 0.25 to 0.3. Retract 1mm. New supply tube, new nozzle.

When extruding only (not printing): initially material flows well and clear then starts spitting steam and cloudy nylon. Flow gets interrupted by bursts of steam resulting in inconsistent extrude. When cooled, clear nylon stretches before breaking, cloudy material snaps before stretching.

When printing, prints are blotchy and rough with layer texture like course felt, and have poor adhesion to previous layer.

Additionally, the material has plugged my head just above the heat chamber twice. Each time I have replaced the supply tube and nozzle. Again, my retract is only 1mm so I know I'm not drawing material up into the tube.

HELP!

[opcode66]

Sucks. I'm gearing up for feedback right now myself. I just wound a bobbin with two coils. Both flat wire. The second is wound a special way to avoid inductance from an AC (alternating magnetic field). It will however induce form moving within a non fluctuating magnetic field (ie the neodymium magnet). Testing now.

[opcode66]

What I've been up to:

- Worked a lot on my transducer spring design. It now functions much better.

- Made an attachment for my wire mill that automatically spools the flat wire as I mill it. Driven by the gears on mill. I can now crank out a whole spool at a time. A lot faster than cranking and manually spooling a few feet at a time.

- Added two more upgrades to my MakerBot Replicator 2. I added a heatsink to the Y axis motor and the filament feed motor. I also made a custom X axis cable tray stain relief fix. Collectively with all the other mods I've made for the machine, on the machine, I'm getting fantastic prints. Especially with my small parts!

- I've wound enough coils to confidently say that I'm quite good at it now. I can wind multilayer coils with surgical precision. Check out some pictures below. I'm finishing the top layer in the shots. There are three layers below the top layer.

- I made my own gaussmeter. That was fun. And, surprisingly easy.

- I wound 2 perfect drive coils and assembled two all new transducers. Nearly all the parts were tweaked yet again. I'll make the linkage for them tomorrow. Then, perform a final bench test. If it sounds ok, I'm going to try cutting with it!

- I want to be able to measure the accuracy of the movement of my torque tube/transducers. Since I have no Feedback at the moment, I tested recording the vibrations with: a mocrohphone, a small full range speaker, and a piezo speaker.

- I rolled a bobbin with both a drive and a special feedback coil. I'm trying to get isolation and no inductance from drive. This is going to be challenging. I honestly feel like adding small highly accurate laser distance sensors is going to be my solution for feedback. Fuck a secondary coil. And, less moving mass with lasers! Nonetheless, I am experimenting with a traditional coil approach first.

[markrob]

Hi,

All looking very good. I assume you are trying a bifilar winding. I'm skeptical that using a non-inductive winding will yield any results since any fields will be canceled out in the winding. But, its easy to do and you'll know for sure very soon.

On the laser front, that might be a big project. To measure my head, I built a simple laser interferometer using a laser pointer and it worked well:

http://users.df.uba.ar/sgil/physics_paper_doc/papers_phys/ondas_optics/doppler.pdf

It would take some major work to get this to be used as a position feedback device on a head.

I really like Fairchild's high frequency RF eddy current sensing scheme. This is detailed in a paper in the AES anthology. Well worth the read. I want to try this sometime.

I have had some success using the drive coil back EMF as the velocity feedback sensor. I used a bridge circuit to null out the drive signal and separate back EMF out. The trick is making sure the null holds up to 20Khz and that it adjusts due to drive coil resistance changes as the head heats.

Mark

[opcode66]

I'm talking about a pre-built, highly sensitive, highly accurate laser distance sensor something like these:

http://www.keyence.com/products/measure/laser-1d/il/index.jsp

They have units with the accuracy required. You can mount them in creative ways using mirrors in order to bounce the beam to where you want to measure and back again to the unit. This is not the only maker of such devices. Two of these built in would give tremendously accurate real time feedback.

Len suggested the Fairchild approach to me. I am also considering it. I really want to go with an alternate method. I feel that trying to minimize inductance from the drive coil is a waste of time and better ways are at our disposal in the modern world.

Here are the coil pictures I was unable to post last night for whatever reason.

IMG_5050.JPG

IMG_5049.JPG

And video of a bench test of a transducer with feedback.

[markrob]

Hi,

Coils look really nice! Super job.

The sensor you are looking at will not work in this application. The sample rate is way too low (1Khz). Not clear what the resolution really is as the spec is based on a average of 128 samples. I doubt any of these industrial position measuring devices will give you the analog bandwidth and/or resolution for this application. The optical approach should be workable, but you'll probably have to roll your own. The laser turntable made in Japan is proof of that, but it is not cheap.

I was really excited last year when TI announced the LDC1000

http://www.ti.com/product/ldc1000#features

This is basically the Fairchild eddy current position sensing system on a chip. Sports some very impressive resolution specs (still might not be fine enough). However, these numbers fall apart once you increase the samplerate. Close, but not quite there for this application. Its really hard to beat moving coil feedback even today. Its probably worth the effort to tame the coupling issue. It has been done by all of the past makers of these heads (the Fairchild being the odd man out here).

Mark

[opcode66]

Thanks for the suggestion. I like this idea. Possibly I can find someone making a more accurate version of this chip???

With respect to he laser, that is not the only one on the market. Just the first I pulled up... I can find one that would meet the specs we need. They exist.

But, what you are suggesting seems a lot easier. And, I could easily work a chip into my transducer design. Thanks again man!

[opcode66]

Bladerunner Bench Test #5 (Final)

Now, I take this all to the lathe. Hopefully, the next video will be of me cutting!

[aaron]

Were you able to print the Neumann cone shape hole for the stylus?

[opcode66]

Yes. A while ago I made stylus holding blocks. Mostly for holding and inspecting the diamond styli I sell. I made the 1:20 taper cone at that time. I copied it and pasted it into the torque tube design.

Right now, I have to redesign a print a number of parts including the cutterhead body itself which takes 3 hours to print. Once I tried mounting the head on my lathe, I realized that there were a number of issues. My vacuum tube mounting hole is way too low. The bottom extension that holds the tube had to be removed because it extended too far down. The vacuum tube now protrudes through the back of the cutterhead body. The mounting bracket on the back was not quite the angle it needed to be and the cylindrical nub was not quite the right size. Also, the slots in the torque tube that accept the transducer pins needed to be widened to avoid the breakage issue I ran into when both channels were linked to it. Finally, I had to adjust the tension spring in my suspension box so as to have very little tension due to the light weight of the cutterhead. I will print the cutterhead body with much more fill today so it is heavier. That should allow me to run the suspension with a bit more tension. And, I think a more solid body will sound better. Finally, I trimmed a bit more off of the front bottom corners of the cutterhead body to avoid contact with the disc when the cutterhead is tilted and in use.

Much later today I should have all the parts printed and I can assemble the head again. Hopefully this will be the last time and the head will mechanically work with my suspension box. At that point, I can perform some test cut. While things are printing I will get some program material setup to cut.

Hoping today I will have my Eureka moment.

Here you can see some of the issues. Everything below the torque tube on the back is getting deleted.