3DEXPERIENCE Tools: Additive Manufacturing Engineer (A3D) Role & FFF Supports

Mike Britton — Mon, 23 Oct 2023 21:51:25 +0000

Alright, so this is a little cart-before-the-horse because I have a whole thing to do about the 3DEXPERIENCE Platform, the 3DX SOLIDWORKS Makers Offer, and fitebots. But this little slice of the 3DX Platform is a capability Team Malice has and I am so happy to operate for us. It enables us to create geometry on our FFF printers that might otherwise be out of reach or, in this case, dramatically improve the speed with which we can create these parts. I originally posted this on my site, so if you want to see me get weird about CAD, CAM, and my non-Team-Malice Projects, check ’em out!

I’m a GoEngineer SOLIDWORKS and CAM specialist, but have extensive experience in Additive Manufacturing. I decided to spend my morning in the 3DEXPERIENCE Additive Manufacturing Engineer (A3D) role. I created a cell for the recently announced Bambu Lab X1E 3DPrinter and prepared a replacement part I designed for my phone charger.

The 3DX DELMIA A3D role brings professional CAM tools to AM. Here we can set up a manufacturing cell, build plate, rules, etc. The current greatest value-add, however, is parametric control over support structures:

I wanted to create these structures in A3D, keep the majority of the structure in model material, and set only the interface layers to my support material in Bambu Studio.

IT WORKED!

In CAM, minimizing tool changes is the number one way to reduce cycle times (and time is money!). Since this printer has only one toolhead for multiple materials, this means that there are TWO time-consuming filament-purges and temperature adjustments per material change.

This is a category of problem — even on multi-toolhead machines, printing an additional body of a separate material introduces compounding acceleration and print head moves on every layer. These contribute to higher cycle times.

Additionally, support materials are usually an industry-specific set of soluble or low-bonding thermoplastics which require a long time to dissolve, or expensive solvents to remove. Both the support materials *and* their solvents can dramatically contribute to the cost of individual parts, as they are more costly than model material. This is one reason why powder-bed and resin-based solutions are so popular — you can achieve geometry that would otherwise be too costly on Fused Filament Fabrication (FFF) processes.

So what are the advantages here? First, cost reduction for cycle times, materials, and post-processing.

The next advantage comes from the fact that operators are able to create, test, and save rules for their support generation. The usual solutions around support materials either:

1) Generate supports in model material – this means that the supports are *extremely* well bonded to your model part, and removal is tedious and can negatively impact surface finish. Breakway supports have been improving over the last year or so, but there can still be drooping, and most slicers only offer primitives (prismatic geometry) to enforce or block supports on model geometry.

2) Entomb models in support material – this means that extracting a part from support material requires a lot of time spent post processing, frequent interaction with chemicals, and a lot of manual labor.

Here, we get the best of both worlds. Minimal cost on support material by setting *only* interface layers to change materials and minimal time in post-processing because only a tiny amount of support material has to be dissolved from the model.

This is one of the roles I’m truly ecstatic about in the SOLIDWORKS channel, and the benefits are enormous. How did they fare on this test?

By being mindful of this simple part design, we can see that editing the interface layers reduced the cost of this one print job by 27% and the total time to print by nearly 50%! If we ignore the preparation time for the printer, we go from taking less than an hour to 2 hours, 18 minutes. The total amount of material used is also reduced by 40% because of the reduced number of filament changes.

I think this primarily represents a lower bound, the best-case scenario for this kind of addition, but it shows how many gains can be made here. Is a single layer of interface material sufficient? Time will tell, but we’ve moved from having to immerse a part in a bath for hours to dissolve material to simply wiping it away with our solvent of choice.

I can’t wait to try this out for several other machines and machine types — if we can unlock these kinds of gains in a few simple steps for FFF printers, what can we achieve with our other processes?

The Great Brushless Drive Debate 2023

Liaw — Sat, 29 Apr 2023 23:02:11 +0000

Our amazing and brilliant Brian Adamson had a wonderful solution for 250lb Malice’s Weight Issue, Brushless Drive.

Immediately, our Top David, Liaw, shot it down. “Our drive problem is solved.” Indeed, David is right, Malice’s drive is very infrequently the problem with why we loose matches. However, I, Bunny, know that if we don’t keep pushing the boundaries, we will get left behind. So when Brian approached me again, I knew we needed to have him get the real data on what it would take to make a brushless Malice drive equal to the brushed we currently use.

He did not disappoint, and came up with the following proposal:

Malice brushless drive proposal by Brian Adamson

29 April 2023

Introduction and Summaries

Introduction

Malice is currently facing complications related to weight management and a teamwide desire for additional features not included with the original design. These features include more robust top frame structure and potential permanent additions of titanium sheet armor. Of prime importance, however, is the desire to retain and improve the anti-wedge front-facing fork design, which has demonstrated tremendous usefulness across two competitions.

Malice was not initially designed for the fork system, and sacrifices are currently being made to create the weight allowances for these retrofits. Those limitations have included restrictions on the overall fork design (as they must stay within an extremely tight weight limit), limits on materials and fasteners used, and limitations on thickness (and therefore, strength) of frame materials. In addition, to create more ‘free weight,’ Malice has begun making use of custom-manufactured titanium fasteners in the robot, which provide adequate strength for their intended purposes, but represent a substantial monetary investment.

Finally, an additional issue has come to light across the last two competitions (Robogames 2023 and Battlebots 2022). Malice has lost drive power on at least one side in several fights, due to the drive motor shearing off of the gearbox. The motor is held to the gearbox face by four 8-32 screws, which are intended only for mechanical connection, rather than axial or lateral load. The gearbox itself, and the motor, are both held in relatively compliant UHMW structures which appear to, in certain circumstances, allow the motor and gearbox to move independently of one another. This movement results in the mounting screws shearing, which allows the motor to back out of the gearbox, allows hardened screw heads to fall into the gearbox, and can cause other mechanical issues.

Proposed Solution

A solution proposed in this document is to convert Malice’s current drive system, which uses high-quality, high-power brushed servomotors from Magmotor, to brushless motors (with hall-effect position sensors) and controllers used in personal electric vehicles (primarily, electric skateboards). These have been used with success by other teams at Battlebots and other competitions, and represent a substantial weight savings (in the most conservative estimate, over eight pounds). In addition to being lighter, brushless motors are physically smaller, which can make mechanical hardening of the drive system much easier. This hardening typically takes the form of traditional magnet-epoxy hardening (which is currently already performed on the Magmotors) and additional mechanical constraint of the motor to the gearbox. This additional constraint will reduce the likelihood of the motor shearing off the gearbox.

Requirements

Combat robotics is a time-constrained activity in a chaotic environment. Any proposed solution must be quick to install, easily maintainable, reliable, and rely on existing bodies of knowledge, with resources available outside of the immediate team. Therefore, this document treats the following as requirements for a successful conversion:

1.) As few parts as possible must be replaced. Gearboxes, especially, will be considered critical components, as much of the current frame design is informed by the shape and location of the gearboxes.

2.) The solution must maintain an adequate ground speed. Weight savings mean little if the robot becomes meaningfully slower on the field.

3.) The solution must use as many quickly-available, off-the-shelf parts as practical.

4.) Motors and controllers must be quickly available, with a wide body of knowledge within the community.

Potential Issues With Proposed Solution

Brushless drive (Here, meaning the combination of brushless motors, brushless speed controllers, and firmware configuration on those speed controllers) is, inescapably, more complex than the brushed alternative. While well-established “recipes” for motor, controller, and firmware configurations exist within the community (for example, MadCatter and 6374 motors, HUGE and 8085 motors, Claw Viper and Revolt RV-100/RV-120 motors), there is not a standardized ‘best practice’ process or document for brushless motor performance. These “recipes” are frequently most-applicable to the exact environment they were derived from, and additional tuning is frequently required when deviating from that plan. For example, the configuration and hardware combination used by the HUGE team with their motor/controller combination may not be directly applicable to Malice, and will require additional tuning. This tuning will consume time and testing cycles. The proposed speed controller hardware in this document (Vedder Electronic Speed Controller, or VESC) is intended for ‘inherently safe’ vehicles (bicycles, electric skateboards, etc) and as such, has many features that are actively detrimental to combat robotics. The process of ensuring these are disabled, and creating the ‘golden master’ configuration, will take time. Finally, brushless drive can be victim to intermittent, non-reproducible artifacts, which can either disable drive entirely until the system is reset, or cause undesirable driving mechanics. Brushed drive can also be subject to the same types of intermittent behavior issue, but anecdotal information suggests that they may be more common in brushless systems.

Technical Discussion

Current configuration

The current configuration of Malice is as follows:

Drive motor: Magmotor S28-D4-400X (“Combat” Magmotor)

Drive motor controller: Castle XL2 (Brushed Mode configuration)

Drive motor voltage: 6S (22.2v nominal)

Drive motor speed: 4617RPM @ 22.2v (roughly 208 RPM per volt [Kv]). Information derived from motor specification of “5000RPM @ 24v”.

Drive power: Approximately 4-5 horsepower (3000-3750 watts) of drive motor power per side

Wheel size: Approximately 12 inches per wheel

Gear reduction: Whyachi P3 12:1 planetary gearboxes

Weight per motor: 6.8 pounds

Approximate Ground speed: 20 feet per second (13.6 miles per hour)

Proposed configurations:

The proposed options primarily, are to replace the Magmotors with 8085-sized brushless motors from Maytech, and controllers with VESC from Trampa Boards. Trampa Boards works directly with Benjamin Vedder (the designer of the VESC) and is as close to a “first party” VESC supplier as exists. Additionally, these are well-understood within the community, and vast amounts of information are available from (for example) Rory Mangles, Ellis Ware, Jonathan la Plain, and Aren Hill.

These motors have a large rotor, dissipate the desired power well, and fit well within the robot. They are well-understood within the community (this size, and brand, of motor are used by HUGE and Lucky) and are relatively economical. There is an additional option to use 63xx-sized motors; these are exceptionally well-understood in the community, and their power capability is commensurate with other 2-wheel-drive, horizontal-spinner robots (for example, Tombstone uses “short” Magmotors on P3 gearboxes). MadCatter has used one 6374 per wheel as well.

Of particular importance will be “soft start” circuitry. VESC does not handle the inrush current spike well, and simply closing a switch will have a very high likelihood of killing the speed controllers. Hal has already seen this in Duck. The Endgame team (at least used to?) sell “soft start” retrofit kits for Whyachi switches, and sell their own switch with integrated soft start mechanisms, which we are already using on the weapon.

Option 1: Shortest Lead Time, Most Expensive

Drive motor: Maytech 8085

Drive motor controller: Trampa Boards VESC6-High Power *or* VESC 75/300

Drive motor voltage: 8S (29.6v nominal)

Drive motor speed: 4736RPM @ 29.6v (160 RPM per volt [Kv])

Drive power: Approximately 5 horsepower (3750 watts) of drive motor power per side

Wheel size: Approximately 12 inches per wheel

Gear reduction: Whyachi P3 12:1 planetary gearboxes

Weight per motor: 2.5 pounds

Approximate ground speed: 20 feet per second (13.6 miles per hour)

Discussion:

This option makes use of parts that are available with the shortest lead time. Maytech manufactures high-quality brushless motors, however the only motors kept in stock are 160Kv, which is notably slower than the current motor system. As a result, this option requires new batteries. This option saves approximately 8 pounds over the Magmotors.

Parts required for this option:

– Custom gearbox mount plates and rear-support hardware

– Custom shafts for 8085 motors to interface with existing gearbox pinions/keys and rear motor support

– New 8085 brushless motors

– New motor controllers (1 controller per motor)

– New 8S drive batteries

– “Soft start” hats for Whyachi switches OR Endgame switches with “soft start” capability

Option 2: Longest Lead Time, Most Direct Comparison

Drive motor: Maytech 8085

Drive motor controller: Trampa Boards VESC6-High Power *or* VESC 75/300

Drive motor voltage: 6S (22.2v nominal)

Drive motor speed: 4884RPM @ 22.2v (220 RPM per volt [Kv])

Drive power: Approximately 5 horsepower (3750 watts) of drive motor power per side

Wheel size: Approximately 12 inches per wheel

Gear reduction: Whyachi P3 12:1 planetary gearboxes

Weight per motor: 2.5 pounds

Approximate ground speed: 21 feet per second (14.3 miles per hour)

Discussion:

This makes use of made-to-order 220kv 8085 motors from Maytech. These have a lead time, according to Maytech’s website, of 25-50 days. This option uses the existing set of Malice drive batteries, and is slightly faster. This option does not require new batteries. This option saves approximately 8 pounds over the Magmotors.

Parts required for this option:

– Custom gearbox mount plates and rear-support hardware

– Custom shafts for 8085 motors to interface with existing gearbox pinions/keys and rear motor support

– New 8085 brushless motors

– New motor controllers (1 per motor)

– “Soft start” hats for Whyachi switches OR Endgame switches with “soft start” capability

Option 3: Shortest Lead Time, Most Uncertainty, Lowest Cost, Lowest Speed

Drive motor: Maytech 6396

Drive motor controller: Trampa Boards VESC6-High Power *or* VESC 75/300

Drive motor voltage: 6S (22.2v nominal)

Drive motor speed: 4218RPM @ 22.2v (190 RPM per volt [Kv])

Drive power: Approximately 5 horsepower (3750 watts) of drive motor power per side

Wheel size: Approximately 12 inches per wheel

Gear reduction: Whyachi P3 12:1 planetary gearboxes

Weight per motor: 3 pounds

Approximate ground speed: 18 feet per second (12.2 miles per hour)

Discussion:

This makes use of rapidly-available 6396 190kv motors from Maytech. These motors are new to me, but the 63xx motors are extremely well-understood as a family, with the primary difference here being that the 6395 has a longer stator (thus, more torque and larger ability to dissipate heat) than the 6374. These are the highest-Kv motors that are available in the shortest period of time, but still cost about 10% of our drive speed. This option does not require new batteries. This option saves approximately 7 pounds over the Magmotors.

Parts required for this option:

– Custom gearbox mount plates and rear-support hardware

– Custom shafts for 6396 motors to interface with existing gearbox pinion/keys and rear motor support

– New brushless 6396 motors

– New motor controllers (1 per motor)

– “Soft start” hats for Whyachi switches OR Endgame switches with “soft start” capability

Option 4: Shortest Lead Time, Additional Speed

Drive motor: Maytech 8085

Drive motor controller: Trampa Boards VESC6-High Power *or* VESC 75/300

Drive motor voltage: 12S (44.4 nominal, 2x of our current 6S batteries in series)

Drive motor speed: 7104RPM @ 44.4v (160 RPM per volt [Kv])

Drive power: Approximately 5 horsepower (3750 watts) of drive motor power per side

Wheel size: Approximately 12 inches per wheel

Gear reduction: Whyachi P3 12:1 planetary gearboxes

Weight per motor: 2.5 pounds

Approximate ground speed: 31 feet per second (21 miles per hour)

Discussion:

This option makes use of rapidly-available 160kv 8085 motors from Maytech, but makes a major change with the battery input voltage. By tying two of our existing 6S drive batteries together in series and doubling the input voltage to the controllers, Malice gains a substantial amount of maximum speed. This option additionally lowers the total amperage requirements, which generally results in cooler-running, more efficient motors and controllers. This option will require redesigning the drive battery holder, but does not require new batteries. This option saves about 8 pounds over the Magmotors.

Parts required for this option:

– Custom gearbox mount plates and rear-support hardware

– Custom shafts for 8085 motors to interface with existing gearbox pinions/keys and rear motor support

– New 8085 brushless motors

– New motor controllers (1 per motor)

– “Soft start” hats for Whyachi switches OR Endgame switches with “soft start” capability

– Series wiring harness for batteries

– New drive battery box

Conclusions

The above options will save a considerable amount of weight, and should offer largely-comparable performance to the existing motor drive system with zero required modification to the existing Malice frames and spares. It may increase the robustness (and as such, mechanical reliability) of the robot drive system, through better-supporting motors that are lighter and smaller, making them more difficult to shear off of the gearbox in the first place. However, these changes come with costs: one option involves replacing drive batteries (a very large monetary investment) and the three other options will involve, at minimum, custom part manufacture and time on behalf of the robot’s owners to retrofit, test, tune, and configure the robot’s drive controllers.

After reading that thorough and amazing proposal, I knew I had to talk to our Top David again. While the decision falls to Liaw, I can overrule him if I don’t think he’s being reasonable.

When I brought this well researched proposal to Liaw, he read it thoroughly. when he came back, he gave me the reasons he still believed we should not go brushless this year for Malice.
1. We have about $4k invested in our current 6s batteries, and to go brushless and get the same power we currently have, we would have to invest $400 per battery, and get 4 sets for 8 total batteries. $3200 more for just the batteries, not including the additional parts we need, when we have reliable, working batteries right now (which we know can take large hits) is not an ideal solution.

2. In addition, we have heard from both Matt Spurk (Kraken) and noticed that our favorite team to emulate, Witch Doctor, have decided that brushless drive is not reliable enough after big hits, and either are, or have returned to brushed drive.

In the end, after much discussion with our team, we unanimously decided that for now, the slight weight savings we would gain is not enough to justify the large extra investment on a problem that is right now, not losing us fights.

We are so excited to have added Brian though, and we have tasked him to looking into data to see if we can upgrade our weapon to brushless instead!

Big Red Weapon Milling!

Liaw — Tue, 02 Jun 2020 01:03:00 +0000

After months of being shut down, we’re happy to announce that the machine shop finally opened up! This means we were able to get our main weapon finished with the mounting we needed! Thanks to our magnificent David Rush for documenting the whole process!!!

First, we have to make sure the very large weapon is secured to the mill base!

Here’s our Red Rush weapon secured to the mill!

Next, we have to measure the inconsistencies from the waterjetting process and clean them up using a boring tool! The bearing hole was off by about 1mm.

Using a micrometer to measure how far off the hole was from the blueprints!

Boring rod tool ready to make it precise for the bearing to be installed!

Boring the bearing hole to match the blueprints!

After we got the hole correct to the blueprints, we have to bore it out to install the bearing!

Boring out the hole for the bearing!

After boring the bearing hole, we wanted to make sure the bearing fit snug!

The hole after boring!

Bearing fitting snugly in the hole!

The next step in the process is to make the holes to mount the pulley to the weapon!

The mounting holes need precision!

Drilling them so precisely

All drilled!

After the mounting holes were drilled, we decided to test the fit!

LOOKS AMAZING! Almost ready for combat! Just one more step!

NOW, the final bit to mill, the tooth holes! The Red Rush Weapon will have a hardened s7 steel tooth mounted for maximum damage.

The counter-boring hole for the tooth mounting!

Counterboringggg

Have to drill through the front!

AND THAT IS IT! The weapon is ready for tooth and final installation!!

Don’t knock things over Rush