[ishi]

It took quite a few hours of hard work, but the new Z-Axis carriage is now in place. What made this CAD exercise difficult is that we do not have a lot of space to put all the things that we need: spindle head, sliders, huge ball screw nut, hydraulic cylinders, etc. Also, we need to make sure that the hydraulic cylinders would not interfere with the mounts for the ATC conveyor when fully extended. And the fact that our column now has these nasty 5 degree draft angles means that trigonometry has to be factored into many of our parametric equations. I don't mind the mathematics side of the story, but it makes for funky-looking numbers that make it much harder to rationalize things. But we finally have a working model, and I like it quite a bit. The ball screw nut feels truly gigantic, but I actually think it's a good thing.

***

High res pictures on public drive:

https://drive.google.com/drive/u/3/f...3dQrx?ogsrc=32

[vicpaulsen]

Morning ishi;
In reading this comment, I'm not convinced that cooling the shaft is more complicated, it might be easier than cooling the nut because the lines connecting to the shaft wound not need to move with the carriage. I'm assuming the ball screw shaft is hollow and would allow the use of a rotary fluid union at the top of the z-axis, and the models show there would be room. You would extend a feed tube to the bottom of the ball screw, to get the chilled fluid to start at the lowest point and flow upward and out thru the union.
Have a look at this one as it allows for high RPM's and pressure for both water and water glycol mix. It uses a 3/8 BSP thread for the connection the only question is if there would be any issue with bi-directional rotation. I've used these in a couple of other machines (single rotation direction) and they have worked well.
http://www.deublin.com/55-000-094120/

vic

[vicpaulsen]

ishi;
In looking at the hi-res pictures i'm very impressed with the clean lines of the EG castings with one exception. The cast blocks where the ATC mounts to looks to add complexity to the EG casting process and mold. As long as you need to have metal mounts bolted to the EG why not bolt them to the outside of the casting. The attached image shows what I 'm trying to say. This would also allow you to have horizontal adjustment for the ATC and possibly vertical adjustment thru the use of cam nuts. It makes the upper part of the EG vertical column simpler and in my opinion much cleaner.

thoughts?

vic

[ishi]

Morning ishi;
In reading this comment, I'm not convinced that cooling the shaft is more complicated, it might be easier than cooling the nut because the lines connecting to the shaft wound not need to move with the carriage. I'm assuming the ball screw shaft is hollow and would allow the use of a rotary fluid union at the top of the z-axis, and the models show there would be room. You would extend a feed tube to the bottom of the ball screw, to get the chilled fluid to start at the lowest point and flow upward and out thru the union.
Have a look at this one as it allows for high RPM's and pressure for both water and water glycol mix. It uses a 3/8 BSP thread for the connection the only question is if there would be any issue with bi-directional rotation. I've used these in a couple of other machines (single rotation direction) and they have worked well.
UNION 3/8 BSP RH | Deublin Company

vic

Vic,

This could work, but most shafts are not hollow, and machining hollow shafts over long distances (1.5m for X) is difficult. If we need hollow shafts on ground ball screws, lead times for them will be a year or more.

Also, I do not understand how that is supposed to work. I am assuming that no water goes through the connection to the motor, only through the supported end, correct? So, does it mean that you have a feed tube coming from the top and going all the way down the ball screw's shaft? Do you have some schematic showing that?

[ishi]

ishi;
In looking at the hi-res pictures i'm very impressed with the clean lines of the EG castings with one exception. The cast blocks where the ATC mounts to looks to add complexity to the EG casting process and mold. As long as you need to have metal mounts bolted to the EG why not bolt them to the outside of the casting. The attached image shows what I 'm trying to say. This would also allow you to have horizontal adjustment for the ATC and possibly vertical adjustment thru the use of cam nuts. It makes the upper part of the EG vertical column simpler and in my opinion much cleaner.

thoughts?

vic

Vic,

Thanks for the kind words. I think you're absolutely right. This part of the design was done in a quick and dirty way and needs to be cleaned up quite a bit. I just wanted to get a first version so that I could check all the clearances. I'll streamline it along the lines that you are suggested as soon as the other two linear axes have been re-designed. I could not see any attached picture though. Would you mind re-attaching it?

Thanks!

Ismael

[vicpaulsen]

Vic,

Thanks for the kind words. I think you're absolutely right. This part of the design was done in a quick and dirty way and needs to be cleaned up quite a bit. I just wanted to get a first version so that I could check all the clearances. I'll streamline it along the lines that you are suggested as soon as the other two linear axes have been re-designed. I could not see any attached picture though. Would you mind re-attaching it?

Thanks!

Ismael

Lets see if this works, this is a very generalized idea, needs to be cleaned up and sized correctly.
vic

[mactec54]

vkp,

You totally made my day! Sometimes, I worry that I'm alone, caught by this "magnificent obsession" that handlewanker finds so amusing. But messages like yours or Roger's give me the boost that I need to carry on. Well, to be honest, I'd carry on no matter what, but it sure feels a lot better when others can share a bit of the obsession or its collateral damages. And I'm really glad that you appreciate the process I'm following. It's every bit as important as the end result, or even more so.

Anyway... Toughtmet? Yes!!! That sounds exactly like what we need. Especially if it can have a slightly different color than stainless steel. A little bit like the red or yellow brakes that you can see through the rims of a sports car. The color serves no purpose other than to say: "there is some serious breaking power in there." Same thing for our nut mount: "there is some serious cooling power in there."

I'll definitely look into it:

https://materion.com/products/high-p...lloys/toughmet

Thank you!

You say Handlewanker finds it amusing, I'm sure a lot of others do also, I don't discourage what you want to do,( I wonder though if this is just a school project ) I support any kind of innovation new designs, new builds, but somethings you are not thinking out at all, so comes across as, where is this going, or even amusing

Did you check out what this Toughtmet material is used for before you placed a color change of your parts, to represent this material, it has no place being used for your Ballscrew supports, on a machine like this, it could be used as an insert, around the Ball-Nut, but your main housing needs to be steel or a high strength cast, the same as the other main parts, they only make the Toughtmet material for bushings, so comes in round stock or tubing, you need some big blocks by your drawing, this may be hard to get or even cost prohibitive

As for your Ballscrew cooling, NSK link, again this is not what you are using so you can not compare to the NSK testing on a 50mm ballscrew to your 32mm Ballscrew, plus the speeds they where testing at you will never reach this speed, they also have direct cooling inside the Ball Nut, your method would not give you the same results, it would be similar, do a study on thermal dynamics to see what method will work best in your design

All your water cooling system will be a logical nightmare, just remember this is your first build, just build a basic machine first, cool where it's needed, then see what changes need to be made for a production machine

Here is some basic's about thermal dynamics
https://study.com/academy/topic/unde...odynamics.html

[ishi]

Lets see if this works, this is a very generalized idea, needs to be cleaned up and sized correctly.
vic

Vic,

The attachment does not seem to work.

[ishi]

This post was posted twice by mistake. Sorry.

[ishi]

You say Handlewanker finds it amusing, I'm sure a lot of others do also, I don't discourage what you want to do,( I wonder though if this is just a school project ) I support any kind of innovation new designs, new builds, but somethings you are not thinking out at all, so comes across as, where is this going, or even amusing

Did you check out what this Toughtmet material is used for before you placed a color change of your parts, to represent this material, it has no place being used for your Ballscrew supports, on a machine like this, it could be used as an insert, around the Ball-Nut, but your main housing needs to be steel or a high strength cast, the same as the other main parts, they only make the Toughtmet material for bushings, so comes in round stock or tubing, you need some big blocks by your drawing, this may be hard to get or even cost prohibitive

As for your Ballscrew cooling, NSK link, again this is not what you are using so you can not compare to the NSK testing on a 50mm ballscrew to your 32mm Ballscrew, plus the speeds they where testing at you will never reach this speed, they also have direct cooling inside the Ball Nut, your method would not give you the same results, it would be similar, do a study on thermal dynamics to see what method will work best in your design

All your water cooling system will be a logical nightmare, just remember this is your first build, just build a basic machine first, cool where it's needed, then see what changes need to be made for a production machine

Here is some basic's about thermal dynamics
https://study.com/academy/topic/unde...odynamics.html

mactec54,

Thank you for the warning regarding ToughtMet, this might not be suitable indeed. But none of the thermodynamics principles that I know would prevent the nut mount from being effective. Would it be as effective as cooling the nut? Obviously not. Can it be effective enough to make a meaningful difference in terms of accuracy? Only tests will tell.

To be clear: this *is* a school project. This is not my primary job, I have no business objectives for it, and the primary purpose of the project is learning. Whether this is obvious or not, I am getting a fantastic education out of this. For example, my familiarity with Fusion 360 has improved dramatically over the past couple of weeks. My understanding of mechanical components such as ball screws or linear guides is much better than it used to be a month ago. And my appreciation for the complexity of 5/6-axis kinematics is much higher than it was a year ago. For better or for worse, this is how I learn. And I share all this on this forum because writing it down helps me. In that respect, this is a very selfish exercise. Does it help others on the forum? May be, but only them can tell. Does it hurt anyone that I am doing it in this fashion? I hope not. But if the noise on the forum is too much, please let me know and I'll try to tone it down. I certainly do not want to be a nuisance to anyone.

As far as building a simpler machine first, I am sorry, but this is not how I like to learn or work. When I embark on a new journey, I like to put myself outside of my comfort zone. That's the only way I know to get things done. I'll give you a couple of examples:

15 years ago, I decided to learn how to ride a motorcycle. I had never been on one, but I liked the idea of it. So, I saved a bunch of money for a year, I went to a local Harley-Davidson store with a friend of mine who had a license, I bought a brand new Fat Boy on the spot (see attached picture), and I rode back home with him, on the passenger seat. I then took lessons at a local school, on a small motorcycle, but I took the practical test on the Fat Boy. That was hard, but it really taught me a lot about balance. I then broke the engine in riding 500 miles at slow speed, never going on the highway. And I learned how to use the clutch on the steep streets of San Francisco, which is not easy for a beginner. This process made me a decent rider, and I am glad to report that I never got into any accident ever since (knock on wood).

Here is another example: I got my Master's degree in Computer Science at a French engineering school. The first six weeks were an internship at a factory so that you can learn what being a factory worker is like. Most jobs are pretty mundane, but I wanted something a bit more extreme, so a friend of mine and I picked the only two spots that nobody wanted: gallery diggers in Europe's deepest coal mine at the time (1,800 meters below ground). I've attached a picture of the working conditions there. 40°C and 100% humidity. You work wearing a speedo, boots, helmet, and gloves. On the first day of work, they give you goggles, a breathing mask, and earplugs, but you toss them after a few minutes because the goggles get fogged up instantly, the breathing mask gets full of dust (no lung disease in this mine thankfully), and the ear plugs prevent you from hearing the Caterpillar truck that is about to kill you. These were the best six weeks of my life... And today, I always make sure to spend 4 to 6 weeks every year as an apprentice somewhere, just to get outside of this comfort zone. Last time was when I learned how to use a mill and a lathe at a local community college. Next time will be working as a stone mason in England. And the one after will be as a lumberjack in Japan. That's how I spend my vacations.

As far as the machine is concerned, I am following a very similar process: I set out a crazy goal (micron-level repeatability on a fairly large envelope), and I do everything I can to reach it, or get as close to it as possible. At first, the task sounds impossible, especially to experts in the field. There is just no way that anyone could do that on a first build. But setting out such a crazy goal, you can focus on what really matters. You push the envelope. And you meet a lot of fantastic people who get inspired by the challenge. Does it work in the end? Sometimes. Does it matter if we fail? Not at all. Why is that? Because we learn a lot more from our failures than from our successes. Education should be an unending sequence of failures. It's only failures that teach you the real lessons. And failure is okay because this is not a mission, this is an education. If you have a mission, you MUST succeed. When I fly as pilot in command, I am on a mission, and I will succeed. There is no room for errors. Failure is not an option. But when I am a student, I intend to fail. I set myself up for failure, because making mistakes and learning from them is my primary job as a student.

The difference between mission and education is the critical part here. Let me give you another example: three years ago, I joined a group of pilot friends who decided to do a two-week air safari in Namibia, flying tiny two-seaters with fabric wings. These planes are very hard (and dangerous) to fly, because they're so light. If you go over a mountain ridge a bit too low, the whole plane might flip over and you're likely to kill yourself (and your passenger) as a result. The main control is a stick, but you don't hold it in your hand like you would on any other plane. Instead, you just use the tip of your index finger to move it around. That way, you cannot apply a lot of force to it, and your flying becomes a lot more precise. The mission was to survive these two weeks in Namibia, flying for 6 to 8 hours every single day. I did survive with nothing more than a bent axle on one of the landing gears, but one of our five planes crashed on the second day (the two occupants survived unharmed). You can see a log of the whole trip there:

Sons of Ader

Because I'm not a very good pilot, this mission required some serious education. To get it, I hired a retired Boeing 747 pilot and I spent two weeks with him, flying every day (week-ends included), on the actual make and model of plane that we would fly in Namibia. And during this training, I asked him to make me fail (safely) as much as I could. So we practiced all kinds of maneuvers, pushing the envelope step by step, always looking for the breaking point. These two weeks were hard. Really hard. But they probably saved my life in Namibia more than once... That was education.

Last but not least, there is something else that I want to demonstrate with this project: I want to show that a commercial-grade machine can be built from start to finish in an electronic fashion. This is how Airbus and Falcon planes are designed today. There is no mockup anymore. Everything is done on a computer. I want the machine to be designed the same way. I believe that by using the right CAD tools, the right online models for parts, and the right online communities (this forum first and foremost), a machine can be designed entirely online. Will there be some mistakes that we won't catch on CAD? Certainly. Will we be able to fix them once we actually build the machine? I sure hope so. And if we don't, I certainly hope that we will learn from the process that lead us to making these mistakes in the first place, because this learnings will be worth a lot more than the time and money we wasted building a broken prototype.

So, no, I won't build a simpler machine first, sorry. I am not doing this to offend you. And I am not ignoring your recommendations either. On the contrary, I really take them to heart, and I try really hard to understand what they mean and how I can factor them into my own process. But I will follow this process, because it is the best one I know to fulfill the specific set of objectives that I gave myself. And I totally respect the fact that you would have a very different set of objectives and constraints for your own projects, especially if you are on missions.

I hope this clarifies my approach, and I thank you again for your continued participation and support.

Best regards
Ismael

[ishi]

Here is the link to the Fusion 360 file for the frame:

https://a360.co/2Of9i9y

Please let me know if it does not work.

I tried downloading the STEP file and importing it back into Fusion 360, and it worked without any problems.

[ishi]

With this latest round of designs, I have made sure to create proper rigid groups for all our components and to assemble them with proper joints. This is making it very easy to check clearances and travels. Here is how I am checking that our spindle head can reach our ATC.

[ishi]

We finally managed to get a CAD model for an HSK 63F tool fork. This allowed us to redesign the mount that will attach it to a pallet of our ATC conveyor. And as you can see on that last picture, we're off by a few millimeters on both X and Y. Offset on Y was expected, because we did not yet adjust the offset of our conveyor mount flanges at the top of our vertical column. But offset on X came as a surprise. Indeed, we were expecting that the axis of the spindle would be coplanar with the C axis when C is at the 0° or 180° positions. This is a bit puzzling... We might have made a mistake, but I don't think so. Instead, I think something is wrong with the CAD model that we got from HSD, so we'll check with them before we offset our ATC conveyor alongside the X axis.

[ishi]

In my previous email, I was to quick to blame HSD for their CAD model, for it was perfect. Instead, I am the one who made a mistake when resizing some parts of the central column. This has been fixed now, and I'll try to be less quick to blame others for my own mistakes in the future... Lesson learned!

[ishi]

This one feels good: I completed the assembly for the Z-Axis counterbalance, only using off-the-shelf parts:

Bimba High-Pressure Cylinder:
https://www.bimba.com/Products-and-C.../TRD-HH-Series

McMaster-Carr Clevis Bracket with Pivot Pin:
https://www.mcmaster.com/#62205k38/=1dveiep

McMaster-Carr Oil-Embedded Ball Joint:
https://www.mcmaster.com/#6072k58/=1dvf06x

The Gas Tanks, Pressure Gauges, Schrader Valves, Hydraulic Switches, Hydraulic Manifolds, and Hydraulic Hoses have all been selected but are not included yet in the design because they don't really matter at this point (they can be installed anywhere we want).

I am so glad that everything fits!

***

High-res pictures on public drive:

https://drive.google.com/drive/u/3/f...3dQrx?ogsrc=32

[ishi]

By reducing the width of our rail beams from 80mm down to 60mm (still plenty enough), we've managed to fit the scale of our linear encoder for the Z-Axis. And we managed to do that with the full scale Heidenhain LC 195 S, not the slimline 495 S as originally planned. The 195 Series has a sturdier construction and higher resistance to vibration. If we want absolute encoding, we're limited to ±3 µm accuracy, versus ±2 µm with the incremental version, but we'll go for absolute. Our effective travel on Z is 670mm (26.4"). Therefore, we had to go for the 740mm version, because the next level down was 640mm, which was not sufficient.

We're now trying to figure out the best way to mount the moving block on the Z-axis carriage.

[ishi]

Here is where we can fit the linear encoder block on the Z-axis carriage (first picture). The second picture shows the whole assembly (encoder block and encoder scale). It's a tight fit, but it should work. Also, we've currently positioned the block right in the middle of the Z-axis carriage, but we might move it up or down in order to make assembly/disassembly easier. This will depend on how the block is actually inserted within the scale, and we need to play with the actual product before being able to tell for sure.

The actual block is not directly mounted onto the carriage casting (or machined block, not sure yet for this piece). Instead, it is mounted onto a mounting block, which is itself mounted onto the carriage. This serves two purposes:

1. Making it easier to machine the carriage.
2. Making it easier to properly position the block with shims across all three dimensions if necessary.
3. Making it easier to switch to a different make or model of linear encoder.

[ishi]

Well, it looks like we're done with the Z-axis for this design iteration. We've pimped the carriage a little bit and made some screenshots with the spindle head rotated by one eighth of a turn on both A and C. Because of the 2-axis spindle head, the ATC conveyor, and the hydraulic counterbalance, the Z axis is by far the most complex axis of the machine. In comparison, X and Y should be pretty straightforward. For X, the challenge will be to design a very rigid carrier that could actually be manufactured. This will be a very large casting, and I am quite concerned about it. For the Y axis, the challenge will be to fit the servo motors within the footprint of the X-axis carriage (before, they were protruding outside of it), without losing any travel (20" is our absolute minimum for Y).

At this point, I am fairly confident that everything will fit, but the way covers could throw us a curve ball, so we'll want to work on these as soon as X and Y have been redesigned. And when we're done with these, we'll start doing some finite element analysis. If anyone is familiar with that part of the process, I would not mind a crash course on it. (^_^)

***

High-res pictures on public drive:

https://drive.google.com/drive/u/3/f...3dQrx?ogsrc=32

[handlewanker]

Wow....after your that short resume' of your life experiences,...(In the late 50's I spent 10 years in Namibia on the diamond mines of CDM)….. I would have to say your best quote would have to be nailed to the wall above your work station with the words deeply inscribed....…"it won't happen today and it won't happen tomorrow BUT IT WILL HAPPEN"...…..that is the one thing I have always quoted whenever I start a project......and as Frank Sinatra said/sung....."I did it my way".

BTW, on the subject of the water cooled ballscrew/nut….."if it ain't broke, don't fix it".....this may not be a necessary factor for the build as it will not be a production machine …...as you have stated.
Ian.

[ishi]

Wow....after your that short resume' of your life experiences,...(In the late 50's I spent 10 years in Namibia on the diamond mines of CDM)….. I would have to say your best quote would have to be nailed to the wall above your work station with the words deeply inscribed....…"it won't happen today and it won't happen tomorrow BUT IT WILL HAPPEN"...…..that is the one thing I have always quoted whenever I start a project......and as Frank Sinatra said/sung....."I did it my way".

BTW, on the subject of the water cooled ballscrew/nut….."if it ain't broke, don't fix it".....this may not be a necessary factor for the build as it will not be a production machine …...as you have stated.
Ian.

Ian,

I like your quotes!

Yes, the water-cooled ball screw nut mounts are interesting only for a production machine, but the switch from granite to a mineral casting encouraged me to research what it would take to make it a production machine. I also developed a better appreciation for the challenge of developing a production machine, and this is getting more and more interesting to me. In other words, when you don't worry about chip collection, chip evacuation, ball screw and linear guides protection (way covers), heat dissipation (after extended usage), or machine enclosure, everything is a lot simpler. But once you start adding these to the picture, a lot of simplification assumptions start falling apart. Therefore, I want to see how far I can push that design, and whether it could approach something that could be used in production. While I'm just doing CAD, this is cheap and easy (it's only costing my time) and some real estate on this forum.

I also noticed something else: once you try to factor production constraints in, it forces you to change the design, and it actually reduces the number of options that you have to make it work. This "automatically" brings the design closer to something that already exists, therefore has a better chance of working in the first place. If you compare my very early designs to the ones that we have right now, they're really night and day, yet my current designs are still very far from something that I would consider good enough. Bottomline: I want to keep pushing in that direction.