6-axis Horizontal Machining Center for Education

[RCaffin]

Couplings: it is standard practice to buy coupling with a slightly undersize bore and to machine the bores to suit your needs.

Cheers
Roger

[ishi]

Hi Ishi

Well, frankly, I think the cooling you have sketched for the ball nut is totally of the overkill. Really way, way too much.

I would run a bit of 1/4" copper tube down one side of the bracket, across the bottom, and back up the other side. With maybe 5-6 small clamps to hold it in place. The brackets would be where the real heat flow happens as they would clamp the copper hard against the support bracket. And a pretty plastic cover over the lot.

And even that would be overkill.

My 2c.
Cheer
Roger

Roger,

I think you're right. But I'm trying to avoid plastic, because it's yet another thing to design and manufacture. I'm also trying to make a statement out of this piece. Something along the lines of: "We're really serious about cooling our ball screw nuts". This falls into the category of cosmetics and marketing of course. But if oversizing does not bring any drawback (in that case I don't think it does), I kinda like it. Also, we'll have to machine our own mounts anyway, so adding these blind holes and sealing flat head screws does not seem like a lot of extra work.

I had one question regarding the nipples though. Do you know what kind of brass nipple NSL is using for their nut?

https://www.nskeurope.de/downloads/l...ling_e3242.pdf

[ishi]

Couplings: it is standard practice to buy coupling with a slightly undersize bore and to machine the bores to suit your needs.

Cheers
Roger

Got it! So, 19-24 for us.

Thanks a lot Roger.

UPDATE: I just spoke with NBK America and they confirmed your suggestion. Most importantly, they can do the reboring for us.

[ishi]

"...….for in the end it's only the journey that matters"......these prophetic words are how I think too......it's better to have attempted the impossible than to have failed with the probable.

At least you are well informed as to the variables...…...if it all comes together like you envisage it, perhaps America will once again be grating cheese...…..oops, I meant be great again.
Ian.

Ian,

My ambitions are much more modest... The place you live in isn't great or awful on its own. You make it what you want. The same goes for people or events by the way...

[ishi]

These screws would be perfect as plugs for the blind holes in our cooled nut mount:

https://www.nbk1560.com/en-US/produc...m/plug/SFMS-G/

[vicpaulsen]

The image called "Diagram" illustrates what I had in mind for the water-cooled ball screw nut mount. It would be machined out of stainless steel in order to avoid corrosion. It would have two water ports (cold in, hot out) and seven internal conduits machined as blind holes. All seven conduits would be sealed with screws with rubber rings, allowing the conduits to be cleaned if necessary.

I've also attached a picture of a ball screw. There, you can see the ball recirculation pipes. I think we could take advantage of that by filling this area with thermal paste within the nut mount. That way, we would significantly improve heat transfer from the nut (especially the balls which generate all the friction in the first place) to the mount.

The end result could be pretty clean actually, and really not that hard to machine: seven blind holes and nine taps (7 for the sealing screws and 2 for the ports).

Afternoon ishi,
I have followed this topic ever since you posted the very first item. I've found the process very inspirational and really have enjoyed all to the comments.
On the topic of cooling the the ball screw nuts, instead of using Stainless Steel why don't you consider the the use of a material called "Toughmet". It is a copper-Nickle alloy that has the thermal properties of copper but much better strength like CuBe Alloy 25. We have used it to replace Alloy 25 on our downhole oilfield logging tools as machine shops in our area are getting where they don't want to work with CuBe because of the toxic properties. It is probably a little more expensive than SS but it machines beautifully.

vkp

[ishi]

Afternoon ishi,
I have followed this topic ever since you posted the very first item. I've found the process very inspirational and really have enjoyed all to the comments.
On the topic of cooling the the ball screw nuts, instead of using Stainless Steel why don't you consider the the use of a material called "Toughmet". It is a copper-Nickle alloy that has the thermal properties of copper but much better strength like CuBe Alloy 25. We have used it to replace Alloy 25 on our downhole oilfield logging tools as machine shops in our area are getting where they don't want to work with CuBe because of the toxic properties. It is probably a little more expensive than SS but it machines beautifully.

vkp

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!

[ishi]

One of our technical advisors suggested that we switch our servo motors for linear axes to water-cooled models. On a grinding machine they recently worked on, this single change pushed the accuracy quite a bit. So, here it is, with a pair of Siemens SIMOTICS 1FT7062.

We asked whether we should do that for the spindle, but the answer came back negative, because the spindle is already water-cooled, and this helps cool the two torque motors of the spindle head. A customer of theirs is running the exact same model of spindle head all day long with no over-heating whatsoever. But we will definitely use water cooling for the torque motor of the rotary table.

I can't wait to see what our water distribution panel will look like...

[mactec54]

These screws would be perfect as plugs for the blind holes in our cooled nut mount:

https://www.nbk1560.com/en-US/produc...m/plug/SFMS-G/

Yes they would work fine, you could also use tapered pipe plugs as well, at this stage you should not be even considering water cooling of any kind, for what your machine is going to be doing, as I said before your 3 rotary axis are going to be doing all the work, just cooling the Ballscrew Nut is not going to help very much without the Screw being cooled also

The heat from the spindle and rotary axes is where all the growth will be, as is with any Z axes, it's not from the Ballscrew when doing normal operations, your rapids are not in the thousands of IPM or even close, so won't have a heat growth problem with the Ballscrews

Could you add the water cooling for the Ballscrew Nuts absolutely, it would be good for kicks-and-giggles

[ishi]

Yes they would work fine, you could also use tapered pipe plugs as well, at this stage you should not be even considering water cooling of any kind, for what your machine is going to be doing, as I said before your 3 rotary axis are going to be doing all the work, just cooling the Ballscrew Nut is not going to help very much without the Screw being cooled also

The heat from the spindle and rotary axes is where all the growth will be, as is with any Z axes, it's not from the Ballscrew when doing normal operations, your rapids are not in the thousands of IPM or even close, so won't have a heat growth problem with the Ballscrews

Could you add the water cooling for the Ballscrew Nuts absolutely, it would be good for kicks-and-giggles

mactec54,

You're absolute right, this is probably overkill. But I really like the sizzle. And the modeling of the nut with water cooling was actually a fun little CAD exercise.

Also, NSK's tests do not seem to agree with your statement regarding the cooling of the nut vs. shaft. Take a look at this document:

https://www.nskeurope.de/downloads/l...ling_e3242.pdf

Without any cooling, the increase in temperature during their test is 14°C.

Cooling of either the nut or the shaft brings it down to 3.5°C, and the cooling of the nut seems to be more effective than the cooling of the shaft initially.

Of course, cooling both is even better, bringing it down to 1.75°C.

Cooling of the shaft is out of the question for us. But cooling of the nut can bring the same benefits. Now, we still need to prove that cooling the nut mount could be almost as efficient as cooling the nut itself. But this is one of the potential innovations that I find really interesting. It might be useless, but it might also work. And it's so easy to do that it seems to be worth a try.

[ishi]

Here is what our water-cooled ball screw nut could look like.

I know this is totally over-kill, but you have to indulge me. I feel like a kid in a candy store right now.

And with this pinkish ToughMet... Come on...

For info, the push in couplers are Metal Work 2L31001 RL31:

https://www.damencnc.com/products/pn..._329_2565_GB_1

[RCaffin]

If you have tubular way-covers you could consider blowing filtered air through them for cooling.

Cheers
Roger

[ishi]

If you have tubular way-covers you could consider blowing filtered air through them for cooling.

Cheers
Roger

Nice! I like you're thinking. A lot. This would help cool the ball screw shafts indeed... And yes, we will get this type of way cover, as soon as I can find a suitable supplier. I'll work on that as soon as the three linear axes are back in the design.

Thanks a lot Roger.

Side question: how do you control the temperature of your pressurized air source?

[RCaffin]

how do you control the temperature of your pressurized air source?
I would imagine that any number of air conditioning vendors would be willing to help. You might need both heating and cooling of course.

Cheers
Roger

[ishi]

how do you control the temperature of your pressurized air source?
I would imagine that any number of air conditioning vendors would be willing to help. You might need both heating and cooling of course.

Cheers
Roger

Fair enough! Then it's really outside the scope of our project. We'll assume that both air and water come to us at the right temperature.

[vicpaulsen]

ishi
I'm glad that my material comment was helpful and I appreciate the comments.
You are very much like my DI (Destination Imagination) kids, as when we work with the teams we encourage them to look at the challenge, break it down into parts they can work on and find solutions. We highly encourage the process as that is where they learn, more from the ideas that don't work than the ones that do work.

Now I've been wondering, if or when you might make dimensional models available, it might be interesting to build a wood version to see what might have challenges in the final design. I realize that you are planning on a cardboard model but............................

If you are interested, the DI web site https://www.destinationimagination.org/

vic

[ishi]

ishi
I'm glad that my material comment was helpful and I appreciate the comments.
You are very much like my DI (Destination Imagination) kids, as when we work with the teams we encourage them to look at the challenge, break it down into parts they can work on and find solutions. We highly encourage the process as that is where they learn, more from the ideas that don't work than the ones that do work.

Now I've been wondering, if or when you might make dimensional models available, it might be interesting to build a wood version to see what might have challenges in the final design. I realize that you are planning on a cardboard model but............................

If you are interested, the DI web site https://www.destinationimagination.org/

vic

Vic,

DI is awesome. I really like their approach.

I'll put all the STEP files on the public drive later this week.

I still don't get the benefits of a wood model, but I realize that I might be missing out something. Give me some time to process it.

Best regards
Ismael

[ishi]

ishi
I'm glad that my material comment was helpful and I appreciate the comments.
You are very much like my DI (Destination Imagination) kids, as when we work with the teams we encourage them to look at the challenge, break it down into parts they can work on and find solutions. We highly encourage the process as that is where they learn, more from the ideas that don't work than the ones that do work.

Now I've been wondering, if or when you might make dimensional models available, it might be interesting to build a wood version to see what might have challenges in the final design. I realize that you are planning on a cardboard model but............................

If you are interested, the DI web site https://www.destinationimagination.org/

vic

Vic,

DI is awesome!

I'll push the STEP models on the public drive by the end of the week.

As far as a wood model is concerned, I still need to noodle on that. I fail to see the benefits over cardboard. And if I have to buy the actual ball screws and linear guides, the cost of that mockup will be significant, which means that mistakes will be expensive. I'd rather squash these bugs in CAD and cardboard if I can. But I will most definitely take a class somewhere in order to practice the installation of ball screws and linear guides, in much the same way that it is demonstrated on the excellent NSK YouTube videos.

Best regards
Ismael

[ishi]

Here is an example of a stupid mistake that can get caught with CAD: when I sketched my water-cooled nut mount, it looked good on paper, because water flow would be helped by gravity. But that was assuming that such mounts would be mounted horizontally. Unfortunately, that is not the case for the Z axis, as can be seen on the attached picture. Furthermore, it looks like I will need two different mounts, one for the left side, and one for the right side, if I want water ports to be on the outside of the carriage. From a manufacturing standpoint, this is not great. And the same goes for supply chain. In such a context, I will redesign the mount to make it more generic: the horizontal internal pipes will be through holes and I will take advantage of the fact that my screws and couplers use the same M5 thread size to allow any kind of configuration (horizontal or vertical, left or right). This will cost an extra 11 screws per mount ($69.74), but I think the flexibility is worth the extra cost.

[ishi]

Here is a redesigned mount that fixes our previous mistake. It's totally overkill as it stands, but it will be good enough for now. Just a proof of concept.

UPDATE: I have made the design more compact in order to reduce deflection. Cf. two additional pictures.