Author Topic: Trackball via Ball Transfer Units *3D Mock-up Made*  (Read 69875 times)

0 Members and 1 Guest are viewing this topic.

Offline BeholdersEye

  • Posts: 3
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #150 on: Mon, 23 November 2015, 00:05:05 »
After all this talk and posting, I hope you will consider doing bluetooth! I have contacted every current manufacturer of trackballs and everyone of them bastards refuse to make a bluetooth version even though they been making bluetooth mice! A USB unit just doesn't play nicely with phone/tablet use! It's a pain, needs adapter, drains device battery, and since only one USB port, can not charge phone/tablet....

It's a bloody conspiracy!

Offline ursulache

  • Posts: 22
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #151 on: Mon, 23 November 2015, 09:39:01 »
1.
Minimizing the contact area is what i'm trying to do. At the moment I see no way of inserting something in the printed part (maybe some very small screws?). I also thought of printing a "real" BTU, with the 5mm ball sitting on 1 mm balls, but the printer I am using can't print that well and also I am missing the 1mm balls.

2.
This is interesting, there is even printer filament made of that polymer but it's 80EUR the spool (250g). I'll see if I can interest the people who's printer I am using in buying some.

3.
You might be right, the ball I am using is much bigger and heavier than the Logitech's ball. If the friction of my system is higher then that of the Logitech's that would indeed translate in a more difficult start. After the ball start's moving, due to it's greater mass, it spins for longer. In this case it's a big disappointment. It means that all the effort put into the nitride balls can't match the fixed teflon holders of the Logitech solution. I got to get those nitride balls rolling!

As for the bluetooth part, my setup involves a donor mouse for logic+sensing so a bluetooth mouse could be used.
« Last Edit: Mon, 23 November 2015, 09:40:43 by ursulache »

Offline jacobolus

  • Posts: 3661
  • Location: San Francisco, CA
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #152 on: Mon, 23 November 2015, 17:55:15 »
A USB unit just doesn't play nicely with phone/tablet use!
As far as I know you can’t really use an external pointing device in a meaningful way on a phone/tablet anyway. There’s no pointer symbol on screen, and the mobile operating systems are designed around direct touch.

What would you do with a trackball hooked up to a phone?

Offline ursulache

  • Posts: 22
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #153 on: Tue, 24 November 2015, 03:29:43 »
When you connect a mouse to an Android device it will show a pointer.
Windows 10 mobile has continuum.
I have no ideea if iOS supports mice.

Offline sinusoid

  • Posts: 160
  • fd > ESC
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #154 on: Tue, 24 November 2015, 15:52:07 »
What would you do with a trackball hooked up to a phone?

They hear me rollin'. They hatin'.

I used to do hook it up like so, but then I took a ball to the ear.

 ;D


1.
Minimizing the contact area is what i'm trying to do. At the moment I see no way of inserting something in the printed part (maybe some very small screws?). I also thought of printing a "real" BTU, with the 5mm ball sitting on 1 mm balls, but the printer I am using can't print that well and also I am missing the 1mm balls.

You could source an old hard drive for small ball bearings. You pull out the central bearing and cut it with a dremel tool or sth in two places so the outter ring splits, then scavenge the balls.

About pushing a needle through it - it's PLA, so when you heat up a needle you can push it through from the outside, until the tip appears inside the bearing cavity, and trim whatever sticks out. If you get it too far, just position it and glue with ABS juice or cyanoacrylate.
Screws are a good idea too, you could try using brass ones.

If you want a batch of that Igus filament - just ask them for samples, they should be able to deliver.

I bought some BTUs, and I'm molding my own ball to go with these, should post pics soon-ish.


Offline ursulache

  • Posts: 22
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #155 on: Wed, 25 November 2015, 03:26:29 »
The BTUs I printed yesterday didn't turn up that well, I'll reprint them today.

I learned yesterday about the existence of UHMW. I will try to source a small bloc and machine it in the form of a small BTU.
« Last Edit: Wed, 25 November 2015, 04:47:55 by ursulache »

Offline ursulache

  • Posts: 22
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #156 on: Thu, 26 November 2015, 04:57:36 »
When you say you're molding your own ball are you referring to the actual ball? If so, why?

Have you tried the BTUs with a ball? How smooth is the movement? What model have you bought?

My printed BTUs are not providing a satisfying movement. The ones I printed yesterday turned up ok, the nitride ball could spin freely inside, but the friction is still too high. Probably a precision housing and better materials are required.

In the mean time I bought a m570 trackball and it is smoother but the ball is way to small and light for my novice taste. I only bought it to have something to benchmark against.
« Last Edit: Thu, 26 November 2015, 06:14:50 by ursulache »

Offline GuilleAcoustic

  • Posts: 77
  • Location: France
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #157 on: Thu, 26 November 2015, 10:04:16 »
I'm planning to start working on my own trackball project in the next weeks. I'm post-poning it since may, time to get my fingers off my ******  :p. Gonna try both roller + ball bearings and ball transfer units. I'll let you know if I have more luck.

Offline sinusoid

  • Posts: 160
  • fd > ESC
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #158 on: Thu, 26 November 2015, 14:57:15 »
When you say you're molding your own ball are you referring to the actual ball? If so, why?

Mainly to get the right diameter (75mm), and to have it empty inside so it's light and has relatively low inertia. Also, I have full control over surface, finish, color, etc.

If I make it, it'll mean I have full independence regarding the parameters of the trackball.
It's also very hard to get it right, and that makes it super attractive :D.

I've done this once with a 3d print directly, printed from 2 parts, glued, polished. It worked quite well for a prototype, so now I want to make a real functional thing.

Have you tried the BTUs with a ball? How smooth is the movement? What model have you bought?

Used an old trackball I had on them, but they were not angled properly, etc. Still, the results are very promising. There's nothing I can see go wrong at this point that can't be countered somehow.

I've got these: http://www.boschrexroth.com/en/us/products/product-groups/goto-products/goto-linear-motion/ball-transfer-units/index
12mm no collar.

Almost no force required to get them rolling.
They feel very smooth without load.
They feel harsher under load, like when you press them against a table and try rolling them around - they oscillate a bit, but still near zero friction. Feel of these is identical to most not-hyper-precise linear motion systems that use ball recirculation.

The only thing I'm worried about now is that the oscillations will transfer to the ball, and make it feel harsh. If that happens, and will prove unpleasant, I'll try dampening it somehow.

Rubberized ball much? Anyone likes Thinkpads? :]


My printed BTUs are not providing a satisfying movement. The ones I printed yesterday turned up ok, the nitride ball could spin freely inside, but the friction is still too high. Probably a precision housing and better materials are required.

In the mean time I bought a m570 trackball and it is smoother but the ball is way to small and light for my novice taste. I only bought it to have something to benchmark against.

Well, it's going to be pretty hard to make a ball spin in a 3d printed element. The steel ball will require some momentum to start rotating, and sliding against the surface, regardless what plastic is used to house it (even if it's super slippy, it's gonna accumulate dirt, for example. Remember ball mice?)
This is exactly why BTUs were made. They are designed to go over this particular problem by simply rolling two elements one against the other. They should be OK as long as you don't put too much sand in them, and parts of them won't start rusting. They just roll over stuff.
When they stop, you replace them.

You could try something like this, with plenty of lube:
118411-0
118413-1

Oh, hey, I have an idea.
LET'S CALL THIS THE IRON MAIDEN TRANSFER UNIT  :cool:

Should be printable if prepared right. (assembled from 2 halves probably)

But from my POV it's best to go with a ready-made element. Those parts are complex enough by themselves.

The only thing that could actually be better than BTUs are magnetic bearings.
They would be several orders of magnitude better, and you wouldn't have to deal with all the electronics usually used to stabilize those systems, because the speeds and momentums on this would be very low, and would not require superb precision (by magnetic bearing standards. Would still be damn precise.)
Though you want to shield user limbs from long term magnetic field exposure due to health concerns.

Offline jacobolus

  • Posts: 3661
  • Location: San Francisco, CA
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #159 on: Fri, 27 November 2015, 01:58:42 »
Mainly to get the right diameter (75mm), and to have it empty inside so it's light and has relatively low inertia.
A dense ball is in general nicer to use. You want something dense and smooth and perfectly spherical. The point of the ball transfer units is to make the ball’s speed easy to control with your finger, regardless of the trackball weight. A heavier ball rolls more smoothly because the ball transfers work better under a moderate load. You also want a material which your finger sticks to just slightly. The balls that come with industrial trackballs are just about perfect (though they could benefit from being slightly grippier): I think it would take a lot of work to do better, and that would be basically impossible using common 3d printing technologies, which are imprecise with a limited choice of materials and terrible surface finish.

Offline ursulache

  • Posts: 22
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #160 on: Fri, 27 November 2015, 06:25:43 »
@GuilleAcoustic
Which BTU are you planing on using?

@sinusoid
I hope you succeed, but I fear it is almost impossible (with home/hobby tools) to obtain the same quality as an industrially produced ball.

I am using a Carom billiards ball made of aramith with a diameter of 61.5 mm. It is a bit on the heavy side (~200g).
If the BTU (or any other support system) is good enough you should be able to control it with ease and without to much effort. On my system, once it starts moving it behaves quite well, maybe with a bit to much inertia.

The balls I am using in the printed transfer units are 5mm diameter so a printer with very good precision is needed in order to have complex models at that size. The one I have access to sadly isn't very precise. Nevertheless, the last printed BTUs had a square hole and I used it turned at 45 deg so no more then 3 contact points at all times, and still the movement was not good enough. There still is to much drag. That is why I think another material for the BTU housing is needed, or the addition of smaller balls just as in a commercial BTU.

As for your IRON MAIDEN, I fear for it's teeth. When you take into consideration the 200g ball and human hand + force exerted by operating the ball it might end up with a few broken teeth very soon. Also I think it has too much contact surface.
 
« Last Edit: Fri, 27 November 2015, 08:12:07 by ursulache »

Offline GuilleAcoustic

  • Posts: 77
  • Location: France
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #161 on: Fri, 27 November 2015, 07:01:49 »
@GuilleAcoustic
Which BTU are you planing on using?

Something along those lines: http://www.omnitrack.com/uk/medium-duty/m-series-push-fit.html ... They have low friction and good speed. Available in several material and a wide variety of mounting options.

About the track ball itself, I'm going for phenolic resin only as it is dense and heavy. Pool size is a must as it is easy to source. Aramith balls are made from phenolic resin.
« Last Edit: Fri, 27 November 2015, 07:03:43 by GuilleAcoustic »

Offline ursulache

  • Posts: 22
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #162 on: Fri, 27 November 2015, 08:21:41 »
In case you want larger then pool size, I've seen a few sets of carom balls available on leboncoin when I bought mine.
pool     ~ 57mm      ~170g
carom  ~ 61.5mm   +200g

I was looking at omnitrack MG8 BTU because of the lower cost compared to alwayse 11MI-05-17, but have not found an option on the site to have them delivered to France. Which reminds me to send them an email asking about this.

The most obvious advantage of the Alwayse BTU is size, it has a max diameter of 8mm vs 18mm for the smallest Omnitrack BTU.
« Last Edit: Fri, 27 November 2015, 08:32:02 by ursulache »

Offline GuilleAcoustic

  • Posts: 77
  • Location: France
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #163 on: Fri, 27 November 2015, 08:54:17 »
Omnitrack has an ebay store: http://stores.ebay.fr/omnitrack?_trksid=p2047675.l2563

Been considering the carom balls too as a good alternative.

Offline sinusoid

  • Posts: 160
  • fd > ESC
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #164 on: Thu, 03 December 2015, 15:34:33 »
A heavier ball rolls more smoothly because the ball transfers work better under a moderate load.

There are better ways of getting a load on a bearing than increasing weigh of the rolling element. Will show later.
I think there is a tad bit too much superstition about trackballs, and not nearly enough experimentation.

I think it would take a lot of work to do better, and that would be basically impossible using common 3d printing technologies, which are imprecise with a limited choice of materials and terrible surface finish.

I never let thinking get in the way of trying.

@sinusoid
I hope you succeed, but I fear it is almost impossible (with home/hobby tools) to obtain the same quality as an industrially produced ball.

Yes, a lot of people seem to think so.
Fortunately there are people out there like David Gingery who have proven differently.
Industrial tools didn't get here out of nowhere, they are developed through known and well documented processes. And I have two things that industrial processed don't have: time and smartness.
Besides, if I fail doing this on my own, who's out to stop me from ordering these made-to-measure at a local machine shop?

Seriously, there is only one limiting factor to what a human being can create: imagination.


The balls I am using in the printed transfer units are 5mm diameter so a printer with very good precision is needed in order to have complex models at that size. The one I have access to sadly isn't very precise.

What printer are you using?
I used to push-fit 2mm magnets into 3d models.
It takes some patience, but when you get the tolerances smoothed out, you can spew out small repetitive elements quite reliably.

As for your IRON MAIDEN, I fear for it's teeth. When you take into consideration the 200g ball and human hand + force exerted by operating the ball it might end up with a few broken teeth very soon. Also I think it has too much contact surface.

I think it's a pretty sucky solution in the first place. I intended this to show a principle rather than a solution. You could get that with metal elements, by hot-pushing them into a 3d print with a ball inside. You could vary the tolerance between the ball and the teeth.
I don't think they would break, though. To get this working, it would be fine if they were 0.1mm in length, just enough to push the ball away from the sides.

Anyway, doing a complete re-thinking and rebuilding a BTU for 3d printing with FDM machines is IMVHO overkill and a beginning of a development hell.
It could be awesome, it could be educative, you'd learn a whole lot about tribology, and perhaps get a job in the industry as part of the process.
I'll watch from a safe distance, though, and chip in some advice.
In the end, personally, I want a trackball, not a BTU.

Dev post in a sec. Want to separate the content. Hope it's not against the forum guidelines.

Offline sinusoid

  • Posts: 160
  • fd > ESC
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #165 on: Thu, 03 December 2015, 15:34:53 »
Stuff done last weekend, but had no time to post.

Molding the ball.

3d printed mold prepared for casting. Used ABS. There's no good solution for this - ABS will get reactive with the resin, and PLA will heat up and fall apart as it cures. Results with ABS are satisfactory as you'll see in a sec. but molds are single use only.
118971-0

Used a syringe to inject the resin into the mold. it had a 3d printed flange for the syringe tip. WOrked out wonderfully, but later when I was carrying it, I tipped it accidentally and some air got in. Aaargh. Should have 3d printed caps for those holes too :/
118973-1

And there it is, one half of the resin ball out of its mold. I had to peel off the inside. Outside got damaged, either due to heat, or chemical reaction. Didn't influence the ball.
118975-2

Calipers. A little bit under 75mm. AFAIR I designed it this way, too lazy to check now. I'll make the other half this weekend and compare. If they won't match, I'll change the molding process.
Vertical measurement is perfectly consistent (=diameter/2).
118977-3

BTU test station, muhaha.
You can see the air bubble. I'll fill this in later with resin. Polishing process will get rid of any irregularities.
Didn't weight it, but I think it's around 40 grams. Used 45ml of resin for this.
118979-4

So, then I tipped it...
118981-5

... and it levelled itself out when I let it go ;_;
118983-6

This is surreal.

Feels a bit rough when under load, and it looks like the BTUs are the issue, but I have at least 2 tricks in my sleeve to smooth this out.

You'll see, if I live long enough.

Offline jacobolus

  • Posts: 3661
  • Location: San Francisco, CA
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #166 on: Fri, 04 December 2015, 00:09:48 »
There are better ways of getting a load on a bearing than increasing weigh of the rolling element. Will show later.
I think there is a tad bit too much superstition about trackballs, and not nearly enough experimentation.
Superstition? I’m just telling you my direct personal experience playing with ball transfer units. I don’t claim any kind of omniscient knowledge though; maybe your ball units behave differently.

Offline ursulache

  • Posts: 22
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #167 on: Mon, 07 December 2015, 10:58:21 »
@sinusoid
I am quite curious to see how your ball will end up. Good luck!

In other news I have postponed any more serious work on this project for the time being. I will restart after the holidays, by which time I should have some transfer units.

In the mean time I found out that IGUS have a presence in France, and it is in my area. Also they have a new product the BB-505-B180-POM which is quite small, having a diameter of only 10.4mm.

Offline ursulache

  • Posts: 22
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #168 on: Mon, 11 January 2016, 07:37:57 »
Happy new year everyone!

I am back from vacation and will order the IGUS ball transfer units in the next days.

Offline sinusoid

  • Posts: 160
  • fd > ESC
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #169 on: Wed, 13 January 2016, 12:22:54 »
@ursulache
Good news!
Let us know how they perform.

I got an old Kensington Turbo Mouse in the mean time to have something to test against.
Tested it's ball on the Rexroth BTUs and it performs much much better.

Also molded the second half of the ball, now waiting to get some free time to glue the halves together and polish.

Offline LuX

  • Posts: 132
  • Location: Finland
  • 🖲️ 🖲️ 🖲️ 🖲️ 🖲️ 🖲️ 🖲️
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #170 on: Sat, 12 March 2016, 04:17:25 »
Any update on those BTUs? I'm thinking if I should make my own trackball or just buy one. The ones readily available don't really excite me.
Here's a mock-up of my "dream" trackball. At least I think it is, I've never properly tried a trackball.

The shape and size resembles pretty much the Logitech g700 mice, being slightly wider and having much larger thumb rest.
In it's current design it uses a 1.5" trackball, and the Omnitrack 9100-A BTUs (12.7mm Ø). I wonder if using those slightly larger BTUs is better than the 8mm ones.
I imagine they would be quieter and smoother, and probably hold angular momentum much better. They are also much more expensive.

Offline kulasart

  • Posts: 1
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #171 on: Fri, 20 January 2017, 14:05:36 »
BB-505-B180-POM from Igus don't work very well with standard 57.2mm billiard-ball. An I think we should stick with metal BTUs. Unfortunately the good one are pricey.

Offline arpruss

  • Posts: 1
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #172 on: Fri, 19 October 2018, 17:06:54 »
I am thinking that the ball transfer units look an awful lot like trackballs. What if one made a trackball that is like a giant btu? A bowl filled with small balls and a big ball on top, with some cap to keep things in place?

Offline deama

  • Posts: 2
Re: Trackball via Ball Transfer Units *3D Mock-up Made*
« Reply #173 on: Sat, 05 October 2019, 12:59:33 »
So how is this project going? Is it dead?
Also, why haven't other manufacturer's used ball transfer units? BTUs existed well before trackballs, so why not use them? Seems like the perfect fit? The only explanation I can think of is that they'd be too hard to clean?