[arcol.hu] T2.5 pulleys, belts and bearings

[Laszlo KREKACS]

Hi,

Just a bit of headsup for you guys,
I'm working on the announcement of self-manufactured T2.5 pulleys and bearings.

If you are curious why I did it, what it solves, or you simply want to
chime in and proofread the upcoming article,
or just want to see photos, here is the draft:
http://wiki.arcol.hu/blog:arcol-t25

Remarks? Suggestions? Feedback?

Best,
Laszlo

ps: Once I finished with it the next thing will be announcing the
chrome version of the hyena family:)

[nop head]

It is perfectly possible to drill a concentric hole on a lathe. That is what lathes are for.

The way I do it:

 Put the pulley loosely in the chuck. Drive a centre mounted in the tail stock into the cone to centre it. Tighten the chuck, remove the centre and check it spins with no wobble. Drill it 4.8 and then ream it to 5mm.

The teeth on stock pulleys aren't made with a hobbing tool, they are extruded from a die and then sliced, so the die must be different for every number of teeth.

What "problem" does flipping the belt cause? The toothed pulleys are nice but they need flanges or need to be considerably wider than the belt.

--
If you want to send a message to this group, please send the email to arco...@googlegroups.com
---
You received this message because you are subscribed to the Google Groups "arcol_hu" group.
To unsubscribe from this group and stop receiving emails from it, send an email to arcol_hu+u...@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.

[Laszlo KREKACS]

Hi,

First of all, thank you for your inputs. It helps clarify the article
before publishing.

On Tue, Apr 30, 2013 at 10:12 AM, nop head <nop....@gmail.com> wrote:
> It is perfectly possible to drill a concentric hole on a lathe. That is what
> lathes are for.

Well the main problem is, you cant really grip the axle/shaft part of
the pulley,
it only sticks out 6mm, and it is not enough for a lathe chuck to hold well.
Normally only one tooth of the jaw holds the workpiece.

It is not a problem with smaller pulleys, but with bigger diameter,
like the 32 teeth version,
it is a real problem, and it does affect your printer.
I know it the hard way.

>
> The way I do it:
> Put the pulley loosely in the chuck. Drive a centre mounted in the tail
> stock into the cone to centre it. Tighten the chuck, remove the centre and
> check it spins with no wobble. Drill it 4.8 and then ream it to 5mm.

Everyone do it like this. And still it depends on your luck somewhat.
I drilled once four 32 teeth pulleys, and none of them was *perfect*.

> The teeth on stock pulleys aren't made with a hobbing tool, they are
> extruded from a die and then sliced, so the die must be different for every
> number of teeth.

I do think you are wrong about this.
Besides, molden products have always lower tolerance anyway.

With aluminium pulleys they are definietly made with cutting tools,
eg. gear hobbing.

>
> What "problem" does flipping the belt cause?

a)
They introduce unnecessary stress to the belt. Causing wearing the
metal strings inside.
Depending the quality of the belt, it may break over time (the metal
string inside),
or it can also delaminate (the toothed part from the steel stringed part)

Both happened to me.

b)
Aesthetically inpleasant

c)
It is limited by the width of the belt. So your maximum machine size also.
(You can't flip a 20mm wide belt...)

>The toothed pulleys are nice
> but they need flanges or need to be considerably wider than the belt.

It does have a flange. Are you referring to the bearings?
They are supposed to be used with mudguard washer, just like now.

Bigger diameter is better for the steel strings inside the belt.

I'm interested in your feedbacks, let it come!:)

Best,
Laszlo

[Laszlo KREKACS]

Hi,

My main motivation for doing this was:
a) having toothed bearings
b) having concentric big pulleys (32 teeth)

And not beating (pricewise or quality-wise) the already available 16
teeth pulleys.
It is a side-product for me, still it might sell the most.

I think the most appealing reason is the already drilled out, and
tapped bore in it.
Which is not an additional cost for me, because I already manufacture
at that size.

Best,
Laszlo

[nop head]

On 30 April 2013 09:37, Laszlo KREKACS <li...@arcol.hu> wrote:

Hi,

First of all, thank you for your inputs. It helps clarify the article
before publishing.

On Tue, Apr 30, 2013 at 10:12 AM, nop head <nop....@gmail.com> wrote:
> It is perfectly possible to drill a concentric hole on a lathe. That is what
> lathes are for.

Well the main problem is, you cant really grip the axle/shaft part of
the pulley,
it only sticks out 6mm, and it is not enough for a lathe chuck to hold well.
Normally only one tooth of the jaw holds the workpiece.

You need to use a smaller chuck if that is the case. Professional machinists must be able to do it reliably otherwise they would not be supplied in that form as standard.

It is not a problem with smaller pulleys, but with bigger diameter,
like the 32 teeth version,
it is a real problem, and it does affect your printer.
I know it the hard way.

>
> The way I do it:
>  Put the pulley loosely in the chuck. Drive a centre mounted in the tail
> stock into the cone to centre it. Tighten the chuck, remove the centre and
> check it spins with no wobble. Drill it 4.8 and then ream it to 5mm.

Everyone do it like this. And still it depends on your luck somewhat.
I drilled once four 32 teeth pulleys, and none of them was *perfect*.

> The teeth on stock pulleys aren't made with a hobbing tool, they are
> extruded from a die and then sliced, so the die must be different for every
> number of teeth.

I do think you are wrong about this.

Maybe. I know they come in long blanks that get sliced but they may be hobbed by a machine with long travel.

 

Besides, molden products have always lower tolerance anyway.

People are using extruded aluminium for there linear motion these days so it must be reasonably accurate. 

With aluminium pulleys they are definietly made with cutting tools,
eg. gear hobbing.

>
> What "problem" does flipping the belt cause?

a)
They introduce unnecessary stress to the belt. Causing wearing the
metal strings inside.
Depending the quality of the belt, it may break over time (the metal
string inside),
or it can also delaminate (the toothed part from the steel stringed part)

It hasn't happened to me yet. If the idler pulley is made big enough it is within the spec of the belt. 

Both happened to me.

b)
Aesthetically inpleasant

 

Really, compared to the rest of the an average reprap machine? 

c)
It is limited by the width of the belt. So your maximum machine size also.
(You can't flip a 20mm wide belt...)

You can cut it in the middle and fasten it back to back with heatshrink. I do that to use up odd lengths of belt.

>The toothed pulleys are nice
> but they need flanges or need to be considerably wider than the belt.

It does have a flange. Are you referring to the bearings?

 

Yes the bearing made into an idler pulley.

 

They are supposed to be used with mudguard washer, just like now.

It doesn't work if the belt touches the washers you get some backlash as the rubber has high friction. I use two bearings and centre the belt by shimming the idler axle until it runs in the centre. The mudguard washers are then only for safety and could actually be removed. 

Maybe a smaller bearing would allow flanges, Or perhaps a crowned toothed pulley would work.

Bigger diameter is better for the steel strings inside the belt.

 

Yes there is a minimum diameter spec,which is higher when it bends backwards than forwards. I haven't had an issue since the original Mendel X axis that bent it both ways. My belts last for years but everything wears out eventually.

[Laszlo KREKACS]

Hi,

I'm clarifying the article, so thank you for the inputs.

> You need to use a smaller chuck if that is the case. Professional machinists
> must be able to do it reliably otherwise they would not be supplied in that
> form as standard.

I have no doubts that it can be solved.
My point is:
1. you need to find a lathe shop, because it is not drilled to the
correct size (blank)
2. average lathe shops have a 100,125,150mm chuck with 3 jaws and
it is extremely difficult to put back in concentric.

I'm sure you can tool it against (4 jaw chuck, collet chuck),
but it is more expensive then your whole pulley.

And it is difficult enough already to find a lathe shop.
And costs (unnecessary) time and money.

((I hope hand drilling with a drillpress or cordless drill is out of table.))

>> I do think you are wrong about this.
>
> Maybe. I know they come in long blanks that get sliced but they may be
> hobbed by a machine with long travel.

I'm not saying my product is better, I have only stated,
that you can cross a supplier which have lower quality toothed pulleys.

>> a)
>> They introduce unnecessary stress to the belt. Causing wearing the
>> metal strings inside.
>> Depending the quality of the belt, it may break over time (the metal
>> string inside),
>> or it can also delaminate (the toothed part from the steel stringed part)
>
> It hasn't happened to me yet. If the idler pulley is made big enough it is
> within the spec of the belt.

Numerous belt datasheet warns against flipping.
I know it can withstand, I used it for over years on my machine too.
But it always bugged me.

>> b)
>> Aesthetically inpleasant
> Really, compared to the rest of the an average reprap machine?

I try to fix my machine. Maybe it is the first baby steps for everyone:)

>> c)
>> It is limited by the width of the belt. So your maximum machine size also.
>> (You can't flip a 20mm wide belt...)
>
> You can cut it in the middle and fasten it back to back with heatshrink. I
> do that to use up odd lengths of belt.

It is a nice *workaround*.

>> It does have a flange. Are you referring to the bearings?
>
> Yes the bearing made into an idler pulley.

I'm going to include some pictures about example mounting.
Thanks for pointing out.

>> They are supposed to be used with mudguard washer, just like now.
>
> It doesn't work if the belt touches the washers you get some backlash as the
> rubber has high friction.

In case of (toothed) 624 bearing:
M4 Bolt - (M4 washer) - M5 mudguard washer - M4 washer -
- (toothed) 624 bearing -
- M4 washer - M5 mudguard washer - (M4 washer) - machine

In case of (toothed) 608 bearing:

M8 Bolt - special M8 washer of >34mm diameter - M8 washer -
- (toothed) 608 bearing -
- M8 washer - special M8 washer of >34mm diameter - machine

> I use two bearings and centre the belt by shimming
> the idler axle until it runs in the centre. The mudguard washers are then
> only for safety and could actually be removed.

Part of the issue (why it tries to run off of the bearing) is the belt flipping.

Best,
Laszlo

[Kyle Kenney]

There are a few grammatical stuff that needs to be changed, I'll update when I get a few minutes.

I'd like to say, I'm really interested in the toothed idlers, something I'll likely buy when they're available.

As a side though, for the idlers, I'd like to point out that crowned idlers could remove alot of extra idler hardware (all those washers) Though, that's generally for flat belts. I'm not sure how annoyingly difficult a crowned toothed idler would be to manufacture, or if would do more long term damage than good.

http://woodgears.ca/bandsaw/crowned_pulleys.html here's a nice article about crowed pullys

What i'm more interested in however, is the chrome (really, as in a Cr mixture?) hyena. I like my hyena now, but I think from cleaning it (probably improperly) it's going to fail soon and a replacement'll be in order. And being the chrome alloy guy that I am, I'd be interested to see what you're coming out with :)

2013/4/30 Laszlo KREKACS <li...@arcol.hu>

[Laszlo KREKACS]

Hi,

On Tue, Apr 30, 2013 at 4:24 PM, Kyle Kenney <dudl...@gmail.com> wrote:
> There are a few grammatical stuff that needs to be changed, I'll update when
> I get a few minutes.

Thank you. I have corrected a few errors, but I'm sure there still
left plenty in it.
So either here or in the wiki, it is much appreciated.
You can rewrite whole section if you think it is more clear or sounds
better in english.

> I'd like to say, I'm really interested in the toothed idlers, something I'll
> likely buy when they're available.

nice:)

> As a side though, for the idlers, I'd like to point out that crowned idlers
> could remove alot of extra idler hardware (all those washers) Though, that's
> generally for flat belts. I'm not sure how annoyingly difficult a crowned
> toothed idler would be to manufacture, or if would do more long term damage
> than good.

Toothed crowned idler. That is some of a challenge! Thanks for the pointer.

> What i'm more interested in however, is the chrome (really, as in a Cr
> mixture?) hyena. I like my hyena now, but I think from cleaning it (probably
> improperly) it's going to fail soon and a replacement'll be in order. And
> being the chrome alloy guy that I am, I'd be interested to see what you're
> coming out with :)

Here is the upcoming article:
http://wiki.arcol.hu/blog:arcol-chrome-hyena

I have not figured out yet the text, so if you have idea,
how should I introduce it, then feel free to comment.

Best,
Laszlo

[rpulkrabek]

I have printed a 36t pulley that fits over a 608 bearing for the non-motor side of the y-axis an incomplete i2 Prusa. I understand that this may affect quality when compared to a precision machined pulley. For this reason, I may be interested in one of your 32t 608 pulleys. Are you able to show any result comparisons? How much would I benefit of having your machined pulley over a printed pulley?

Also, I have trouble sourcing mudguard washers. Would you be able to include these in the sale, or would you be able to include flanges as they are on the pulleys for the motors?

[Laszlo KREKACS]

On Thu, May 2, 2013 at 8:46 AM, rpulkrabek <rapul...@gmail.com> wrote:
> Are you able to show any
> result comparisons?

No real comparison. It should affect parallel lines near the edge.

> How much would I benefit of having your machined pulley
> over a printed pulley?

I don't think printed pulley is better then having a bare bearing
(without anything around it).

> Also, I have trouble sourcing mudguard washers.

It is not easy to come by. And what I have found is 2mm thick,
and heavy (like 30g or so).
I'm working on manufacturing 100pcs disks for convenience (only 0.5mm
thick, lightweight).
But obviously it is not as cheap as washers (machines making washers
have stencil,
and can manufacture thousands per hour).

I still want to be under 1 - 1.5EUR for 2 pieces in the final price.

> Would you be able to include
> these in the sale, or would you be able to include flanges as they are on
> the pulleys for the motors?

For flange there is not enough "flesh" in the aluminium to apply.
The other reason, that it would be wider in that case then the bearing itself.
So hard to mount on the machine.

Best,
Laszlo

[Carl]

I recently found you wiki on the T2,5 belts, pulleys and bearings... I would love to find out prices on these components for a project I am currently working on... I can't see the items listed on shop.arcol.hu... are they still available?

[Laszlo KREKACS]

Hi,

I intend to finalize the article and put everything onto the webshop next week.

There have been a lot of work going behind the curtain, like:
- above 32mm diameter washer has been manufactured per our need,
that means 0.5mm thick, and not 2mm what the usual washers are
- bugfixing. Concenticity was still an issue.
So we built a measurement jig to verify each pulley is within the
0.1mm tolerance in concentricity.

So right now I have:
T2.5 belt (6mm wide) per meter
T2.5@16 pulley
T2.5@32 pulley
T2.5 608 bearing
T2.5 624 bearing
>32mm diameter "washer"

Since I'm now building a better machine (with no price constraints to
see the limit of FDM),
I'm using 30mm Bosch profil for it.
That means M6 bolt can go onto the profile rail.
So I'm manufacturing (still waiting for the bearings to arrive):
T2.5 636 bearing. It is the same as 608, just it has 6mm inner hole,
and not 8mm.

All of the above one I have at least 50-100 pieces.
Basically the first truely bugfixed batch from everything.

I'm now onto the job of determining the price of all the above.
I would greatly appreciate any pointers how much should it costs.


That said, If you want before the "official" sale,
just ping me privately, by ordering anything through the webshop.
I'm sure we can agree on a price, I don't mind selling it even at loss,
just to see what the feedback is.


Best,
Laszlo

[Carl]

Done! I hope to hear from you soon! :-)

[Ante Vukorepa]

I’d love to beta test, but unfortunately, i’m about to print a pretty sizable “order” (not really getting any money, just paid material) so can’t do any significant changes to my printer until that’s done, which is probably when it’ll be in the web shop anyway.

-- 

Ante Vukorepa

[nscadnathan]

How do these compare to the regular GT2 pulleys?  I need to replace the ones on my Rostock because they are chewing up the belts.  Do you have pricing figured out?

[Kyle Kenney]

I'm building a new printer, a kossel. and I'm gonna need some of these pulleys and bearings.

2013/8/25 nscadnathan <nscad...@gmail.com>

--