T2.5 pulleys and belt

TheCase Wrote:
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> Dale, apparently, I am OK with reaming them out
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Having the tools helps a lot, doesn't it? If I'd known you had a lathe, I wouldn't have even bothered to question you.

This "doing it wrong" business crops up in a lot of places that have people from a lot of backgrounds doing technical things. I see it most often in motorcycle forums where people have memorized cookbook methods for how some things should be done and can't accept that deviations are possible. Very frustrating for those who actually understand the thing in question. The worst I ever saw was while waiting for a trailer after a motorcycle breakdown. I happened to meet a woman in the restaurant where I was waiting who bragged about all the different kinds of maintenance she does on her own vehicles. The problem is, she had memorized all of it, and understood none of it. So, she was dogmatic about the right way to do things, even when I could see she was wrong. At least she was self-sufficient and getting it done. And the conversation helped pass the time. The trailer was coming from 3 hours away.

I don't know how much of that blind technical dogmatism we have here. I do know that with so many people coming from so many backgrounds, we don't all see things from the same perspective. Some people can see things others can't. Really great stuff is coming out of that mixture, and we get to learn things we couldn't see before.

I just printed some T2.5 motor pulleys from PLA and they seem to work fine. I used 0.35 nozzle, 0.20 layers and 0.36 track width.

Here's the design: [www.thingiverse.com]

Regarding the doubt and confusion, it's often because the people speaking don't have any real scientific background and are cook-booking their "brilliance", a sad outcome of the Apple phenom that allows folks to claim they are the latest fad (ie, "nerd" or "geek") by virtue of an app that does the work for them. Paint by numbers is all and well when it comes to producing someone else's ideas, not so when creating.

Regarding the question at hand, I'd note that if you need a tight tolerance on your metric shaft, an SAE part can easily be drilled out to fit, and you don't really need a lathe to do it, just a fresh #8 drill bit and a steady hand or a drill press. As to where to purchase, I've seen a multitude of domestic vendors that offer parts suitable for use in rep rap printers using the nema 17, 5mm shafts by using that technique, and at significantly lower cost than SDP.

That is, a #8 if you will have set screws (5.0546mm) , or an M6x1 coarse metric for a press fit.

I've used www.econobelt.com with great success.
I personally use XL, but they have many kinds there.

I am not sure the relationship, but the website feels like SPD-SI or an offshoot in some way.
It shows QTC as a top portal to econobelt, but has the SPD-SI book with their QTC logo on it??

They have CAD models for download, and plastic and aluminum pulleys.

I resorted to ABS printing my XL pulleys for my large format Ultimaker styled gantry machine.
The steppers have aluminum ones though.

Dave

It all was cracks me up when I read the list of info when some on asks what is the stock Polly and belt spec for a reprap Printer. I think the question needs to be focused first to:

Witch Reprap printer and to version: (For instance)
RepRapPro Mendal II, Latest Multicolor printer.


Unfortunately I am like the Guy how asked the question right off. I don't have even the plastic Polly to look at (So any one how knows) This would be a good time to start a Spec Sheet.

RepRapPro Mendal Latest Multicolor printer
T2.5 pulley
16 teeth
5mm bore
width : 10mm

This I think is the Spec. If this is the case you should be able to go to any of the Sources mentioned and find.
Note - This do's not mean you have to stick to this spec though.

I was under the understanding T2.5 was old now and the suggested belt was GT2 as its made for what the reprap does.

iv just upgraded from T2.5 to GT2 and 1st thing i noticed was the belt is much smoother. The T2.5 belt was very stiff.

The old belts were T5 (5 mm pitch). T2.5 (2.5 mm pitch) works just fine.

Enlightx Wrote:
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> I was under the understanding T2.5 was old now and
> the suggested belt was GT2 as its made for what
> the reprap does.
>
> iv just upgraded from T2.5 to GT2 and 1st thing i
> noticed was the belt is much smoother. The T2.5
> belt was very stiff.

GT2 is not superior to T2.5, even if it is indeed superior to others like HTD. In fact GT2 is very prone to grime buildups in my experience.
GT2 is good for very large belts running fast. In small pitches like we use, not so much.

The T2.5 is stiff because the tensor cables are metallic, not fiberglass. And in our application (low power but precise positioning) this is better as it means you can use higher tension. You need to use alu pulley though.