Sinclair ZX80 / ZX81 / Z88 Forums

If someone could provide me with complete and accurate dimensions I could 3D print it using TPU filament. It is strong yet flexible and could very well be the ticket here.

I could even pull the dimensions from a complete but no longer functional belt if necessary.

Just wanting to pitch in and lend a hand to the project.

Mike

Please see the attached, I hope it would help.

Thanks, Claudius. That does give me the belt length. What I hope to do is create a belt with integrated teeth, so it may require my purchasing a printer with an intact belt so I can get it dimensioned as perfectly as possible. Let's see, how much is in my PayPal account?

I wouldn't buy a printer in the hope to get a non broken belt. It's hopeless.
I can tell you a little about the teeth:
They are like a Trapez, 2mm at the base and one mm at the top flat part. Height one mm.
And from my experience print the belt in a circle with the teeth vertical. not straight line lying and glue
Hth kind regards Paul

Thanks, Paul. Yeah, it would be printed as you described. Would you happen to know the distance between the teeth and/or how many teeth? I know I should be able to calculate that given the dimensions you provided, but sometimes I am mathemategically challenged. If it is 1mm thick and 5mm height and 275mm length as described in the attachment posted by Claudius, that may be sufficient data to give it a go.


Mike

Sorry I am on my mobile with only edge connection. A quick search on this forum or the tlienhard forums should give you the precise answer. It takes me approximately five minutes to load the empty reply page.
Tomorrow evening I can answer when I have wifi again.
I am very interested in the print data as well because I have two 3d printers as well but I have no skills in 3d design. I have fusion 360 but no clue how to handle it. Every time I try something I follow a YouTube demo. But it takes me an hour to follow a 5 minutes demo (including having the same result on my system)
Kind regards Paul

I now have a CAD drawing for the ZX printer belt based on the dimensions given by some fine folks here. Once I figured out how it wanted to be drawn, it wasn't a difficult task and only took a couple of hours. My filament should be here by the first of next week and will see how it turns out then.

In the meantime, here is a screen grab.

I bought ZX printer with deteorated belt, but I've measured parts of it. Real belt tooth width (an average) is less than 1mm in thickness. In range 0.5..1.2 mm. The template I've provided earlier supposed to be printed on film and glued so that the first and last tooth marks are matched. There are 48 teeth (but 49 teeth marks on a template). Pitch is 275/48 ~ 5.73mm. Belt thickness ~1..0.8mm. It's very flexible. But it should be also a "rigid" in stretching along it's length, like real belts (not simple rubber)
Anyway, you need ZX printer to fine-tune belt tension (length) and tooth dimensions as well as fine-design small contacts holders. On my version of laser-film belt I made contacts holders of two small carbon round rods (1mm in diameter, 8mm length), glued on the outer side of belt. Actually any plastic small round rod should work as well. The exact place of contacts holders actually does not matter due to the principle of operation of ZX printer's "running print heads" (roughly at opposite sides of belt is enough, inside of opposite teeth spacings)
I also have a 3D printer, but need a smaller nozzle (0.2..0.3mm) to print such tolerances

svid123, I counted the lines several times in the Template file you attached but always came up with 46 teeth. As I do not have either a ZX Printer or an old belt to use for guidance I am reliant upon measurements given by other very helpful posters. Confused.

mhudson52 wrote: ↑Mon Apr 02, 2018 3:37 pm svid123, I counted the lines several times in the Template file you attached but always came up with 46 teeth. As I do not have either a ZX Printer or an old belt to use for guidance I am reliant upon measurements given by other very helpful posters. Confused.

Well, it's strange but I've counted 49 lines (48 teeth) ))
Also, I don't have disassembled ZX printer right now, but pitch can be calculated as P = C/N, where C - circumference of ZX printer's pulley (C = PI*D), N - number of cuts on a pulley. As I remember, real pitch value will be slightly different from calculated for optimal smooth performance, because it's not a multiply of length of the belt and belt itself with teeth has a thickness. That template was rendered programmatically, to get best tolerances template