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Conveyor belt as Y-axis

Posted by atorox 
Conveyor belt as Y-axis
March 19, 2010 03:17AM
Hi,

My mendel is still in pieces around the world ;-)
But an idea occurred to me while reading this blog:

[charlespax.com]

How about replacing the Y-axis with kapton conveyor belt on a static heated bed so that the conveyor belt movement replaces the Y-axis movement and when the piece is ready moves the ready piece away so that mendel could be used for continuous production. And even be used to print larger than bed pieces if over hangs can be printed.

atorox
[finreprap.blogspot.com]
Re: Conveyor belt as Y-axis
March 24, 2010 09:10PM
I had to sit back and think about this for a second.

This is actually not a bad idea. If the 'continuous' strip of kapton was laid over the pad on a Mendel that would work, since there is only one axis on the build area. Both X and Z are isolated. Its genius!

You should draw up some ideas. I was thinking that if the kapton sheet had holes punched out of the sides like old printers you could drive it with reprapped gears too!

Any thoughts?
Re: Conveyor belt as Y-axis
March 24, 2010 10:03PM
How do you plan on holding the flexible sheet down hard enough to resist the force of warping?

Nophead found that a vacuum wasn't enough - the "pull up" force is stronger than atmospheric pressure. So unless your reprap is in a pressure vessel that won't work. Or at least won't entirely eliminate warping like a rigid bed would.

Stretching it tight won't work either - the pull force on the sides approaches infinity.

You'll need a rigid bed of some sort to resist the warping forces. I've seen a couple ideas floating around that might be sortof workable. But getting a rigid bed that's flexible enough to roll and doesn't leave unsightly seams in the print surface will be quite a trick. One I'd love to see you pull off. Keep us posted!


--
I'm building it with Baling Wire
Re: Conveyor belt as Y-axis
March 24, 2010 11:00PM
Thats why i mention the old printers. Where there are hole in the sheet and toothed gears on the side driving it and keeping it stretched plus the sheet should be tight long ways as well. This is not a solution for all plastics. If you are using plastic with strong warping then you are out of luck. This is not the solution for you, but if you are using PLA or something similar. Then this is the solution i believe.
Re: Conveyor belt as Y-axis
March 25, 2010 01:03PM
I was thinking having something like of two rolls with sprockets on edges for some tension for feed an low vacuum on the table to keep kapton smooth.

I would like to try making conveyor belt mendel either with or without vacuum but getting big enough piece kapton and the holes for sprockets in it probably will bee too difficult.


--

atorox

[finreprap.blogspot.com]
Re: Conveyor belt as Y-axis
March 25, 2010 01:08PM
Why do you have TWO THREADS with the same topic in different subforums? eye rolling smiley


Bob Morrison
W├Ârth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse
Re: Conveyor belt as Y-axis
March 25, 2010 01:47PM
Because this idea bothered me too much and there was no comments for few days I thought that perhaps this was wrong forum for it :-(


--

atorox

[finreprap.blogspot.com]
Re: Conveyor belt as Y-axis
March 25, 2010 07:54PM
Only thing that bothers me about the conveyor idea is the Kapton ageing issue pointed out in the Heated bed thread over in the General forum.

Basically, it seems as though Kapton ages, or at least it is slightly damaged each use as the part is removed. In a belt scenario, this means that the belt will get weaker and weaker over time. This could just lead to stretching (which will expand the distance between the holes, making the sprocket/tractor feed fail), or to a total failure of the belt by snapping.

Note: Has anyone measured how much kapton film (thick enough to be a belt) actually expands when heated to say 120 Deg C? That expansion in itself may cause issues for the sprocket/tractor feed idea.

Also: How to you plan to join a length of kapton film into a belt? That join will most likely be the weakest part (especially if the belt is under tension to keep it flat). Also, if it's unable to be printed on or travel over the surface of the bed, then you need to worry about that too.
Re: Conveyor belt as Y-axis
March 26, 2010 12:57PM
So kapton would not be optimal belt material after all.
How about teflon baking liner?
These are teflon coated fiberglass that are rated for -190 - +260 centigrades.

My plan was just to use thread to sew the belt together and move belt just back and forth not all around.


--

atorox

[finreprap.blogspot.com]
Re: Conveyor belt as Y-axis
March 26, 2010 11:18PM
Seems that materials like ABS stick to kapton fairly well, and when they are removed from the surface (even after cooling) they take a tiny bit of the surface with them. As such, I personally wouldn't use a belt and then print directly on the belt itself. Having kapton tape applied to the surface of the belt however (which can be re-applied when it gets to be a problem) solves the issue nicely. If it gets damaged, you simply replace the layer. The belt itself doesn't get much wear from the printing process, and therefore you'd expect it to last longer.

If you don't intend the belt to go all the way around, then the join shouldn't be an issue.

That said: If you aren't going to drive it all the way around, you could just use a straight long piece, and attach it directly to a roller on each side of the bed. No need to have a loop as such. Biggest issue in each case might be getting the ends square on the belt, and making sure the rollers are square to each other, so that it will sit flat.
Re: Conveyor belt as Y-axis
March 27, 2010 01:58AM
i have been thinking about this and its simple.
elongate the belt area, 2x the length
mount the tape on a plate.
join the plate's to make a belt.
heat the printing area.
cool the non printing area, fan or other,
hold the plates down with rollers of some kind.


this idea falls apart for me, at the holding the plate down, and heating the plate, if its moving then its harder to heat the plate unless you move the heater as well. we will see how it flush's out once i build it.

the plate would me made from something springy and non thermally conductive, like stainless steal. the plate would be as wide as the size of the tape, 1.5. but i need to check that

this would most likely end up with the lines at the point the plates match up. but that would be something i am willing to live with.

this idea gives you a hot area, for printing, a cool area for cooldown, print time and cooldown will be the same amount of time. once one object is done cooling and the next one is done printing, then the belt is advanced and the cool object should pop off in to a bin.

side note, this can work the same but make the plate bigger and forgo the belt. then you end up with something that looks more like a normal paper printer with a Z axis. but then you need the plate and some type of feeder. i like the top idea better
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