Paste Extruder (a work in progress)

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sthone
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Re: Paste Extruder (a work in progress)

Post by sthone » Mon Mar 14, 2016 3:50 pm

Cool thanks again... that makes things really easy, with these two options I should be able to get this dialed in a think.

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sthone
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Re: Paste Extruder (a work in progress)

Post by sthone » Mon Mar 14, 2016 4:15 pm

This stepper I'm trying to use for this project was actually a defective one and the gear that spins planetary gears isn't secured to the main shaft and it slips... the guys at MG told me to try a certain loctite to try and fix it but I can't remember what # it was. Anyone know what is use to secure gears to shafts like this?

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ednisley
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Re: Paste Extruder (a work in progress)

Post by ednisley » Mon Mar 14, 2016 4:48 pm

sthone wrote:secure gears to shafts
Assuming that the gear won't ever come off, just epoxy it and move on. I'd use steel-filled epoxy, along the lines of JB Weld from your local auto parts store, with a fixture to hold everything in alignment.

The advantage of epoxy is that it fills voids: most Loctite adhesives depend on anaerobic curing and don't work well with sloppy fits. Loctite 640 sleeve retaining compound assumes a "slip fit" that's generally tighter than the usual "doesn't quite fit" I'm stuck with:

http://www.quicktite.loctite.com/produc ... 7931798529

Breaking a Loctite bond requires about as much heat as for epoxy, so you should regard either method as permanent on a stepper motor shaft; the heat will wreck the bearing before the bond falls apart.

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sthone
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Re: Paste Extruder (a work in progress)

Post by sthone » Mon Mar 14, 2016 6:36 pm

I didn't think something like JB Weld would work because the gear is such a tight fit, I thought I would need something that could wick in between the gear and shaft but I have some JB weld so I guess I can give it a try first and see what happens. Thanks....

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ednisley
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Re: Paste Extruder (a work in progress)

Post by ednisley » Mon Mar 14, 2016 8:09 pm

sthone wrote:because the gear is such a tight fit
Ah! I misunderstood; I thought you had more slop than that.

You're right about the epoxy not being the right tool for a close fit like that. The 640 sleeve retainer ought to do the trick. If it has no play at all, then 263 high-strength should do the trick.

http://www.na.henkel-adhesives.com/indu ... 7951950849

I've always known it as "the red Loctite", but they reuse the same color for many formulations, so go by the number rather than the color.

No matter what they say about "oil tolerant", clean the gear & shaft with acetone (or its ilk) for best results.

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sthone
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Re: Paste Extruder (a work in progress)

Post by sthone » Mon Mar 14, 2016 10:17 pm

Yeah.. it's pressed on there tight and works occasionally but the gear ends up slipping down the main shaft after awhile and loses contact with the planetary gears. Let me tell you that was a fun time trying to diagnose that extruder problems on a brand new printer. :roll: The MG guys hooked me up with a new motor though and told me to fix this one and use this on some other project so here we are.

I normally only use the Loctite variety for threads so it's either "Red or Blue" for me too. :D I do have some industrial red laying around somewhere so I'll give that a try, if that doesn't work I'll order some 640.

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sthone
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Re: Paste Extruder (a work in progress)

Post by sthone » Fri Mar 18, 2016 3:46 am

Pasteruder 05.jpg
Pasteruder 06.jpg
Pretty sure the red Loctite did the trick for the gear on the motor although I haven't fully tested it yet.

I also did a quick redesign and added a door and latch to hold the syringe in to allow for quick reloads.

I'm hoping to get back to some testing this weekend and trying out those settings you guys recommended, hopefully I can getting it dialed in a little better with those.

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jimc
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Re: Paste Extruder (a work in progress)

Post by jimc » Tue Mar 29, 2016 4:21 am

very cool

hanming
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Re: Paste Extruder (a work in progress)

Post by hanming » Fri Jun 16, 2017 5:33 pm

Hi, I'm developing a printer of viscous fluid for a lab and interested in your design. Can you upload the solidworks or modeling files? Thanks a lot

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