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Linear Bearings for 15mm rods

Posted by ninthbit 
Linear Bearings for 15mm rods
October 29, 2015 03:33PM
I've run into a situation where I got to scrap a large Epson scanner. Besides 3 nice Nema 23 motors, and several switches/sensors, I also kept the base that has 2x 25 inch rods with a 15mm diameter.

These seem like great rods to use for a diy printers X axis, but I can't find any linear bearings for this size. I can easily find 12mm and 16mm. Is this an odd size, or is it some kind of nominal vs actual thing? Any ideas how I can make use of these?

I have a pile of other smaller scanners to scrap, I just loved the idea of getting these 25in rods setup. The others look to be 14inch at 8mm.

If you couldn't tell, I'm still very much a noob on this, so thanks in advance.
Re: Linear Bearings for 15mm rods
October 29, 2015 07:15PM
If you do find 15mm linear bearings they would probably be very expensive.
I use shafts out of scrapped printers that are odd sizes but i used the bronze bearings that were in the printer.
I found them to be much better (smoother and quieter) than the cheap 8mm bearinngs you find on many 3d printers.
One rod I printed bearing holders to hold the bronze bearings,one rod I modifies the plastic holders to fit my bed.
Re: Linear Bearings for 15mm rods
October 29, 2015 09:02PM
Search for bronze bushings
Re: Linear Bearings for 15mm rods
November 02, 2015 08:26AM
Wow, you have a reason to spend all your time and money at hardware store, mate!
Linear bearings are not only way of sliding motion.
You could use bronze\brass bushings in self-made collets. they even don't have to be whole cylinders - just enough to grab a rod.
you could use radial bearings also - put a pair of them aside and couple of washers between - you've got a nice linear roller.
Most plastics slide over metals well - it's possible just make a round or triangle hole and it will be sliding nice.
If you have a place to buy a teflon rods or other raw form (plates, chunks ...) - you could drill a piece and have a very nice linear motion.
i've met a reprapper once who used a piece of soldered copper wire spooled over rod as a makeshift bushing and results were quite awesome.
Re: Linear Bearings for 15mm rods
November 02, 2015 03:54PM
The more I read about different designs, the more I'm thinking I'll be scrapping together a pretty crummy printer. Then I'll use it to print the parts to make a much nicer once; reusing the rods, motors, hot-end, and the like. smiling smiley

I'll go ghetto fabulous on the gen1, and then print up something nicer to hold brass bushing for the gen2 rebuild.

Thanks everyone!

Edited 1 time(s). Last edit at 11/02/2015 03:54PM by ninthbit.
Re: Linear Bearings for 15mm rods
November 03, 2015 07:27AM
It's good to have two printers, mate.
Having two machines, they could fix and upgrade each other.
Three is a wee over the top, but two are Ok, imo, in terms of sustainability.
After 4 gen, i own a self-build delta mini-kossel clone and one cartesian strand - a bastard mix of printrbot and smartrap-inspired designs.
But - i'm planning to 'go corexy' from 'ere, so last one is going to be cannibalized in a some time.
It's always fun to watch robots mating process, yeah.
Re: Linear Bearings for 15mm rods
November 03, 2015 07:33AM
Here, mate - for your considerations.
It's a prusa-madmax-ratstrap from one handy reprapper from Belorussia.
I'd say print quality is more than acceptable.
Re: Linear Bearings for 15mm rods
November 03, 2015 03:45PM
What is it about a crappy machine that makes it crappy? Poor frame design/construction and crappy parts. If you rebuild a crappy machine to make it better, what transforms the crappy parts into good ones? At best, what you end up with isn't a good machine, it's a slightly less crappy machine. If you want a good machine, you need good parts. Sure, you can make bushings out of camel turds, and they might work for a while, but just because you can doesn't mean you should. Doing things the right way costs a little more up front, but saves you untold hours of effort and the time and cost of rebuilding a crappy machine into slightly less crappy one.

Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
Re: Linear Bearings for 15mm rods
November 03, 2015 07:35PM
It's mostly a matter of being cheap, but also about custom parts. For example, the extruder. A lack of gear options leaves me going direct drive with whatever I can hack together. I'll probably have to mount it on the carriage too, just to make it simpler.

I was thinking of using some 3/4" MDF I have laying around as well as 1/4 hardboard for the frame and carriage. Keedly gave a few ideas for linear motion that I'll have to experiment with.

The hack job will hopefully be good enough to print the gear box stuff for the extruder. I'll also try and tighten up the rails with proper mounts as well as use brass bushings.

Being an enthusiast nerd with no real commercial use for a 3d printer. The goal is staying cheap. With an Ebay hot end and china imported knockoff arduino electronics I figure I can do this pretty darn cheap. I have free motors, rods, and a few belts.

I would LOVE to even setup a seperate diy filament extruder so I could recycle kitty litter buckets and milk jugs. I've got two paper shredders that may work to supply a motor for a geared down auger/cylinder setup. The other may be used to chop the plastic to tiny shreds. smiling smiley my concern with this idea is that a single spec of dirt can clog the hot end of the printer, so I'll probably skip this idea and just buy new filament I can trust a bit more.
Re: Linear Bearings for 15mm rods
November 04, 2015 06:04PM
There are gear drive extruders available. I use a BullDog XL with an E3D v6 hot-end and have not had a single filament jam since I put them on my printer last December.

Son of MegaMax 3D printer: [www.instructables.com]
Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]
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