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LM8UU, fishing line, etc. Lots of questions!

Posted by Yvan256 
LM8UU, fishing line, etc. Lots of questions!
June 06, 2012 02:12PM
I know it's a bit late in the process with all your design already done and all, but IMHO it would be simpler to get the parts if more parts were similar.

I noticed that you require two different kinds of LM8UU linear bearings (LM8UU and LM8SUU), most vendors on eBay/etc sell them in packs of 8 or 10 LM8UU.

Can the LM8SUU be replaced by LM8UU?

Edited 1 time(s). Last edit at 06/06/2012 06:38PM by Yvan256.
Re: LM8UU
June 06, 2012 02:23PM
Yvan256 Wrote:
-------------------------------------------------------
> I know it's a bit late in the process with all
> your design already done and all, but IMHO it
> would be simpler to get the parts if more parts
> were similar.
>
> I noticed that you require two different kinds of
> LM8UU linear bearings (LM8UU and LM8SUU), most
> vendors on eBay/etc sell them in packs of 8 or 10
> LM8UU.
>
> Can the LM8SUU be replaced by LM8UU?

Unfortunately not. The carriage is 40mm wide/long and that is equal to an LM8uu and a LM8suu. I do believe you could just use 1 LM8uu and just eliminate the LM8suu's but I have not tested it like that. It may cause a small amount of play at the head. My very first Tantillus used all printed bushings by TriffidHunter. You could also use LM8uu's + some short printed bushings.

Most people selling LM8uu's on eBay can provide you with LM8suu's on request.


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Re: LM8UU
June 06, 2012 06:38PM
I've checked your building instructions again, and I have a few more questions if you don't mind. Long time reader, first time poster as they say...

I was able to get two step motors for 5$ each: Sanyo Denki 103H5208-0841 and 103H5208-0841 (both listed as 2 ohms, 1.8 degree). They already have what seems to be 2mm pulley on them (the short belts that came with the whole assembly have S2M100 and S2M196 printed on them). They even have anti-vibration mounts (two mounting plates with a rubber in the middle). Would these motors be okay for a Tantillus? What do you use on yours and in the indiegogo packages?

Another question is about the Honeywell fishing line. What model number are you using? (PWR80150, etc) and which color? Since I've read that some people are having difficulties printing with some colors of plastics, I'm guessing the color of the fishing line could also change its durability.

At first I wanted to build a Mendel, then a Mendel90 and now a Tantillus. The smaller size and increased portability of the Tantillus are important factors for me. I would, however, build it maybe 50~100% bigger as I'd like to have a build envelope big enough to make gamepad and mouse casings, etc. The height is fine at 10cm, however.

Do you think there would be any problem with a 150x150x100mm or 200x200x100mm build envelope for Tantillus?

I had an idea about lowering the cost of the electronics, on the drivers side. Instead of using high-end drivers (Pololu's cost nearly 15$ each and AFAIK we need at least four drivers) to go with microstepping, would it be possible to gear down the motors mechanically and use lower-priced ICs like the L293D since you already use herringbone gears anyway?

I would probably go with a wooden Tantillus, do you know if the panels can be cut using a 0.250" router bit or does it need something smaller?

And last, would it be possible to get a sample printed on Tantillus? Do you have any 100mm makerbeams printed in PLA laying around?

I'm sorry if that's too many questions.

Edited 1 time(s). Last edit at 06/06/2012 07:14PM by Yvan256.
Re: LM8UU
June 06, 2012 07:43PM
Yvan256 Wrote:
------------------------------------------------------
> I was able to get two step motors for 5$ each:
> Sanyo Denki 103H5208-0841 and 103H5208-0841 (both
> listed as 2 ohms, 1.8 degree). They already have
> what seems to be 2mm pulley on them (the short
> belts that came with the whole assembly have
> S2M100 and S2M196 printed on them). They even have
> anti-vibration mounts (two mounting plates with a
> rubber in the middle). Would these motors be okay
> for a Tantillus?

Yes those are the motors I used in the prototypes and on my Prusa. (Those are really good motors and worth a fortune brand new $50 - $200 depending on specs)

What do you use on yours and in
> the indiegogo packages?

This part number may change as the quantity I order may change which supplier I use for the Indiegogo campaign. But they will most likely be 42BYGHW

>
> Another question is about the Honeywell fishing
> line. What model number are you using? (PWR80150,
> etc) and which color? Since I've read that some
> people are having difficulties printing with some
> colors of plastics, I'm guessing the color of the
> fishing line could also change its durability.

Interesting thought, The only reason they color it is for visibility but you may be correct in the properties being a little different. I am using green [www.powerpro.com] the roll I have does not have a part number on it. It is marked 65lb test.

>
> At first I wanted to build a Mendel, then a
> Mendel90 and now a Tantillus. The smaller size and
> increased portability of the Tantillus are
> important factors for me. I would, however, build
> it maybe 50~100% bigger as I'd like to have a
> build envelope big enough to make gamepad and
> mouse casings, etc. The height is fine at 10cm,
> however.
>
> Do you think there would be any problem with a
> 150x150x100mm or 200x200x100mm build envelope for
> Tantillus?

I am confident it can be made wider with very little if any changes to the axis parts. But deeper could be an issue for the cantilever Z axis.

>
> I had an idea about lowering the cost of the
> electronics, on the drivers side. Instead of using
> high-end drivers (Pololu's cost nearly 15$ each
> and AFAIK we need at least four drivers) to go
> with microstepping, would it be possible to gear
> down the motors mechanically and use lower-priced
> ICs like the L293D since you already use
> herringbone gears anyway?

Microstepping makes it very quiet. Because the cable drive already makes the steps per mm twice that of a prusa I ran one with 1/8th stepping instead of 1/16th and it was very loud compared to 1/16th.

>
> I would probably go with a wooden Tantillus, do
> you know if the panels can be cut using a 0.250"
> router bit or does it need something smaller?

1/4" is to large for the bolt holes that hold the LCD and electronics but will be fine for the rest. You will have to hand cut or relief cut all the corners on the finger joints that keep the case aligned. Also the corner brackets snap into little notches in the corners and they would need to be cut with a 1/8" bit or eliminated and glue the corners on (thats how the first wood ones were made).

>
> And last, would it be possible to get a sample
> printed on Tantillus? Do you have any 100mm
> makerbeams printed in PLA laying around?

I give a lot of it away but I am sure I could find something. PM me and we will see about getting you something.

>
> I'm sorry if that's too many questions.

Thats what I had this forum made for. I am sure others will also like to know some of these answers.

Brad


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Re: LM8UU, fishing line, etc. Lots of questions!
June 08, 2012 04:13PM
Yet another question... I see in the building details that there is "plastic bushings". Can they be replaced by 24mm LM8UU's? Some vendors on eBay already have kits of 12 bearings, I asked one if they could sell kits of 10 x LM8UU + 2 x LM8SUU. Prices for these have really dropped lately!

Or would it be possible, if replacing the plastic bushing by LM8UU's, to use a single (centered) LM8UU in the middle and drop the LM8SUU?

I.E. instead of

plastic bushing---LM8UU+LM8SUU---plastic bushing

I would go with
LM8UU---LM8UU---LM8UU

It would add two linear bearings to the kit but it would also drop printed bearings as well as two different kinds of linear bearings.

I'm also thinking about going with the copper bushing from old printers and scanners, depending on what I can find.

Edited 2 time(s). Last edit at 06/08/2012 04:32PM by Yvan256.
Re: LM8UU, fishing line, etc. Lots of questions!
June 08, 2012 04:30PM
Yvan256 Wrote:
-------------------------------------------------------
> Yet another question... I see in the building
> details that there is "plastic bushings". Can they
> be replaced by 24mm LM8UU's? Some vendors on eBay
> already have kits of 12 bearings, I asked one if
> they could sell kits of 10 x LM8UU + 2 x LM8SUU.
> Prices for these have really dropped lately!

No the printed bushing can not be replaced with real linear bearings because the rods they travel on also rotate and linear bearings don't like having their shafts rotated at all.

They can be replaced with Igus bushings designed to replace linear bushings. [www.igus.de]


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Re: LM8UU, fishing line, etc. Lots of questions!
June 08, 2012 04:33PM
> linear bearings don't like having their shafts rotated at all.

I didn't know that, sorry!
Re: LM8UU, fishing line, etc. Lots of questions!
June 08, 2012 04:40PM
Yvan256 Wrote:
-------------------------------------------------------
> > linear bearings don't like having their shafts
> rotated at all.
>
> I didn't know that, sorry!

No worries, I designed it to use them everywhere and found out after that they get damaged if you try and rotate the shaft to much. The good news is the opening for them fit all kinds of other options like the Igus and Bronze (with adapters).


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Re: LM8UU, fishing line, etc. Lots of questions!
June 10, 2012 08:25AM
It seems someone is already using those RJMP-01-08.

Can't wait to receive the samples. I've also asked a quote for 50, 100 and 200 units, I'll forward you the information via PM once I get it.
Re: LM8UU, fishing line, etc. Lots of questions!
June 10, 2012 02:15PM
I was actually given the part number by another RepRapper in my original announcement thread in the general section.


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Re: LM8UU, fishing line, etc. Lots of questions!
July 17, 2012 12:18PM
So I got some RJMP-01-08 bearings. They were expensive and took a month to come.

They are supposed to be 0 - +0.04 tolerance but they seem to be about 8.14mm and are very loose on my 8mm g6 shaft which is supposed to be -5um to -14um. My best attempt at measuring it with a micrometer makes it 7.983 even though my cheap digital callipers say 7.97. The guy I bought the shaft from over a year ago says his current stock measures 7.991 - 7.994 with a high end micrometer. I only have an imperial one with no vernier for the fourth digit. I had to photograph it with a USB microscope and measure the picture with callipers!

I can insert a shim of Kapton film that measures 0.14mm between the two!

Also the RJMP page says it is a drop in replacement for standard recirculating linear bearings but it is in fact 1mm bigger outside diameter than an LM8UU and 1mm longer.

All very disappointing and I have no idea what is going on, I will ask IGUS.

The advantage LM8UU have is there is some preloading so they don't have any play, at least when they are new. With bushings is seems you can never get an exact fit so there will always be some play. 0.14mm seems far too much for a printer. Even if they were in spec there could be up to 0.051mm, which again is too much.

I am not sure using the same shafts for linear motion and rotation is a good idea. What sort of bearings do Ultimaker use for this?


[www.hydraraptor.blogspot.com]
Re: LM8UU, fishing line, etc. Lots of questions!
July 17, 2012 02:35PM
nophead Wrote:
-------------------------------------------------------
> Also the RJMP page says it is a drop in
> replacement for standard recirculating linear
> bearings but it is in fact 1mm bigger outside
> diameter than an LM8UU and 1mm longer.

The Igus bushings I have tested for this were a press fit and once pressed in did fit the shafts perfectly. But it did require many attempts to get the part the correct size to get the press just right. Hence why I am not using them on the units I am selling. The extra length will not be an issue at all so that does not matter (except it is not really a drop in replacement).

> The advantage LM8UU have is there is some
> preloading so they don't have any play, at least
> when they are new. With bushings is seems you can
> never get an exact fit so there will always be
> some play. 0.14mm seems far too much for a
> printer. Even if they were in spec there could be
> up to 0.051mm, which again is too much.

This is true. But from my experience running a machine with the printed bushings for a few months I have to say that the bushings on the rotating shafts can have play without any effect to the print quality. The cables are what keep the head where it needs to be regardless of the rods being bent or having the bushings worn out.

> I am not sure using the same shafts for linear
> motion and rotation is a good idea. What sort of
> bearings do Ultimaker use for this?

They use a long brass (bronze) bushing [wiki.ultimaker.com] . I do have some split printable LM8uu's that I was planning on testing as replacements for the current ones when they wear out. The idea is to remove the old ones with a knife or dremel or simply crush them with pliers and replace them with the split ones so you never have to take apart the machine. But I am yet to need to replace them.

The first machine (printed one) had all printed LM8uu's and I've had to replace all of them except the XY ones we are talking about.

Edited 1 time(s). Last edit at 07/17/2012 08:31PM by Sublime.


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Re: LM8UU, fishing line, etc. Lots of questions!
July 17, 2012 04:15PM
Have you considered a pair of shorter bronze bushings instead of the printed plastic ones, unfortunately I think most of them are 16mm outside diameter instead of 15mm for LM8UU's, that's what I was considering when I was looking at an Ultimaker like design. My backup plan was to machine them out od Delrin, but thats probably not practical for most people.
Re: LM8UU, fishing line, etc. Lots of questions!
July 17, 2012 05:41PM
Polygonhell Wrote:
-------------------------------------------------------
> Have you considered a pair of shorter bronze
> bushings instead of the printed plastic ones,
> unfortunately I think most of them are 16mm
> outside diameter instead of 15mm for LM8UU's,
> that's what I was considering when I was looking
> at an Ultimaker like design. My backup plan was to
> machine them out od Delrin, but thats probably not
> practical for most people.

Willworkforplastic who has recreated the Laser cut Tantillus in Solid Works is planning on using those and has modified the XYends to fit the 16mm. I do not know if they will work on the printed machine because the XYends can not be any bigger because of clearance issues.


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Re: LM8UU, fishing line, etc. Lots of questions!
July 18, 2012 04:32AM
Sublime Wrote:
-------------------------------------------------------

> Willworkforplastic who has recreated the Laser cut
> Tantillus in Solid Works is planning on using
> those and has modified the XYends to fit the 16mm.
> I do not know if they will work on the printed
> machine because the XYends can not be any bigger
> because of clearance issues.

Yup I have, simply by opening out the 15mm hole to 16mm and not increasing the wall thickness. So overall dims of the XY block is the same. Bearings I am using are made by pacific bearings [www.pbclinear.com] . I believe they are the FM 08, you do not want the FMC 08 as these have a oversided ID, by I think 50┬Ám. Can't tell you how good they are yet as I have not got my tantillus going yet. The reason I am using them is I had them lying around doing nothing so thought I might as well put them to good use.
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