Minor Prusa modification During my initail building of the frame I found this to be an issue: [img]http://i195.photobucket.com/albums/z284/njineermike/Prusa/PrusaYaxisBeltAlignmentProblem2.jpg[/img] and belt runoff from a slightly canted gear when tightened into place: Y-axis extended: [img]http://i195.photobucket.com/albums/z284/njineermike/Prusa/Yaxisbeltrunoff2.jpg[/img] Y axis retracted: [img]http://i195.photobucket.com/albums/z284/njineermike/Prusa/Yaxisbeltrunoff.jpg[/img] The runoff continues until the belt pops off the gearing. If you'll look carefully, you can see the gear tilted slightly differently in the 2 pictures. To avoid having the belting drag along the all-thread, I added another roller and fender washers on the bottom rod: [img]http://i195.photobucket.com/albums/z284/njineermike/Prusa/PrusaBeltFix1.jpg[/img] By adjusting the roller assembly laterally, any belt runoff from a canted gear on the stepper can also be mitigated. https://reprap.org/forum/read.php?1,95108,95108#msg-95108 Mon, 15 Jun 2026 03:34:35 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?1,95108,108487#msg-108487 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,108487#msg-108487 Ssss General Thu, 01 Dec 2011 14:17:51 -0500 https://reprap.org/forum/read.php?1,95108,97945#msg-97945 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,97945#msg-97945 nophead General Fri, 16 Sep 2011 16:13:10 -0400 https://reprap.org/forum/read.php?1,95108,97812#msg-97812 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,97812#msg-97812 nophead General Thu, 15 Sep 2011 14:16:34 -0400 https://reprap.org/forum/read.php?1,95108,97808#msg-97808 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,97808#msg-97808 bryanandaimee General Thu, 15 Sep 2011 13:23:19 -0400 https://reprap.org/forum/read.php?1,95108,96135#msg-96135 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,96135#msg-96135
In fact even quite obvious overshoot / ringing in the movement of the bed caused by the springiness of the motor and belt combo don't seem to have any noticeable effect on the filament path. I don't see any rippling at corners, etc. I expect I would if I increased my outline speed though.

I don't don't think spring mounted build surfaces are good for quality. I prefer a rigid mount and leave the Z axis nut traps open at the bottom so the nozzle cannot be driven into the bed with much force.]]> nophead General Wed, 31 Aug 2011 08:22:52 -0400 https://reprap.org/forum/read.php?1,95108,96129#msg-96129 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,96129#msg-96129
Yes, soft/absorbing material must be constrained, and the reference must be provided by a hard surface.


And of course... for all usual plastic melting purposes, the Z axis is almost never active while the extruder is printing. Its contribution to "noise" is minimal.

So better to concentrate on X and Y motors isolation.]]> Lanthan General Wed, 31 Aug 2011 07:38:45 -0400 https://reprap.org/forum/read.php?1,95108,96123#msg-96123 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,96123#msg-96123
My Prusa is almost silent and my other machines with MDF boxes around them are a lot nosier but they work better,]]> nophead General Wed, 31 Aug 2011 05:22:40 -0400 https://reprap.org/forum/read.php?1,95108,96115#msg-96115 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,96115#msg-96115
My concern would be with transmitting the motors vibration to the smooth rod and the frame and thus amplifying it .

I adopt basic isolation and dampening measures nearest of the vibration sources each time it is possible. I tend to slip a cork (or similar) gasket in the contact area between the motors and the mounts.

Not clear to me if this would be possible here. You'd need two dampeners:
- one between the motor and the bottom plate
- one between the motor and the upper assembly plus rod]]> Lanthan General Wed, 31 Aug 2011 04:22:34 -0400 https://reprap.org/forum/read.php?1,95108,96044#msg-96044 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,96044#msg-96044

]]> nophead General Tue, 30 Aug 2011 14:38:50 -0400 https://reprap.org/forum/read.php?1,95108,96031#msg-96031 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,96031#msg-96031 Lanthan General Tue, 30 Aug 2011 10:10:03 -0400 https://reprap.org/forum/read.php?1,95108,96021#msg-96021 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,96021#msg-96021 nophead General Tue, 30 Aug 2011 07:59:39 -0400 https://reprap.org/forum/read.php?1,95108,96016#msg-96016 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,96016#msg-96016 THX for the clarification, that was not entirely clear from the rendering. What about the Z smooth bars?.]]> Lanthan General Tue, 30 Aug 2011 06:58:55 -0400 https://reprap.org/forum/read.php?1,95108,96008#msg-96008 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,96008#msg-96008 nophead General Tue, 30 Aug 2011 04:57:03 -0400 https://reprap.org/forum/read.php?1,95108,95992#msg-95992 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,95992#msg-95992 Issues emerge from the belts, but also from the shaft play in dremels & co. (proxxon is said to have less play)

side note: I'd love to see more development of skeinforge's milling capabilities. There are very few open source toolpath generators really operational.

I started drafting something along Nophead's idea, but with 12 mm smooth bars.
The beauty of his design is that it can easily adapted either for very simple cuts (possible to buy MDF pre-cut), or for a more elaborated routed design.

Possible improvements: The Z axes and motors are held in the air by cantilevered pieces. This solution is very straightforward, but vibration-prone. In my routed version I intend to anchor the Z smooth bars ends into the base plate. The mount has a box design for increased rigidity.



I'd lile to double the vertical plates to pour some epoxy-sand in the middle. We'll see.

I'll have to stop designing for the next couple of months tough. Duh.
]]> Lanthan General Tue, 30 Aug 2011 03:24:24 -0400 https://reprap.org/forum/read.php?1,95108,95949#msg-95949 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,95949#msg-95949
Quote

Have you thought about using a closed box instead of an open one?

Yes if you want to print ABS build a box around the base and omit the two bracing pieces. The box has to be a lot taller than the Z axis to allow the filament to enter via a small hole in the middle without bending too sharply when the X axis moves. The design I show above is equivalent to the Mendel or Prusa, which can print PLA without a box, but this design is easier to box as you get one face for free.

I don't think a belt driven machine will make a good router. Belt isn't stiff enough. You need ball screws for milling, but then they are not fast enough for FFF. A machine that does both milling and FFF will always be compromised and not particularly good at at either.]]> nophead General Mon, 29 Aug 2011 17:57:22 -0400 https://reprap.org/forum/read.php?1,95108,95916#msg-95916 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,95916#msg-95916 I like the prusa i have now but there are too many places that can be improved on.
If i were to make every change i wanted, i would have to rebuild her anyways.
Im thinking up some different designs and ideas to make it as rigid and isolated as i can.
Study enough to print something out.
swap out the extruder with a router and route a PCB
and have tolerances that are much tighter.
as i proceed further i will let you all know my progress.
-E]]> 420e General Mon, 29 Aug 2011 14:47:14 -0400 https://reprap.org/forum/read.php?1,95108,95907#msg-95907 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,95907#msg-95907
Have you thought about using a closed box instead of an open one? With a closed box, you get a heated chamber almost for free.]]> Dale Dunn General Mon, 29 Aug 2011 12:37:02 -0400 https://reprap.org/forum/read.php?1,95108,95899#msg-95899 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,95899#msg-95899 mikey General Mon, 29 Aug 2011 10:59:45 -0400 https://reprap.org/forum/read.php?1,95108,95708#msg-95708 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,95708#msg-95708 -------------------------------------------------------
> I see what is
> going on in the improvements of the machine as a
> similar evolution of steady improvements on design
> deficiencies and real world tests to determine
> feasibility.

Certainly, and the more you dig into the wiki the more you can appreciate the long way. With an emphasis on biomimetics of course, and, as Erik pointed out, strongly addictive aspects. B)-

But (I suppose) in other industrial settings there are minimal specs you are supposed to meet: the minimum your machine is supposed to be able to do is known, and used as a reference.

Maybe we are missing that aspect : what are the minimal specs a machine needs to meet to be called, for example a Mendel? Not about self-reproductivity (IMHO a non-issue as long as we have to keep injecting purchased metal at each generation to compensate "analogic losses") , but about, for example, the tolerances of what we are able to make: are we OK if our pieces come out at plus or minus 1mm? or 0.1 mm? or half that value? Some practical uses of our plastic thingies strongly depend on those specs too.

Second example: what would be the acceptable vibration reference values for our machines frames, a proxy for stiffness/dampening? (mental note: we can do FFT analysis on recordings of machines frame noise up to 10 KHz and it said to be a valid tool for evaluation. Alternative: accelerometry, also within reach)...
etc.

One or several sets of reference values, built on consensus, could help makers, sellers and developers meet on a common ground.

It seems to me there might have been (moderate) attempts of that in the past (?)]]> Lanthan General Sat, 27 Aug 2011 15:59:07 -0400 https://reprap.org/forum/read.php?1,95108,95705#msg-95705 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,95705#msg-95705 mikey General Sat, 27 Aug 2011 14:53:29 -0400 https://reprap.org/forum/read.php?1,95108,95696#msg-95696 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,95696#msg-95696 +- a half mil at most.
The nylon bushings have more play in them then that so binding is not an issue.
in fact it bound up worse with one smooth rod on both sides.
And rocked back and forth a few mms.
Having 2 has made my Z super stable with a total rocking motion of .5mm
It also opens up the idea of moving Z motors to bottom,
and moving the side braces of the whole prusa out and increase the build surface.

In my opinion it was well worth it.
Its just a hack now with plexiglass and zipties
NOw that im finally printing, and with some decent quality im going to design some mounts.\
This shit is ridiculous though,
IMO more addictive then crack lol
Happy Hacking and printing
-Erik]]> 420e General Sat, 27 Aug 2011 13:02:03 -0400 https://reprap.org/forum/read.php?1,95108,95693#msg-95693 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,95693#msg-95693
With the price difference between LM10UU and SC10UU narrowing (currently the latter are sold on eBay at $4.20 per piece including postage), there are prospects for further simplification...]]> Lanthan General Sat, 27 Aug 2011 12:17:16 -0400 https://reprap.org/forum/read.php?1,95108,95689#msg-95689 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,95689#msg-95689
Reduced parts count,
Increased freedom,

Simplification is good!

MDF, optionally stabilized by epoxy, is a winner.

For increased rigidity: At some point you might feel the need to box those two vertical pieces in the YZ plane with an horizontal piece over the top.
...

Side thoughts:
Am I glad I purchased as large a CNC router as I could afford instead of that BFB thingie B)]]> Lanthan General Sat, 27 Aug 2011 11:27:18 -0400 https://reprap.org/forum/read.php?1,95108,95680#msg-95680 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,95680#msg-95680 -------------------------------------------------------
> Nophead,
>
> Suspense is building up.
> Could we have a peek look at your redesign?
> (when?)

This is what it looks like at the moment.



It still have to add belt anchors / endstops, etc. The design is fully parametric and is shown with 10MM rods and an overall volume the same as Mendel. That gives a 200x 200 build area but a very tall Z axis so I will probably make it a lot lower. An advantage of not using the triangular frame means all the axis sizes are independent of each other and are just a matter of changing the sheets and rod lengths.

The Y axis belt is half the length by putting the motor and idler under the bed. Since they are screwed to 12mm MDF sheet (instead of hung from springy bars) they can take any amount of belt tension without moving.

The Z bars are also attached to rigid sheet so should be able to the X axis impulses without moving. I might make the top bar clamps triangular if they prove not stiff enough.

The X motor and idler at the same level as the bar, so the tension will not bend the bars.
]]> nophead General Sat, 27 Aug 2011 08:12:38 -0400 https://reprap.org/forum/read.php?1,95108,95674#msg-95674 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,95674#msg-95674
@NoobMan: Yes, the long Z nuts, tried 'em at the very start, you can see 'em in "old" pictures like her: [www.thingiverse.com] , but the testing got totally obscured by Z motor power distribution problems until I wired 'em serial. In the mean time I had replaced the coupling nuts by normal nuts to reduce friction.

From that experience: the longitudinal play of the nut on the rod feels very similar as that of "standard" nuts. But backlash shouldn't be much of a problem since the Z axis is constantly preloaded by the weight of all the stuff residing on it, and travel along Z is (usually) one-way. My provisory conclusion is that the benefit provided by long nuts would be quite marginal. And we don't want to transfer lateral forces to that woobly axis.

2 Z rods: would provide us with a centered path for the belt in the middle.
At the cost of added viamins.

Yes I am also following closely the nice work of Emmanuel and the Cypress guys.

About my mods: I have found myself trying to keep 'em as much as possible compatible with the existing setup and clearances, so as to provide a path for upgrade from a "standard" configuration without the need of re-touching the parts that (apparently) work well. I am not yet desperate enough to want to re-cut or re-print my X carriage.

This option of course poses limits on design freedom, just like reuse of other people's code. Sometimes it is more satisfying and straightforward to start with a clean, fresh slate.






I am not happy with the current state of this mod: much time spent trying to keep some existing features and code. Some might need to be dropped in the end. No rounded corners, and the code is still a disgusting mess. Will clean up a bit before posting.

the x-end-motor-mod basically provides a stronger (8mm) wall for the motor, and an H structure should provided increased rigidity. Somehow addresses concerns about play between the different planes.

Stuff I am not yet sure about:
- the LM8UU clip mount
- and above all the cuts along the lower surface (GregFrost's), I'm concerned about their impact on stiffness.

What would you do?

the x-motor-cover is based on a torsion box idea (like the Y), and optionally can be fitted with one or two threaded rods (or maybe also smooth?) that run along the belt and join both x-ends. (still missing: the idler end & cover designs, shouldn't be hard). The x motor's pulley is supported in both side, and there is a 10 mm clearance for the belt.

When carefully adjusted, fitted with the 2 additional rods and bolted together, both parts should provide a rigid L (as in "Lanthan" ;) ) structure

Must check clearances with the carriage and limits to Z travel height.

Please analyze and comment.

Cheers,


[attachment 5174 x-end-motor-mod.png]
[attachment 5175 x-end-motor-cover.png]
[attachment 5176 x_motor_cover.stl]
[attachment 5177 x-end-motor-mod.stl]
]]> Lanthan General Sat, 27 Aug 2011 06:46:59 -0400 https://reprap.org/forum/read.php?1,95108,95659#msg-95659 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,95659#msg-95659 double X axis seems better in terms of equilibrium on each side of Z rods, and pretty cheap. Basically it would look like 4 smooth rods in a square / rectangle placement, and then both X terminations can be exactly the same piece, each with a motor and an idler facing the other end.

So dual carriages and dual extruders, independent on each other except they would be on same Z. Having issues with an extruder -print with the other one. Or have different filaments or nozzles.

On carriage can be parked when the other is used, but also a further interesting thought is, why would i bother finding extra pins for second Y motor, just hook it up along with initial Z, just will move in reverse each time, so when one will make a directional move and stop, the other will make the same in the opposite direction at exact same time and probably would help with some inertial dampening or something like that, keeping X steadier overall. Haha, dunno if it would actually work like that but it just might - if the end pieces are strong and rigid enough.

Edit:
Also another point, in original prusa files for those parts, the Z nut that is engaging the movements for Z axis is on the lower part and by default one can only use a very small nut. There are "coupling" nuts (i think thats the name, not sure), that are much taller, like 4-5 normal nuts placed each on top of each other. That should be better to use, so the point where the nut is trapped inside the hexagonal ring should be moved upwards a few cm.

Edit2:
I would also incorporate the doubler mod [www.thingiverse.com] in both axis X and Y to be used by default. I think its worthy and all machines should have it. Y mount can be also made wider like 2 cm, only in the area where its clamped to structural bars, in rest can be like 7-8mm or so (motor area), and i believe that would make it stiff enough.]]> NoobMan General Sat, 27 Aug 2011 03:22:31 -0400 https://reprap.org/forum/read.php?1,95108,95631#msg-95631 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,95631#msg-95631 mikey General Fri, 26 Aug 2011 17:33:32 -0400 https://reprap.org/forum/read.php?1,95108,95615#msg-95615 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,95615#msg-95615 translate.google.co.uk] and the one Emmanuel is working on [reprap.org]. I think these solve the X motor rigidity problem, and more tightly constrain the X-axis bars to the Z-axis rod.]]> droftarts General Fri, 26 Aug 2011 14:29:14 -0400 https://reprap.org/forum/read.php?1,95108,95589#msg-95589 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,95589#msg-95589 -------------------------------------------------------
> If the X-axis rods were clamped solidly in the
> X-end holder,

Got that solved. This provides a decent grip on the smooth rods, if installed on both ends,

[www.reprap.org]

at low cost. Just make sure to drill (2.5 mm) and tap (M3) a couple of faces 120 degrees apart, and not 180 as I did.

> tensioning the X-axis belt would not
> pull the Z-axis rod in, and an additional Z rod
> would not be needed. That's why I'm not a fan of
> the current push-together X axis holders - they
> need a clamp.

Clamping force must be higher than what is provided by the plastic tabs.
GregFrost further refined that plastic tab concept by providing optional closed ends "adjustable" with axial nut traps. Still I am not sure it is the way to go.

As for me, I'd prefer to go back to bolted-in clamping pieces for the rods. But there is little clearance to do it right, and monolithic design provides (maybe) some structural advantages..

>Tightening the Y axis can pull the
> threaded rod in as well; it might be worth fitting
> a strengthening rod across, like the lower Z rod
> support, if there is space under your Y axis.

There is space indeed (I have installed the middle transversal over the rods because of Z rod lengths issues).
Also: Looking at the Selis Mendel designs, there are pieces on both Y ends connecting both threaded rods in the middle. The Y motor mount is providing this on one side. For the other end, one might design something to be slipped and tightened on both sides of the idler.
Using the old but proven double nut system has an additional benefit: increases rigidity (as compared with self-blocking nut)

>
> Also, if your motor mount is twisting, you can
> straighten up your motors and fix the pulley run
> out with a couple of washers between the motor and
> the mount, on the 3mm motor mounting bolts, but
> just on one side (whichever way it needs
> adjusting).

Will work, but not entirely satisfying, because the lack of rigidity will still promote vibrations. I'm completing a redesign of the X motor mount with the pulley encased in a torsion box, plus an 8 mm thick motor wall - and I am quite tempted to add also one single threaded bar connecting the torsion boxes on both ends. Unobstrusive and just over the belt. At least I'll leave this possibility in the design, like the rest, that would provide an optional upgrade path...]]> Lanthan General Fri, 26 Aug 2011 11:07:14 -0400 https://reprap.org/forum/read.php?1,95108,95575#msg-95575 Re: Minor Prusa modification https://reprap.org/forum/read.php?1,95108,95575#msg-95575
Also, if your motor mount is twisting, you can straighten up your motors and fix the pulley run out with a couple of washers between the motor and the mount, on the 3mm motor mounting bolts, but just on one side (whichever way it needs adjusting).]]> droftarts General Fri, 26 Aug 2011 08:36:08 -0400