Tuesday, March 27, 2012

A Z-Axis Wobble Limiter Proposal

Once we have identified that we might have a Z-Axis wobble issue with .125 resolution prints, we need to decide is it's bad enough to worry about or not.

Z-Axis Wobble under a 40x Microscope

The reason I chose an extruded triangle for creating my test tower is that I knew it would form and sharp edge that would provide the best look at the wobble under a microscope.  I wasn't disappointed.  Now, remember, each layer is just .125mm high.  So, with this better image, I estimate the wobble is probably just between .25mm and .50mm.  That is not very much.

Pulled back a bit, we can see how shallow the wobble is in the case of my RapMan.  This image also shows that the wobble mirrors one turn of the threads of the threaded robs.  The pattern will always be the same length.  Only the depth of the pattern will change depending on how badly the threaded rods are bent.  This is so shallow that it probably represents a single rod, not all four.

Wider View of the Z-Axis Wobble Evidence

In my case, I really don't think it's a show-stopper.  However, this is a blog about 3D printing and that raises the bar on the level we need to expect for ourselves.  And, that is nothing less than the best prints that might be possible from a 3D printer.  Period.

That means addressing the problem if for no better reason than the general issue among all users needs to be addressed.

Z-Axis wobble is a well known issue for most 3D printers.  So, there are some very good solutions floating around in various 3D and RepRap forums.  There are even fixes that you can download to replace the default Z-Axis system that came with your RapMan.

There is one problem with each of these solutions.  They require taking your RapMan apart to replace the Z-Axis lifts on all four corners of the RapMan.

My goal, in pondering a solution was to find a way to minimize or eliminate wobble WITHOUT taking the RapMan apart.  I wanted to be able to continue the original RapMan system for raising and lowering the bed.  I have no clue if the solution I am proposing will work.  At the moment I have run out of filament and can't build and test the idea immediately.  But, I can describe the proposal.

Here is a rough image that, hopefully, explains what I am planning to try.  There is a LOT of design work yet to be done beyond this rough concept drawing.

Proposed System - Rough Outline
First, the blue section represents the original parts that hold the nuts that raise and lower the bed on the threaded rod.  You'll have to imagine the nuts and springs that comprise the lift mechanism.  The hole in the blue part represents the hole for the threaded rod.

Normally this plate would be directly connected to the bed frame.  But, in this case I'm proposing to put some parts between the lift plate and the bed frame.

The first of these is the bottom red part.  It bolts to the lift plate in place of the bed.  It has a fixture into which we will insert some spring steel (Grey in the above image) that can be obtained in any hobby store.  The optimal gauge and length we will need has yet to be determined.  It is this wire that will provide rigid support for vertical movement while dampening lateral movement.

The wire fits into a similar fixture in the underside of the top red piece.  It is locked into place with a set screw and/or appropriate glue.

It is the top fixture that isolates the wobble in the blue section.  Notice that the hole through which the threaded rod runs is larger in this fixture.  We do not want it to make contact with the threaded rod.  As I said, this is a rough approximation of the plan.  In the actual part, it will have to be made so that we do not have to remove anything.  So, the right side of this section will probably have to be in two parts.  And, the hole on the far right, which represents the hole for the smooth outside support rods will actually be two bearings.  Again, this is simply a rough concept.

The bed support will be bolted to the top red part.  This part will be isolated from the source of the Z-Axis wobble by the spring separating the top and bottom units.  And, the bed will be steadied by the top component's connection to the outside vertical support rods.

Hopefully, then, the spring will make a tight vertical connection while allowing the lower section to wobble without that wobble being transferred to the top section and bed support.

Until the replacement filament arrives, we won't know if this technique will work.  But, we do know that if it doesn't we have not altered the basic Z-Axis operation and can return to it fairly easily.

I'd love to hear ideas pro and con about this proposal.  Perhaps you have already tried something similar.  If so, please let me know.

What is RepRap & RapMan Z-Axis Wobble?

I'm fairly confident that any issues with the Y-Axis alignment and the Bed Leveling alignment on my RapMan has been successfully solved using the new tools that I designed to make the process more precise.

But, when printing at .125mm, it is apparent that one more issue may need to be tackled.  And, that is probably some issue with some relatively minor Z-Axis wobble.

This video isn't all that great.  The lighting is poor and the image is 640x480 because it was shot at 240fps so we could analyze the image in slow motion.  I'll try to get better images of all four threaded rods this evening.
However, it is still useful enough to use right now.

What this video shows is that if there is any wobble at all, it is very. very minor.  Yet, because we are working with such tiny tolerances, it is still noticeable in the printed output.  As the following samples show.

Here is the test object.  It's a tower having 3 equal sides.  This shape was chosen because it results in 3 sharp edges.  It was printed at .125mm resolution.  And, as you can see, there are some visible ridges that probably indicate Z-Axis wobble.

Test Tower
Looking at a crop of the image, we can see the ridges a bit more distinctly.

Test Tower - Crop showing ridges more clearly
By laying the tower on its side and angling the light to create shadows, the ridges become more identifiable.

Lighting to accentuate the ridges
While we can see an interesting pattern in the above picture, it's not so clear as to how many layers there are in the repeats of that pattern.  For that we need a microscope.  Again, the following picture was created using the worst microscope I have in my collection and the camera was hand held to the eyepiece.  So, it's not the best we can do.  Even so, it is helpful to see for this article.

Ridge pattern through a 20x microscope
The most important thing about this image, and something with which I want to follow up, is that the ridge pattern looks to be about 12 rows.  If 12 (or so) rows equates to a full turn of the Z-Axis threaded rods, we have evidence of Z-Axis wobble.  Yes, it's on a small scale.  The wobble appears to be less than .5mm.  But, it is there.  And, theoretically, we should be able to get that down to virtually zero.

In subsequent posts, we'll explore some of the solutions that other 3D printer users have come up with to deal with this issue.  But, before we leave this subject, it might be interesting to see what we are up against in dealing with the threads of the threaded rods.

Threaded Rob Up Close and Personal
If you click on the above image, you will see that threaded rods aren't always as cleanly threaded as we would like.  In fact, I don't believe I have ever seen a perfectly clean threaded rob.  This one is as good as any I've seen.  Yet, it clearly has some defects and/or debris that might affect the print.

While looking at the screw, it dawned on me that I should be able to place the test tower next to the threaded rob and take some macro images to see if the threads match the pattern of ridges.  I'm guessing they do.  :)

Sunday, March 25, 2012

Fine tuning RapMan 3.2 - Hot End clearance

The RapMan gives us several tools to raise and lower the hot end relative to the bed.

The first, and most basic, way to set the distance between the hot end and the bed is a long screw that hangs down from the extruder assembly.  Each time we select the bed height option on the console, the printer homes the machine so that this bolt can activate a switch and then the printer uses that position to move to the center of the bed and lower the hot end to the position called for the bolt's length.

The manual calls for adjusting the hot end so that it barely touches the bed.  "Barely" is the operative term.  I'd like something a little more measurable.  To get the most precise setting, I decided to use a mechanic's tappet gauge.  So, I started with the 0.102mm leaf on the mechanic's gauge to get the hot end as close as I am able to measure. But, through trial and error, I found that my particular printer responded best (laying down an undistorted raft) at 0.254 for PLA.

Here are the steps I use.
  1. Press the Z-Height Selection
  2. Make sure the Z-Height Offset is 0
  3. Try the 0.254 leaf of the gauge under the hot end.
  4. If there is a lot of clearance, tighten the adjustment bolt.
  5. If there is no clearance, loosen the adjustment bolt.
  6. Exit Z-Height adjustment

Repeat the above steps until the gauge just slips under the hot end.  Do NOT make changes to the Z-Height offset.  You are setting the base point and will use the offset to further fine tune for different situations or special cases.

I understand the critical nature of getting the hot end (Z-Axis) height right for the raft.  But, it's still unclear to me that it makes much of a difference in subsequent layers as the Z-Axis increments should take care of itself in spite of the starting height as long as the height was sufficient to create a starting raft.

And, the optimal height for any given printer with any given material might be a bit different.  That is because the setting you end up using is the setting that is able to lay down a nice raft without tearing it or distorting it.

The point is that we can get more precise in by using tools, like a mechanic's tappet gauge, we are better able to control our printing environment on a repeatable basis.

Fine Tuning RapMan 3.2 - Precise Bed Leveling

Making sure that the RapMan 3.2 bed is level is probably among the most important things we can do to ensure better results.

The build manual and the display panel gives up some tools to level the bed using three bolts.

But, my eyes were having a hard time seeing the hot end height.  So, I decided to make some tools to help me do this more precisely.  First, I bought a set of mechanic's valve tappet gauges.  Using a gauge under the tool that I am going to describe is the most precise way to ensure that all points are even.

First the tools...

Bed Level Tools

 Basically, these two tools are hung over the X-Carrier rails and hang down.  The four points are an even length.  Here is how they are used.

Tools hung over at each end of the X-Carrier rails.

Notice that that a tappet gauge is being slipped under one of the pointed rods.  Adjust the height of the bed using the console until the gauge can be just slipped under the point.  It should NOT lift the tool.  Now, by simply using the bed leveling bolts, ensure that the gauge just slips under each of the other points.

Do this front and back.

Gauge being used at the back of the bed
These tools are a LOT easier to see than the tip of the hot end because you can place them so close to the edges of the adjustable bed assembly.  You can get up close and personal.

Finally, I had created an earlier set of alignment tools designed to do the same thing.  However, these sat on the bed, itself and had clips similar to those of the X/Y Carrier alignment tools.  I now use these just to verify that the bed is level.

Verifying that the bed is level

The latter step  is not really required.  I simply have the posts already and it's a good tactile way to verify that the bed is level.  Raise or lower the bed until one of the tools clips easily on the carrier rod and the other tool should also clip easily.

Once bed leveling is complete, we need to adjust the hot end height.  And, for that I also use the mechanic's tappet gauge.

Fine Tuning the RapMan 3.2 - X Carrier Alignment

So far, I have not found a single defect in the design of the RapMan 3.2 that I could pinpoint for you.

However, the printer is only going to print as well as we have built our RapMan printer.  And, I am determined that I am not going to be content until I have assured myself that the printer I have built is as good as any other RapMan out there.  And, that means finding ways to fine tune as many of the variables as I can.  And, at least for me, this means a By-The-Numbers approach to alignment.

Fortunately, the RapMan can help us out here, by allowing us to build alignment tools that we can use to ensure that we are as close to the most precise tolerances as we can get.  I want to talk about some that I've created for myself.

The first is a tool that allows me to align the Y-Axis travel.  The RapMan uses two belts for the Y axis.  And, it's possible that these two belts are pulling at an angle.  The best way to ensure that both belts are adjusted so that the X-Carrier is in perfect alignment is to measure the distance on both the left and the right sides to make sure they are equal.

Here is the alignment tool that I built for this job.  We use two.

Y-Axis Alignment tool
Notice that these alignment tools have a small half circle and a large half circle.  The small half circle fits over the top front rail and the large half circle fits over the front carrier bar for the X-Y carriage.  Clip the tool on the front rod and move the X-Y carriage carefully until it's possible to easily clip the tool onto the first rail of the carriage.  Do NOT force it.  Here is what it looks like.

Left Side Y-Axis Tool Attached
Then clip the other alignment tool to the front rod and ease it down to the carrier rail.  Again, do NOT force it.

2nd Alignment tool attached to front rail

Alignment tool being lowered to carrier rail

If the 2nd alignment tool will not easily clip onto the carrier rail, then the carrier is out of alignment.  Loosen the Y-Axis pulley at the back right of the printer and pull or push the right end of the carrier until the tool can easily be clipped to the carrier.

Carrier aligned
Then tighten the pulley.  The carrier should now be aligned.  But, you may want to remove the alignment clips and try the steps again to ensure that the X-Carrier is, indeed, permanently in alignment.

Tuesday, March 20, 2012

RapMan 3.2 Unattended Print:125mm - Part 1

Good news!

I arrived home this evening to see the print job still going strong.  An hour or so later, the job was done.  The RapMan successfully printed without intervention and unattended for more than 13 hours!

Once again, for now, I am using a point and shoot.  So, the focus isn't going to be as clear as it could be.  I am leaving the support material on until I can take some better images tomorrow.

Peyton Duncan - Chow: View #1 at .125mm
While the detail is a bit greater in the above image, there are what appear to be printing errors at the rear of the dog.  They might be related to the support material for the tail since they can be seen on both sides as View #3 shows.

Peyton Duncan - Chow: View #2 at .125mm

Peyton Duncan - Chow: View #3 at .125mm

Peyton Duncan - Chow: View #4 at .125mm
 In the above picture, it's clear that there is a bit more detail that comes through at the mouth and eyes.  But, as I hold the two different prints in front of me to compare them visually, those details isn't nearly as different as I'd expected.

Peyton Duncan - Chow: View #5 at .125mm
The top view shows a VERY different outcome between the two different prints.  There appears to be tiny holes near the ears and a prominent hole in the tail.  Again, a better camera and lighting will show this more clearly.

BOTTOM LINE:  For me, the additional printing hours did not yield the kind of difference I had hoped to see.  But, the real proof will be side by side comparisons once the support material is removed.  However, it's important to remember that I am new to both the software and the printer.  An error or oversight in either would yield unexpected results.  I wonder if the result will be the same if  I tried this experiment a year from now.

However.  It cannot be overemphasized that the RapMan, with a roller bearing hub, is a workhorse!

I plan to seek ideas as to what is taking place on the .125mm print in the RapMan forums.  I'll post an update if I find out anything significant.

RapMan 3.2 Unattended Print at .250mm

UPDATE:  I did manage to figure out why the .125mm test was not, initially. printing well.  It didn't dawn on me that because the layers were 1/2 the thickness, I needed to raise the bed to compensate.  Once that was done, it was running fine when I left it this morning.  Hopefully, it completed the job.  I'll find out in an hour or so.  I HATE DC area traffic!  LOL!

Before leaving for home... and hopefully finding a higher resolution print of Peyton Duncan's Chow waiting for me... I managed to capture some better images of the printed model from my RapMan 3.2 printer.

Nobody is trying to fool anybody.  An extrusion printer doesn't cost $400,000.  Neither does it perform like one.  But, it still does a very credible job at rendering what one creates.  And, frankly, I'm quite pleased with the result at .250 vertical resolution.  So, here are some images.

NOTE:  Any lint, etc. comes from the fact that this poor guy spent all day in my pocket.  :)

Click on any image to see larger versions... 

Peyton Duncan - Chow View #1:  .250mm

Peyton Duncan - Chow View #2:  .250mm

Peyton Duncan - Chow View #3:  .250mm

Peyton Duncan - Chow View #4:  .250mm

Peyton Duncan - Chow View #5:  .250mm

For these next two images, which only appear to be identical, I raised the F-Stop for each to try to get a bit more depth of field.  I think it helped.

Peyton Duncan - Chow View #6:  .250mm f16.0

Peyton Duncan - Chow View #7:  .250mm f18.0
As you can see, the RapMan, once properly set up, begins to crank out some very nice 3D prints!  And, that is even at the Mid-resolution.

Note for Peyton...  I KNOW that is a DIME in the image and not a quarter as you asked.  How in the world did you think I might have a quarter to my name left while I'm spending all my money having fun buying tools and materials for my RapMan???   LOL!

Note for everyone else...  Peyton is my nephew.  And, I have a LOT of respect for his work and for him personally.  Both Peyton and my artist daughter Cheryl continue to amaze me with their talent. Here is just a sample of Cheryl's beautiful sculpture that got me interested into digital photography and  3D printing in the first place.

Fleurette by Cheryl Meeks

I'm surrounded by geniuses and loving it!

Now... I gotta get out of here to see what awaits me at home... a mess or a Chow!!  :)

Monday, March 19, 2012

First Unattended Print!

I apologize for the images.  All I had was a point & shoot that does not seem to like to focus on white plastic objects.  :)

I'll take better images tomorrow.

The important thing about this post is not the quality of the photography; but, the fact that the roller bearing hubs WORKED!   This morning before leaving for work, I started printing Peyton Duncan's Chow figurine and when I came back this evening it had successfully printed.

This may not seem much to you.  But, it's a HUGE milestone for me.  It means I can print complex or larger objects and still get some sleep.

First, let's discuss the object being printed.  It's a beautiful image of a Chow dog.  It's by artist and photographer Peyton Duncan, and the STL file is uploaded on the Cubify site.  More of Peyton's art and photos are on RedBubble.  If you want a real treat visit his sites.  But, beware.  He's got quite a unique sense of humor!

I made the decision to print the Chow at the middle resolution for my RapMan, .250mm.  That made the run 5+ hours.  It's not that I didn't trust the new spool hubs to work.  It's just that... well... I couldn't be absolutely sure that they would work flawlessly for 5 hours.

Not to worry.  They worked like a charm... as did the RapMan's print engine.  When I came home this evening this is what greeted me.

Chow with Support

The Chow was finished and ready to be cleaned of the support material.  Interesting, Axon seemed to use a different strategy for the support materials that made it very easy to remove.  Here is the cleaned version.

The layers are clearly visible at this compromise resolution,  It will be interesting to compare this version with the one being printed at .125 resolution.

All-in-all, however, I am very pleased with both the process and the result.


I'm afraid that I will NOT be testing the finer resolution tonight.  For some reason, which I will have to test with something smaller, the RapMan is not printing correctly at the highest resolution.  It's probably an extruder pressure issue.  And, I don't have time to mess with it tonight.  We'll all have to wait for an update!   ARRRRRGGGGHHHH!  LOL!

Sunday, March 18, 2012

RapMan Reel Holder Using MOI 3D

Moment of Inspiration, or MOI 3D, is an absolutely wonderful application.  I installed it two days ago and was immediately able to design some things that will be not only useful to me; but, other RapMan and RepRap users as well.

One of the things that became immediately apparent when my RapMan was completed was that unless I baby sat the printer, the filament would not feed well.  As soon as enough filament had been used that more should be unreeled, the drag simply was too much for my extruder.  That may or may not be the fault of my extruder roller pressure.   But, if so, with my lack of experience, I couldn't trust I would set it right.

So, I determined that roller bearings would probably solve the problem.  And, it did!  I cab now leave the printer unattended for hours on end without a failure to feed.  That was a MAJOR breakthrough!

So, I want to show you how MOI 3D enabled me to go from having absolutely NO experience with the program to creating hubs permitting me to use bearings to support my RapMan filament reel,  My first hub probably took an hour to an hour and a half.  All the subsequent designs took well under an hour and most less than a half hour.  This is remarkable since (1) I am NOT an artist; (2) I am NOT an engineer or draftsperson and (3) I'd not even seen this program before installing it.

I not only created one roller bearing hub.  I refined the design a number of times with different goals in mind,  MOI 3D allowed me the freedom to do this in very easy fashion.  Here is my first design.

First MOI 3D project.  A filament reel hub with roller bearing
As you can see, this is a relatively simple design.  But, it has some features that might not be apparent.  One feature is that it accommodates two different 8mm Inside Diameter bearing sizes, 16mm and 22mm.  This nested design was easy using MOI's Boolean operations that make it easy to remove material.  The lofted shape was accomplished using MOI's scaling.

I then felt I wanted a lighter weight hub.

Attempt at lighter hub using MOI 3D

This design definitely created a lighter version of the hub.  And, it retained the design allowing for a choice be two different sized bearings.  But, it did not allow me to use the 8mm bolt that came with the RapMan reel holder kit.  The bolt wasn't long enough.  So, I used a 5/16" threaded rod to see how it worked.

It worked BEAUTIFULLY.  What a difference!  The bearing allows the filament to be played out with no intervention by me at all.

But, if a hub was to be useful to a wider audience, it should probably be designed to be used with the bolt the user already has.  So, back to the drawing board.

Hub designed to work with the original reel holder bolt

 This design accomplished several goals.  First, it was light.  Secondly, it was designed so that the 8mm x 7mm x 22mm bearing I found at a hobby store would mount flush to the top of the hub.  This meant dropping the ability to also use a 8mm x 5mm x 16mm bearing.  But, the flush mounting was critical to being able to be used with the 8mm x 120mm bolt used with the RapMan Reel Holder.

Here is the above design being used to print the final design.  Note, too, that MOI 3D allowed me to design a base for the filament reel holder that keeps it locked into place.

Test Hub in use with original bolt

While the above design worked beautifully, I still felt that I could lighten the hub even further.  So, I came up with one more design.

Final RapMan Filament Reel hub Design

As you can see, this final design is very, very light.  Yet, it has turned out to be as effective as all the other designs.  Here is an image of the final product.

Final RapMan Filament Hub Printed

While I am very grateful that I was able to come up with something that allows my RapMan to run for hour on end with attention, I am even MORE grateful to have found MOI 3D.

Here is the final version of the reel hub being used with the RapMan filament reel holder, including the original bolt.

Final RapMan Filament Reel hub Design in the Reel holder

I will be putting up all these designs onto various sites.  The last design will be uploaded to 3D Systems' Cubify site that is now in beta.

I'm loving this software and printer combination.  And, I look forward to the new Cube when it arrives.

Tuesday, March 6, 2012

Follow the Directions!

I have good news and bad news.  First, the bad news.

The Bad News.

My precariously built hot end has failed.  It has clogged.

The Good News

The good news is that the failure had nothing to do with the quality or reliability of the RapMan kit.  It was all me.  And, the reason why that is good news is that, hopefully, I can help other new builders avoid the mistakes that I have made.

Mistake #1 - Cutting the PTFE insulator too short.

The directions call for cutting a small slice off the end of the PTFE insulator.  The operative word here is SMALL.  I sliced off a tad bit too much and, from my research about clogging problems, this is DEFINITELY not a good thing.  It apparently allows melted plastic to rise up and cool, clogging the hot end assembly.

I am ordering a new pre-built hot end.  But, I am also ordering a non-built hot end kit so that I can demonstrate the RIGHT way to do it.  At least the RIGHT way is the plan.  LOL!

But, for now, make sure you cut just enough of the material to square the end, taking off as little as possible.  Put that squared off end into the PEEK insulator leaving you enough room to cut it again when you assemble the wooden MDF plate.

The directions were absolutely clear.  I wasn't!

Mistake #2 - Not paying attention to the material type before taking it from the box.

In taking out the material I've been using for the duck tests, I failed to pay attention to whether it was PLA or ABS.  I simply made the assumption that it was ABS.

That meant that I was selecting a test model that was built for ABS, which requires a hotter temperature than PLA.  This overheating also probably contributed to the results I'd been seeing and the ultimate clogging of the hot end.

The type is not printed on the reel.  It is only printed on the box in which it is shipped.

I usually toss boxes immediately.  But, fortunately, I had not tossed it yet.  So, I was able to correctly identify the correct material type.

I'm learning that a perfect build is all about paying attention!  Fortunately for me, Bits From Bytes makes a very high quality product, has anticipated people with my building skills and makes a pre-built hot end available on their store! :)

Monday, March 5, 2012

Bed Level Adjustment - Using the Test Duck

Once the build of the RapMan 3.2 is completed, it is time to try to optimize the print.  This generally involves two critical adjustments. 
  • Positioning the bed relative to the hot end (Distance)
  • Leveling the adjustable bed.
The most critical adjustment is the one that determines how high the hot end will be relative to the adjustable bed.  This is determined by the 70mm bolt attached to the extruder head.  It is better to start with the bolt fully extended.  Because if it is set too short, you will not only scrape the bed; but, you will melt it as well.  I'll go into this adjustment more fully when I can take some images of the extruder and bolt.

But, for now, I want to concentrate on the effect that an out of level bed will have on your prints.   We'll use the test duck that you can download from Bit From Bytes.

Here is my first attempt at printing the duck using the black filament that came with the kit.  I believe you should be able to see the images at full size by clicking on them.  Forgive the dust on the ducks.  They've been around a bit.  LOL!

Duck Test #1

The duck is printed facing to the left of the RapMan and it looked pretty good for a first print as I was watching it form.  But, when I removed the duck and took a look at the back side, it was apparent that I had a lot of work to do.  But, what was that work?  What made the back side bad and the front side good.

The first hint came as I looked inside the duck.  It's hard to photograph.  But, for each of the missing lines in the above image, there is a strand inside the duck that is unconnected.  The instinctive answer is to raise the back part of the adjustable bed, thinking that the gaps were caused by lack of adhesion.

Duck Test #2
So, using both bolts in the back of the adjustable bed, I raised the back one quarter turn on each bolt.  As you can see, it's better.  But, notice what happened to the raft.  It stuck to the table so firmly that I had to run out and buy a razor blade holder.  Even then I practically destroyed the duck in the process of removing it.


Starting again, and thinking if a little good, then more is better, I loosened the bolts in the back a bit more.  WHOOAAAA!  NOT good, as you can see from the third test.

Duck Test #3

This was NOT due to adjusting the entire bed lower.  It was due to raising the back of the bed too much.
Of course, this prompted me to come up with a better way to level the entire bed before going on to the next test.  I will talk about the method I came up with in another post.  But, for now, it is enough to say that I came much closer to getting the bed level on the next pass.

Duck Test #4

Now, we are getting somewhere.  We are very close to honing in on the right bolt tension to level the bed.  But, as you can see, the back side of the duck STILL has some issues that are not apparent on the front side of the duck.

So, I loosened the back bolts by 1/6 of a turn on both sides.

Duck Test #5
At this point, it loos like we are going in the wrong direction.  But, pushing onward, it seemed like a good idea to adjust just one bolt, since the roughest parts were at the head end.  So, the left bolt was loosened another 1/6 turn.  And, another print was tried.

Duck Test #6

The great thing about this test, is that it made it apparent that bringing the bed up in the back was probably NOT the right solution.  In fact, it seems to be making the problem worse.  So, just before I left home this morning, I took the bolts back to their original position and TIGHTENED the back bolts by 1/6 turn.

We'll see how that works.  But, it is clear that leveling the bed is not only tricky; but, vital if we want to have perfect 3D prints.  And, observing the results above, my thinking is that LOWERING the back part of the best might result in smoother layers after all.  We'll see.

But, there is another observation I'd like to make.  That is the fact that looking at the raft for each duck can tell us a lot.

The raft at the right was created with Duck Test #3.  The black tint comes from the fact that there was some residual black left in the extruder.  The important thing to note with Duck #3 is how WIDE the raft filaments are in comparison with the other rafts.  This is because the hot end was too close to the best for that run.  And, it made it VERY difficult to remove.  By, test 5 I'd realized that the 70mm bolt should be lowered more.  But, the filament is still a little fat.  Test #6, was much better, except for a fat section as the print started.  I'm not sure why that happened.  But, both #5 and #6 were much easier to remove than earlier test runs.  It seems to me that a dedicated post related to what a raft might be able to tell us is in order.

But, for now, the leveling quest is continuing.  Stay tuned for tonight's result!  I've really enjoyed this quest and I hope it is helpful to all those trying to set up a RepRap or RapMan 3D printer.

Refining the RapMan Print and Tool Find

I'm in the midst of refining the quality of the print from the RapMan 3.2.  I will have pictures shortly to show my progress.

I'm using the duck model, that is among the test models to download from Bits From Bytes and it seems to be a great test subject.  I'm consistently getting good results on the side of the duck toward the front of the RapMan and consistently NOT getting perfect results on the back side.  This seems to be a bed leveling issue.  And, I'm chasing that down.

The tolerances are incredibly close.  So, it doesn't take much of a turn on a bed adjustment bolt to send things in the wrong direction.

In the meantime, I found the perfect ball-head hex tools for your RapMan build from a U.S.A. company, located in Colorado called ToolsDelivered.

You'll need 3 different sizes of the BAHCO BALL-END HEX SCREWDRIVER

The three sizes are...
They work beautifully and are much easier to use than the normal hex wrench.

Sunday, March 4, 2012

RapMan 3.2: The Build Experience - Part 6

Now the fun REALLY begins... Calibrating and Fine Tuning the RapMan 3.2 Extreme 3D Printer.

I just finished building a RapMan 3.2 Extreme 3D Printer.  While this image was taken at the 3D Systems headquarters, it is the same model that I just finished building.

RapMan 3.2 Extreme
I first want to comment on the last portion of the build, beginning with the hot end and extrusion assembly.  Up to that point, I gave very high grades to Bits From Bytes on their build documentation.  But, at the most difficult and critical phase of the build it seemed to me that the writer just fizzled out.  That may be due to the fact that the 3.2 version was different than earlier versions.  And, it also may be that because the plastic used in the head assembly is clear that the images are almost impossible to convey the construction adequately.

Whatever the reason, I felt that the last 1/3 of the documentation could be improved considerably.

In particular, the long 70mm bolt that hangs from the extrusion head was not completely explained in a way to could have resolved some of my early issues with the hot end dragging along the bed, melting it.  This was compounded by the fact that the firmware for my machine did not actually use the Z-Offset setting from the control panel.  The Z-Offset setting, when working is the best way to fine-tune the relationship between the hot-end and the bed... once the bed is completely level relative to the X-Y assembly.

Once everything was assembled and adjusted as well as my old eyes, augmented by a magnifying glass, could get it, the print testing started in earnest, using the supplied duck model.

I have spotted some interesting things that I will go into more deeply once I have printed out several test models of the duck to see if I can get it to print evenly on all sides of the duck.  Right now, one side is printing better than the other and it could be bed tilt, belt tension or an as yet unidentified problem.  But, at least we can move on to using the RapMan.

I will say this.  The resolution is better than I expected on the "good" side of the duck.  Now to get ALL sides printing that well!  :)