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Buildlog Title: The Chimera Project - Laser + 3D Printing

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Builder: bdring
Member Since: 2009-11-22

Tuesday, September 14th 2010 - 2:46 AM

I decided to try a nice long run to see how well the extruder is working. I saw a lot of these bottle openers at the Maker Faire.

This took about 45 minutes to run. The extruder ran flawlessly. My laser etched bed held it down firmly as you can see by the nice raft. I forgot to insert the penny before the picture was taken, but trust me, I am enjoying a beer right now.
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reader comment Comment from: lasersafe1 on Sunday, September 12th 2010 - 12:30 AM
Perhaps you could build a table using the toe pads from 1000 Gecko lizards. That'll hold.

Saturday, September 11th 2010 - 9:18 PM

I have a really cheesy bed that I am doing my printing on and the parts don't stick real well. It is basically a scrap of Acrylic that I scuffed up a little. Just for fun I decided to run a cross hatch with the laser. I ran it about 0.50 in out of focus to get a wider sloppier line. I missed selecting 2 lines in the CAM program so there a couple gaps, but it should not matter. Eventually I will get a heated bed, so this is just temporary. I am going to use some magnets to hold the piece in place.

It was fun not having to even remove the part to go to laser mode.
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bed1.JPG

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reader comment Comment from: benwyne on Wednesday, September 8th 2010 - 9:49 PM
Great work Bart!!! I'm really pleased that progress is being made. It's a shame about your bowden approach, I was aiming to use a big'ol NEMA23 plus makerbot mk5 pulley. Are you thinking of using a bigger stepper aswell?

My mendel build is coming along well so I'm also looking at 3D printable laser cutter with great interest.

-B

Tuesday, September 7th 2010 - 10:17 PM

My first real object.

Is there a "Hello World" object that people print? That sounded like a lot of time, so I just printed a B. I need a real printing surface. This started to move after a while so I held it in place for 10 minutes.
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Still on it's raft

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Tuesday, September 7th 2010 - 1:08 PM

Extruder is mounted on the carriage. I just duct taped the 3D printer carriage and laser carriage together for the X motion. It worked fine.

The motor has never stalled or even slowed down with either method. It just slips on the ABS. I am using the MK5 drive wheel. I tweaked the design of the idler wheel and the split Acrylic pieces right around the wheel and that seamed to help. I also ran the temp up to about 240C. It is not a very robust design. It would be nice if it just worked...no adjustments needed.

I might upgrade to the whole MK5 system soon. I hate to pay for a whole system, because I have a lot of the parts already. I asked on Thingiverse about the material thickness, but no responses yet. I would like to hold out for the stepper motor too. The Bowden cable needs a high speed feed method.

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reader comment Comment from: rEd86 on Tuesday, September 7th 2010 - 12:44 PM
So did you get it working with the motor mount on the carriage or with the bowden cable system?

What type of motor are you using for the extruder? If it's the one that comes with the Makerbot, I wonder if it has enough torque to work with bowden cable system.

--Ed

Tuesday, September 7th 2010 - 12:28 PM

I finally got my extruder working enough to print a few test prints. I need to make a decent bed to print on. I am just printing on a piece of Acrylic now. I am going to laser a cross hatch pattern into it to give it something to bite into. A heated bed would help too.

I had some trouble with the Z axis misbehaving. It would not move consistently. It appeared to be missing steps. I currently have very high steps/mm. I lowered the max speed and it does a lot better.

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Friday, September 3rd 2010 - 2:37 AM

I can't get the Bowden cable system to push enough to get decent flow. Here is my setup. The cable is a smooth fit with just enough clearance, but it still adds a couple pounds of force. Note my little tensioner screws the push on the pinch wheel. That allowed me to fine tune the pressure, but still not enough. I was all a temporary setup of course.
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bowden_setup.JPG


So I decided I need to crawl before I try to run, so I made a smallish mount for the motor right on the carriage. I will give it a try tomorrow.
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local_motor.JPG

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Wednesday, September 1st 2010 - 2:47 PM

Back off the idler for quick feed...yes probably. That is a good idea.

I am not sure I meant the "compression" is totally in the filament. If the filament were incompressible the PTFE jacket might start to stretch to store some "pressure". There might also be some energy stored in the geometry of the loop. A classic Bowden cable is the hand brake on a bike. When you pull hard the jacket moves and and returns. That move back is a release of some energy. There is no visible effect like this, but it would happen slowly on my setup.

Videos: I would like to see just a free feed of material into the air so I get a feel for that. Then a print speed with that setting. I am working with a totally new machines.xml that is probably screwed up too.

I wish I had taken some pictures and videos. I just ran out of time last night. I'll post something soon.

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reader comment Comment from: rEd86 on Wednesday, September 1st 2010 - 2:06 PM
Can you back off your idler wheel enough so that you can feed the 30" of ABS into the cable quickly? That will be a must for when you're changing plastics - both for loading it and backing it out. (with several colors available for printing, your creative side will want to express itself)

Even though there is compression in the filament, I would think that backing it out would act the same way - you've just got more pressure in the cable as well as at the nozzle. Keep in mind there is some squirting on a Makerbot as well when you stop the motor. I can record/post some video for you so you get a baseline if you want. The three factors that effect how much ooze are the temperature of the nozzle, the size of the nozzle hole used, and the speed of the extruding motor. (how much pressure has built in the nozzle)

This is going to require a lot of trial and error since there isn't any good documentation (to my knowledge) about bowden cable use with extruding. A lot of tweaking on the extrusion speeds and the motor speeds and various times. (straight lines verses tight curves, etc) There are a lot of settings in Skeinforge that the community has tweaked for the Makerbot over time. I don't know if you've found this reference yet but it may be helpful:

http://wiki.makerbot.com/configuring-skeinforge

Good luck!

--Ed

Wednesday, September 1st 2010 - 1:04 PM

I got the whole thing assembled and installed last night. The extruded heater and thermistor behaved perfectly getting up to temp rather quickly and holding there with a nice flat line. I fed some ABS into my motor and it started pushing it through the long 30" PTFE tube. It took about 5 minutes.

The head started squirting plastic, but the motor was slipping a lot and I did not feel I was getting much material out. I made a quick set of set screws to add a micro adjust method of pushing the idler wheel. That helped a lot and while I was not real happy with the plastic volume coming out, I decided to give a print a try. The sequence of everything looked good, but the head was moving way faster than the plastic was coming out. I ran out of time and stopped there. I need to figure out how to adjust for all that.

The Bowden cable appears to add some extra resistance to the motor. The bowden cable stores a lot of compression in the filament, so it continues to squirt a lot after stopping. I might see if I can add some extra reverse time to the stop sequence to relieve this. I have no real feel for what is right and what is not. I need to do some research and watch some videos.

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Tuesday, August 31st 2010 - 2:10 AM

So I debugged the cable problem pretty easily. I was then able to control the motion via the ReplicatorG control panel. +/- was right on all axes. I know you can easily change it, but how lucky is that.

I am new to RepRap, so I played around with it a little to get familiar with it. The speeds and resolution were all wrong so I needed to create a new driver for my machine. You do this by modifying machines.xml. It took me a while to figure out the one in the program directory is not the one you change on Rev 0018. It is in C:\Documents and Settings\bdring\.replicatorg. I copied the basic CupCake machine and only adjusted the axis parameters. See my settings below.

Code: Select all
<machine>
      <name>Buildlog.Net G540 Laser</name>
      <geometry type="cartesian">
         <!-- different pulleys on X and Y axii -->
         <axis id="x" length="300" maxfeedrate="1800" scale="49.2126"/>
         <axis id="y" length="300" maxfeedrate="1800" scale="49.2126"/>
         <axis id="z" length="300" maxfeedrate="500" scale="5669.2913"/>
      </geometry>
      <tools>
         <tool name="Pinch Wheel Extruder v1.1" type="extruder" material="abs" motor="true" floodcoolant="false" mistcoolant="false" fan="true" valve="false" collet="false" heater="true"/>
      </tools>
      <clamps></clamps>
      <driver name="sanguino3g">
         <!-- optional, defaults to first serial port found.    <portname>COM1</portname> -->
         <!-- required: we need 8 bit and 38400 baud. -->
         <rate>38400</rate>
         <parity>8</parity>
         <!-- optional, defaults to 1.                          <databits>1</databits> -->
         <!-- optional, defaults to N.                          <stopbits>N</stopbits> -->
         <debuglevel>0</debuglevel>
      </driver>
      <warmup>
      </warmup>
      <cooldown>
(Turn off steppers after a build.)
M18
      </cooldown>
<machine>


rep_driver.jpg


Since my extruder is not setup, I did not try to run a real STL file. I did create G-Code for one so I could study it. I made a simple "draw a box" program and it worked. There is no acceleration parameter, so you need to keep the speeds pretty low to avoid jerking.

I then wanted to have some fun so I wrote a very basic post processor for Vectric Aspire. I drew a quick Hello World and generated a g-code file from it.
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hw_aspire.jpg

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I imported it into ReplicatorG and gave it a whirl. It is drawing HELLO WORLD. It would actually do it with the laser, but the speed is a little low and it would not turn of the laser between strokes because the laser enable is not hooked up to a RepRap.
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Next step is setup up the extruder and mounting the printer head on the track.

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reader comment Comment from: rEd86 on Monday, August 30th 2010 - 10:48 PM
Wow, that must have been fun to debug. Glad to hear you figured it out. We look forward to seeing things in action!

--Ed

Monday, August 30th 2010 - 10:45 PM

It works! Stupid "parallel port" cable didn't have a pin 25. Some 25 pin cables are actually serial port cables. Video coming soon!

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Monday, August 30th 2010 - 1:28 AM

I temporarily mount all the reprap parts on a piece of MDF. This will keep them from moving around while I test. I used my Sparkfun "Premium Jumper Wires" to attach them to a 25Pin breakout board.

I got a nice 600W ATX power supply on sale at Fry's.

reprap_setup1.JPG


reprap_g540.JPG


Unfortunately the RepRap motherboard is not moving the motors yet. I get what appears to be good Step and Direction signals to the G540 when viewed on my scope, but no movement yet. Does anybody have any ideas? I am not worried about things like steps/mm yet, I just want to see some movement.

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Sunday, August 29th 2010 - 3:10 AM

I have the extruder motor section complete. I mounted it on the inside wall on a short piece of extrusion. I think I am going to move it to the outside. I don't think there is a good way to spool the plastic here. If I mount it to the outside I can build a little reel there too. There will be less to reconfigure when switching to laser mode.
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motor1.JPG

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Friday, August 27th 2010 - 8:12 PM

52365K614 3ft for $3.23. I have not tested it yet.

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reader comment Comment from: benwyne on Friday, August 27th 2010 - 8:09 PM
Hi Bart,

Interesting approach! I'm currently building a mendel aswell as your laser cutter and would like to use a bowden cable approach. What's the mcmaster carr part number for the PTFE tubing you're using?

-B

Wednesday, August 25th 2010 - 2:59 AM

I cut my extruder motor parts cut tonight. I am not using the 'dino' parts. I will determine a mounting location and method after I get this assembled.
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extruder_motor_parts.JPG

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Tuesday, August 24th 2010 - 1:33 AM

I think I am going to go the easy route and make a very simple MaketBot adapter PCB. This will allow either a parallel port or a MakerBot motherboard to control the steppers. I guess you could even hook this up so a parallel port controlled standard MakerBot stepper drivers. I choose the most common stepper board parallel port pinout.

I should be able to get about 25 of these for around $100 from Gold Phoenix.
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maker_adapter.JPG
Maker/Laser Adapter

makerAdapter.jpg

MakerLaser.pdf
Schematic
(24.43 KiB) Downloaded 713 times

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reader comment Comment from: rEd86 on Friday, August 20th 2010 - 3:17 PM
Not only are you an endorser but you're living it daily with the things you are contributing here! :)

I am excited to see what everyone is doing in this space - it will be fun to meet many of the pioneers at the summit. I am particularly interested in efforts being made to easily identify sources for parts to various projects. I have heard of efforts from DigiKey, McMaster-Carr and others to where you can click on a "parts list" on a DIY site and get directed to their site with all the items already in your shopping cart. Standardizing on this and making it easy to source parts is the next step in the movement.

--Ed
comment Buildlog Author Comment: bdring on Friday, August 20th 2010 - 1:20 PM
Comment From Buildlog Author

No, I would love to attend both the Open Source Hardware symposium and Maker Faire, but can't swing it. I was an early endorser though.

http://www.buildlog.net/blog/2010/07/op ... re-summit/
http://www.wired.com/beyond_the_beyond/ ... -hardware/
reader comment Comment from: rEd86 on Friday, August 20th 2010 - 12:59 PM
Excellent! This is why I am building my own laser - rapid prototyping. You've been able to go from concept to an actual part in a matter of days.

Thanks for sharing what you have done so far.

BTW: are you planning on going to the Open Source Hardware symposium in NYC next month? It is the Thursday before Maker Faire. I am trying to arrange my schedule to make it to both. There is a big movement with sharing designs and with equipment like this, people will be able to design and construct kits that were not possible before. Desktop manufacturing is here!

--Ed
reader comment Comment from: thechoochman528 on Friday, August 20th 2010 - 4:11 AM
I hope that threading the insulator retainer plate resolves the issue of insulator blowout and or leaks.

I blew two PTFE barrels on mine before switching to the makergear hybrid peek/ptfe barrel.

Friday, August 20th 2010 - 3:39 AM

I cut the parts and test loosely assembled the extruder. This uses a stock MakerBot nozzle, barrel and insulator. The rest is custom. I threaded the lower metal plate. I thought this might reduce stress on the insulator. The tubing threads into a 1/4-20 coupling nut.
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head1.JPG

head2.JPG

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Wednesday, August 18th 2010 - 9:06 PM

slide into and lock in place
...yes i was thinking along the same lines. This uses some thumb screws to lock it in place.
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bowden_head3.JPG

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reader comment Comment from: rEd86 on Wednesday, August 18th 2010 - 6:11 PM
Great job! Another source that has done a lot with extruder head design is:

http://www.makergear.com/

They are in the Midwest (Cleveland Ohio I think) and have been a pleasure to work with. Rick has really improved on the MakerBot process and has a new compact head pictured here:

http://www.makergear.com/blogs/frontpag ... sneak-peek

I think they would be a great solution for our final version. I see a u-slot that this would slide into and lock in place... I can reach out to Rick to see what his thoughts are and if he would be interested in getting involved. We've ordered a lot of products from him for our MakerBot at the HIVE13 space.

--Ed

Wednesday, August 18th 2010 - 5:59 PM

I got the tubing from McMaster already. McMaster is amazing. I ordered it at about 1:30pm yesterday and it was delivered the same day! i am about 15 miles from the warehouse.

I thought a great way to attach this would be to thread the tubing into each end. It did an experiment on both the HDPE and PTFE, which are both 1/8" ID 1/4" O.D. I think it turned out great. That is a 1/4-20 thread.
The trick is holding onto the slippery tubing. I used a 1/4" lathe collet. I put a 1/8" brass rod inside first to keep it straight and keep it from collapsing. The thread hold strong (about 40lb pull) on a standard thickness nut. The thread is very slippery so it will easily loosen. I think I might use a long coupling nut to get more thread engagement.

This is the PTFE tubing. It has a tighter ID and is more slippery, so that will be my first test.
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threaded_tubing1.JPG

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Wednesday, August 18th 2010 - 3:05 AM

I decided to run with the suggestion rEd86 proposed. This moves the motor away from the moving head and feeds the material Bowden Cable style. This significantly reduces the size of moving head. I show it next to the laser lens carriage, but it could simply quick mount to the carriage.

I decided to go with mostly stock MaketBot parts to start with. I am sure many people can suggest improvements, but I need to get something going so I can get up to speed on how these things work.

I ordered the parts from Makerbot and have some tubing coming from McMaster. i will try both HDPE and PTFE. I want to get a feel for the flexibility and the friction.
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bowden_head1.JPG

bowden_head2.JPG

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reader comment Comment from: rEd86 on Monday, August 16th 2010 - 7:03 PM
I wasn't thinking about removing the entire laser carriage but just having a spot to mount the extruder when necessary. If the carriage is a little longer and has another hole just like where the mirror/lens is mounted, with a couple of threaded screws to lock the extruder on is all that's needed. (the same hole can be used to mount a flex-shaft for a small dremel like router) I see the cabinet being closed when using the laser cutter but open when extruding (so there's room above for the ABS feed line) and using other heads.

Yes, the extruder is definitely the weakest link. This can be due to several reasons:

1) The heating element is usually hand-wrapped nichrome to keep it at the right temperature, monitored with a thermistor. Over time these elements can start to come apart and effect how exact the temperature of the nozzle is.
2) With the Makerbot, a standard motor is used to feed the ABS. You can't vary the feed rate depending on the tightness of the curve, which you really need. The RepRap Mendel uses a stepper motor to improve upon this.
3) Many variations of the extruder have been developed over time, since the PTFE thermal barrier on a Makerbot wears down over time and does not handle pressure and heat well, gaps form where plastic oozes out. You need a hot tip area to melt the plastic but a cooler barrel further up to dissipate the heat from the rest of the head.
4) The original extruder designs also didn't allow for easy changing of plastics. (whether color or types) Newer designs allow for quick release mechanisms to improve this.

The other issue when printing larger items with ABS is the fact that the plastic will warp if it cools down too quickly. (the edges will start to curl up) Many use a heated platform to reduce/eliminate the warping. Others have tried a heated chamber to allow for slower cooling.

I haven't had much of a problem with having a geared wheel with an idler wheel, but we have also rebuilt/upgraded our extruder head a couple of times so maybe that's why. We are looking for a quick-connect option, although I don't know what one of the other guys at our hacker space is considering.

Later!

--Ed

Monday, August 16th 2010 - 5:43 PM

I was actually considering that. I am having trouble finding a quick (and easy) release system for the print head.

Right now the belt is not in an ideal spot for adding another carriage as needed. The best I have come up with is a quick way to loosen the belt while the other carriage is put on.

It sounds like the extruder system is the weak link in these systems. What typically goes wrong? Is it the feeder slipping? Does the melted material ever start squirting up backwards?

Has any one ever tried two, geared together feed rollers instead of a feed roller and an idler?
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geared_roller.JPG
geared_roller2.JPG

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reader comment Comment from: rEd86 on Monday, August 16th 2010 - 3:49 PM
Bart,

Before getting too far with this extruder design, you should look at what they've done here:

http://www.ultimaker.com/

By removing the extruder motor from the moving head, you eliminate a lot of vibration, which effected the precision of the print. I think it's a much better design and is something we should consider. It also makes it easier to change "heads" since most of the extruder hardware can be permanently mounted in the case area on the left by the other electronics. The extruder itself would be a "quick connect" item that just snaps on the gantry. When not used it would just be coiled and stored in the enclosure on the left. (at least that's how I imagined it working)

Thoughts?

--Ed

Sunday, August 15th 2010 - 2:36 PM

I cut the parts for one z carriage. There a few things I might change, but it should work for testing. The extrusion parts are on order and should be here mid next week. I want to get some Weld-On 3 Acrylic Cement to permanently fuse these parts together. I am not sure if I want to use 3 or 4 v groove wheels, so I allowed for both options and made it symmetrical.
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I also started modeling the MakerBot Plastruder. Their design purposely elevates the extruder head. I actually need to get it lower because the Z surface is lower on my design. I am going to order a unit from them soon.
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plastruder_model1.JPG

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Saturday, August 14th 2010 - 4:04 PM

Chimera: An Animal descended from two genetically different animals.

After seeing all the quality 3D printed parts at Maker Faire I really wanted to build my own printer. While I was trying to justify the $600-$900 it would probably cost, I realized that my laser could probably be converted to a dual purpose machine. It already had all the motion control needed. That would save a lot of time and money. Also all the others building my laser could benefit.

z_rail1.JPG

z_carriage.JPG


Currently the Z Axis is not ideal for a printer because it is not constrained from XY motion while moving. It wiggles a bit when moving. I decided to add another v wheel track for the Z. I have also heard that some people are having a little wiggling when engraving at high speed. This should help.

z_rail_extr.JPG


I am using the widest Misumi 25mm extrusion available 80mm. I think that should work. I do not know if I need this on both ends, but I have material on order for two. I decided to try the smaller v-rail this time. I don’t know why I went with the next size up for the laser. I think I had some already. I got the material and it should work fine. This rail could save about $50 on a build.

rail_dims.JPG

sm_vrail.JPG

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