Very Hungy Caterpillar Cookies

My first original success on my Thing-O-Matic!

And after a little baking (by my Girlie):

And a little bit of icing (also by my girlie):

You can grab him off thingiverse.com if you’re feeling Hungry!

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Thing-O-Matic Motor Woes

My TOM lives, well it did, now it’s dead. The extruder is playing funny buggers, it works, it doesn’t, now it only works for about 27 seconds (a very similar time to that of http://wiki.makerbot.com/the-great-motor-mystery).
My solution was first a lot of screaming, followed by some deduction.
Disconnect the motor, put my multimeter on the Extruder controller, it works perfectly, +12v, 0v, -12v no issues. Connect my extruder motor and it does nothing, and the outputs on the Extruder go dead too.
The resistance on the motor measured at 2.0 ohms, waay too low. Put the motor on a 9V battery, it works (slowly), then re-check the resistance, it’s a more normal 47 ohms.
Reassemble everything, start the extruder, soon enough it stops, again at the point where the resistance is down to 2.0 ohms. My guess was something inside the motor, so the next step was to knock the motor apart.

You’ll need the following to do it properl:

  • A Vice
  • Screwdrivers
  • A razor blade or scalpel
  • A very small file
  • Point nosed pilers

Stage 1: Disassemble the motor + gearbox.

Take the front off the gearbox, it’s only two small phillips head screws. Put them SAFE. :-)

Remove the front of the gearbox and put it safe too!

Now to remove the gear cluster. Try to pull ALL the gears out together, this will keep em in the correct order, if you mess it up don’t worry, I’ll show you how to re-order em. :-) Don’t lose the small brass spacer either! This is what my gear cluster looks like removed:

All 6 gears, and the little spacer.

You’ll see three small screws in the bottom of the gearbox, they are pretty tight, remove them all, and be careful that you don’t lose the little spring washers that live under each screw. Put the screws aside safe. The three screws (in the bottom of the gearbox):

Now you can remove the gearbox and the spacer (it will magnetise itself to the motor body, pull it off!

You’ve freed the motor form the gearbox, now it’s time to get that motor apart….

Stage 2: Disassemble the motor.

Use a phillips head screwdriver to take the two screws off the back of the motor, remove the plastic cover.

Now put the motor in a vice LIGHTLY. You only need to hold the motor, it is pretty fragile.

Use a small punch or a flat blade screwdriver to punch one of the four tabs outwards (do this only towards the front or back of the vice, so the motor doesn’t twist in the vice). Rotate the motor 90 degrees, repeat 4 times.

Once all four tabs are punched you’ll be able to use a screwdriver to gently pry the back from the motor. If it resists you too much, perhaps you need to do some better punching!

Once the cover is pryed off, put it safe, it has the two brushes in it (we shall talk to it later!).

To get the core out of the motor you will need to punch the gear off the end of the shaft. To do this use a piece of stiff wire, or a small nail, it just needs to be smaller than the motor shaft.

Put the gear safe!

You can now simply pull the core out of the motor, the only thing holding it in there are the magnets.

Stage 3: Clean + Modify the Commutator + Brushes

Cleaning the accumulation from the commutator pickups. Pull the 3 washers off the back of the motor core, one of mine stayed on, but you MUST get the large one off (it is the second washer in the stack) if there are only two washers, it means one is hiding in the motor backing don’t lose it.

Now clean out the gap with a scalpel or razor blade:

Just scrape each of the three gaps a few times, you may be able to see the junk that you scrape out. Be careful not to slip out of the gaps and scratch the pickup surfaces!

If you can get hold of a small square or triangular file, you can do waht I did, use the edge of the file in each of the gaps, jsut to smoothen the edges that the brushes will have to jump:

Now the commutator is fixed (you can check teh resistance between each pickup surface if you like, it should be around 30+ ohms).

Fixing the brushes. This is VERY important, I didn’t the first time, and only got 1 hour printing before I had to come back to this point and fix the brushes.

Basically the brushes are a dumb shape. The only contact of the brushes with the commutator are through the 2 teeth on each pickup. These are wearing down fast, and depositing all their pieces into the commutator gaps. Grab your file!

This image shows what the pickups look like on the left, and what mine now look like on the right:

Using a pair of point nosed pilers grab each brush arm as close to the brush as possible, then gently (the brushes are soft) file the two teeth off the brush:

I also filed the two edges that meet the commutator joints with a slight bevel, it works for me, so I’d suggest you do the same! Your brushes should end up pretty flat like this (I know it’s hard to see):

Once both brushes are done, you’ve finished fixing the issue. It’s time to put things back together!…

Stage 4: Reassemble the motor.

Put the backing onto the motor core, being careful to align the bushes onto the commutator properly. Insert the core + backing of the motor into the magnetic case together, making sure the bushes stay where they belong (the rear only fits on one way). Once you have the backing back in place, put the motor back into the vice and punch the tabs in to hold the backing down properly.

Now you need to punch the small drive gear back on, get a small piece of plastic tube, or a small nut, something that fits over the motor shaft. Gently punch it down till the gear hits home:

Screw the white backing onto the motor, and if you’re unsure of your work, test the motor on 9 or 12v.

Stage 5: Reassemble the gearbox

Place the spacer back onto the motor:

Then put the gearbox back on, and screw it down with the three tiny screws (don’t forget the spring washers).

Now the first three gears are all the same (they have 14.36 written on the back). Put the first one on the lefthand shaft:

The second gear goes on the right shaft (another 14.36):

The third gear goes on the left shaft, again it is a 14.36. (I forgot to take a photo)

The fourth gear is a different one, it goes on the right shaft, and is the closest gear in this photo:

Note that this gear has both small and large teeth. The small teeth are on the bottom and will mesh wit hthe last 14.36 gear, the large teeth are on the top and will mesh with the next gear. With gear 4 installed the box will look like this:

Gear number 5 is the shorter of the remaining two (the closest in the photo):

In place it looks like this:

Gear 6 is the only one left, insert it onto the top of the right stack:

Now put the small spacer onto the top of the left stack:

Put the top back on your gearbox, and screw it down with the two screws:

Now put your motor back into your makerbot. :-)

Stage 6: Burn some Plastic! I’m up to one hour of building so far. Had some intermittent stopping of my extruder, so I removed my relay board and it has been perfect since. Good luck my fellow botters!

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Importing a Thing-O-Matic into Australia

Oh the fun!
Wait till the Aussie dollar is really good, then buy a Thing-O-Matic, how easy! Wrong :-S
As the value of the bot is >$1000AU (based on the exchange rate as the item enters Australia) it has to go through customs and thus I had to pay the duties and taxes, as well as a processing fee ($48.85)!

This whole process cost me $186.68 and a lot of time. Now this will make life easier for anyone else wishing to import a makerbot:

#1 Buy your Thing-O-Matic
#2 Complete a B374
#3 Complete the Payment Advice form (and thus pay the man)
#4 Wait for your delivery

#1 buy the bot, (don’t buy extras, they will cost +10% in this package, and complicate the B374 form).
It will ship, get stuck in customs, and Aus Post will send you a letter. It informs you to either submit a B374 (N10) form, or pay a broker to do the work for you.

#2 Complete a B374
Download the form!
http://www.customs.gov.au/webdata/resources/files/B374-Importdeclaration-good_N10-July10FinalTypeableversion.pdf
It’s butt-ugly, but don’t scream too loudly, fill it out on your computer, then you can just email it in to customs.
Section 1: Name Address, Phone, Email (Email is important, it’ll make things much faster)
Ignore the Client Identity, you don’t have one.
Section 2: Sender Details
Last Name (or Organaisation): Makerbot Industries
Phone: 718-522-4803
Address: 87 3rd Ave, Brooklyn NY 11217
Now move on to Section 3:
Mail Reference (It’s on the aus post letter, next to the bar code)
Number of parcel(s) 1
Weight of parcel(s): “not known” You MUST put that exact line in the box, type “not known” into it!
Country of Origin: America (United States of)
Date of export or invoice: You don’t have the exact export date, so put the invoice date in like so: 20/12/2010 (Invoice)

Description of goods. This is the mission-critical part, what is a makerbot? I read a lot of the import tariff guide to find this info:
http://www.customs.gov.au/site/page5663.asp
It exists under:
Section 16 – Machinery and mechanical appliances; electrical equipment; parts thereof; sound recorders and reproducers, television image and sound recorders and reproducers, and parts and accessories of such articles..
From that the bot is located in:
Goods – 8443.9 to 8466.94.00
http://www.customs.gov.au/webdata/resources/files/chapter84goods_e.pdf
The code for the bot is:
8443 9190 69 Which translates to Printers -Other – Parts.
Description of the goods: Thing-O-Matic Kit (3D Printer Parts Kit)
Tariff classification of the goods: 84439190
Stat code: 69
Quantity: 1
Value of goods: 1225
Value of postage and insurance:
Tick the US box and put the postage in: $139.85 for me. :-S
Total Value of goods: Tick the US box, put 1225 in.
Section 4:
Put your name and date into the boxes, you don’t need to get a signature into the pdf if you are emailing it in.

On the next page there is a spot for additional information, this is what I put in there:

The entire content of this package is 1 parts kit to assemble a Thing-O-Matic 3D printer. It was listed as a printer + printer electronics on the Australia Post Article Details: as can be seen by the attached invoice, I purchased the entire package as a single kit of parts.
Seller web site is: http://makerbot.com/
Item on web site: http://store.makerbot.com/makerbot-thing-o-matic.html

That completes the B374 form, now to email it in:

Attach a pdf of the invoice from Makerbot, and a print out of your bank statement showing the value you paid to makerbot. I did this and it sufficed as the ‘proof of value’ customs require.
You MUST have an identity block at the bottom of your email, make sure it’s got your name, address, phone, etc.

Stuff it all together in a polite email and send it off to customs in your state:
http://www.customs.gov.au/site/postClearingGoods.asp#Whatisthetariffclassificationofmygoods
Check your Reference number from aus post, the first letter is the important character:
N – [email protected] or
V – [email protected] or
Q – [email protected] or
W – [email protected]
Mine was V, so I emailed Victoria.

Then wait….. Mine took 2 working days.

#3 Complete the Payment Advice form
I got a reply via email containing a document called Payment advice v2.doc
Don’t try to edit this document on your PC, print it off, fill it out, then scan it back in. It’s a long way around, but it works!

You will need to attach a copy of something with your signature on it. (I think this is because they don’t expect you to print it off sign it, and scan it), but regardless the form says provide an ID with your signature as well, so I did. Scanned the front of my drivers licence, and attached the .jpg to the email. Use the reply button, so the reference numbers all stay in the email subject and body.

Send it off and hopefully you’re done! It took less than 12 hours before Customs hit my credit card (seems they are eager to process deposits :-) ).

#4 Wait for your delivery
I’d suggest a cool beer, whilst you collect all the tools you’ll need to birth your bot into the world.

How customs calculate your duty:

The exchange rate….. Customs valued the makerbot on the day it landed in Australia. For me that was the 30th Janurary, 2011. The exchange rates used by Customs are found here:
http://www.customs.gov.au/site/page4277.asp

They take the total value (Item + Postage, I know the postage bit is weird) and use the exchange rate of the day to convert it to AU dollars, then charge you 10% of that. Throw in a $48.85 processing fee and you’ve got your total.
Note: Other items may also be taxed an import duty, the classification of makerbots is duty-free so there are no extra hidden costs. These tariffs are usually around 5% of the ‘value’ as per above.

Happy Importing!

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Makerbot Resistor Woes – My solution (In progress)

Given the issues with the poor resistors on the thing-o-matic extruder head, I’ve been working on my solution, I’ve not had the issue yet, as my makerbot is still stuck in customs.
My solution goes back to winding your own nichrome heater elements, and will involve setting these elements inside of the original power resistor bodies.
Nichrome wire – easy
Spare resistor shells – easy
Ceramic material to seal / suspend the heater……..
This took a long while to find at a reasonable price…….
Enter Fireplace cement. It’s rated well beyond what the extruder requires, so my next stop is to get some, check the electrical conductance, and to start winding my heaters. I was going to purchase this locally, and get testing, but it was around $30 per 850grams. Online it sells for a fraction of that, about $15 per 500 grams, so I’ll wait for the post and enjoy a coffee from my savings.
Stay tuned for the results (about 1 week I hope )

Well it has taken a lot longer than 1 week, but I’ve got the Fire Cement and have started my experiments to fit 15cm of NiChrome wire into the space of 1 hollow 10w power resistor. Current attempts involve winding the NiChrome around an M4 bolt and trying to set the cement to the NiChrome, Not the bolt. Success will be guaged when it has all set.

A standard M4 bolt did the trick…. The second time.

Turns out the ceramic epoxy bonds really well to the bolt.

Some Petrolium Jelly fixed the bonding issue, and allowed me to create a small hollow, well spaced heater coil. I’ll be plugging it, mounting it in the resistor shell, and silver-soldering the wires next.

Stay tuned….

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So it begins….

1 hour wrangling with mySql, and now I’ve forgotten what I was going to post. :-(

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