LaserCut Mendel by Tech Zone Remix

I did not have too much trouble with the assembly. Fine adjustment was difficult. There was not enough bottom clearance for the belts and I jacked the whole RepRap up on scrap wood parts from my try at a wooden Mendel. The Y-axis 360-bearing was missing one popsicle stick, plasmator is right. I have always saved lots of those for throw away single use epoxy mixer/spreaders and just step drilled one replacement and glued it in place. It does not look like it will hold up under sustained use, but if it holds for long enough to print the parts I needed. . . it is the right size for 1:1 replacement in RepRap'd parts. It is a good bootstrap device.

My problems are with the ReplicatorG and Skeinforge software. ReplicatorG throws errors on the resultant code right from the start. Nothing that I've run through the software tool chain has worked for me without hand editing of the the filename_export.gcode file with Find/Replace. Skeinforge drops in useless temperature settings. 192 C will not do for ABS, in fact it will break the MakerBot Plastruder. Skeinforge outputs code to turn off the extruder and then does not turn it back on (M103 and no M101). Printing on 3M #2090 is pretty useless for me. anything bigger that nophead's grub screw gear warps before it is half way done and the print has to be aborted. My best attempt thus far hit a hardened high spot about 6 layers from the top and knocked the part off the bed, frustrating. I have yet to have a successful print, none of that has to do with TechZone at all. I just need to build a heated bed and I avidly read Adrian Bowyer's and nophead's posts and blogs. Google Alerts serve me well for that.

There are also some weird moves that occur at random. I attribute them to lack of shielding. Because of the lack of clearance underneath I threw all of the MakerBot Electronics up top which cost me Z-axis travel and probably is causing the interference. Tinfoil hats for the wires soon to come. I need to slow to a crawl (which has happened anyway) and using some facsimile of the scientific method, changing only one parameter at a time.

caveat emptor, as plasmator said, but you get what you pay for and I am satisfied with the price/performance ratio of the TechZone parts. A full and detailed set of instructions would have been nice; but I managed to put is together from one photo. I had been reading the RepRap wiki for months prior to my order and spent a lifetime working in wood having started out as an apprentice foreign car mechanic/ parts washer in 1965.

I posted a set of photos of my assembly here: [reprap.org] Scroll to the bottom for the beginning.

I've not been following threads on the forum as I should have been as I have been trying to catch up on our orders. Most of the responses we have received so far to the Laser Cut Mendel have positive and we appreciate everyone who has helped us. I know we are not perfect and we appreciate the feedback we have gotten from everyone so far, good and bad. With the electronics we did have some soldering issues in the past and those were addressed as soon as we became aware of them. All of our electronics are now tested 4 ways before shipping, including on a working Mendel to make sure it works as expected.
The design of the axis pieces is to be light but apply firm pressure against the smooth rod through the bearings. We want the axis pieces to glide, not grip. They are made from 3-ply plywood which is much stronger than a Popsicle stick, though I suppose someone could try one in a pinch(a little sticky though).None of the four assembled laser cut Mendel we have required epoxy to make them durable, but that is one of the benefits of an open source system, anyone can make their own changes to suit their needs or desires.

If you have had a bad experience with us, please let us know. We want to have a good reputation and that is built by happy customers. We will do what we can to make it right. If you have concerns about the laser cut replacement for printed parts, also let us know. We are open to suggestions and design changes(as some of you know).

I bought my kit while I was at MakerFaire (post-processed). As soon as I got back from the fair and got to my room, I jumped online and ordered a set. The parts are very high-quality (obviously; they're lasercut), but did require a little sanding/reaming to get everything in working order. I was missing a few pieces from my kit (one frame bracket was fubar, and the y-axis was nowhere to be found) but I e-mailed Lambert and the replacements are on their way. A word to the wise: If you buy a Mendel hardware kit from Ultimachine, invest in a good ruler or micrometer that reads up to 300mm. Jigging is a pain if you don't have a good measurement device. Also, when gluing the pulleys, BE CAREFUL! I used Gorilla Glue, and it expands. A lot. I spent ~2 hours scraping glue off of pulleys.

-Adam

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"Day breaks, but decay soon follows."

Quote
ziplock
A word to the wise: If you buy a Mendel hardware kit from Ultimachine, invest in a good ruler or micrometer that reads up to 300mm. Jigging is a pain if you don't have a good measurement device.

Discussions about Ultimachine Mendel hardware kits should probably be in their own thread, to avoid things getting muddled.

I just received an Ultimachine hardware kit, and await arrival of my (RP) parts before I will do anything with it, probably another week or ten days before they will get here. I have a cheap digital readout caliper, but it's a 6in one, not 12in. The 12in ones seem to be around US$50 locally, US$35 on ebay -- not exactly inexpensive in relation to a US$200 kit, so I hope I won't need one.

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Jonathan

I too worried about accurate measurement of long distances, having only a 1" Starrett micrometer and an assortment of inside and outside calipers. The lack of great accuracy may be contributing to my inability to complete a single successful print. Warping without a heated bed has been a major problem, that and my ignorance of Skeinforge's settings and electrical (RF) interference. Striking hardened bits of ABS ooze with the extruder tip and losing steps has been my biggest problem.

Here's what I did to gauge the 6 vertex pieces while constructing the Cartesian frame. A piece of leftover all thread (cheap Bolt & Nut Supply 5/16"'); 4 nuts and 2 fender washers. Lock a washer between double nuts at one end of the rod. Lock the other washer down the at distance you wish to maintain. With cut washers I place the sharp edges face outward and all my tests were inside measure. All of my vertex distances in 2 planes were gauged with a pair of these rod-nut-washer setups. It creates a "feeler gauge" of any length and easily locked my Mendel's fasteners +/- 0.001" without any other tools. This exceeds the accuracy of the lasercut or RP parts being assembled.

hey guys, just waiting on one of these arriving this week.(got the kit on ebay)
this is gonna be my first try at a cnc so hoping its not *too* bad
thnx for putting up the build pics today, was getting nervous i was gonna get a box full of random wooden shapes that i wouldn't know what to do with.
hows everyone else getting on with this build? what kinda timeframe should i be looking at for the build/ getting up and running? i have hobby level electronic experience and am a 2nd year programming student though not much mechanical experience...
this is gonna be fun..
cheers
evo

Start by reading every post here and follow each link and read there. Get the software and install it. ReplicatorG, Skeinforge, Pleasant3D (for Mac OS X), check out Thingiverse and search for "calibration". Get a metric measuring device.



Google is your friend, learn to use it. I just entered "wiki lasercut Mendel assembly", basically your query here with the addition of 'wiki'.

This is one of the results [reprap.org].

Bookmark it. Look at each of the links in the body of the text. I built mine from the single picture at the top of the page with one excellent assist from the designers. One set of the photographs is by me, the link is the previous posts as well as here. Kimberly and Lambert, the creators of this version of the Mendel, have posted a very good step by step set of photos in another link on the page.

YouTube has extensive step by step videos of Mendel assembly from RP parts. Read the wiki itself, discover the founders names follow their online posting. Set a Google Alert that sends you daily or weekly web crawls of the following:

RepRep Mendel
Lasercut Mendel
Adrian Bowyer
nophead
MakerBot

Read, read, read. Join MakerBot groups.

Get Open Office installed. Download and read the .ods files for the Mendel. They'll help with hardware acquisition. There are whole shopping lists for fasteners, use them. McMaster-Carr for fasteners, VXB bearing kit from NationalSkander. 8mm ground rod . . (forgotten who) Small Parts has it. Buy "Allen" brand allen wrenches not Radio Shack tools.

"A fool learns from his own mistakes. A wise man learns from other's mistakes."

A PayPal account really helps. I left many of my experiences and fixes on the wiki. Keep asking questions

Edited 2 time(s). Last edit at 06/13/2010 10:24PM by stevew.

Be warned that I posted the detailed assembly pics, not the creators, so it is just another opinion, not to be taken as gospel. I had a bit more to go on than stevew thanks to his build blog, but he didn't have the full kit, he got the laser cut parts, and sourced his hardware and electronics from elsewhere. As I have progressed, I have found that I made a few mistakes. The belts require more space than the bearing and 2 washers between two mudguards as I have shown in most of the pictures - an additional washer is needed for smooth running (I also dont think that you are supposed to have a mudguard washer on each side of the bearing).

I also initially put the x carriage on upside down and now I think I have the back at the front and I have installed the z axis now, so it will be a pain to correct that. I may just leave it. It looks like it wont matter, but the X belt clamps are at the front.

I would encourage you to take as many photos as you can during the assembly and post them. Particularly if they are better than mine. I was hoping to create a step by step guide that was easy to follow, but I dont think I knew enough to start with. It would be good to build another one knowing what I have learned and take fresh photos on the way.

Edited 1 time(s). Last edit at 06/15/2010 08:25AM by Greg Frost.

We can all assist one another. This request goes out to everyone using a Mendel that reads this. Getting a working Cartesian machine was easy for me. Getting ReplicatorG and Skeinforge has been the tough part.

The main problem that I am having is my extruder tip, MakerBot's, hits hardened ABS ooze or strings and the X and Y-axis steppers lose steps resulting in failed prints. Turning up the stepper driver power is not the answer, maybe an extruder tip made from a cap nut would help. The MakerBot extruder tip catches and can break an extruder and/or the X-axis carriage. Maybe my Z-axis configuration is wacky; however empirical testing shows that it is move 10 mm when asked to move 10 mm.

Make sure that your extruder temps are hot enough before powering up the extruder. Too cold and the extruder jams and breaks. Until you know that your prints succeed stay close, ready to hit reset - stop - or kill power. It will save your machine to be there.

At the end of a print, aborted or successful, I'd recommend reversing the extruder and backing out the filament. ABS cooks and changes chemical structure and can jam during the next heat cycle. I back mine out and snip the tail, ready for the next try.

On the subject of ABS cooking, and to see some inspirational printing see this post and read the comment. My comment there concerns the poisonous byproduct of ABS that you may want to read and consider. [hydraraptor.blogspot.com] The styrene monomer in ABS is not good stuff in large doses - been there, done that in 1965.

Anyone willing to share their configuration ReplicatorG's machines.xml from a working Mendel? Mine uses stainless steel all thread 5/16" as the Z-axis lead screws. M8 thread is the standard; but any info would be a point to navigate from, Kimberly and Lambert? What do you use?

The values for length, maxfeedrate and scale were derived by empirical testing using MakerBot electrics and steppers and starting with MakerBot Cupcake values and testing. I'm going backwards now and going to hand code a short G-code script to re-check that my X, Y and Z-axis move 10 mm when asked to.... Right now, running the extruder along a metric tape checks out ok for X and Y. To test the Z-axis, I use a test object of known size and jog up until is fits. A mechanics feeler gauge can help.

I suspect electrical RF interference is also causing failed prints, and intend to add shielding to the wires. Tinfoil hats as it were.

Here's my addition to machines.xml for ReplicatorG. Version 016 adds the excellent temperature graphic.
{{ Note: File had to be attached because the Phorum software sucks. If does not honor standard forum commands, neither quote or code work corerctly. Boo, hiss}}

For anyone leery of downloading a file (and you all should be!) the file may viewed on a forum that runs good working forum software that honors code and quote [www.teamhackaday.com] Its a long page, just search for "xml".

Other posts on teamhackaday may be NSFW. There is no nudity; however, I use four letter words Folding@home is my all consuming activity. I'm about #1,381 out of 1.4 million contributors. ref: [folding.extremeoverclocking.com]


[EDIT: machines.xml file has been removed. It was wrong. My post-extrude measurements on the 20 mm calibration test box from Thingiverse is coming out at about 22.5 mm. Apologies to any who downloaded it. My tests with ReplicatorG, jogging along a tape appear to be a failure. Back to square one...

Edited 2 time(s). Last edit at 06/16/2010 10:04AM by stevew.

Quote

Note: File had to be attached because the Phorum software sucks. If does not honor standard forum commands, neither quote or code work corerctly. Boo, hiss

class Thermistor:
   "Class to do the thermistor maths"
   def __init__(self, r0, t0, beta, r1, r2):
       self.r0 = r0                        # stated resistance, e.g. 10K
       self.t0 = t0 + 273.15               # temperature at stated resistance, e.g. 25C
       self.beta = beta                    # stated beta, e.g. 3500
       self.vadc = 5.0                     # ADC reference
       self.vcc = 5.0                      # supply voltage to potential divider
       self.vs = r1 * self.vcc / (r1 + r2) # effective bias voltage
       self.rs = r1 * r2 / (r1 + r2)       # effective bias impedance
       self.k = r0 * exp(-beta / self.t0)  # constant part of calculation

   def temp(self,adc):
       "Convert ADC reading into a temperature in Celcius"
       v = adc * self.vadc / 1024          # convert the 10 bit ADC value to a voltage
       r = self.rs * v / (self.vs - v)     # resistance of thermistor
       return (self.beta / log(r / self.k)) - 273.15        # temperature

   def setting(self, t):
       "Convert a temperature into a ADC value"
       r = self.r0 * exp(self.beta * (1 / (t + 273.15) - 1 / self.t0)) # resistance of the thermistor
       v = self.vs * r / (self.rs + r)     # the voltage at the potential divider
       return round(v / self.vadc * 1024)  # the ADC reading

Nothing wrong with quote and code tags from my perspective.

Yes Mendel won't plough through blobs, you need to not have blobby prints. HydraRaptor, with screw drive, will plough through plastic blobs (and aluminium bed when too low) but it can sometimes knock tall thin objects off the bed, so again blobs are bad.

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[www.hydraraptor.blogspot.com]

Thanks nophead. I tried three times, met failure, descended to four letter Anglo-Saxonisms. My bad. Will dump page source when off phone and learn.

My machines.xml for RepG is bad, yet more to learn.

The forum tags use braces rather than angle brackets.

Edited 1 time(s). Last edit at 06/15/2010 01:58PM by nophead.

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[www.hydraraptor.blogspot.com]

Two requests:

1. If anyone has a working TechZone Mendel either with M8 Z-axis lead screws or SAE 5/16" lead screws, please post your machines.xml data for your machine. Mine was wacky and I've deleted it.

2. Has anyone tried heating the aluminum build platform? I bought extra wire and thermistors and dielectric tape for an eventual heated bed. Adrian Bowyer's heated bed (see: [blog.reprap.org] ) has me thinking. . . Is this why the bed is metal in the original design of the TechZone Lasercut Mendel?

I am installing my Y axis and it appears to be a very tight fit between the frame vertices at the extremeties of movement. Is it supposed to move that far? See this image: [reprap.org]

Also, the aluminium printbed insert seems to obscure the mounting holes. Is my printbed insert too wide(it didnt fit in the routed recess until I did some further hacking with a scalpel)? See this image: [reprap.org]
Are the screws that mount the printbend supposed to clamp the printbed insert down?
Do you print directly onto the aluminium?

Edited 2 time(s). Last edit at 06/23/2010 03:19AM by Greg Frost.

Print bed: i,m using the thick sheet from techzone.. its setup so that when the screws are installed the washers will hold the alum insert in place...

Greg Frost, My printbed supports also strike the vertexes at the extremes of movement. The printbed itself has no clearance issues. I've installed MakerBot opto end stops and current Y-axis range of movement is approximately 160 mm (~6 3/8"). I set my vertex distances from the file [objects.reprap.org] (requires Open Office to view the file) J2 = 234 mm -> distance between vertex faces, which are measured parallel to the X-axis.

The designers intended that the aluminum build plate be notched to allow passage of the screws. I too used washers at first, but removed them to add clearance.

Quote from an email:

Quote
Lambert Andrus
I also knew that the build plate needs to have a little filing done, but I wanted to make sure that the plate itself gets attached under the screws too, I have found that a sharp knife does a fine job of cutting a little notch in the aluminum (although the knife is usually not sharp when done).

I have added an 1/8" acrylic build sheet on top of the TechZone printbed (wood/aluminum) and with the aluminum notched the M4 hex heads are almost flush. Now I am going to try heating the aluminum as per the founder, Adrian Bowyer's Heated bed [blog.reprap.org] I have extra nichrome and the appropriate tape. I have scrap glass from junk HP scanners to cut which will replace my acrylic build surface.

So far I've had little luck getting ABS to stick without warping to 3M #2090 blue tape. Here are my attempts so far [img227.imageshack.us]

My greatest difficulties have been my ignorance of Skeinforge's settings and the gcode and some electrical interference. The MakerBot DC motor is noisy in RF and my stepper motor wires need shielding which they lack. There's some "cross talk", by which I mean the X or Y axis will move without a step any commands just from RF interference.

The latest ReplicatroG 0017 is very good and appears to be converging with the MakerBot RepRap Host. They are written by the same people. RepG now includes Skeinforge and compiles gcode from STL files. (I run OS X and this really helps)

ABS doesn't stick to blue tape, it is only good for PLA in my experience.

ABS will stick to acrylic at low temperatures and to PET or Kapton tape if the bed is hot.

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[www.hydraraptor.blogspot.com]

Thanks nophead. I've a spool of PLA that I've yet to try and will try some of that before I disassemble my machine a bit for further mods.

Hi all,

I started working on a lasercut set, but some instructions are missing on the website. I managed to make the different axes but I don't know how to make the extruder. Where can I find the instuctions?

If you didn't get the lasercut parts to fabricate a geared extruder, then use Google. When my Techzone Lasercut Mendel was shipped in April their extruder was still in development and I purchased a Plastruder from MakerBot (~$225 with spares kit). Google "reprap mendel extruder" and there are 33,600 returns. The MakerBot Plastruder is heavy and large, not the best idea for a Mendel. It severely limits the height that could be achieved, Z-axis. I've a plan to makeover the Plastruder into a Bowden remote extruder and have purchased the tube listed in the build instructions for that type. I have also purchased the RP parts for a Wade's Extruder from beverageexpert and have yet to purchase the fasteners for that. There are excellent sources for kits and just raw parts. The MakerBots use a DC geared motor, a geared stepper extruder is the most accurate at this time.

I highly recommend that you look at what the founder of RepRap has been and is doing, Adrian Bowyer. Also search for and read past posts of nophead of Hydraraptor fame and you will learn lots. You will also be blown away by the amazing traya of parts, see: [hydraraptor.blogspot.com] and dig back through his work. Join the MakerBot group at Google groups for there is invaluable information published daily (you'll get an email digest) relating not only to MakerBots but also the software which has been the most difficult for me.

Right now I'm still mired in software (and weeds and firebreaks for the coming fireworks). My motherboard, extruder controller and stepper drivers are all from MakerBot. RepRap.org has the plans for everything. and involvement in as many sources of info as you can find and manage will slowly build up knowledge in you of other peoples' trials and troubles, so that you can go forward avoiding the mistakes that we have all made.

Thanks for the info. I did find a couple of pages about the geared extruder, it should be enough to make it I hope, but the extruder kit I received came without all the holes, I would have like some more details instructions.
Never mind, I will take some pictures and put the result on the lasercut extruder page if it works.

ok, I found the page on the geared extruder (http://reprap.org/wiki/Geared_Nema17_Extruder_Driver) but I cannot make sense of what I have here: the lasercut parts don't look similar to the plastic ones. If anyone there has a lasercut extruder, can you send me a couple of pics please? That would help a lot.

Sorry for the multiple posting, I didn't read the previous messages correctly.

To Stevew: Actually, I did buy the lasercut parts to fabricate the geared extruder. I know now that it was too early in development but here I am, stuck with this set without any instruction on how to build them together. No info on the net, no info on the lasercut wiki page. Has anyone here have the lasercut geared extruder?

Lionel,

Mine sits in a ziplock bag, a mystery that has evaded my comprehension this far. Best suggestion is to write to Kimberly and Lambert Andrus at TechZone and ask them for a photo of an assembled one. I purchased a Wade's geared extruder in PLA from beverageexpert(sp?) which also sits in a bag as my fastener supply does not have the appropriate parts and McMaster-Carr orders are qty. 100 only. Haven't done much work of late as I'm out of money and have EMI troubles that cause consistently failed prints. That and issues with the Skeinforge settings that have me stumped. Right now I am setting up MakerBot Nema 23 motors to drive a CNC platform from K2CNC. Should anyone have a picture of the Lasercut geared extruder, please post it here.

The EMI I can deal with with homemade shielding (tinfoil). Skeinforge is a tougher nut. I follow Makerbot group postings and get several emails each day detailing the struggles others are having with both the mechanics and software. It let's me know that I'm not alone and provides insight into ways to move forward. All part of the price we pay for involving ourselves in the new. Imagine making your own automobile parts from ore and coke in a backyard blast furnace as well as one's own machine tools. I've done the making of a lathe from scrap metal in a backyard furnace from Dave Gingrey's books. This is harder.

From scrap metal? That's great! I would like to try that myself if I had enough room at home (meaning, a second home, probably). Weel done, Stevew!

About the extruder, I have contacted Kimberley via ebay, I suppose I should have some pictures to show soon. I will post them here if I get something.

About the EMI, maybe it would be a good idea to include a good filter on the 12V supply. That would be one more board to design, but I suppose it would be worth it.

In my case the interference is causing spurious steps on other axis. The ribbon cables and the wires from the stepper boards currently run next to one another and appear to need separation and/or a grounded shield around them to ensure that that is not the source of the extra steps. I twisted everything and even plaited the stepper motor wires with a whip 'braid' but my Mendel setup has then touching. "Distance is your friend" said the radiologist - electrical and nuclear Plan to use baking foil or 0.001 brass shim stock on wide tape and ground them and see how that works. There's some junk stainless braided hose around from car parts that would look cool but is too hard to work.

stevew: regarding your "EMI" issue, I think that it is far more likely that what you are seeing is more related to ground bounce than to radiated EMI. You should make sure that the power and ground leads that connect your boards are as short as possible and use relatively heavy gauge wire. If you still have problems, I would look at adding some bypass capacitors to the power rails.

Lionel: Did you ever get you extruder assembled? I have mine mostly assembled, but I'm unsure of how to mount it to the X carriage. I have uploaded some pics on [reprap.org] If you have made progress, please share your experience.

I am now trying to get the extruder board working, but I cant get it to read the temperature. I have connected the
thermocouple board in accordance with
[reprap.org]

What firmware should I be using on the extruder board?
The page referenced above says this:

For information on the Firmware, and to download the firmware file, see
TechZone_Thermocouple_Firmware page.(coming soon)

But the "coming soon" page is still missing.

Greg,

Thanks for the "Ground Bounce" idea. I'll set up a star ground set of wires back to the PS. On my 2nd set of MakerBot electronics for a MillStrap build, I wrapped the 10'-0" ribbon cables and the power leads separately in grounded baking foil and taped that with 2" packing tape. My Mendel has all unshielded wiring and the 3 ribbon cables and stepper wires run right next to one another. I may undo them and shield them as well.

Thanks are also in order for the great picture set of the TechZone geared extruder assembly. Yours is the 1st that I've seen.

Re: Your extruder board and temperature readings. What electronics are you running and which software?

Steve