Mendel Prusa build

The printed parts arrived this morning so a great way to start the weekend. I had already bought the threaded rod and SS rod so after unpacking the box of goodies I got straight into cutting the rods down to size. The kit I bought comes with the printed parts plus all the hardware and the printer bed. It still needs the motors, electronics and a power supply and I bought some used motors off ebay and a power supply from a supplier fellow kiwi NelsonRap put me onto. The good thing about the kit is it comes with all the bearings and small parts that you could spend a lot of time sourcing plus it was a lot cheaper than me buying them all individually.
The printed parts are very high quality and were printed with a fine layer height, and they needed little or no trimming.
I soon got onto assembling the frame and the instructions supplied with the kit made it virtually fool-proof. It is basically a Mendel Prusa but I have noticed a few parts are slightly different from the one featured on the Wiki pages. The rod lengths are slightly longer for one. Probably just some minor evolutionary development.

Edited 1 time(s). Last edit at 07/14/2012 10:10PM by Wired1.

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Richmond, New Zealand
Thingiverse ~ YouTube

Finished the frame assembly today, took about 4 hours start to finish. I'm impressed with the printed parts I got from MakerFarm, no skimping on printing height there. The kit had more than enough of everything needed to assemble the printer and the only thing I had to buy was a 1.5mm allen key for the pulleys. I managed to over-tighten one of the pulleys and damaged it but ti will work long enough to print a replacement so I guess that will be the first project.
Time-lapse video here [youtu.be]

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Richmond, New Zealand
Thingiverse ~ YouTube

The electronics arrived this morning so I spent the day wiring up all the micro switches and motors and connecting up the Printrboard. I fired up Pronterface at about 6:00pm and the Y-axis motor was not happy. This turned out to be a missing connection to one of the four poles when I extended all the motor cables. Second test and all three axis are moving freely although the X-axis appears to be inverted. The micro switch for the x-axis is on the right and when I press the X-home it drives toward it and stops but when I press the X+10 it drives the other way so not sure if that is right - I would have expected it to drive to the right. The hot end heats up but not the bed so I need to figure that one out too.
On basic calibration 10mm on either x or y axis returns a 12mm move and I think this is because I swapped the stock pla cogs for alloy ones which have an extra couple of teeth. Z axis drives about 9 mm for a 10mm command and I think this is the 5/16 to 8mm threaded rod pitch difference. So tonight I will read up on how to change the firmware and tomorrow I will hopefully get it running correctly.

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Richmond, New Zealand
Thingiverse ~ YouTube

Quote
Wired1
...although the X-axis appears to be inverted. The micro switch for the x-axis is on the right and when I press the X-home it drives toward it and stops but when I press the X+10 it drives the other way so not sure if that is right - I would have expected it to drive to the right.

...and WHY would you have expected it to drive to the right with X+10?

If your Home switch (MIN) is on the right hand side that would mean X = 0 is when the Home (MIN) switch makes contact.
X + 10 would then move 10 mm to the LEFT.

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Bob Morrison
Wörth am Rhein, Germany
"Luke, use the source!"
BLOG - PHOTOS - Thingiverse

Yes it seems to be correct he way it is going. The only reason I thought it was wrong is that Pronterface has the nice big graphic display with +X going to the right. The other two axis agree with it's layout.
I managed to make some changes to the firmware today. It seems the version of Printrboard I am using is newer than the information on the reprap/wiki page and they ahve changed a few things like the boot jumper polarity and the firmware uploading method. I was also doing it on an olcder machine out in the shed which is running XP and a lot of the software just doesn't like it. So today I brought it all into the house and set it up on my main computer running Vista and everything started working.
I have now adjusted th X and Y travel to compensate for the alloy 12-tooth sprockets and changed the Z axis rod to the metric pitch of 1.25mm and then printed a 25mm cube which came out 25mm high and 23mm wide and long so getting closer.

Is there a configutation/tuning guide anywhere on this site or the net? I would like to know how high off the bed the hot end should be plus I need to fine tune the X and Y dimensions.

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Richmond, New Zealand
Thingiverse ~ YouTube

The nozzle should be off the bed by about 2 thickness's of printer paper

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Experimenting in 3D in New Zealand

Thanks Gary, I adjusted it to that and it is already printing better.
This evening I designed a new part for the machine to take the PLA spool above the top two bars then printed it out and it is not bad for a first print. I have since realised I need to alter the desing slightly so that it can be slotted on rather than the way I made it but it was really just a test print anyway. As soon as it cools down I'll check the dimensions and see what needs tweaking.
I haven't gotten my heated bed working yet as it is missing a thermistor and the PrintrBoard can't deal with that so I am printing cold on masking tape but it seems to have worked out OK.

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Richmond, New Zealand
Thingiverse ~ YouTube

Bloody awesome, now what to make next?

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Richmond, New Zealand
Thingiverse ~ YouTube

A Rostock, like everyone is rushing to build atm (why stop at one printer?)

[reprap.org]

Nah, they look look like they have a high build area but apart from that I can't see the advantage - other than artistic merit i guess. I think the basic prusa is a good place to improve like better resolution.
Redesigned my Spool clamp so that it snaps in place over the top bars and printed it out tonight. I went octagonal this time and it isn't as clear as hexagonal for sideways printing. I guess 45 degrees is too steep for the extrusion to stick to. Might try building up a round section - see if that works. I guess these design limitations are well known to the hardcore users
By the way - two of these are intended to go in the middle of the bars not on the end where it is sitting in the photo - that's just where I sat it to take the photo

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Richmond, New Zealand
Thingiverse ~ YouTube

What type of masking tape are you using?

The thermistor fell off in transit for my Huxley, and I have only just got it working. So for the first few weeks I was printing cold. Looking at several forums, I found that the blue 3M tape is the one to use. Most of the time, this worked well for me printing PLA. Though some of the larger pieces lifted at the edges. Also, the surface of the tape only lasts a few prints before it needs to be replaced.

I have been using Sellotape brand painting masking tape- the purple one which is about 3 day from memory. It was just a roll I have in the shed and it works very well. I just ran out tonigh so I will get another roll tomorrow of the widest one I can find as the joins are the ripple spot.

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Richmond, New Zealand
Thingiverse ~ YouTube

Bought some of the Scotch Blue tape today and it looks like a better version of what I was using. In one of the photos below you can see the sellotape brand tape was lifting at the front slightly. Still came out OK but the one I am printing now should be better.
Last night I redesigned the bracket as a two part thing which i printed today. I reduced the layer height to 0.3 and added z-axis lift of 0,3 which I have read reduces the head catching blobs of filament. I also added some code to do a quick purge at the start and it improves the starting squirt but I will add a bit longer I think.
Next up I will design and make the top of the spool holder and some end caps for the recycled cabled reels I am using.

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Richmond, New Zealand
Thingiverse ~ YouTube

I could never get tape to stick during prints it always lifted along the joins which is why I went to heated glass

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Experimenting in 3D in New Zealand

Yes it isn't ideal but my thermistor is a few days away and I am impatient It is working OK but I am changing the tape for every print.

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Richmond, New Zealand
Thingiverse ~ YouTube