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I thought I was being very careful when I spent over an hour sanding the Ujoints. And even after that I ended up over sanding two spots. I now have a little side to side action, about 0.011" on the worst one. What should be used as a shim?

If these parts require such tight tolerances, can be purchased in machined aluminum parts?

Use rubber band, it takes up the sidelash

tricklaser.com.. carbonfiber arms

Yes Tricklaser are fine but for a quick fix i think rubberband will do it in the short run, i made my own 6mm carbonfiber arms with ballends from Hobbyking 3mm 5pc 4.88$, but then you have a problem with the axles witch are not metric

Gimbal wrote:Yes Tricklaser are fine but for a quick fix i think rubberband will do it in the short run, i made my own 6mm carbonfiber arms with ballends from Hobbyking 3mm 5pc 4.88$, but then you have a problem with the axles witch are not metric

Do you have a picture of your arms? I am interested in how you went from 6mm down to fit the 3mm ballends.
Perhaps the Hobbyking part number? I know, curiosity killed the cat but I can't help myself.

Shure thing, but my mistake the carbofibre tube are 8mm Od and 6mm Id and the ballend have 6mm shaft, so it's a snugg fit secured with Locktite superglue

http://www.hobbyking.com/hobbycity/stor ... duct=18628

sorry for the crappy pic but i'm having a bad link on my side

Krak,
When I built my effector, I didn't like the pockets molded in the brackets. The ones that look like they accept a nut. So I machined a delrin washer to fit in the pocket. Does two things-1. more(flatter) bearing surface for the aluminum joint to run on, and 2. I could control side lash by the washer thickness. It's tricky because it's a small part to machine. They seem to be working though.

Gimbal wrote:Shure thing, but my mistake the carbofibre tube are 8mm Od and 6mm Id and the ballend have 6mm shaft, so it's a snugg fit secured with Locktite superglue

http://www.hobbyking.com/hobbycity/stor ... duct=18628

sorry for the crappy pic but i'm having a bad link on my side

What would you consider the best source for the 8mm OD 6mm ID Carbon Fiber tube? I like the setup with the alloy ends and I would like to duplicate it to see if it is better or
on par with the magnetic arms coming out.

I just happen to have some laying around so go for what's most convenient or even alu it's not critical, aim to save wight and $, you know i assembled them in about 20 min, after i released that original was crap

I just ordered N 52 3/8 magnets from Amazing Magnets they have 6.5kg force, will use them with 10mm CF tubing and fixed 15mm ball at effector and skates, so like somebody else here use the CF-end as gliding surface and just support the ends with shrink tube

I went out and picked up some delrin washers from my main shop. I haven't fitted them yet, I think I can make them work.
So the rubber band idea is to please the rubber band around the two the arms to act as compression, is that the idea? When I first read Gimbal's reply I was envisioning placing the rubber band between the housing and the alum ball joint.

Please forgive the newby question, but what is the point of the magnets? I'm sure once I have the machine all together and running I'll figure out what needs upgrading right away. But what are the top 5 trouble spots on this machine?

Thank you for all the responses so far. It was this forum that pushed my purchase decision to this machine verses the other options out there. I cut my teeth on a Thing-O-Matic and while the forums for maker-bot machines are great, the base product leaves much to be desired.

Hi, there is no really big probl with the RM my decision to make new arms was that it takes less time for me to make new one than to sand original, an besides i have the part's laying around, just follow the thread and you will be fine. So put youre RM together tune it and enjoy You know RM are the best you can get

krak wrote:Please forgive the newby question, but what is the point of the magnets? I'm sure once I have the machine all together and running I'll figure out what needs upgrading right away. But what are the top 5 trouble spots on this machine?

My Rostock MAX has only been running for two weeks, so (a) I never worked through the problems that the first generation builders had, and (b) I don't really have that much experience yet.

Top problem: tuning this printer (or any DIY printer) is tough. The distributed settings and Gene's manual get us 80% of the way there, and then we test and iterate a lot.

• Other problems?
• I wish the bed got hotter and heated faster.
• The hot end + Bowden tube make it hard to control retraction.
• I think the side-mount filament spool/extruder looks goofy.

I also oversanded my U-joints. I used rubber bands, and they've been just fine. LINK.

So I guess I was wrong. I didn't over sand them, at least that turned out to be the case once I installed the ujoints on to the carriage. Once I did that I had to sand them again. Now I feel like I have been sanding parts for two days. I think I'll put the beer down, go to bed, sleep, grad a cup Joe and continue in the AM. This build is taking a bit longer than I was expecting it to.

I am finally past the point of sanding. YAY I used a wood file and then the 7 emery board trick from here:
http://forum.seemecnc.com/viewtopic.php?f=42&t=1527

A little lithium grease helps out too. On to the next part of the build.