Sanding - What, Where and How?

[Eaglezsoar]

I have read virtually all the builds and their various threads and throughout everyone talks about sanding. No where do I see instructions
or a guide on what to sand, only comments like sand the arms to fit the ujoints. Is there any place where it tells you what on the arm to
sand, the inside, the outside, the end of the arm and are there other things that need sanding. Perhaps someone can point me in the right
direction with a little more guidance in regard to all of this sanding I keep reading about.

[cambo3d]

here is one spot (actually 12 spots), i'll upload the other photos for u to see also, if i have any good shots.
sand both sides of the ujoints injection molded plastic here

another place for sanding on the delta arms

the cheapskates

[MorbidSlowBurn]

I don't have a picture handy but you also want to sand the ujoints on the cheapskate bearings. All places where you sand will be plastic. Also try not to use metal tools to pry the arms off the ujoints as it can damage the ujoint. What is tough to see is the "pin" on the ujoint also causes friction on the arms, therefore the arm holes need to be adjusted to reduce friction. I used a hobby knife to scrape the hole on the arms (read this hint on the forum). The object is to make all joints as loose as possible without any play. A good measure is that with only one side of the arm connected it will fall straight down under gravity. You might want to mark each joint so that you always put them in the same place.

When sanding remember that the screws holding the pieces together will create slight bulging of the plastic. Try to sand with the screws in on the platform and the cheapskate bearings. Constantly test fit as you sand. Again you don't want any play in the joints, just as little friction as possible.

The arms took me the longest to sand and get to a point I was happy with. Remember the friction in these joints don't prevent you from printing. Too much friction normally appears as small holes in solid fills and slight gaps between perimeters and infills.

[Eaglezsoar]

Thanks guys! Those tips were exactly what I was looking for and the pictures were fantastic!
This is why I'm glad I bought the Rostock - people on this forum are willing to help each other.

[cambo3d]

eaglesoar that will be $5, =P

[Eaglezsoar]

eaglesoar that will be $5, =P

Please put that on my account on the account I don't have any money, I bought the Rostock.

[cambo3d]

eaglesoar that will be $5, =P

Please put that on my account on the account I don't have any money, I bought the Rostock.

lol

[MorbidSlowBurn]

Although money is good. Payment in filament is also acceptable

[Eaglezsoar]

1 foot of PLA is on the way. Darn I sent it to the wrong address!

[cassetti]

Take your time and make sure you're testing every connection over and over to ensure everything moves easily - they should be smooth as butter. But you apparently don't want to sand too far to the point where the item has 'play' (because you sanded too much).

Good luck, this was one of the most tedious aspects of the printer build in my opinion.

[Av8r RC]

I found that my arms were binding a lot on the pin. So I took a reamer and opened up the holes, I believe it was 4mm.

[Cleveralias]

A bit later in the process than would have been ideal, I ended up using feeler gauges to make a stack to the required size which I used to get the plastic parts down very close to where they needed to be. This speeded things up greatly and minimized the test fitting quite a bit. This step would have been much less tedious had it occurred to me sooner. Hope it helps!

[Eaglezsoar]

A bit later in the process than would have been ideal, I ended up using feeler gauges to make a stack to the required size which I used to get the plastic parts down very close to where they needed to be. This speeded things up greatly and minimized the test fitting quite a bit. This step would have been much less tedious had it occurred to me sooner. Hope it helps!

That is an interesting approach but I have difficulty visualizing how you did that. Is it possible to elaborate more on how you did this?

Carl

[JohnStack]

During the Midewest Rep Rap, one of the builders who had brought his machine suggested that sanding the bearing races on the arms should provide more or less a free swing of the arm when you held the cheapskate. Don't know if it helped but we did that. We took the axle and wrapped sand paper around it and then twisted it around a bit.

[Cleveralias]

A bit later in the process than would have been ideal, I ended up using feeler gauges to make a stack to the required size which I used to get the plastic parts down very close to where they needed to be. This speeded things up greatly and minimized the test fitting quite a bit. This step would have been much less tedious had it occurred to me sooner. Hope it helps!

That is an interesting approach but I have difficulty visualizing how you did that. Is it possible to elaborate more on how you did this?

Carl

I did end up marring a couple bearings getting them in and out test fitting, so this way reduced the need to only test fit once or twice since I could get the arms very close without actually inserting them. This and a 4mm bit by hand (plus very slight ream) for the pins and I thought I had it nailed. Recently, however, found a bit of friction so I'm back at it. Also the slightest bit of slop side to side from the cheapskate and carriage in a couple points I plan to address with some .002 ptfe washers on their way (http://www.mcmaster.com/#95630A420). With this second attempt I'm hoping I'll have this settled.

[Eaglezsoar]

Thanks for the pictures, I can now understand how that can save a lot of time having to do the remove -test process.
Good luck in getting everything dialed in.

Carl