3DR Delta Bot (continued)

[Nicolinux 288]

Back in july an idea sparked on the german subforum to build RichRap's 3DR Delta Bot.

 

• http://richrap.blogspot.co.uk/2013/07/3dr-reprap-delta-printer-part-1-release.html
  

 

After many weeks of organisation, and hunting for parts, we finally met to build the printers. Actually we met to build three 3DRs. Also Nallath from Ultimaker chimed in and helped us with a few spare parts (many thanks! - and we haven't forgotten you, you'll have a little thank-you package soon).

Before the meeting we had only one "situation" where missing parts would have been very problematic. Hat tip to "My Home Fab" - they delivered super fast and took the time to talk to us in person to fit our obscure choice of features

 

• http://www.my-home-fab.de
  

We met at onkelgeorg's place (many thanks Jörg for the hospitality!)

 

Please observe the two Ultimakers doing their thing. Everyone of us had bought their Ultimakers and we made good use of them since we redesigned some parts. Ok, all but Jörg who was printing Fairphone cases non stop

 

And speaking of redesigning, this was actually the least bright idea because it took too much time (we only had 2-3 days). We opted to build everything from scratch - even the hotends (E3D v6 here, the other two guys went with Merlin hotends):

 

Of course we didn't finish, but the frame is built and we will "only" have to fit the electronics and fiddle with the firmware...

Btw. one remark about the UM2. I drove close to 1000km for this weekend and I didn't have to calibrate the heated bed not even once. Very pleased with its stability.

 

[nallath 1,120]

Nice to see that all the parts we had around the office helped you guys

 

[jonnybischof 60]

So.... Have you guys gotten your 3DRs to work yet?

 

[Nicolinux 288]

Not yet. But some of did manage to assemble everything and (I presume) would fiddle with the firmware. Will keep you posted. Since I have a heated bed, I have a bit of trouble planing the where the cables should go because I don't want them to be visible outside. The electronics of the 3DR are mounted on the top and I need to have one pair of cables going from the heated bed at the bottom to the top. From there another pair of cables should go to the power supply. I don't know how RichRap designed it, because I never saw a fully assembled 3DR connected to the power supply.

 

[jonnybischof 60]

I wondered why Rich decided to put the electronics to the top when the motors and the (potential) heated bed are in the bottom. The only thing that needs to be on top are the endstops - and long cables don't matter to the endstops (when done properly).

Anyways... keep us posted

Something coming from my side in the next few weeks, but it's still too early to brag about it

 

[thirty6 3]

Are nuts!! I have always wanted a delta and now i have ran out of excuses.

What size is the print bed?

 

[Nicolinux 288]

It is 180mm diameter but due to the ball joints we used it is restricted to 140mm. But you don't want to get too close to the towers anyway.

 

[jonnybischof 60]

For those who have already assembled the frame: How sturdy is it? Is there any wobble when you hold the bottom part and wiggle the top?

I've seen a Kossel build (must have been some early model) in our local FabLab which uses acrylic parts to hold the profiles together. It's probably the worst construction I've ever seen

The 3DR is quite different in that matter - so how well does it do?

 

[Nicolinux 288]

Hm, hard to say since I don't have any point of reference to compare the "wobbleness". It is not overly sturdy as it wobbles. However, according to some 3DR users it produces very accurate prints and I guess that's at least some indication that the wobble is not such a big problem or that it is sturdy enough.

 

[DidierKlein 729]

Really curious to see how it turns out, i'm very interested in Delta printers (mainly because they look pretty cool).

Will you guys make some kind of step by step tutorial of the work you did?

Do you need a lot of technical knowledge to build it?

 

[Nicolinux 288]

As you can imagine, I am very curious how it turns out too... The deltas sure look cool - also one of the main reasons for me to build it (and also as an experimental platform).

To be honest I don't think I'll have the motivation to create a step by step tutorial... But Rich did a pretty good job of explaining it here:

 

• http://richrap.blogspot.co.uk/2013/07/3dr-reprap-delta-printer-part-1-release.html
  

If we are to write something down, then rather some kind of errata for the official guide.

And you don't need that much technical knowledge to build it. But it sure helps to be crafty since there are a few opportunities where you need to get a bit creative and drill holes through stuff or adjust parts. If you intend to build one, I can help you.

I am not finished myself, still have some headaches with the (non standard) heated bed and cable routing (posted earlier about it http://umforum.ultimaker.com/index.php?/topic/7431-3dr-delta-bot-continued/?p=72813).

The next step that I am looking forward to least is cutting the carbon fiber rods. I heard from a few people that they are a b***h to saw. Let's see how it turns out

 

[jonnybischof 60]

I would make a vise out of PLA for the cfk tubes! Just a tunnel to place the tube in firmly, and a 90° slit to saw through the tube. And probably use a metal saw with fine teeth.

If you want to minimize (carcinogenous) dust getting into the air, you can spray water over the stuff regularly.

I ordered cfk tubes from robotdigg.com, they're 180mm long which should be just right. I don't really have an idea about the correct length of the effector arms yet. The operating principle is still black magic to me. Trying to draw the effector for my delta printer today, actually...

 

[jonnybischof 60]

I'm putting together the effector rods:

This is how I did it:

1. tap an M3 hole into the ball joint (or not - you can also just screw in the headless bolt. But it's nicer if you have a clean thread)

2. Take an M3 x 16mm headless bolt and screw it into the ball joint (8mm deep, so that 8mm stick out). I put some glue into the hole so that it wouldn't come loose again (ever).

3. Make sure the carbon fiber rod is cut straight and clean (I had to sand it down to get a clean edge). Then put some glue into the carbon fiber rod and push the ball joint in.

4. Let it dry long enough! Araldite Rapid takes about 48 hours to cure all the way in this configuration! (depending on air humidity it can take up to a week).

BOM:

Effector rods and ball joints from robotdigg.com (very recommendable shop!)

You can buy an actual headless screw (recommended) or just behead an M3x16 screw.

Araldite Rapid - alternatively use any fast-curing 2-component epoxy glue.

I noticed that the headless bolts I'm using are actually the heaviest part of this assembly (carbon fiber rods are awesome ). It's still very lightweight, but I wonder "how" lightweight it should be, and at what point the weight would become a problem.

That also concerns the effector itself and the linear carriages (probably more than the effector rods...)

Is there any resource / advice on how much weight there should be?

Of course it's easy to say "make it as light as possible", but stiffness is just as important as light weight...

By the way:

I'll make my effector rods 220mm long (ball joint's hole to hole). Circular bed with 170mm diameter. The towers are 205mm away from the platform's center (carriage fixing point is around 180mm away from the center).

I have no clue how well that's going to work out. I guess I'll just try and see

Building materials for the frame should arrive by the end of the week, will keep you posted

 

[Nicolinux 288]

Oh very nice. You took a simpler approach to the ball bearing joints - didn't think of that. We just made our own adaptor. About the rod length, I read somewhere that someone also used 220mm. You loose some build height but you can use the entire build plate in return.

No resource about weight - so stick to "as light as possible"

 

[jonnybischof 60]

I've seen RichRap's adaptors. They look bulky, but they might be even lighter than my screws...

I chose the steel hardware mainly because of the stiffness (and the sleek look). But then I realised that the balljoints themselves aren't stiff at all... You can bend them by hand :(

I'll see how it all turns out..

Meanwhile I found a source for round heaters: http://www.ultibots.com/kapton-heaters/ (been searching for a while...)

They have full 170mm diameter kits, and other stuff needed to build a delta printer. They have good international shipping options so I didn't mind the parcel going half way around the world.

 

[Nicolinux 288]

I bought this heated bed:

 

• https://www.reprapsource.com/de/show/7007
  

Doesn't fit the 3DR directly, but one can create small adapters. I intend to print them in XT (or ABS).

 

[jonnybischof 60]

Looks nice. Not cheap, but it seems to be well-made. The 3 buttons for probing are an interesting idea, I was thinking of trying out something similar, in case manual levelling turns out to be annoying (which it shouldn't be).

/edit:

Misumi order will arrive thursday. I CAN'T WAIT :shock:

 

[jonnybischof 60]

Finally I got all the lasered metal parts (except for a decorative piece that I just forgot to order - no clue why...) and started to build the frame.

I only put up one tower for now because I still have to do a lot of corrections on some printed parts. For now, it seems I'll have a very solid frame with the awesome Misumi profiles and the massive 4mm aluminum sheets in the bottom and the top.

What bugs me is that the linear bearings are very loud when travelling on the shafts. One bearing alone is nearly silent, but inside the carriage it's pretty bad. I noticed the shaft spacing on the printed carriage is 0.3mm too small (shrinkage). Correcting that now - but the carriage still moves easily but makes a lot of noise.

It could be the "all metal" construction which generates these resonance noises. Do you have that problem on the 3DR as well?

 

[Nicolinux 288]

I don't have that problem here. It really might be due to resonnance on the metal frame. The linear bearings are not silent (not by far). Let's see how loud they are when the motors come into play

 

[jonnybischof 60]

... Let's see how loud they are when the motors come into play

 

That's exactly what I'm afraid of here

I noticed the leading holes for the linear shafts are a little bit too large on my prototype - but I might have to re-think that design anyways. It looked better in Sketchup than in reality..

 

[Nicolinux 288]

That's why I decided to stay pretty close to the original design. I want to build a working printer that I can improve later if the need arises.

 

[chrisp 10]

Alright.....you guys have sparked my interest with this 3DR Delta Printer. I have been reading all of RichRap's posts and github files. I Just started printing the 3 base pieces and plan on using most of my parts from the Tantillus build that I never got around to finishing. I like how the 3DR is put together. It seems like a much easier build than the tantillus and way easier to mess with. Besides that, I'm really impressed with his progress.

 

[jonnybischof 60]

welcome aboard

What electronics are you planning to use?

I've got a Megatronics v3 laying around that I'll try to hook up to my Delta. Might also try the Smoothieboard which might be more suitable due to the higher processing capability...

 

[Nicolinux 288]

Well Rich still has not released the promised 5th article about the 3DR. I whish he would put a bit more love into that machine since it is a great idea. I am almost finished with mine - mind you finished means, cabling. The fun starts when the firmware fine tuning works as expected™

 

[chrisp 10]

welcome aboard

What electronics are you planning to use?

I've got a Megatronics v3 laying around that I'll try to hook up to my Delta. Might also try the Smoothieboard which might be more suitable due to the higher processing capability...

 

I plan on building it the same as Rich, then possibly toying with a few other ideas once it's working.

 

Well Rich still has not released the promised 5th article about the 3DR. I whish he would put a bit more love into that machine since it is a great idea. I am almost finished with mine - mind you finished means, cabling. The fun starts when the firmware fine tuning works as expected™

 

Post some pics of your progress when you get a chance. Rich seems to have many projects going on constantly, so I would assume patience plays a huge role with this project.