A different multi-extrusion approach - UM tool / printhead changer

[ultiarjan 1,223]

I was also thinking I could try some different nozzles, the one I use here is an E3D, I'll try one I got from "swordriff" and maybe later I'll try with an original UM2 nozzle.. and I can probably print a bit colder...

 

[foehnsturm 969]

My attempt too meet this one http://www.thingiverse.com/make:106961

Layer height 0.12mm, Faberdashery red and glow in the dark, 4 hrs printing time, no ooze shield / wipe tower etc.

I'll stop with bi-colored animals now.

 

[SandervG 1,521]

finally, repeated foehnsturm's repeat accuracy test

redesigned my head a bit, made it a bit smaller, with a bit better weight balancing, and added the bigger magnets (only in the head, not in the pickup, will maybe do that later)

 

sorry for the long video, just skip the first 2 minutes or so..

 

 

Now I dear to call it a bit of a succes...did a little print with a head parking every layer, so in total 147 times.

 

The print in itself is ok, just the stringing caused by the retraction is ugly. If you look at the back of the print the accuracy is fine. Did a print before this one without retraction and that was better, but not good enough.This failed because a magnet got loose (the loctite didn't work that well, now use bison).

 

@foehnsturm > do you use any retraction during parking? What settings?

 

I'm also not totally happy with the parking, although it went ok for 147 times, it just does not sound good, will try to make a little more accurate parking dock.

 

Asked UM support for extra parts to build a 2th head, but no reaction sofar... think this might delay my progress.

 

Very interesting! I am happy to see you are also involved.

About the extra parts, what is your ticket ID?

 

[ultiarjan 1,223]

Hi sander, ticket is View Ticket: #AXD-271-31757

It's only open for 4 days... so still well within expected response time

 

[foehnsturm 969]

One advantage of this design is that the hotends always travel to the same position when not in use. So it should be relatively easy to add some kind of nozzle wiping / cleaning device on this path with no extra movement needed

There are printers which have this somewhere in the back of the printer and move the printhead over it every time when changing extruders.

 

[SandervG 1,521]

Hi sander, ticket is View Ticket: #AXD-271-31757

It's only open for 4 days... so still well within expected response time

 

I'll pretend I didn't hear that and make sure you get a reply today.

 

[ultiarjan 1,223]

thanks!

 

[macua85 52]

Hi Sander,

No worries if cant help, but I also raised a ticket for some parts to complete my slightly different attempt at this. Its ticket number View Ticket: #VKV-691-87184 if you do get a chance to look into it (only raised today so certainly not expecting to hear back yet).

Thanks

 

[aviphysics 9]

Regarding the (pickup) sound:

Greasing the wedge shaped part works wonders! I used "Titanfett".

Retraction:

One of my two (supposed to be identical) hotends shows almost no oozing / stringing with a retraction of 2 or 3mm (direct drive!) when parking. No idea how the 2 or 3mm translates to with a bowden.

The other one oozes with the same settings. :???:

Congratulations for accomplishing this with an almost original UM2 setup!

 

Could the difference just be the color?

For example, this gizmodorks dark gray PLA filament I haven't been able to do much at all to stop it from stringing. On the other side of things, their clear PLA had almost not stringing at all.

[neotko 1,417]

I been fiddling with the dual extrusion basic stls trying to adapt it to umo stock heads. So far the progress it's ok.

The neodiums are fit inside the holes, that lowers the clamp power, but the neodiums have good strengh. Anyway on the final design I'll loctite them. Prolly I'll try to use neodiums that come with an m3 hole, a mix of the ones that let you have a clean clamp because the angle of the hole and the others, they will arrive on monday so will see.

The idea it's to use that 'half' cut parts that are like the wood stocks, and saw off them in half. With my spare V2 hotend pack they come 2, that should be enough for 2 stock heads. I want to use the wood ones because Peek Isolator upper part only reaches 30-50C (that's what my thermal camera tells me at least) but the body of the peek insulator reaches easyly 100-130C on the outside. So that's why I wan't to saw in half the wood parts, to have a good and safe clamp on the peek insulator.

I did a few mistakes on the measures but they are easily fixable.

Also by using just half of the wood size I saved quite a bit of space and since the clamp area it's 50cm long because the wood size I think it was a nice first approach . Now I need to cut the wood in half and check how this holds the weight.

Edit: Don't mind the print quality I printed at 9mm3 speed XD

 

[macua85 52]

Neotko - I wouldn't recommend the 'skin' over the magnet approach. I have tried this and is has quite a big impact on the holding force of them.

Are you going to recycle your UMO linear bearings of buying spare set?

 

[neotko 1,417]

I though I could use the bearing from my UMO, you think it's better to get a new set?. I suppose that way I could have my head ready to plug it without having to reassemble everything umm..

No the skin it's just temporary for using and removing the magnets. I just use a lighter and the skin peals so I can remove them until the final design its set. Also I think that I will use round magnets that have space for an m3-m4 to avoid the glue.

 

[macua85 52]

Yea thats the reason I want to use another set of bearings. I tried my first iteration of this design last weekend which failed. Would have taken forever to get a working printer again had I taken the bearings out of my UMO hotend. But then again, I leave that fully assembled and just use the heater and thermocouple driver for the new part so its easy to put back together.

I'm hoping for another iteration this weekend, already started the deigns...but I need the bearings before i can do any testing.

 

[neotko 1,417]

Seems I have hit a wall.

The plywood idea was ok on my mind but after reading some documents about the heat that can withstand at more than 100C it starts to loose weight and at 150 starts to become charcoal, at 200C can combust. So not a good idea.

Anyone knows somewhere in europe than can cnc 2 small parts in aluminium?

 

I uploaded the pdf/step files to my dropbox if someone can give me a hand please pm with prices or if someone can point me to a good shop for this small amount, that could be superb

https://www.dropbox.com/s/tg7kft99lgjekuy/HALF-1048-A2P-A.zip?dl=0

 

[foehnsturm 969]

What about laser cutting the flat, approx 3-4 mm thick part of the piece and using some washers in the corners?

If you order say 5 pieces with 0.8 mm thickness an stack them that would be quite cheap and of better quality than laser cutting 3 or 4mm thick aluminum. I use cutworks.de but there should be similar job shoppers in Spain.

 

[neotko 1,417]

That's a perfect idea, much cheaper than cnc for sure and will do the job just as well.

For this weekend since I still have day and a half free I'm going to try to MacGyver this

That's aluminium folded from baking boxes my wife 'had' (now they are mine XD) after folding and bench vice it with one aluminium oven mold, so 2 more to go and then some drilling and should be nice. If it don't holds well I'll put some loctite 638 that can withstand 180C without problems. Edit: Bad idea never try again

 

[macua85 52]

Had some time to work on the this today. I've taken all of my other versions down, and uploaded version 5. I've probably said it before, but I think this is the one. I'm printing it now, will soon be able to tell if its going to work. I've added support for the main module to make printing easier...even with support mine was lifting in the corner.

https://www.youmagine.com/designs/e3d-v6-modular-print-system-magnetic

Purpose of redesign was to make magnets more efficient (removing the skin), and adding rigidity to the e3d carriage. I've incorporated somewhere to mount the thermocouple amplifier on the e3d module, and fan wire slots on the main carriage. I'm pretty sure with the magnets in direct contact, there should be plenty of holding power.

 

[mastory 44]

I've been watching this thread with alot of interest. I have a suggestion for an improved geometry for the nozzle cartridge engagement cones. I'm drawing on my long experience in machine tool design with jigs and fixtures. For easier engagement and disengagement and better repeatability, I feel the following geometry is preferable. Cone A marked in the picture is a true conical pin and conical hole and provides a point location in the XY plane and a Z height by the mating of the surfaces. Cone B is a true conical pin and a conical slot which qualifies the joint rotationally in the XY plane around point A and also a Z height. Locator C provides merely a Z height . The apex of the cones are designed with clearance to the bottom of the conical hole & slot. There is also clearance by design between the planar surfaces. This geometry is more permissive to less than perfect precision. This is akin to what was found with the print bed that 3 leveling screws is preferable to 4. For best stability, place the features as far apart in the Z plane as possible. For a further improvement in location repeatability, the male cones can be replaced with spherical features, however a tradeoff will be made with the longevity of the contact surface.

For this application, I would place the conical features horizontal and as low as possible above the nozzle.

The picture shows 2 pairs of the mechanical joint with one half of each transparent

Hoping to help

 

[neotko 1,417]

I like cone B since it might get more x/y as you say. Also the cones need to have some 'slippery' so they disconnect on a smooth way. I like your B cone. I'll try that for me second part of the designs as soon as I find a company that can make me some aluminium. There's not even one online shop that can just buy/pay fast like the shop foehnsturm pointed. A shame that shop don't delivers to spain :(. Also I think for the final design a propper cnc part would really help to calibrate the heads small differences.

This monday more magnets arrive. I want to try the circled ones with m3 holes (easy/fast to screw). Also got some bearings on the way like Macua85 said, good idea to be able step back in just a few minutes.

[aviphysics 9]

I've been watching this thread with alot of interest. I have a suggestion for an improved geometry for the nozzle cartridge engagement cones. I'm drawing on my long experience in machine tool design with jigs and fixtures. For easier engagement and disengagement and better repeatability, I feel the following geometry is preferable. Cone A marked in the picture is a true conical pin and conical hole and provides a point location in the XY plane and a Z height by the mating of the surfaces. Cone B is a true conical pin and a conical slot which qualifies the joint rotationally in the XY plane around point A and also a Z height. Locator C provides merely a Z height . The apex of the cones are designed with clearance to the bottom of the conical hole & slot. This geometry is more permissive to less than perfect precision. This is akin to what was found with the print bed that 3 leveling screws is preferable to 4. For best stability, place the features as far apart in the Z plane as possible. For a further improvement in location repeatability, the male cones can be replaced with spherical features, however a tradeoff will be made with the longevity of the contact surface.

For this application, I would place the conical features horizontal and as low as possible above the nozzle.

The picture shows 2 pairs of the mechanical joint with one half of each transparent

Hoping to help

 

I imagine that in time, the design might start to include inserts for the mating surface. Maybe something sort of like the thorlabs design on their KB1X1 part (I hope that their design isn't patented.)

I think the advantage of slightly over defining the coupling is that you have a little more insurance against wear. What I have found in practice, is that PLA will tend to work itself into a perfect fit over time.

edit: Just thinking. For the inserts, on one side you could have a plate to trap the ball bearings and on the other side you could have a precision plate with slots cut for the ball bearing to mate with. Both plates could probably be relatively thin and fit on top of a 3d printed structure.

 

[macua85 52]

Neotko, where did you order the bearings from?

 

[neotko 1,417]

I order them from makertronics.co.uk - Linear Bearing LM6LUU 6mm Long Bushing

 

[ultiarjan 1,223]

Quick update.

Decided to rotate the hole setup, want to have the 2 heads in the left and right front corners, better with the bowden setup.

Redesigned the pickup, ditched the modular head and made a smaller one. Due to the rotation (height difference) I had to redesign the head and parking as wel.

Made this little thing to get some extra space at the left;

https://www.youmagine.com/designs/adjustable-home-switch-offset-bracket

 

And I'm printing another (mirrored) feeder for my "rail system" setup.

I have most of the parts, all hotend parts and electronics, will use a 2th "olson block" and I got the confirmation of my UM order for the last parts (fans & bracket & stuff). So It looks like I should be getting somewhere next week Ofcourse I forgot some stuff like the feeder spring and bearing but I'll hopefully have some alternatives laying around

 

[mastory 44]

I imagine that in time, the design might start to include inserts for the mating surface. Maybe something sort of like the thorlabs design on their KB1X1 part (I hope that their design isn't patented.)

I think the advantage of slightly over defining the coupling is that you have a little more insurance against wear. What I have found in practice, is that PLA will tend to work itself into a perfect fit over time.

edit: Just thinking. For the inserts, on one side you could have a plate to trap the ball bearings and on the other side you could have a precision plate with slots cut for the ball bearing to mate with. Both plates could probably be relatively thin and fit on top of a 3d printed structure.

 

That Thorlabs part is pretty cool. It should be easy to duplicate in printed parts. You just have to press dowel pins in for the rods, and ball bearings into the other half. A key thing though is the devices ability to resist shearing forces is relative to the magnet pull and the angle of the engagement geometry (and the friction of those surfaces). I think with a set up like the Thorlabs part, this angle will be relatively shallow thereby lessening the ability to resist lateral loads.

 

[mastory 44]

I like cone B since it might get more x/y as you say. Also the cones need to have some 'slippery' so they disconnect on a smooth way. I like your B cone. I'll try that for me second part of the designs as soon as I find a company that can make me some aluminium.

 

I'm not sure I'm understanding you correctly. To use my suggestion, you need a complimentary set of A's and B's in the least, if not the C for the third. The main idea is to not have competing geometry fighting for registration in the same direction. Another option would be use the A and B features together with a raised step or spherical surface (such as a rest button)