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Dale Dunn
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Dale Dunn
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I'm thinking sorta seriously about adapting this for the Z axis. It's probably cheaper than the Ø10mm bearing rods, and maybe easier to deal with (aluminum can be cut to length much more easily). With custom long carriages, it might even be more rigid.
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Hips?
Prints like abs but more resilient in my (limited) experience...

Cheap too... great material... going to print a lot of my ingentis bits in hips...

Don't know bout long-term tho...
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Dale Dunn
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Discussion  - 
 
Here's my idea for a Z axis drive for an Ingentis or derivative. Again, all three axes are shortened by 200 mm to keep everything in view.

The M6x1.0 threaded rod gives 0.005 mm per whole step, but will be admittedly slow. The threaded rod is supported by 696-ZZ bearings. I didn't want to support it at both ends, but with the Z stroke I think I can get, it will be 425 mm long. The green piece carries the nut and isolates the carriage (blue) from any wobble in the screw. It's a derivative of this piece: http://www.thingiverse.com/thing:20147 The nut carrier will twist slightly on the screw with any wobble, leading to small, cyclic Z position errors. If I have any noticeable banding, and I can't straighten the screw, I'll have to come up with a nut carrier that doesn't twist with wobble.

But all that's beside the point. The point is, driving the Z axis with a screw like this gives you a simple Z axis drive that won't fall when power is lost, and there should be room for 300 mm of Z axis stroke within the standard Ingentis frame dimensions. 

The pulleys for the Spectra line are 624-UU U-groove bearings. The square tube is more 10x10x1 aluminum.

It just occurred to me that the bearing at the motor end of the screw is redundant. And I have an idea now for a way to decouple screw wobble from the carriage without inducing any Z error. I'll implement that as the rest of the design matures.
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Didn't mean to have the last word ! I like this design idea for the economy of parts, and with a lead screw could be very good.
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OK. Well, I'll keep both links, just in case there's a problem. I can't remember if that sub-forum self-purges anyway.
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Attention Domino's Pizza: The blitz of unskippable 15 second commercials on YouTube has entirely put me off of your pizza.
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Drive fans, listen up. The US government thinks it can get its hands on the stuff you store online -- without a warrant. (At Google, we push back when they try.) We think they should need a warrant to see documents, spreadsheets, or anything else that's yours, whether online or offline. 

This petition to the White House needs your signature by Thursday to get a response, so tell the government to get a warrant: http://goo.gl/EozWJx
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Dale Dunn

General discussion  - 
 
I think it's time for me to start planning the upgrade to multiple extruders.
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Nice, picking away support material can be laborious
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Dale Dunn

Questions/Help  - 
 
A question from a stepper noob: I have steppers on hand from Massdrop, with current, voltage, and holding torque specs. For the purposes of designing and selecting related mechanical components, I need an estimate of the largest torque the stepper will deliver at common 3D printer voltages and current. Is it as simple as multiplying the holding torque by the ratio of rated electrical power to planned electrical power?
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OH, OK. So if I understand this correctly, 24V is only helpful if the controller can emit step pulses faster than the driver can maintain current at 12V. A clock-limited controller like the Arduino may not be able to deliver enough steps at 1/16 microstepping to justify higher voltage. So I would probably need to be willing to use 1/8 or lower microstepping if I want to take advantage of the speeds enabled by 24V. 

Since force on a wire (and thereby holding torque) is dependent on current and geometry only (EE principles is seeping back into my head from 20 years ago as I type), selecting supply voltage is a non-issue for my structural design phase. Perfect. Thanks tons.
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Dale Dunn

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 #HP
 
Here's a design study of a tool changer based on the old HP pen plotters. They didn't seem to need an extra motion control of any kind to pick or stow a pen on the carousel. I had never had an opportunity to dismantle one to see how they work, so a bit of Googling led me to the HP online museum where a user's manual showed me enough of the mechanism to figure it out. The gist of it is this: Spring-loaded fingers on either the carriage or the carousel grip the tool. During a transfer, the carriage is forced against the carousel, and the empty side fingers force the other fingers off of the tool, gripping it in turn. Every time the carriage and carousel come together, the tool is transferred from one side to the other.

I adapted that concept to an E3D V5 Bowden hot-end. The hot end is gripped on a modified fan shroud, instead of by the groovemount. In my models, the green side is the carriage, and the purple side is the station in the tool magazine (if the wiper wasn’t a dead giveaway). Clearly a lot of detail is missing, such as screws, and springs in the obvious places. I only put enough effort into the design to see if it pans out.

The tool-changer’s advantage is the lowest possible moving mass for multiple tools. Lower mass allows higher acceleration, which tends to allow higher quality or speed. The tool changer also allows the opportunity to design for large numbers of tools, including things that aren’t extruders. Things like digitizing probes, swivel-knives, pens, and maybe small machining spindles. 

The primary disadvantage is complexity. A printer with a single travelling beam (H-bot, CoreXY, etc.) can give up about 55 mm of travel on one side of the machine to mount a row of tool stations. So no other controls need to be added than are necessary for the tools themselves. Anything else will need to be able to move a magazine of tool stations into position for the carriage to pick tools from.

Whether it's worth the trouble is not an easy question to answer. The carriage-side parts are about half the mass of a 2nd E3D V5. The Kraken appears to be amazingly mass-efficient for 4 extruders. I think it will still add significantly more moving mass than this tool-changing carriage, but I don’t have good enough numbers for the Kraken’s mass to be sure the tool-changer complexity is worthwhile. It does seem obvious that the simplicity of the Kraken makes it an obvious choice as the development platform for multi-extruder printers.

I think something like this will become necessary in the pursuit of utmost speed, but for now, I think I’ll need to be content with mounting a 2nd V5.

Images and some models files in the Drive folder linked below.
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+Dale Dunn +Adam Thorp there are a number of reasons:
-Water cooling is a pain to set up and service. It also introduces a whole bunch of risk; I've not had a serious leak but with a moving carriage, there's a chance something will come loose and suddenly your PSU and elecronics are wet.
-It's hard to service and maintain; It's very fiddly to remove a Bowden tube or undo a blocked nozzle because everything is so close together.
-Micro adjustment of nozzle height is frustrating and requires fila gauges.

Don't get me wrong here, I like the Kraken, it's a fun HE but it's only generation 1 and there are plenty of improvements that could be made. Principally getting rid of the water and air cooling with several small fans. 
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Discussion  - 
 
OK, here's the idea I got based on the work +Shauki Bagdadi has been doing on his Quadrap. There's still a ton of work to be done here, but I've at least worked out that it all fits together without interference. Clearance is a little tight. There's 2 mm between the beams and 0.5 mm between the Ø5 mm shafts.

Right now, the moving mass is a few dozen grams more than his, but I have much smaller drive pulleys. So he should have higher travel speed, and I should be able to accelerate faster with the same steppers.

I'm still planning the same overall frame dimensions as Ingentis. I have the frame scrunched together to keep everything in view at the same time. Compared to Ingentis, this is using 19 mm less vertical space and perhaps 45 mm less horizontal space. I'll have a better number on that when I get an extruder carriage worked out. I don't intend to mount a Kraken. 

The drive pulleys are 15 tooth, 2 mm GT2, and all the bearings are 5x5x4 MR1052RS. Happily, the Ø10 mm bearing rods and their cost are gone.
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+Dale Dunn Strike what I said, you are not driving anything with the pulleys, you are simply moving the belt unidirectionally, in which case, since the bottom of your belt is parallel with your travel motion, it is the same as if you had both pulleys the same diameter.
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General Discussion  - 
 
Oh, so that's why it was pulling to the left.
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Yea I've also got one of the original ones too
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For those who remember back in the day.
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