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Nick's 3D printer build
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Nick
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Yep, its a PTC element. The thermal camera shows the actual ceramic heater parts are at 200 degrees - how do PTC heaters self-regulate their temperature? I replaced the fan with a higher flow rate one as I figured it was better to have lots of warm air rather than a trickle of really hot air - does that sound reasonable? Perhaps I need to check what the actual air temperature is coming out of the heater - it feels quite hot but maybe not enough.

The heater is recirculating the air - there a some leaks around the edges of the box but not much heat is escaping that way.
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Post Mon Jul 11, 2016 10:04 am 
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Nick
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"Well, there's your problem!"

I just realised what the problem is, and its shown right in that last thermal image. The fan is forcing so much air through the heater that the average air temperature is only getting up to around 55 degrees. The answer is to use a slower fan that allows the air to get up to a higher temperature as is passes through the heater element. I will dig out a slower fan or slow the current one down.

I still think a high flow rate is better for evening out the temperature inside the enclosure, so maybe a second fan just to circulate the heated air is worth trying.
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Post Mon Jul 11, 2016 10:17 am 
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DumHed
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if the box is sealed the heat should be staying in, so the flow rate shouldn't make much difference
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Post Mon Jul 11, 2016 10:42 am 
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Nick
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More parts:

Virtually all the parts have arrived now; I just received the electronics and the X axis slide:



I can see why the HiWin linear slides are used in high-end machinery, its made like a Swiss watch and has absolutely no play in the carriage. The controller board and LCD control panel also look well made. The panel isn't colour or touch sensitive but still an improvement on the Cocoon.



The controller really packs a lot into the 56 by 100mm board, I particularly like the replaceable stepper drivers. Panucatt have three different stepper modules to choose from, or you can wire larger external drivers.



The longer Z axis rod and the trapezoidal thread arrived from TEA transmissions. TEA had really good prices on the 12mm rod, less than the CNC Shop for better quality chrome plated rod. The threaded rod also looks to be good quality but the bronze nuts are a huge disappointment! They are very loose on the thread and have a ton of backlash Crying or Very sad. They may be acceptable as they will be pre-loaded by the weight of the X axis gantry.

The big question now is whether to work on the custom parts for the printer or parts for Decimator Laughing.
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Post Mon Jul 11, 2016 12:28 pm 
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Nick
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Its just raining parts today; I'm like a fat kid in a chocolate shop - I don't know what to grab first Laughing! The power supply, felt insulation, hardened nozzles and bed heater all arrived and now its just down to the home-made parts.

I experimented with the leadscrew and nuts; with a small spring between the nuts all the backlash disappears without adding much friction. It can be added to the design quite easily, the question is whether its worth it?
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Post Mon Jul 11, 2016 5:42 pm 
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Glen
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Our plasma cnc has an axis off some 3d printer angus had, Theres the standard bolt on acme nut attached to the z axis block with a floating nut on the bottom and a spring between. The floating nut has two flats on it and sits in a double D hole in the z axis block. Seems to work but if you dished out the money for hiwin slide might as well just use a ballscrew.
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Post Mon Jul 11, 2016 6:19 pm 
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Nick
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That arrangement is exactly what I thinking of! There are some issues with using ball screws: The 16mm size is common and relatively cheap but the size of the nuts is huge compared to an 8mm ACME nut and will mean a major redesign. The other problem is the pitch: most 3D printers have a 2mm pitch and the ball screw is 5mm, leading to a loss of precision and having to mess about with the firmware.

Unless I get unknown quality 8mm ball screws off Alibaba, they are very expensive. Perhaps the best thing is to complain about the fit to TEA and see if they can do anything about it - worse case is two extra nut for $50.
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Post Mon Jul 11, 2016 7:56 pm 
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marto
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I am seeing a lot of weight going in to printer here. I hope its decoupled from the head?

Realistically it doesn't need to be very rigid at all its not like a mill where 1mm of deflection is going to kill you. Mass for the vibrations is the big thing and I have found that as you get to the speeds that you actually get into trouble with rigidity you are already beyond the point where your extruder will struggle. Simply because of the amount of heat you need to put into it.
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Post Mon Jul 11, 2016 9:55 pm 
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Nick
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Good points! I probably went waaaay overboard on the rigidity; I started out designing a printer and ended up with an industrial gantry router Laughing. This is the 75 x 38mm X axis channel and the 63 x 63 Z axis towers:



Those Z towers could easily be filled up with concrete or epoxy granite to really add vibration killing mass.

I am keeping the fast moving parts as light as possible; the X carriage only has the hot-end, cooling fan and levelling sensor mounted on it and the heavy extruder is fixed to the frame with a Bowden tube feeding the filament.

I'm not sure what you meant by decoupling the weight from the head?

With the printing speed, I will be happy if the printer only goes as fast as the Cocoon. To try to print faster, I got the E3D Volcano hot-end, which is designed to transfer as much heat into fast flowing filament as possible:



It has the heater aligned with and very close to the nozzle. It comes with up to 1.2mm nozzles, this is the 0.4 and 1mm versions.
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Post Mon Jul 11, 2016 10:44 pm 
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Nick
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TEA's response to the wonky lead nut was disappointing - they basically ignored it all together and just asked for more details on the ball screws I asked for a quote on. They have to order them in from O/S, which will take weeks so I am not going to bother Mad.

Perhaps this is the simplest option:



The Ninjaflex washer takes out all the backlash once it is slightly compressed between the nuts. It is a bit too stiff at the moment so another prototype is needed to get it just right. Once the tension is adjusted just right, the washer can be glued in place to stop the nuts separating.
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Post Tue Jul 12, 2016 9:38 pm 
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Valen
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Send this guy a message about your ballscrew/nut desires, he may well be able to source them, and he does the end machining as well ;->
http://stores.ebay.com/linearmotionbearings?_trksid=p2047675.l2563

He's pretty quick off the mark and did all the stuff for our mill.
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Post Wed Jul 13, 2016 9:15 am 
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Nick
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Now that the bots are well sorted for the Nats event, its back to the printer. The Z rail support blocks are finished after some drama - who knew that a 12mm drill cuts holes well under 12mm?

Most of the aluminium is now rough cut to size and ready for machining. This is a mock-up of the block that couples the Z and X axis; it is probably the most complicated part of the build and will make the top of the printer extremely rigid:



If the leadscrew & nut don't work out, there is room to bore out the block and fit a small ballscrew. Now that the aluminium is cut and the size of the printer is locked in, its time to make the plywood base. It is 600 by 640mm, surprisingly huge given the build plate is only 300 by 300mm.
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Post Sun Jul 17, 2016 7:55 pm 
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Nick
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More testing:

The printer build is still taking a back seat to championships preparation but I had to test out a heated bed idea on the i3 printer today. Printing with HIPS filament requires a 110 deg, C bed temperature and after a very long warm-up time, the i3 could only manage 96 degrees, well short of the target.

One of the features on the new printer is insulation on the bottom of the bed heater to decrease warm-up time, so I tried it on the i3:



This is two layers of felt, wrapped in a layer of kapton. The kapton just holds the felt together and makes it easy to slide under the bed. When inserted the insulator completely fills the gap between the the plates, which is important - one layer didn't have much effect. With the insulator in place, the bed gets up to 108 degrees, close enough to the recommended setting Very Happy.
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Post Tue Jul 26, 2016 5:39 pm 
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Nick
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Assembling the printer base:

Its been a while, what with the national championships and multiple bot builds getting in the way. Today, I made a serious start on the base for the printer; its made of two 18mm sheets of marine ply 600 x 645mm, glued back to back to straighten out the warp. It has been under-coated with a shellac sealant to keep out moisture and prevent expansion due to humidity changes. Once all the holes are drilled, it will be painted with hammertone paint.



There are so many things still to do that its hard to decide what comes next - probably replacing the printed platform supports with aluminium.
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Post Sun Sep 11, 2016 9:23 pm 
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ThomasMaloney



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Wow, this has been an article a long time coming. Although I would love to see some of the products from the home built 3D printer first before I go about to make one of my own. I admit I didn't read all the comments here, but if someone could also direct me to where to get the material that the printer will print with, that would be awesome! Cheers!

Post Mon Jul 10, 2017 2:21 pm 
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