Cheap 3D printers

[John ShepherdParticipant @johnshepherd38883]

Neil

I take your point about some of my mods not making much difference but take issue on the 'mistake of replacing threaded rod with ball screws' . A machined ball screw can provide greater precision and at least equal resolution as long as you also upgrade the stepper driver.

There are many variable when 3d printing and I think it is good practice to reduce as many as you can for piece of mind if nothing else!

John

[ZebethyalParticipant @zebethyal]

I take your point with regards the precision of a ballscrew compared to a rolled threaded rod from a manufacturing point of view, but am struggling with how the ballscrew provides the same or better resolution.

Assuming a standard stepper motor with 200 steps per revolution, 1/16 uStep and a gear ratio of 1:1 (direct coupled)

For an M5 threaded rod (0.8mm pitch) you have 4000 steps/mm

For an Acme 1/4-16 (1.5875mm pitch) you have 2015.75 steps/mm

A Stepstick A4988 can do 1/16 uStep and currently costs £1.00 or less on Ebay, unless you are looking at 1/32 or better uStep which will cost much much more, you are not going to beat the threaded rod for resolution.

On my Prusa i3 clone I built from a set of printed parts I have M5 threaded rod with pvc tube as a coupling and have no issues with resolution and have only twice had issues with the coupling coming loose – I have had more issues with the original printed parts failing and needing to be replaced with items that have more infill.

 

Edited By Zebethyal on 15/11/2018 14:09:42

[Neil WyattModerator @neilwyatt]

Posted by John Shepherd on 15/11/2018 10:49:49:

Neil

I take your point about some of my mods not making much difference but take issue on the 'mistake of replacing threaded rod with ball screws' . A machined ball screw can provide greater precision and at least equal resolution as long as you also upgrade the stepper driver.

There are many variable when 3d printing and I think it is good practice to reduce as many as you can for piece of mind if nothing else!

John

It's the stepper, rather than the stepper driver you need to replace to restore the resolution, as ever finer microsteps rarely deliver real world increases in precision.

Going from a pitch of 0.75mm to 4mm (typical for ballscrews sold for 3D printers) is reducing the vertical precision by a factor of more than five, as most printers use 16-microsteps already, you would need to go to at least 128 microsteps to get better results and I don't think any affordable stepper is going to deliver even 64 steps with comparable accuracy to 8 or 16.

Neil

[JasonBModerator @jasonb]

Would some of that lost precision be regained by the better accuracy of the ball screw/nut combination compared with a bit of studding and whatever is used as the nut?

I can see that with a finer pitch you get better resolution but if that is say +-0.01 for studding vs say +-0.001 of a ballscrew you have gained as much as you have lost

Edited By JasonB on 15/11/2018 15:14:39

[Ian PParticipant @ianp]

I have some parts to make and the idea of an affordable (less than £250 say) printer rather appeals to me because making the part in the picture on the milling machine is a pain (I need about 50 of them) in about three weeks time. Currently I use Delrin because it machines nicely but the material is really not critical, although black is preferable.

Its about 20mm long and the protruding peg is 5mm diameter, am I being realistic in expecting to buy and assemble a printer and get usable results without a long learning curve?

Ian P

[John CParticipant @johnc47954]

I have several Aldi hand and power tools, all of which do 'what it says on the tin', but are not pretending to be high-end products. With that in mind, what would the forum think of this:

https://www.aldi.co.uk/balco-3d-printer-/p/086887240233900

John

[STUART BILLINGEParticipant @stuartbillinge76757]

What are peoples views on 3D printing model kit sprues that are no longer produced? Is it frowned upon? Is it legal?

[Michael Cox 1Participant @michaelcox1]

Posted by John C on 19/11/2018 17:05:09:

I have several Aldi hand and power tools, all of which do 'what it says on the tin', but are not pretending to be high-end products. With that in mind, what would the forum think of this:

https://www.aldi.co.uk/balco-3d-printer-/p/086887240233900

John

I bought one of the ALDI printers and I am very pleased with it. The only problem that I have had is that the springs on the bed for the levelling screws are too short and they do not hold the bed in a reproducable position. I 3D printed some spacers to fit under the springs and everything is better now.

Mike

[John HaineParticipant @johnhaine32865]

Posted by STUART BILLINGE on 07/02/2019 00:16:54:

What are peoples views on 3D printing model kit sprues that are no longer produced? Is it frowned upon? Is it legal?

If you do it for your own purposes and don't sell them I doubt anyone would object. Depending on how old the design is any copyright may have expired anyway.

[Rik ShawParticipant @rikshaw]

I bought one of the ALDI Balco 3d printers a few weeks back. It was brain dead on arrival – would not power up. After customer support led trouble shooting they advised that the power supply must be dead. Unit was returned and full refund issued without a problem.

A week after I returned it I noticed they had reduced them by £50 to £250 but now I see they are back up to £300 again.

Rik

Edited By Rik Shaw on 07/02/2019 12:08:40

[I.M. OUTAHEREParticipant @i-m-outahere]

One lesson i learned the hard way was to be mindful of the fact a cheap printer will have a cheap build surface that more than likely won’t be flat . This causes some headaches when you start using the whole build plate and i had a lot of trouble getting descent bed adhesion even with a raft, i changed over to pyrex for a build plate but discovered this was also warped . I have some new pieces coming from a different supplier and i hope they are at least reasonably flat , i havent measured how out of kilter the other pieces of glass are other than lay a straight edge over them and on one side it became a see saw and the other side had a substantial gap in the middle – maybe half a mm or so . The mk 2 heat bed i fitted is way better than that but it if i lay a straight edge across it at 90 deg to the sides it has at a guess a 5 thou dip in the middle that decreases as it heats up to near perfect at 70 degrees but laythe straight edge diagonally it is much worse so maybe some of the corners have dog eared ,might take it down the workshop and give it a rub on the surface plate with some blue and see how f i can sort that out as well.

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