Hello

Glad to see you having some fun. It is a huge learning curve. Small holes allways come out smaller than intended and may need to be larger 0.2mm say than the size you want in the 3d design. Outside sizes are normally ok.

The most important step to take is calibrate the extruder e-steps and then find a flow rate o match the roll of filament you are using. The esteps is done once only and matches the filament size to the knurled extruder wheel but the flow rate will vary from roll to roll of filament even of the same type.

Size problems come from over / under extrusion. To much will make a part come out bigger.

No need to calibrate X or Y

regards Steve

Looking good!

What material are you using? To some extent size errors are due to the material shrinking as it cools. For PLA I find that a good starting point is to scale by 1.005, ie, half a percent. Thin walls print best if they are a multiple of the nozzle size. My nozzle is 0.4mm so I chose 0.8mm, 1.2mm and so on. A raft or brim helps the first layer to adhere. It's usually controlled in the slicing software.

Andrew

Hi All,

I also treated myself to one of these just before Xmas and the initial setup was OK until testing time when the z axis was found to be binding.

Found an excellent YouTube source for a careful rebuild: The Edge of Tech

Then printed the dog which was perfect. Went on to do the top plate for a small tripod which was good but though holes a little undersized. Will post some pics after the new yea when we get back home.

Overall very impressed with the unit.

Happy New Year to ASll!

Martin

I have had an Ender 3 for a couple of months and am still climbing slowly up the learning curve (and at times it seems I need crampons and an ice axe …..!)

I had one issue when I tried to print a design downloaded from the internet and sliced it with the Creality software but twice it stopped halfway through at the same place (printing from SD card). Using Cura it printed OK.

I don't know whether it is a memory issue or a bit of iffy code in the downloaded design as I now have a good print and I don't want another. Since then I have stuck to Cura though.

Here is an original hard to find cast iron plane fence and the 3D print taken from its measurements:

Dimensions were all good within acceptable limits.

Cheers, Martin

However I'm wondering about the strength of teeth

The right choice of filament should allay any strength fears? Carbon loaded? Perhaps reinforcing, afterwards, with dowels in printed holes would provide extra rigidity? I’m thinking of getting a printer shortly, but have to wait for the too-popular Sovol to become available again…. and looking forward to IanT’s reports which hopefully will come along shortly.

.

I’m keen to see how that goes, Dave

[ being the general sort of mechanism scale in which I am interested ]

I’m almost certain that the Meccano gears are injection moulding, which of course can be more homogeneous than something built from extruded filament.

MichaelG.

I also had to change the pressure angle on my Balzer gears, partly to make the different pitch gears mesh and partly because of the same type of interference.

Interesting to see how you get on with gears. Using same printer with 0.4 nozzle, anything under mod 1 is a little rough on the tooth form.

You will also need to check/adjust carefully the wall count and thickness in the cura layer view. If that shows big gaps on tooth crowns, then there will be big gaps in the print and the teeth will be weaker. You have to play with settings to minimize the effect.

Second issue I had trouble with is elephant footing – tried every which way to get rid of that and in the end had to resort to chamfering the top and bottom layers.

third issue is differential shrinkage between filled area and solid top surfaces – there would be some shrinkage across the middle of the teeth relative to top and bottom cured to some extent by chamfering the top 3 or 4 layers.

if using PLA for gears, consider post print heat treating them ( soak at constant 60-70c for a couple of hours in thermo controlled oven). You will be amazed at how tough and heat resistant the gears become, but you will have to calibrate the shrinkage amount so you can size the print correctly to allow for, typically 3-5% reduction on the XY axis. if Z is important, then you may need to allow for 1-3% expansion. Depends on material, fill, thickness etc.

Having said that, eventually I have printed perfectly acceptable gears for the Myford and Minilathe that perform very well as screwcutting and feed gears. course they wont last as long as metal, but the ones I substituted on the minilathe driven off the metal tumbler pinion are showing no signs of distress after 9 months use and if I do break one I can just go print another!

Expect to print gears quite slowly with high fill and as many walls as you can manage to get a good tooth fill with a 50t MOD1 10mm gear taking about 2 to 3 hours to complete on the bed.

When using high fills and big gears, warping becomes an issue, so higher filament and bed temps needed which of course makes elephant footing worse…. and so it goes.

Edited By Martin of Wick on 30/12/2019 11:02:37

You lot ought to read my book

Overall size accuracy is generally good because its laid down bit by bit unless you get serious shrinkage or warping every bit stays where it's put and accuracy derives from the drive mechanisms which are lightly loaded and should be low backlash.

One issue is the 'ribbed' texture which means overall size as we measure it is over the outside of the ridges. If you make tow bits to fit together, these mesh together which can mean a 'perfect' fit ends up loose.

There are settings that you can use to compensate automatically for elephant's foot, the oversize of internal and external dimensions. It is worth printing simple test objects over and again to iteratively getting these settings right.

It's possible to adjust settings for thin walls, default is generally not to print anything with less than two passes (e.g 0.4 x 2 = 0.8mm with a standard nozzle). Easy to enable single thickness walls and some slicers will attempt thinner walls by reducing the amount of extrusion, but don't expect miracles.

The raft is good if you have a delicate object that is liable to break free during printing OR you want to avoid 'elephant's foot' so it's a good idea for gears.

The brim (like the brim of a hat) is excellent for adhesion and stopping distortion of corners, but has to be cut off, so not ideal for gears.

The skirt is the useful default if you are confident of bed adhesion, it gives the best finish on the underside.

Expect all sorts of entertainment when it comes to supports, Cura now has many different types and all I can suggest is playing with these.

There are also lots of fun settings like alternate extra walls which helps bind the walls to the fill and lots of fill settings.

One I like in Cura is 'fuzzy skin' which adds a random offset that gives a deeper but more attractive texture and an improved feel to objects. No good if you want a smooth or mating surface. I think one advance we can expect will be to assign different textures to different faces of an object.

Neil