My custom Cartesian

OBELIKS

Do you need to move it up?
I think that if you move the bearing on the screw above the pulley (attach it to the vertical extrusion), both pulleys will be roughly aligned.

wilriker

@obeliks said in My custom Cartesian:

I think that if you move the bearing on the screw above the pulley (attach it to the vertical extrusion), both pulleys will be roughly aligned.

I think this might result in a very odd and unfavorable angle to fix the bearing. If you look at the picture of the full printer in the second post you can see that it is quite a distance from the vertical extrusion to the lead screw.

Still, reverting-with-improvements will give me the best solution, I think. I will get an even finer Z resolution and free access to my leveling screws again. And from what I read in another thread these jaw couplings should also reduce noise a little bit (which is nice but honestly not really important on the Z axis).

OBELIKS

Oh, I didn't notice the distance.

wilriker

@obeliks Yeah, the recent images are misleading in this aspect.

stewwy

Just converted to a 2mm lead screw, now I can print at any layer height to 2 significant digits without worrying about height accuracy.

i.e. 0.10, 0.11, 0.12..... etc

Previously, with a 'normal' lead screw, the only accurate heights where , 0.1, 0.15,0.2....etc.

first print is on as I type

oops, meant to mention, you are unlikely to need a reduction ratio because the torque needed is much reduced from an 8mm pitch.

Torque needed should be about 25% of what is needed for an 8mm pitch, the number of steps has changed from 400 to 1600.

wilriker

@stewwy said in My custom Cartesian:

Just converted to a 2mm lead screw, now I can print at any layer height to 2 significant digits without worrying about height accuracy.

i.e. 0.10, 0.11, 0.12..... etc

Just did the same today. Images will follow.

Previously, with a 'normal' lead screw, the only accurate heights where , 0.1, 0.15,0.2....etc.

That seems odd to me. What lead did your lead screw have previously? On 8mm lead it would be 0.04mm increments. To get to 0.05mm increments it would have needed a lead of 10mm. I rarely came across this type of lead.

oops, meant to mention, you are unlikely to need a reduction ratio because the torque needed is much reduced from an 8mm pitch.

Torque needed should be about 25% of what is needed for an 8mm pitch, the number of steps has changed from 400 to 1600.

I never used the reduction ratio because of lack of torque. I only used it to convert a physical 8mm lead into a logical 4mm lead.

stewwy

@wilriker said in My custom Cartesian:

That seems odd to me. What lead did your lead screw have previously? On 8mm lead it would be 0.04mm increments. To get to 0.05mm increments it would have needed a lead of 10mm. I rarely came across this type of lead.

You are right, we had a party last night so still a little hazy!

Note to self: don't press submit without thinking it through lol

deckingman

As well as better resolution, you get other benefits too from using a finer lead. Effectively you get better gearing so can use a smaller motor or a single motor to drive say 3 screws via a single belt. The shallower helix angle also means that if you have a heavy bed, it will be less likely to drop under it's own own weight. I did a bit of a write up on my blog almost two years ago which explains things https://somei3deas.wordpress.com/2017/01/31/z-axis-lead-screws/

stewwy

@deckingman said in My custom Cartesian:

As well as better resolution, you get other benefits too from using a finer lead. Effectively you get better gearing so can use a smaller motor or a single motor to drive say 3 screws via a single belt. The shallower helix angle also means that if you have a heavy bed, it will be less likely to drop under it's own own weight. I did a bit of a write up on my blog almost two years ago which explains things https://somei3deas.wordpress.com/2017/01/31/z-axis-lead-screws/

That write up is one of the things that prompted me to order one, so thanks

deckingman

@stewwy said in My custom Cartesian:

That write up is one of the things that prompted me to order one, so thanks

Blimey - that's 3 people who have read it

wilriker

@deckingman said in My custom Cartesian:

Blimey - that's 3 people who have read it

Does that include me already? Because I read it, too.

Phaedrux

@deckingman I read the whole rag front to back when I was planning out my printer. There must be a few of us with more time than sense.

OBELIKS

Definitely, that is a very helpful blog.

deckingman

Strewth - there are 6 of you who have read it!

wilriker

@deckingman I even have a subscription to your blog added in my feed reader, so I get notified of new entries even if you do not announce them here.

timcurtis67

@deckingman said in My custom Cartesian:

Strewth - there are 6 of you who have read it!

Ian,
Add me to the list. Now it's 7 people

lui2004

Hi

Is it possible that you can Upload your config for the anet am8 ?
Because i have the am8 with duet wifi and i dont know how to beginn

Thanks a lot

wilriker

@lui2004 said in My custom Cartesian:

Is it possible that you can Upload your config for the anet am8 ?

Sadly, I cannot. Except for the extruder and the PSU I more or less changed every single part of the printer for something different and I don't have an old version of my full config.g. The only thing remaining from that time is the excerpt I posted in post #2:

M92 X100 Y100 Z400 E96.939                         ; Set steps per mm (at default 16x microstepping)
M350 X16 Y16 Z16 E16 I1                            ; Configure microstepping with interpolation
M566 X600 Y600 Z24 E300                            ; Set maximum instantaneous speed changes (i.e. jerk) (mm/min)
M203 X6600 Y6600 Z720 E3000                        ; Set maximum speeds (mm/min)
M201 X2000 Y2000 Z100 E10000                       ; Set accelerations (mm/s^2)
M204 P400 T1000                                    ; Lower accelerations when printing though
M906 X500 Y500 Z500 E700 I30                       ; Set motor currents (mA) and motor idle factor in per cent (increments of 100mA, rounded down otherwise)

But what is it that you are missing to get your config completed? I am happy to help you with that part (even though answers on the weekend usually are very slow for me).

wilriker

So, some small updates here:
I am in the progress of switching to 24V. The PSU I already have, the bed heater is ordered from Keenovo (200x200mm, 200W, thermostat 150°C) and should arrive somewhen this decade (currently waiting on 5-6 shippings from China partially for over three months). Also heater cartridge is ordered.

Apart from that I am also switching to standby-hot-dual-PSU mode. I currently use an old USB phone charger to provide 5V to the Duet as well as to a small relay board. The relay then switches on and off via PS_ON and will give or cut power to the (still) 12V PSU. It let's me feel again a little bit safer in therms of failing MOSFETs and uncontrollable heaters.
The phone charger will be replaced by a small Mean Well 5V PSU (RS-15-5) somewhen in the next couple of weeks.

Wyvern

@wilriker
If you are worried about the heating element mosfets on the duet, you can install a mosfet tube, it offloads the board, going straight to the PSU and only uses the boad's mosfet circuit as a signal.

That's what I did with my ramps board with my big 310x310 bed, and since I still had the part, I put it on my duet, it allows the board to better cool the drivers since it's the board itself that is the heatsink.