# Specific 3D Printers, Scanners, & Hardware > RepRap Format Printer Forum > MakerFarm Forum >  Lead screw upgrade

## adamfilip

Can anyone recommend a precision Ground Lead Screw or ballscrew and Nut that I could purchase that I could swap in for the existing Threaded rods on the makerfarm i3v 12"
ideally same diameter

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## printbus

I could have missed them, but when I looked into this before your last lead screw thread, the smallest I was finding were 8mm.

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## sniffle

depending on the pitch you may have to swap the X motors to a geared X motor to have enough torque to be able to lift the X carriage

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## printbus

Most know that I nitpick and analyze the core of these printers to no end...

The existing Z motors theoretically *should* have the ability to drive the Z axis faster, especially after reducing the microstepping ratio from 1/16 to say 1/4 (which I have done).  Reducing microstepping has two benefits. There's a limit to how many step commands Marlin can and will process in window of time, and the default 4000 steps per mm feed is already a pretty heavy number of step commands.  Reducing microstepping reduces the number of step commands required, or conversely, for the same number of step commands more rotation can be obtained.   Increased microstepping comes at a loss in torque; reducing the amount of microstepping should provide more torque.  There's a precision loss with reducing microstepping, but to date no one has challenged my position that we don't need 0.250 micrometer precision in the z-axis (1mm/4000 steps per mm).

In practice, however, I have found the Z motors can't be driven to the theoretical maximum on my 8-inch printer, likely because they just don't have the torque to do it.  Yeah, setting Z up with little acceleration might help but that detracts from the speed increase we're shooting for.  When I ran into that block, I dropped pursuit of M6 or M8 threaded rod upgrades, and certainly the lead screw thought.  

The x-carriage is surprisingly heavy.  I'm surprised by it every time I have the z-nuts disengaged.  The 10 and 12 inch printers will be even heavier.  The longer lead on lead screws is going to make things worse.  Not only are the narrower lead screws hard to find, they're also typically "4-start" threads and you have (IIRC) 8mm per rotation lead.  From the motor perspective, there's a big difference between moving the x-carriage 0.8mm per rotation with the M5 rods and 8mm per rotation with the lead screws.  Find a 5mm lead screw with no more than 2 thread starts and I'm on board.  Well, I'd give it some serious thought. 

Like sniffle said, before you know it you're looking at geared motors to deal with the torque.  The other option I've pondered is actually adding a counterweight for the X-axis.  That's not really all that far fetched - put pulleys at the top of the frame, looping lines from the X-carriage over the pulleys to some fishing weight lead ballast on the back of the frame...

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## sniffle

Considering most of us are printing at either .2 or .3 mm layer height, inluded with the geared torque that gearing is also how we regain that precision for moving those small movements.

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## adamfilip

I need to replace one of my z rods as its now bent, so I would like to take the opportunity to switch to a 3-4mm lead screw or ball screw if budget permits

1mm per rotation preferred
But I'm willing to look into geared steppers to achieve better precision

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## printbus

> no one has challenged my position that we don't need 250 micrometer precision in the z-axis (1mm/4000 steps per mm).


Wait. I forgot the conversion from millimeters to meters.  The Z axis resolution is actually 250 nanometers per step.

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## adamfilip

http://www.mcmaster.com/#precision-a...screws/=vtnouc

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## adamfilip

Thoughts on this lead screw
http://www.mcmaster.com/#6642k11/=vtockj
comes in 18" lengths

and either these nuts
http://www.mcmaster.com/#6642k31/=vtoeev

or these nuts
http://www.mcmaster.com/#6642k21/=vtoexq

Each rotation is 1/41.7" = .02398" = .609mm

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## brochapman

For what its worth I did this mod http://www.thingiverse.com/thing:449341 and have had much better z axis movements and resolution.  I originally got two 12" acme threaded rods and that greatly reduced the z height, I have since purchased a 36" piece and cut it down to the same length as the stock threaded rods.  

I know this is not a precision lead screw but it works really well for me.

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## printbus

> Thoughts on this lead screw


I'm going to leave this to anyone who's already done any form of a lead screw replacement.  I think it was TechMasterJoe that said he had bought some rod to use. Where's he at with his mod?

I think it was either Prusa himself or Triffed Hunter that argues that on a threaded rod Z you ideally have a layer height that is an even number of full steps (not a microstep).  I didn't bring up the Prusa calculator, but it seems if you follow that rule you'd end up with some odd layer heights.

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## MiniMadRyan

> I'm going to leave this to anyone who's already done any form of a lead screw replacement.  I think it was TechMasterJoe that said he had bought some rod to use. Where's he at with his mod?
> 
> I think it was either Prusa himself or Triffed Hunter that argues that on a threaded rod Z you ideally have a layer height that is an even number of full steps (not a microstep).  I didn't bring up the Prusa calculator, but it seems if you follow that rule you'd end up with some odd layer heights.


This was of great discussion over on the printrbottalk forums, as the Printrbot simple used an acme rod. The layer heights suggested were weird, 0.28, 0.323 and so forth depending on what you wanted.

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## printbus

> This was of great discussion over on the printrbottalk forums, as the Printrbot simple used an acme rod. The layer heights suggested were weird, 0.28, 0.323 and so forth depending on what you wanted.


Yeah - I've previously joked about how when I compared the effect of metric and Imperial rods in the Prusa layer height calculator, I thought about sending Colin a thank you note for using metric rods in his printers.

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## MiniMadRyan

> Yeah - I've previously joked about how when I compared the effect of metric and Imperial rods in the Prusa layer height calculator, I thought about sending Colin a thank you note for using metric rods in his printers.


I agree. I remember the weird layer heights on my printrbot; in order to minimize the 'z-ribbing' effect on prints, caused the prints to be i believe 2% taller than they should have. Aside from some minimal wear on the metric rods on the MakerFarm, I've been more than happy with their performance.

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## printbus

> For what its worth I did this mod http://www.thingiverse.com/thing:449341 and have had much better z axis movements and resolution.  I originally got two 12" acme threaded rods and that greatly reduced the z height, I have since purchased a 36" piece and cut it down to the same length as the stock threaded rods.  
> 
> I know this is not a precision lead screw but it works really well for me.


When I was looking for solutions earlier, I had ran across that.  It looked like a promising option, except for the possible issue with Imperial vs metric threads.  Can you elaborate on what you mean by "much better z axis movements and resolution"? How do you have DEFAULT_AXIS_STEPS_PER_UNIT and DEFAULT_MAX_FEEDRATE set up for the Z axis?  Have you had any issues with the NEMA17 motors being able to drive the Z axis?

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## brochapman

> When I was looking for solutions earlier, I had ran across that.  It looked like a promising option, except for the possible issue with Imperial vs metric threads.  Can you elaborate on what you mean by "much better z axis movements and resolution"? How do you have DEFAULT_AXIS_STEPS_PER_UNIT and DEFAULT_MAX_FEEDRATE set up for the Z axis?  Have you had any issues with the NEMA17 motors being able to drive the Z axis?



I am at work now, so this is off the top of my head.  DEFAULT_AXIS_STEPS_PER_UNIT is set to 2015.7 for Z, the person that designed the mod says it should be 2015.748.  I dialed in 2015.7 through the front panel and have not looked back.   I will have to look at the firmware tonight to tell you the MAX Feedrate.  The Nema 17 motors have had no issues with driving the acme screws.  I had my concerns and kept monitoring them for over heating and they actually stay cooler now than with the threaded rods.    Here are a couple pics of my install, http://www.thingiverse.com/make:100198 (please ignore the wiring mess, its on my todo list to clean up  :Smile:  )

What I mean by better resolution is that before I would randomly have tiny gaps or bad layer adhesion.  I tried everything people recommended but it was random, the first 20 layers would be fine then a bad layer, then 10 more and another bad layer.   and it was completely random, next print it may be 10 layers before a bad one.  I was thinking it was a bad spot in the threaded rods so I replaced them with no change.   my original threaded rods had a slight bow to them and that always bugged me.  Now after this upgrade all those issues went away.  

Like everything it seems in 3d printing this is my experience and your mileage may vary.  I never liked the threaded rods with the tubing connector.  

I will try and get some pictures this evening to show how it prints now, I think all the old prints are broken apart in my scrap pile.

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## usarmyaircav

I will keep this in mind as an upgrade, as I seem to have some inconsistent layer gaps, and my z rods are not straight and it bugs me, so this might be a nice update, and potential fix.

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## adamfilip

What do you guys think of this product i found on amazon
http://www.amazon.com/Miniature-Qual...s=M6+Leadscrew

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## printbus

> What do you guys this of this product i found on amazon
> http://www.amazon.com/Miniature-Qual...s=M6+Leadscrew


Interesting...

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## adamfilip

http://www.qtecstore.com/pages/screw...rive/page.html

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## adamfilip

OK i ordered two of these..hope they are going to work well

http://www.qtecstore.com/pages/screw...rive/page.html

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## sniffle

I'm interested in how this turns out, and how you install them, try to remember to take lots of pics because if this turns out well there will probably be several who do this :-)

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## adamfilip

im considering switching over to a Nema 17 Geared stepper to give it more resolution. but im confused about what voltage range and amperage i can run on a rambo

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## adamfilip

I am going to need to add a 2nd backup Z endstop incase it decides to forget the drop the ABL probe and since the Lead screw block is solid.. unlike the Nut trap used with the stock config.. I iwll need to readd my bed springs for safety so if it doesnt dive down.. it wont crack the glass or something else

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## sniffle

What about attaching it to the x carraige?  How are you planning to handle that?

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## rhonal89

Anyone seen this. http://www.thingiverse.com/thing:687929/#files . Looks like it would be a good upgrade to the wood frame. Video  http://youtu.be/6SyZbSSrLB8

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## adamfilip

> What about attaching it to the x carraige?  How are you planning to handle that?


Im hoping to go directly into the extrusion.. but I will see how things align, its taking a while to get the parts.. hope it shows up soon

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## adamfilip

I finally received the lead screw order.. Looks really good.. I will try and get it setup and running this weekend. stay tuned for Work in progress photos.

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## adamfilip

Spent half the day making the necessary parts.. 
Longer mount for Z motors, Plate to attach to X and topper bearing plate
had to make a few small corrections.. and drill out a hole or two i forgot
make s shim and its looking and working really well so far

Havent adjust the Steps yet.. thats next

the quality of the leadscrew is excellent.. very impressed considering the cost

I still need to put back the springs onto my headed bed.. as a safety as with this setup there is no nut trap that would pop out
and im going to add a second Z endstop so it triggers before the spring bottoms out. last thing i want is if the Z goes crazy for it to crank down and crack my glass or worse.

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## adamfilip

A few more pics

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## adamfilip

I will update my stl files and post for all to enjoy

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## misquamacus

That all looks great, good job! I'm looking forward to your results.

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## adamfilip

I wired up so two endstops are connected to the same plug into the rambo
but now neither seem to trigger it.. I dont understand why..
they should each operate independantly.. they are not in series

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## adamfilip

ok, i figured it out.. looks like th Microswitches are on when not pressed and off when pressed. so I rewired them in series, and all is right in the world  :Smile:

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## adamfilip

Stepper steps changes from 4000 to 2560 in Marlin with the M8 Lead screws are 1.25mm per rotation, vs .8mm per rotation
im thinking of getting a 5:1 or 4:1 geared stepper

do you guys think it will make any difference
i would turn off microstepping in marlin this way

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## sniffle

> Stepper steps changes from 4000 to 2560 in Marlin with the M8 Lead screws are 1.25mm per rotation, vs .8mm per rotation
> im thinking of getting a 5:1 or 4:1 geared stepper
> 
> do you guys think it will make any difference
> i would turn off microstepping in marlin this way


you would also have more torque to handle the weight of the X carriage and it would take a lot of the strain off of your motors... you might still use microstepping, but only 1/4 as a 4:1 ratio using 1/4 microstepping would technically give you 1/16 microstepping... but i don't know how marlin would handle that unless there were an option somewhere to set that you are using a geared stepper...  that's a subject that needs further review... but it's a thought either way

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## adamfilip

I have updated my files and posted them here

http://www.thingiverse.com/thing:704091

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## adamfilip

I think you would simply adjust the steps.. and change the microstepping
no other adjustment should be necessary

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## adamfilip

would it matter if i went with a geared nema 23 vs a 17
im not concerned about the torque.  I just want it to be super accurate

http://www.omc-stepperonline.com/gea...pg4-p-145.html

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## sniffle

i thought about that after i posted that just now got back to actually say something :-P

higher gear ratios are more important for accuracy, but torque is also important to be able to move the carriage...  a nema 23 would just add even more torque

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## jheikkila54

Question in regards to this... Would going with the m6 lead screws be a better option then the m8?

http://www.qtecstore.com/pages/leads...nut2/page.html

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