I would like more z movement. Does anyone have experience swapping out the z motors with longer screw ones? Where would I find the size and specs that I would need to match? Is there enough interest to make a link to longer motors and rods (or just the regular ones) in the not shop?
wouldchuck wrote:
I would like more z movement. Does anyone have experience swapping out the z
motors with longer screw ones? Where would I find the size and specs that I
would need to match? Is there enough interest to make a link to longer motors
and rods (or just the regular ones) in the not shop?
aliexpress will have them available in many lengths, get something with an 8mm
lead screw and as small a motor body as you can get (otherwise the motor will
keep you from going down as far as you probably want to)
before you order, check how far the current motors move the nut with one turn
and get your new ones to match (it’s probably 4mm or 8mm/turn)
the new motors will come with new nuts.
David Lang
2 Likes
Thank you. That is really helpful. I did not know about that.
wouldchuck wrote:
Thank you. That is really helpful. I did not know about that.
In theory, we can change the pitch of the Z axis, but it’s best to match and
avoid surprises 
David Lang
Found the description
8mm x 2mm pitch lead screw with POM nut.
42mm by 42mm nema 17 short size 23mm tall
4 wire
I suppose I would like a 200mm shaft or so.
Ideally I am looking for the exact thin motor we have but with a longer shaft.
When I search for this I get thousands of hits that aren’t quite right. Is there something I am missing about online shopping for stepper motors? I am getting bogged down.
It looks like I can buy a new longer shaft and there is a video that shows a guy breaking the glue that holds the shaft in place and then replacing it but it feels like there might be a better option. I can get clamps that would let me add the new screw to the end of the old one. That is cheap and might work.Matching 10mm linear bearing rod (300mm) is kind of expensive from grainger
wouldchuck wrote:
Found the description
5mm x 2mm pitch lead screw with POM nut.42mm by 42mm nema 17 short size 23mm tall
4 Leads
so, this says that it’s 2mm between threads, but there are 4 threads
interleaved, so it will move 8mm per rotation
I suppose I would like a 200mm shaft or so.
Ideally I am looking for the exact thin motor we have but with a longer shaft.
When I search for this I get thousands of hits that aren’t quite right. Is there something I am missing about online shopping for stepper motors? I am getting bogged down.
it is a mess
this looks like about the right thing:
the leadscrew is listed as Tr8x8(P2x4), so this is an 8mm diameter (Tr8), but
the same 2mm pitch with 4 starts(leads)
this is nema 17, so it matches the 42x42
this is showing 34mm tall, which is shortish for a nema 17 but not as short as
the stock 23mm. This means that ‘all the way down’ would be 11mm higher than
stock, (adjust the z offsets or spoilboard thickness accordingly)
It looks like I can buy a new longer shaft and there is a video that shows a
guy breaking the glue that holds the shaft in place and then replacing it but
it feels like there might be a better option?
a good system has the motor shaft and the leadscrew as one piece of metal, not
glued together
https://www.omc-stepperonline.com/250mm-5mm-diameter-2mm-pitch-trapezoidal-lead-screw-ls-aa-250
I can get clamps that would let me add the new screw to the end of the old one. That is cheap and might work.
that seems like a mess
Matching 10mm linear bearing rod (300mm) is kind of expensive from grainger
look at aliexpress, they will be much cheaper
David Lang
1 Like
Thank you for helping to look. Yeah It is hard to find something that is as short as the original motors. When I wrote 4 leads, I meant 4 electric connections. Some of the motors were separated out that way too. I don’t know how many threads our stock maslow has on the rod I just tried to follow one around and it may only be one thread? @bar do you know what the specs are on the stock motors? It looks like motors are sold by how many degrees each step is
Here is the video of the guy switching out leadscrews: https://www.youtube.com/watch?v=NmmFoBsSfEQ
It looks like the prusa motors are a little taller and have a different number of threads on the screw but might work. Z Stepper Motor w/ Leadscrew for Prusa i3 | Partsbuilt 3D
Yeah, it took me a long time to find those 
I believe that they had to be custom made because I couldn’t find any off the shelf that were short enough.
They are 1.8 degrees per step
1 Like
Bar wrote:
Yeah, it took me a long time to find those
They are 1.8 degrees per step
what is the lead screw? 8mm diameter, but how many threads at what pitch?
David Lang
Thank you. It is 8. Will change it above think the calipers were in a groove
I suppose the diameter of the shaft wouldn’t matter too much if the pitch was still good. So for replacement and forked designs we will need to have a batch made or use thicker. The ones made for the prusa MK3 look close
I just wound a piece of string around it. It is a single thread at 2 mm
1 Like
wouldchuck wrote:
I suppose the diameter of the shaft wouldn’t matter too much if the pitch was
still good. So for replacement and forked designs we will need to have a batch
made or use thicker. The ones made for the prusa MK3 look close
The diameter of the shaft will determine the size of the nut, if the nut is a
different size, then it won’t fit the bolt holes in the frame.
If the pitch isn’t the same, that means that it will take a different number of
steps to move 1mm. FluidNC is designed to do this with steppers, and it should
be in the maslow.yaml file. I think this capability is still there, but enough
has been changed that I wouldd want to dig in before assuming it’s still there.
when worrying about the thickness of the motors, think about what bits you use
and how far down you have to move to use them. The stock maslow design puts the
end of the chuck just above the botton of the sled. If you use a spindle instead
of a router, its really easy to have the chuck go out further (which would
eliminate a good chunk of the problem with thicker motors.
I also have designs that would let you flip the motors over, put them at the top
of the towers
see
David Lang
1 Like
Thank you. A spindle might be a good thing to buy at some point. It would do many things that I want. I feed my maslow money slowly so motors felt affordable but 500 or so for a spindle seemed more than I was happy dropping all at once. It is one of those things though that would probably save money, frustration and time in the long run.
wouldchuck wrote:
Thank you. A spindle might be a good thing to buy at some point. It would do
many things that I want. I feed my maslow money slowly so motors felt
affordable but 500 or so for a spindle seemed more than I was happy dropping
all at once. It is one of those things though that would probably save money,
frustration and time in the long run.
that would be a very expensive spindle
something like this (0-100v DC) ~$100
or this (48v brushless) ~$150B
David Lang
1 Like
Sorry, bit late to this, I have done a bit of experimenting around these on my various builds.
I think most of this has been covered, but just in case:
- The rods are 10mm, look for ones for linear bearings / linear motion such as:
Amazon.co.uk
If they are too cheap they are likely to be not very dimensionally accurate. - The Z lead screws are 8mm diameter, 2mm pitch/lead (Tr8x2).
- If you want to use Z-motors it’s non-trivial but kind of doable (i’ve experimented for my big-spindle build). I think bar said in the thread they’re custom, if you want to DIY you need to take a standard Nema 17, flip the core (so it can be screwed to the sled), and then use a 5mm-8mm solid coupler. Unless you’re using a spindle you’re likely to end up with the collet height too high (which might not be unsurmountable, i’ve experimented a bit with moving the lead screw nut up into the columns). And you need some wiring adapting too as most NEMA 17 motors come with 6-4 pin JST-XH leads, and you need male JST-PH to plug into the control board.
If someone organised a longer-lead-screw group order for some motors I’d probably join in, though the MOQ might make it unrealistic…
1 Like