Stepper motor brake

How to install 24 v electromagnetic brake on the x-rail stepper motor. On the journeyman x-50.

Hey Carl,

(continuing the discussion from Shutdown on wallmount)

the brake is mounted on the rear of the stepper, not on the front.

In case you cannot retrofit the brake to the stepper, you can also replace the stepper with one that already has a brake mounted. The X stepper of Journeyman is 23HS30-2804S (datasheet here) and the corresponding model with brake is 23HS30-2804D-B200 (datasheet here, brake datasheet here).

To be exact, Tom @TMToronto picked up his X-50 rail at the Onefinity Factory and reported the stepper is 23HS30-2804S-C1 but @onefinitycnc says here it’s a 23HS30-2804S-RV. Since I don’t have the machine here I cannot say immediately what stepper is found on mine.

What you also would need is a power supply with 24 V 500 mA for the brake.

EDIT: Just saw that the model with brake does not correspond because the one with brake has shaft diameter 8 mm while the other has shaft diameter 6.35 mm. Possibly manufacturer has motor w/brake with correct shaft diameter available. Will have a look at the weekend. If not, we got to get another coupler.

Hey Carl @Nightman,

a little update: My partner asked the manufacturer and the answer is you cannot retrofit this brake to Onefinity X-50’s stock 23HS30-2804S stepper, but you can mount it to model 23HS30-2804D which has a rear shaft. Unfortunately the latter (which is also available with brake already mounted) has a 8 mm ø shaft while the model on Onefinity X-50 (while being otherwise identical) has a 6,35 mm (=1/4″) ø shaft. So either we try to find a coupler with a 8 mm hole on one side or we could use a drill to enlarge the 6.35 mm hole on the coupler to 8 mm.

EDIT: Since the manufacturer offers a wide range of couplers, it is easy to find a suitable one to replace the stock 6.35 mm – 10 mm coupler on the Onefinity X-50:


8mm-10mm-flexible-jaw-coupling-20x30mm-cnc-stepper-motor-shaft-coupler--1656__background_cropped_67pct
Flexible Jaw 8 mm – 10 mm shaft coupler

What about this type?

Hey Tom,

ah, these mount on the front!

Had a look, the brake with NEMA 23 footprint is for 3/8″ (9.5 mm) ø shaft

https://www.idicb.com/-/media/Files/Literature/Brand/inertia-dynamics/catalogs/p-7874-idi-sections/product-page-specific/p-7874-idi-mpc-ordering-info.ashx

I have been contemplating a different solution to this issue, but for heavy spindles on the Z axis.
I started investigating constant force springs as a solution. Here is my idea for the wall mount application (forgive the quick crude drawing). It would take a bit of creative mounting, but I could see the end attaching to the Z assembly - the other coiled end attached with bolts where the x axis motor mounts. See examples below. Correct force of spring would need to be determined. It should line up nicely with my mounting suggestions.

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Some people prefer to counter the mass vs add more electronics that do not reduce stress/wear on the motor.

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Hey Tom,

Ah, okay! 1/4" shaft diameter, on input and output, here it is! Thank you!

So that would be a solution for Onefinity X-50 stepper. Would need to be planned with additional space for X motor.

MODEL PART
NUMBER *
NEMA
FRAME
INPUT
SHAFT
DIAMETER
(INCH)
OUTPUT
SHAFT
DIAMETER
(INCH)
TORQUE
(INCH/LB)
MPC23 8923-x331 23 1/4 1/4 3

I am tired got to go to bed!

Hey Tom,

I like your solution, because

  1. It’s logical, because you meet a force (the force of gravity) with an opposing force (the restoring force of a constant-force spring) – it’s like using anti-gravity. Fascinating.

  2. In contrast to the electromagnetic brake, you do not constantly consume 11.5 W of power.

But I also like Jim’s solution. Because

  1. solutions that consist of a piece of wood have been successful for millions of years. I like that!
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A brake would be needed if one of the axis is converted into a rotary axis. For a wall mounted 1F I would go with a spring to reduce the impact of weight (although most of that weight is on the Z axis when it’s on a table). But I would add a brake just in case. If the power goes out or you shut it down and the X axis isn’t at the bottom it’ll want to go there. I think it would be more of an issue with the Journeyman due to it’s X axis having a courser pitched lead screw.

Do you think it would best to go with a tool balance retractor. I have 2.2 kw spindle and 80 mm bracket on it. When I went to home it as soon as the z rail assembly touched the y rail to set the x hard limit it error out and shut the power off to the stepper motor. Which caused the z rail assembly to drop rapidly down to the other y rail. I caught it before it hit the bottom. I believe the weight of the spindle vs the makita router is to much for the sensitivity to set the hard limit. That is why I’m leaning towards a tool balance retractor. But I have to figure what weight range I need to get. What are your thoughts on this?

Thanks for your help,

Carl

I have seen people use a fishing scale, or you could use a Newton meter, to lift the mass of the combined assemblies. That would give an idea of the counter mass/spring force needed.

Some of the tools I work on have a brake on them specifically so if the power is cut to the stepper it prevents exactly what happened to Carl can’t happen.

Another option for a spring would be a window balance.

That is what I was thinking of using a fish scale. But, I have to wait till tomorrow to get it out of my boat. I’m new to this tool balance and tool balance retractor. I seen on you tube a video https://youtu.be/X7-6HAyUHcI
It shows an example of a balancer, retractor and a positioner. I think a positioner would best. What are your thoughts on this?

Thanks,
Carl

Those products look interesting. At first glance the positioner looks like the correct choice, but it might be worth it to contact the company (or others like it) to discuss your application. I think it really depends on the mechanics inside each. Regardless, I think the solution that does not require an additional force to extend the gantry would be appropriate.

I just checked the weight of the z-rail assembly w/2.2 kw spindle with fish scale and holding weight is approximately 25 lbs. So, I’m thinking a tool positioner of 25 to 30 lb. What are your thoughts on this? Wall mount

Thanks, Carl

Can you explain a little more on your statement ( I think the solution that does not require an additional force to extend the gantry would be appropriate). I’m a little confused about that.

Thanks,
Carl

I think I meant to say Z assembly not gantry.

Some of the tool positioners/extenders may require the use of extra force to pull down against an internal spring - in your case making the steppers work harder to pull down the Z assembly.

Did you check that you tube link out that I enclosed previously, the last example in the video caught my interest when he added extra weight and it didn’t move. But, with a slight tug or push it moved. That caught my attention. What do you think?