Z-axis homing - Y-axis tuning - ClearPath servo firmware updates

Regarding the brake...

You can buy add-on brakes that work the the Clearpath from Automation 4 Less.  They are specifically designed for Nema23 and Nema34 stepper/servo frame sizes with 3/8" and 1/2" motor shaft sizes.

They essentially go between the servo and the existing mount, and are powered with 24vdc.  When the power is off, a heavy spring engages the brake.  When powered on, an electromagnet releases the brake.

They are not cheap, but neither are they extremely expensive.  Very easy to install, but will require another cable (two wires) to be run through the gantry to the brake, as well as a 24vdc power source and a relay to control the brake on/off. One of the Mesa outputs can be used to trigger the relay with LinuxCNC's "Machine-On" output signal.

www.automation4less.com/product/category...systems/servo-brakes

As was mentioned earlier, a gas spring (or two) would be significantly cheaper, but will require some fiddling and thought to install.  They can get a little awkward to mount as they need twice the Z- stroke length unless you mount them at an angle.

An internet image search for "z-axis counterbalance" should get you some ideas on springs, gas springs, and counterweights.

This gives me some things to think about for awhile. I'm very grateful for everyone's comments and suggestions and the time they took to post here for me. It's very kind.

I'll have to see about getting the proper PNP switch or the proper resistor somewhere. If those switches have a resistor and they work then maybe having two might not be a good idea? I'm not sure, but that's what my dad thought. I do think doing it right would be ideal though. So thank you to everyone for providing all of the information about them. It's super helpful.

The cost isn't really an issue, their price is fairly reasonable if they last, but unfortunately it seems I can't get those breaks delivered to Canada so maybe I can find them somewhere that will deliver to me or at least something like them, now that I know exactly what I'm looking for. In fact, I did a search and noticed there are actually similar ones on the Teknic website here:

teknic.com/products/spring-applied-power...rakes/NEMA-23-brake/

There are a couple things that concern me though which might help me choose between these types of breaks or the counterweight or gas spring breaks. I don't know if those Teknic breaks are as powerful as the other ones and maybe it doesn't matter, maybe they would be fine. I don't know how much force they have to hold so I suppose the first order of business is figuring out how to measure how much force it has to hold to know which break to get. I'm sure there are calculations and math and whatnot involved which I'm no good at so I'll try to do some research and see if it works out.

Another thing I'm curious about is when doing an e-stop if it uses the break and if there is a way to disable that or maybe that's something I would actually have to enable in the first place and it's disabled by default because I have to connect pins in hal. I only want to apply the break when the machine loses all power and not on an e-stop so that it doesn't wear out the break which I'm guessing is a thing. So I'm wondering if maybe there is some way to set it so that it doesn't use the break in an e-stop and only when the machine loses power or if it's just going to be like that by default.

Thank you everyone! This is very valuable information and I really appreciate everyone's time. This is really great. What a nice community. It's all starting to make more sense now with everyone's great knowledge being imparted onto me. Thank you!

Counterweight is the best solution, gas springs do work but require a lot of testing and adjusting and must have much more usable travel than the axis it is on as it does stiffen a lot near the end of the travel.
Brake is the worst solution as the whole weight of the axis must be countered by the servo drive/motor causing load all the time while the machine is enabled, and inevitably will drop a bit every time the machine is enabled and disabled.
E-stop should always engage brakes, but no worries about it, when the power is cut to the brakes they will lock the motor. Brakes should be controlled by the "machine is enabled" pin as that will engage them when there is a drive error or joint following error, and when e-stop is active.

swift.gate0199 wrote:

There are a couple things that concern me though which might help me choose between these types of breaks or the counterweight or gas spring breaks. I don't know if those Teknic breaks are as powerful as the other ones and maybe it doesn't matter, maybe they would be fine. 

They'll be fine.  You just pick the one that matches your frame and shaft sizes.

If you want to measure the z-weight, just put a kitchen scale on the router bed.  Let the Z-axis sit on the scale - maybe with a block between the spindle and scale - and that'll get you close enough if you go the counterwight/spring method.

The weight on the scale is not the force the brake has to hold; the brake just has to keep the screw from rotating - which is much less than the actual weight of the axis.  I bet you can hold it up with two fingers.

As Tommy indicated, all methods are some compromise.  Brakes add inertia to the rotating components and length to the servo assembly, counterweights add inertia to the whole moving mass, and gas springs - even constant-force types - can be fiddly to get the value and geometry right.

It all depends on what you feel more comfortable doing.

Hi swift.gate0199,

I am an Application Engineer with Teknic. I ran across your post and wanted to encourage you to contact Teknic’s engineering team. We should be able to provide recommendations regarding several of the issues you described.

You can contact Teknic’s support via our website ( teknic.com/contact/ ) or by giving us a call at 585-784-7454.

Best,
Bradley N. – Teknic OEM Application Engineer

Thank you for the all the help and the info everyone! This is awesome. I really appreciate it.