Messages

11

General Mach Discussion / Re: Only X-axis motor is working

« on: April 09, 2018, 01:08:22 AM »

Hi,
I note you were talking 34 size steppers which could easily be 700 oz.in without a gearbox and therefore capable of 1500 lbf
at stall. 1500lbf deserves respect.

Craig

I've rethought the 34's. I have a plan for 23's with 430 oz/in which is still finger breaking territory.

12

General Mach Discussion / Re: Only X-axis motor is working

« on: April 08, 2018, 09:39:10 PM »

Without a gearbox, a crash should just cause the motor to skip.
I think it will be a good idea to design a failsafe element. Thanks for mentioning it. I will put it in the back of my head as something to work on.

13

General Mach Discussion / Re: Only X-axis motor is working

« on: April 08, 2018, 07:26:27 PM »

Hi,
all my ballscrews are direct drive. I use those el-cheapo aluminum couplers with a spiral slot in them. They flex a bit
and result in 'lost motion' which is not desirable but what has happened is on the odd occassion where I've crashed
the coupler shears off rather than wrecking the gearbox/stepper/ballscrew. Something like a mechanical fuse.


Craig

I was thinking of using those but maybe something a little beefier than the cheap Chinese ones. I know there are a few styles of the cheap ones though so who knows.
I don't need to buy a new ballscrew every time I make a programming mistake.

Maybe a coupler system like this will work

14

General Mach Discussion / Re: Only X-axis motor is working

« on: April 08, 2018, 06:07:59 PM »

I think you underestimate what a belt drive onto a ball screw can do. Do not EVER let any part of your body get in the path of an axis movement. These machines can crush skin and bone without raising a sweat.
I agree with Craig about the rest.

Cheers
Roger

I hope I didn't give the impression of ignorance on the strength of belt drives and such. I'm intimately aware of what kind of power I'm looking at.
I've been very lucky in life that my hard learned lessons haven't separated me from my body parts, not that it didn't come close a few times.

I was thinking direct drive with the ballscrew for a couple reasons. Reason one being that one ballscrew is already set up as a direct drive.
I suppose if I had an issue with the axis being too slow (unlikely on the lathe) then I could gear it up instead of down.

15

General Mach Discussion / Re: Only X-axis motor is working

« on: April 08, 2018, 01:31:35 PM »

Thanks again, guys.

I think speed won't be that much of an issue. True my ballscrews are 5mm but they will be on my mill/lathe and that would be plenty fast for that. Those would end up being direct drive with the numbers provided, though. I was intending to set up the long axis with a gear reduction but with the speed being set to what it is, I won't be doing that.

As for the steppers I have vs new ones, on the router table, I want to do the build with the new motors simply because it will be belt drive and not screw drive. The belt drive will need a little more torque than these little 1A motors can provide. It's going to be moving a 2.5 foot (almost one meter) carriage that will probably weigh 40 pounds (20K) on the X axis. I don't want to mess around there. I picked the motors I have based on specs on a machine that moves a similar sized carriage. It's just a CNC knife cutter but the dimensions are similar.

Hearing that the Gecko drives only have one setting for stepping (microstepping) is a little bothersome to me but I'm going with the voices of experience. The worst thing that could happen is I replace them with a different configuration and use them on a different project.

I don't know how much my PC would have to perform to get the kernel to run at 45mhz but it's a clean computer. The only thing it will be doing is running the Mach3 program.
I'm also not above upgrading that as well. In fact, it's part of the plan in the long term.

Keep in mind that everything is low budget to get proof of concept. Not including the CNC table itself, I'm only into this project a couple hundred dollars so far. I do have enough info on the components, now, to know it will work.

I really do wish I could put together an encoder feedback. I know it can be done but that's above my pay grade for a while. Someday, maybe.
Along with that, I eventually want to be able to do CNC threading on my lathe. For that I will need to make sure I have either a stepper driven main drive or an encoder on the main drive. That will be a different learning curve, for sure.

16

General Mach Discussion / Re: Only X-axis motor is working

« on: April 08, 2018, 02:15:18 AM »

I'm looking at these.
https://www.ebay.com/itm/THREE-CNC-Gecko-G-201X-ONE-YEAR-WARRANTY-stepper-motor-Drivers-WITH-EXTRAS-G-201/330679891164?epid=1726495475&hash=item4cfe0eb4dc:g:NtoAAMXQk-FRFA7r
Gecko G-201. They should be able to handle the finished platform. I like that they have built in anti-resonance.

17

General Mach Discussion / Re: Only X-axis motor is working

« on: April 08, 2018, 01:34:46 AM »

I was looking at VEXTA drivers and it seems I need to watch the ratings on them. The motors I'm going to use will be 3A so I can't be getting a 1A driver.

18

General Mach Discussion / Re: Only X-axis motor is working

« on: April 08, 2018, 12:57:39 AM »

Hi,
this is a capable driver:

https://www.ebay.com/itm/Leadshine-AM882-Stepper-Drive-with-Sensorless-Detection-Up-to-80VDC-8-2A/121235083471?hash=item1c3a2c90cf:g:Gd4AAMXQOT5Q~Sn9

Try one and see, you want a path to a solution, this is a path...

Craig

Thanks for the link. I'll have to wait for an Ebay 15% day and then place an order. (They've been having a lot of those days lately)
I think it might be a good idea to buy one and see how it performs compared to my TB6600 based driver.

FWIW, the current driver still loses steps even on 800 microstep setting. It just seems to be less actual rotation is missed. Load on the motor or no load on the motor seems to yield the same results.

19

General Mach Discussion / Re: Loud noise from steppers and machine

« on: April 07, 2018, 10:59:20 PM »

Having just gone through all this with my learning curve, I would say that you set things up differently. What you are now having is probably resonance.

The fact that you say the machine is cutting 4X the original configuration tells me your previous drivers were set to microstep and your new TB6600 drivers are set to single step.

I think that once you set the drivers to microstep, and recalibrate your settings back to their original, your problem might be solved.

FWIW< I'm also using the TB6600 based drivers and microstepping did a lot for my issues.

20

General Mach Discussion / Re: Only X-axis motor is working

« on: April 07, 2018, 10:54:28 PM »

I understand what you guys are saying and if finances worked that way, I would go that way.
I don't need a perfect table at the get go. I need proof of concept. Once I have proof of concept I can justify adding funds to the project. Any upgrades, that take funds, before proof of concept will delay the project.

The drivers will be easier to swap out than the motors will which is why I decided to do motors first. The power supply is something that I know isn't adequate for the proof of concept.