Danilo, I am planning to build a MechMate in Hungary. May I ask you where did you order the laser cut and bent parts?

Many thanks!

Being from Hungary you will be better finding a laser or waterjet cutter near you to do the job then shipping heavy parcel.

And if you have a question about lasercut parts there is a thread just for that, no need to post in all european threads :)

Thanks for the quick reply! Actually, I posted first in a more general thread, where I received the advice to post on the threads of European builders. :-)

Can you perhaps send me the DXF files for the laser cut and bent parts so that I can contact a local company with them?

I think they come with the plans you buy to build the mechmate, ask Mike he is the owner (metalhead username on the forum)

I did buy the plans two days ago, but these are only the PDF files. I also asked Mike for the dxf file but haven't received an answer yet. So that I wasn't sure how others ordered their laser cut parts and started to ask around.

From the download section:
So he should be able to help you with those. Hope he answers you soon.

Sometimes Mike is away for a few days with his Day Job.
I'm sure he'll pop in and take care of you.

Just a teaser

http://cnc.rs/mechmate/zaxis%20(Small).jpg

1610 ballscrew
20mm round rails
spindle mount

With Am882 drives I get more than 1600 RPM on the shaft so 16.000mm/min rapid on Z axis , up or down makes no difference. The aluminium block, bearings and spindle seem too light to back drive and drop, so the Z axis stays in place without any help.

Looks well made. I am curious of the position of the spindle in the mount and how you get the 200mm of travel and still have clearances.

I got full 200mm clearance with the longest endmill (100mm or more) and still able to touch the spoilboard with the tip of the spindle.

I don't doubt it. Just the teaser pic have me thinking.

Looks very good Danilo, enough teasing, lets see it installed!

Heck, just a video of it running on the bench would be awesome.

I would mount your spindle on the other side ( the long slide).

I'm just wondering. What stepper motor brand are you using?? 1600rpm on the shaft sounds like a lot.

The stepper driver he is using is a good one.
Lots of digital tricks inside.

Ross

I know, I'm running the same drives on my CNC. But I'm having trouble getting much more than 600rpm from my motors without sensorless stall detection kicking in on my drives.

I have run an AMCI stepper with a Gecko drive controlled by an Oriental Motor controller at 50 rev/sec. It all depends on the hardware and that is within the spec of the particular stepper.

Statements like that are meaningless as whatever you have set your microstepping to significantly impacts that performance.

Ross

Also weight and friction of your set up impacts on performance.
There is just not enough to go on to make any comparison.

Ross

Fair enough. I can only tell you that we were testing the limits of the drive to see if it was robust enough to be put into production. We only require a lower rev of 20 but needed to run tests on an unproven component in our setting per our engineers. We were trying to reach the stall point of the motor as our approved driver would not go above 20. I did not want to run above the spec sheet. I was only stating that they can be run faster is everything is correct. I do stand corrected Ross, sorry for the misleading post.

My entire machine is running on square type rails, and they run very nicely.
But if I try to get greater speed from the motors than 600rpm, then the motors stall. I'm affraid that it might be those rather cheap chinese motors that I've got. I might save some money and get some better quality motors, perhaps even the ones from Leadshine which is pre programmed into the drives.

Hi Pete

I was referring to Kim's statement so your in the clear :)
Kim's post was just one of these "well mine's not working" statements that leaves a little too much to guesswork.

Ross

Hi Kim

Your supply voltage has an impact on this.

Ross

My setup is this.

70vdc PSU
1600oz-in motors on all axis (Longsmotor)
8x microstepping.

2010 ballscrews on x and y, 1610 ballscrew on z.

I am running same motor as before Deitech 9802 on 48 volts.
I was able to run X and Y axis to around 42m/min, but I am still using 18m/min to lower the tear and wear on pinions and rack (the rack is not perfect and I get a lot of noise on higher speeds)

Fox, mounting the spindle to the longer plate is not adequate, no manufacturer in the world does it, it was the main reason to make a new Z.
First reason is that for the same clearance you need higher gantry.
Considering that the spindle body is stiff you use its strength to stretch the Z down.
Second is that plate, spindle and bearings have smaller weight to pull up than large plate, guides and spindle.
Stiffness is the same as the bearings have constant load rating.

Here are some pictures to illustrate above statements.

MULTICAM Z AXIS
http://cnc.rs/mechmate/2011-09-27_10-29-15_163.jpg


Moving bearings VS moving rails, spindle position is a bit different as I experimented a bit but found that spindle in the middle of mount is satisfactory

http://cnc.rs/mechmate/Screenshot%20...2019.22.11.png

Also, the 90% of cutting happens while the Z i lowered all the way down.

Moving bearings has the same stiffness all the way but moving rails has lowest stiffness while lowered to do the finish cut.

I just checked the specs on the motors you are running.

I can see the phase resistance and inductance is way different than on my longsmotors.

The Deitec 9802 has a phase inductance of only 2.4mH, where mine has 22mH, and a phase resistance of only 0.65 Ohm And mine is 1.9 Ohm. I have heard before that to high a phase inductance can cause low stall speeds.

So I'm guessing that might be the trouble with my motors.

Hi Kim

Your motor wiring also impacts on keeping torque up at higher revs.
We have a habit here of wiring only one half of the coils but bipolar parallel gives the most "power" if you have 8 wires available but demands the most from your PSU. You are already high on voltage at 70V so probably little to be gained there.

I also see that you are using 1600oz-in motors.
I have been solidly whipped trying to tune large NEMA 34 size motors in the past to run at high speed. Even to the point of assuming the motor was faulty, bought another to have the weak performance of the "big" motor continue.

My only solution to stop missed steps was to use a belt reduction, this returned the power and the motor still was able to achieve the traverse speed required all be it at a higher RPM.
On my Mechmate installing a 4:1 reduction did produce a reduction in top speed over the ungeared motor so there is no free lunch.

If you are thinking about new motors probably lots of spec reading and a reread of the motors section here on the forum might be the solution.
As you are a Leadshine fan, the next level up on drivers that has the encoder feedback, the 'Easy Servo" range has the additional ability to play catch up like a servo does.

I have tested these drives and they are a very different animal even to the setup you currently have.
The heating is very low to the point of near ambient temps unless worked hard. They also manage torque differently.
In my tests a smaller 1000 oz-in motor provided far more power the larger NEMA 34 std stepper.
This is of course expensive but as I have already confessed to replacing motors randomly to fix a problem, there is nothing worse than spending more money to have the same issue remain unsolved.

Ross

I think it could be friction, weight of your machine and the motors in your case Kim. I thought you could disable the stall detection somewhere in the leadshine software.

At 1600 rpm you must be loosing torque danilo ? And for a z I see not much use at those crazy speeds ?