Motor size for heavy gantry/qtplasmac

[kn612]

Looking for recommendations for servo motor/drivers/mesa hardware to power 500lbs+ gantry. I have a project table to build. It has nema23 baldor ac servo motors with 28:1 reductions that I wouldn't mind keeping but I don't know the condition of them. The flexdrive drivers are still here however I don't know how to make them talk with mesa hardware/linuxcnc.

Plan on using qtplasmac, a 7i96s, 7i84 for more inputs, thcads for ohmic and THC.

[robertspark]

https://www.google.com/url?sa=t&source= ... __5p-qgpmi

could use step and direction mode, best to reuse in my opinion.

you are probably best to ask on the linuxcnc forum about the drives as someone has probably done it before

[Rodw]

x2 with Robert. These are a high quality driv. There are other Mesa cards that allow it to be controlled with 0-10 volts signal

[kn612]

This hardware is 17 yrs old so I'm a little hesitant to spend the time figuring out how to use it. The drivers are quite expensive if any need replaced in the future and I have no condition of the motors. I picked up this gantry fairly cheap so I don't mind spending a little bit for some affordable servos

[robertspark]

those servos are very powerful 1.36nm, 510W and are geared at 28:1 motors to move a 500lb+ gantry and accelerate FAST to the cutting speed.

hence that 1.36nm of torque becomes 38nm of torque! at up to 124 rpm at the output onto the table

if you intend on using linuxcnc you will have a learning path ahead of you anyway

if you really want to replace them and spend some money then have a look at clearpath who do servos and stepper replacement drives or replace like for like

I have never seen the point in a heavy gantry for plasma but if you really want to throw 500 lbs around go for it, I'm not sure what better cut or finished article you are going to get at the end of the process, but I am just a hobby user so am always happy to learn

[Rodw]

Clearpath would be a poor substitute because their torque curve is designed to replicate a stepper motor.
These motors will produce that 1.36 Nm of torque right across their rev range from 0 rpm to their max speed of 4000 rpm. That is way above what a stepper can operate at.

If you were to replace the motors with steppers, the gearboxes would not suit their torque curve and RPM so you would also need to replace them adding to cost
.
Baldor is a high quality brand and should still be in working order for a long time to come. If they were to fail, Chinese substitutes could be had for as little as $200 but their max speed is likely to be 3000 rpm.

Neither Robert or I are the experts here, It would be best to ask on the Linuxcc forum for guidance. There a many people there with extensive experince with retrofits of similar motors and drives.

Retaining what you have is the best way forward. Anything else will neuter the hardware. Build the control box with the right hardware fot $200 or so and if something else fails, worry bout it then but replace with compatible hardware.

[robertspark]

+1 what rod said

[SegoMan DeSigns]

Guess I'll be the odd man out on this one, My ClearPath SDSK NEMA 34 x 1400 oz moves my 400lb gantry just fine.. Sometimes big gantry's are a must due to table size and / or installed tooling. Aluminum profile in the larger sizes has a poor weight / ft ratio. I went with 1/8' x 4"x6" rectangle tubing and saved over $500. I just had to drill & tap some holes.

Max speed on the motor is 1130 rpm with my chain / sprocket gearing I yield .886" of travel per / motor revolution. I have rapids at 700 ipm due to the size / weight of the gantry. I cut from 16 Ga to 1-1/4" plate. My suggestion is to contact tech support at Teknic with your information and let them help you speck it out. They have great customer service.

[Rodw]

Guess I'll be the odd man out on this one, My ClearPath SDSK NEMA 34 x 1400 oz moves my 400lb gantry just fine.. Sometimes big gantry's are a must due to table size and / or installed tooling. Aluminum profile in the larger sizes has a poor weight / ft ratio. I went with 1/8' x 4"x6" rectangle tubing and saved over $500. I just had to drill & tap some holes.

Max speed on the motor is 1130 rpm with my chain / sprocket gearing I yield .886" of travel per / motor revolution. I have rapids at 700 ipm due to the size / weight of the gantry. I cut from 16 Ga to 1-1/4" plate. My suggestion is to contact tech support at Teknic with your information and let them help you speck it out. They have great customer service.

But you don't have a 28:1 gearbox so following your lead will entail additional expense for replacement gearboxes. The machine is fully engineered now by the manufacturer, so stick to that is the best option.

[SegoMan DeSigns]

Teknic has a lot of options, I chose what was best for my application with their help. He stated he did not know the shape of the gear boxes, that is why I suggested he contact them.

[kn612]

Guys I got this gantry for free. It was in a shop fire, so insurance paid out. All the electronics were covered in soot. I cleaned up the touch screen monitor and it works, using it on my precision plasma gantry table, along with the oxy/fuel head that was on it. The hypertherm microedge computer turns out but no display out of it. It has an Inova kaliburn THC, that powers on but I have no idea if it works. I have enough gear rack and rail to make a 8x14.

The drivers power on, when I wire them to the motors and put 24v to the enable pins the motors spin. Was reading through the manual, I think to make it work with pulse and direction the drivers need flashed with some software called workbench v5. It looks like workbench runs on 32bit windows. I don't have a 32 bit windows computer at the moment. Or am I confident in my computer skills.

With how much soot was on everything I don't want to take any chances with any electrical failure in the future. I have a few ideas to power it.

1. Find replacement servo drivers that will talk with the existing motors.

2. Source drivers and motors that are NEMA 23 with same size shaft to use the 28:1 reductions and motor mounting.

3. Change all drivers, motors, gearbox (would make my own belt reduction and mounting). There is plenty of room on this gantry to make nice motor mounts.

With my thinking I was contemplating going with clearpath 34s. No drivers to mount and I can use the mesa hardware that I have on hand and am familiar with.

My main goal is to use qtplasmac on it. This cnc plasma is hobby/farm use. I think it would be awesome to control what was a very expensive table new with open source software.

I just don't know much about servos, computers, software, etc. I only know it's alot easier letting the cnc cut plate instead of doing it with a handheld plasma or a cut off wheel! I do appreciate all help along the way. A few years ago I didn't know what mach 3 or sheetcam even were

[kn612]

!!!!!! Found software called workbench v5.5, it works on windows 10. Configured the flexdrives for step/direction and now have movement with a 7i96s and qtplasmac

[Rodw]

Great work!
Glad you left your comfort zone
Onward and upwards!

[weldguy]

Nice! Never heard of it, glad you found something to work with. Hopefully you can get the gantry moving soon. Post pics if you can.

[SegoMan DeSigns]

Glad you put some life back into the beast!

[kn612]

What's the thoughts on using a heavy industrial style gantry for air plasma instead of high def? Since I am able to use the original servos spec'd for it there shouldn't be any issue accelerating out of corners. My current table has the 6ft precision plasma mag 7hd gantry with 620oz/in steppers and up around 750ipm jogging it has lost steps occasionally jogging. I usually run a jog speed on that one at 500ipmso I'm not concerned with being able to hit fast rapids.

[Rodw]

Keeping the original motors and you shold not have issues. Looks like you have closed loop motors with encoders now.
Qtplasmac is only really designed for air plasma

[weldguy]

If you do a lot of artistic detailed cuts in thinner gauge metal it will be a little limiting but for anything else I figure it will do a great job.

[robertspark]

it's all about acceleration, anything over 400ipm is not really required.... nice to have but not essential

most of the book cutting feedrates are set at 400ipm.

acceleration of 0.3g (~116 in/s/s) is desirable (or better)

commercial machines seem to target 600ipm..... helpful for a big bed I guess and a long rapid traverse, but I'd rather have higher acceleration at a lower feedrate.

[Rodw]

Some commercial machines with heavy gantry get up to 0.8g accelleration.
ANything over 0.3g means machine rigidity is a major issue.
This kind of gantry is usually bolted seperately to the floor and the table is freestanding and not connected to the motion frame at all. Tables can be many metres long, some locally are 90 metres (with a few gantries)