Initial design advise wanted

[driftspin]

So... choosing between slaving 2 nema23 and a single nema34 ...
Or maybe a servo like Boyan said.

As far as i understand is a debated item...

Lookslike it comes down to speedy acceleration but complicated setup vs more robust setup but more expensive parts... and maybe inertial acceleration is slower due to heavier motor (bigger diameter) and 2 balscrews instead of 1 to drive..

Am i right about the above?

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[driftspin]

BTW...

I am adding up prices based on 4 nema23 and linearparts from chai.
Steel frame and all shielded cable, magnetic limit switches.
4 psu's
2x65v dc diy toroidal
1x24v dc din rail
1x5 v dc ?!? Samsung smartphone USB charger hahaha

Waterpump for spindle.

Paint, 105 209.

Aluminum for Z
Fastners
Smal tools like spiral taps and stuf

Chinese 4 bearing vfd/2.2kw spindle.

But no motion controller ...yet...
Figured... mach3/4 is needed anyways... and a BOB too...
So a motion controller can be added later when room is spared in the controls cabinet.

+/- 3500 euro... does this sound like the right ball park figure?



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[Clive S]

So... choosing between slaving 2 nema23 and a single nema34 ...
Or maybe a servo like Boyan said.

As far as i understand is a debated item...

Lookslike it comes down to speedy acceleration but complicated setup vs more robust setup but more expensive parts... and maybe inertial acceleration is slower due to heavier motor (bigger diameter) and 2 balscrews instead of 1 to drive..

Am i right about the above?

Verstuurd vanaf mijn SM-G7102 met Tapatalk

Servos need a lot of setting up I believe and I don't think there are many on here with them.

The price is about the same for two motors or one as you only need one drive if using one motor.

Not sure what you mean. You will need two screws either way

[driftspin]

Servos need a lot of setting up I believe and I don't think there are many on here with them.

The price is about the same for two motors or one as you only need one drive if using one motor.

Not sure what you mean. You will need two screws either way

Clive.. i understood the single nema34 setup has a disadvantage ... it is bigger in diameter and has to run about 2.4 meter of belt between the screws.

The inertia of a nema 34 is higher than a slaved nema 23 setup, right?


A single long belt nema34 on 2 ballscrews vs a slaved dual nema23 software controlled solution.

Hmm sounds like i just made my choice aaaargghhh... no.

Is a stepper +/- 6nm nema34 still an option or is the twin ballscrew 70+ kg gantry asking for a servo solution.

BTW i dont want to start a discussion here on single 34 vs slaved 23.

Grtz Bert

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[Clive S]

2x65v dc diy toroidal
1x24v dc din rail
1x5 v dc ?!? Samsung smartphone USB charger hahaha

Waterpump for spindle.

A 50v 0 50v AC toroidal when rectified will give you about 72Vdc if you are using AM822 drives that would be good.

A 24Vdc din rail PS something like this;- https://www.aliexpress.com/item/DR-3...08.4.22.RcR90i

water pump https://www.aliexpress.com/item/Prac...2-37daba8373ea

motion controller needs to be at the top of your list some have the bob built in.

Don't buy any powers supplies until you know what controller you are getting as some run on 5v others need 12v or 24 v.

In fact leave all the electronics until the frame is built.

[JAZZCNC]

With 70Kg + Gantry then I'd advise you go with servos if you want very best performance. Setup isn't so much an issue these days modern servo drives are much more forgiving. The Main downside is cost.?
With servos it's not just the Motor/Drive cost you have to factor in the that to get the very best out of them you'll need Motion controller that can provide the required Pulse frequency. Most of the cheaper USB Controllers like UCCNC etc cannot provide the required pulse rate to get the full speed and resolution out servos. Electronic gearing is required and this comes at the cost of resolution. However for most routers this is sacrifice that can be made without affecting machine performance. It just defeats the point of one main advantage of servos.

If your going with belts then 8Nm Stepper motor will be minimum and best run on Mains voltage drive to get best from it and give decent speed.
I've just built two Routers with 1250 length cut that runs Belt drive twin 2010 screws with 4.5Nm 34 motors running 72Vdc AM882 drives with Gantry aprox 45Kg giving 700mm width cut and they will happily run at 10,000 mm/min with acceleration 1200s/s.

Now with bigger 8nm motor you won't get those speeds with only 72Vdc but with Mains voltage drive then you will and probably more. Obviously the higher weight and inertia of the Gantry will play bigger part in lowering performance but still you'll get at least 8000mm/min with 10mm pitch screw which is more than enough for most routers at this level/size.

Like Clive mentions Don't cut corners on the Motion controller. Avoid USB it's too twitchy. Ethernet is by far more stable.
There are several suppliers of Ethernet Motion controllers depending on what control software your thinking to use. My prefered choice and only controller I'll use with Mach3 is from Cslabs. However the new Ethernet card and UCCNC Software from CncDrive are very serious challenge to Mach3 so worth close look. Not used this Combo yet so can't comment properly but I'm hearing good things from People who know there stuff and who's opinion I trust. I Will be testing shortly along with the Cheaper Stand alone controller.

Then you have the stand alone controllers like may have seen mentioned lately on Forum (but I don't advise you take Boyans lead and connect two drives to one Signal Output.) Not sure if the 4 axis version will allow Slaving but if your using belts this won't matter and could use 3 axis version.
Again Can't comment or give an informed opinion but I will shortly have one to torture so will post something at some point.

hope this helps.

[driftspin]

So i have been reading a lot in the meanwhile.

I found this calculator for critical speed.

https://www.zappautomation.co.uk/ind...culators.html#
And for comparison
http://www.thomsonbsa.com/pdf/bsa_en...og_section.pdf


With about 1500 mm between the bearings, (long axis),
And about 900 mm between the bearings, (short axis),

SFU 1610 @ +/- 1500 mm (+/- 10mm core dia* = +/- 500RPM max * 10mm pitch) = 5 mtr/min
SFU 2010 @ +/- 1500 mm (+/- 15mm core dia* = +/- 800RPM max * 10mm pitch) = 8 mtr/min

SFU 1610 @ +/- 900 mm (+/- 10mm core dia* = +/- 1400RPM * 10mm pitch) = 14 mtr/min



It looks like 2010 is a good investment for the Long axis

I made a redisign of the frame to trade off some stiffness and complexity of the gantry vs frame.

Ill post soon since steel is on the way :-)

[driftspin]

ok so does the ballnut on the gantry count as a bearing for length calculation?

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[driftspin]

Epoxy 105 209 questions



What would be a sufficient epoxy thickness and width mounting surface for hiwin type 20mm rail?

My box section is 120x80mm so the flat surface width of the 80mm side
is about 60 mm wide... would 50mm wide and 5 mm thick be enough?

After welding the overall flatness of the frame will be in the +/- 1.5 mm range... so 3.5 to 6.5 mm epoxy thickness after optimum leveling by spirit level..

I am planning to do a single epoxy pouring of the x rail mounting surface and bed supports.. this will give me a good start for a level bed vs x rail

Total needed epoxy amount will be in the 3.0 dm3 range at 5 mm thickness

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[Boyan Silyavski]

Epoxy 105 209 questions



What would be a sufficient epoxy thickness and width mounting surface for hiwin type 20mm rail?

My box section is 120x80mm so the flat surface width of the 80mm side
is about 60 mm wide... would 50mm wide and 5 mm thick be enough?

After welding the overall flatness of the frame will be in the +/- 1.5 mm range... so 3.5 to 6.5 mm epoxy thickness after optimum leveling by spirit level..

I am planning to do a single epoxy pouring of the x rail mounting surface and bed supports.. this will give me a good start for a level bed vs x rail

Total needed epoxy amount will be in the 3.0 dm3 range at 5 mm thickness

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40mm width and 3mm thickness of the epoxy are the minimum for 20 size Hiwin rails. 5mm thickness as all around is ok. 6x6 or 8x8 steel bar welded to frame will provide nice strong cheap channel for pouring in the epoxy. If not a continuous weld, then prime all well to check for leaks. Then pour on second step.