welding steel base or just getting aluminium extrusion

**Desertboy** · 31-12-2017

Originally Posted by Boyan Silyavski

This machine is crying out loud for servos. That's my opinion.

What's your opinion on
http://www.leadshineusa.com/productt...y-servo-motors

If I understand it these are not real servos but somewhere in between

**Boyan Silyavski** · 31-12-2017

Originally Posted by Desertboy

What's your opinion on
http://www.leadshineusa.com/productt...y-servo-motors

If I understand it these are not real servos but somewhere in between

I decided long ago - No to closed loop steppers. Too close to real servos price. 750w servos from BST will much better. Mine machine is all over 400W Samsung servos and i could not be more than happy with them. I doubt this machine will be heavier or much different than mine anyway. If i have to repeat, i will go the same way, like new used second hand brand servos from reputable seller, together with cables and so. If i am making the machine for a client, then new 750w chinese servos. But that's me.

PS. Just as a side note, brand servos like mine and the panasonic will spin to 6k rpm happily, as opposed to cheap servos. So actually you will never use them at 100%.

**reefy86** · 31-12-2017

Cant decide what i will need until i finish my gantry design and report back as the way i am going like boyan said is i may need servos which i was trying to avoid, what price range am i looking at per axis setup for servos? the hiwin rails and ball screws are whats taking up a lot but i am in no rush

edit.. just going to point out just in case someone can rescue me from over designing which eventually is going to push me to servos lol, the only thing i will be cutting is wood or up to 10mm acrylic and thats it but it does need to be a solid gantry for 3d carving. i will however want to make a small machine to mill aluminium and steel eventually :)

**reefy86** · 31-12-2017

can you mix steppers and servos? was thinking off having just servos on the long axis that moves the gantry

**Desertboy** · 31-12-2017

Originally Posted by reefy86

can you mix steppers and servos? was thinking off having just servos on the long axis that moves the gantry

In linuxcnc seems easy enough

https://forum.linuxcnc.org/10-advanc...stepper-system

Not sure about Mach 3 but if I'm going servo go all the way all 3 axis ;)

If you're using standard ballscrew at the lengths you want you'll probably see screw whip with normal steppers never mind servos so you might need rotating ballnuts or R&P to see proper performance from servos.

Google screw whip calculator to get a good idea of what a normal ballscrew can do but it's nowhere near 6k rpm Boyan quoted that servos will do.

**reefy86** · 31-12-2017

already have rotating nuts in mind, from the looks of it my gantry is weighing between 150-200kg so is this a deffo servo route then?

**Desertboy** · 31-12-2017

Originally Posted by reefy86

already have rotating nuts in mind, from the looks of it my gantry is weighing between 150-200kg so is this a deffo servo route then?

200kg's! this seems excessive for a wood router a hell of a lot of weight to be moving at speed it's like 1/5 a car you'll need chuky motors.

Have you considered buying a 2nd hand router
https://www.ebay.co.uk/itm/CNC-Route...IAAOSw1cNaOuvj

haggle with them you might get it for £4.5k ;) I find if you visit people and wave cash at them you can get some leeway ;)

**Boyan Silyavski** · 31-12-2017

If you are tight on money for the build, you could buy cheaper square rails than Hiwin. Find a good factory and buy from them. it will be wise to make a plan and follow it. My machine cost me somewhere around 6-7k totally. 8x4 machine can not be made properly for 5k. you have 3k for rails, ballscrews and so, 2k for electronics and motors, 1k for metal for frame and so on. Though i lied to myself some time that i can make it for 5k.

And i had all necessary machinery and skills to design it and make it 100% by myself. And not first build, mind that.

So make a plan, follow it, be persistent, do not make any mistakes and you will do it.

**reefy86** · 31-12-2017

this might be a stupid option for some people but i would prefer to build it rather then buy one just purely for the knowledge i will learn on the way and if something ever packs up in the future then i will know how to fix it. 200kg is alot of weight just for cutting wood but there will be a lot of rapid movements for 3d so i need the gantry to be solid. i was thinking about fixing the gantry and moving the bed but i have future plans so i will need the space for other things.