Parts for 4x8 router

[3Dsigns]

Still trying to find the right parts.
I want to build a 4x8 router with plenty of power and speed.
Would these motors be powerful enough for my x and y axis?
http://cgi.ebay.com/ws/eBayISAPI.dll...6973&rd=1&rd=1

For the x axis, would 9' be too long too use a ballscrew....if they make one that long? Or would a rack be better?
Would a rack be faster?

Can these motors be connected directly to the ballscrew shaft or do they need a gearbox?

Why do some use Lovejoy couplings between the motor and shaft?

For the linear rails, is a a "square rail" more stable, stronger, tighter, more durable...whatever, than a round one?

Thanks for helping!

[wcarrothers1]

Rack would be better for the long if you want speed.
would need transmission or to find a thompson planetary gear drive (like I did for the rack)

most ball screws give enough gearing for direct. My shorter (50" Y and 10" z are direct ball screw) how ever plan on slower rapids depending on size of ball screw.

Motors look similar to the ones I got from camtronics.

people use love joys to couple to help with alignment, vibration ect. I suggest you use them as well or some other coupler type (helix, love joy ect)

Rails depend on design. Either way the 4" axis rails would need some support, Depending on how you design will determin the type you can use. mine happened to be round. 60" span of 1" hardened. With thompson support structure. Would not have worked with out the supports (ie just 2 spans of pipe with out support)..

b.

[3Dsigns]

Where did you get your racks and gears etc?

Those motors do look like the camtronics ones. Would those 1100oz motors be strong enough?

So, would a "higher pitch" ball screw give satisfactory speed without stalling out?

Thanks!

[rustamd]

Originally Posted by 3Dsigns Where did you get your racks and gears etc? Those motors do look like the camtronics ones. Would those 1100oz motors be strong enough? So, would a "higher pitch" ball screw give satisfactory speed without stalling out? Thanks!

I got my gear rack from http://www.stdsteel.com/gr_stock.htm very good quality and very affordable. Gears and belt I got from econobelt.com I went with AT5 for minimum backlash.

You can all get your gears from www.sdp-si.com , http://www.mcmaster.com and few other places. But i found STD and econbelt cheapest for whta i needed(for my router table)

[3Dsigns]

Originally Posted by rustamd I got my gears from http://www.stdsteel.com/gr_stock.htm very good quality and very affordable. Gears and belt I from econobelt.com I went with AT5 for minimum backlash. You can all get your gears from www.sdp-si.com , http://www.mcmaster.com and few other places. But i found STD and econbelt cheapest for whta i needed(for my router table)

Thanks!!

[3Dsigns]

Am I looking at this wrong....or are the motors for the x axis INSIDE the gantry on this rig? Or are the gearboxes inside the gantry with the motors connected to the back of the gantry behind the end plates?
I'm liking the simplicity of this design.

Is the motor for the y axis on the z axis assembly?

http://cgi.ebay.com/CNC-4x8-ROUTER-T...QQcmdZViewItem

[rustamd]

yea, looks like motor is on inside with just shaft and spur gear sticking out. Doesnt look like it uses any kind of reduction, which isnt a good thing really...

[wcarrothers1]

Ya I would not touch that one with a 10 ft pole.

Anyone mounting their rack pointing up should reconsider. I'm glad mine is under alowing things to fall out of the rack. Else I'd get dust, chips ane more in mine.

see my Prety much finished...

thread for more ideas that might help you do some things.

Lots a people are big fan's of their own designs here. and of course I'm one of them. Has out performed in every way for me and have not had any issues structure or otherwise with it. And over all the cost was cheep..

The camtronics 1100oz are plenty for my machine anyway. I have them on all 3 axis how ever if you planned correctly you could probably usea smaller one on Y and smaller still on z (and even smaller if you counter weight Z?) how ever something to be said of the weight of the router holding the Z possition if you don't have backlash screws..

but in any case I could have done maybe 1100 oz on X to carry the gantry, and maybe half that on the Y and Z and still been ok I think. How ever the big motors are nice and never under powered.

My screws and racks came from mc master. I know 22deg racks are suposed to be better then the 14.5 from mcmaster. but will say mine seem to work just fine.

I scored the Thompson planetary off ebay for 70 bucks. That simplified the power transfer to the rack a LOT. I didn't want to do a multiple belt reduction as some have done. it is a 10:1 and it would have cost me a LOT more in bearings and pulleys to do it any other way I think. Works and was cheep..

Also here is a pic of 1 thing I make with my machine

b.

[3Dsigns]

It would need to be a pretty small motor to fit inside a piece of 80/20 aluminum like that. It looks like 3x3. Also, wouldn't there be a heat dissipation problem with the motor enclosed with no circulation around it?

[3Dsigns]

That's a solid looking machine!

Yeah...rack pointing down makes sence for sure.