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View Full Version : Any thoughts on this design for a gantry setup?



Dwayne Dibbley
31-01-2015, 06:57 PM
http://www.ebay.com/itm/CNC-Router-Kits-Engrave-Mill-Plasma-Travel-24-x49-Commercial-Milling-/261751815691?

Thanks

EddyCurrent
31-01-2015, 08:43 PM
You have to keep in mind that manufacturers at this level want something they can build quickly, easily, cheaply. My opinion is that the cross beams making up the gantry are not deep enough in the Z direction. If they were the same width but 3 times deeper then okay. Also the side plates would need to be 20mm thick.

Lee Roberts
31-01-2015, 10:00 PM
Have you read the description for that listing Eddy?

.Me

Dwayne Dibbley
01-02-2015, 11:34 AM
You have to keep in mind that manufacturers at this level want something they can build quickly, easily, cheaply. My opinion is that the cross beams making up the gantry are not deep enough in the Z direction. If they were the same width but 3 times deeper then okay. Also the side plates would need to be 20mm thick.

something like this? Original on left, 3x on the right.

EddyCurrent
01-02-2015, 12:53 PM
@Lee, No I didn't fully read it but what's the learning point ?

@Dwayne Dibbley, yes, the one on the right looks better to me, also you might have one cross beam as you've drawn it but the other like the original, that way it's more rigid in both directions.
Hopefully more people with mechanical background will give their opinion.

crazydiamond
03-02-2015, 02:51 AM
Not crazy about the single bearing on the y axis.. Also I'm always suspicious of non-branded rails (didn't see any mention of the brand in the description). Spk64 over on CNCZone found a supplier of profile rails and bearings on aliexpress (Three Ring Precision Machinery) for dirt cheap. He ordered them and ran some tests.. Basically they're not hardened to the same specs as the big name brands (THK, NSK etc) and will surely fail much sooner. Funnily enough they're fully compatible/interchangeable with the THK HSR line (basically a complete copy, but to a lower spec)... Not saying it won't work well for hobby use, but just something to consider.

Devin

EddyCurrent
03-02-2015, 10:51 AM
Not crazy about the single bearing on the y axis..

I think you mean sigle ball screw, also while I understand on your side of the pond that would be the Y axis, on this side it's the X axis, no big deal with that just mentioned it to prevent any confusion.

njhussey
03-02-2015, 01:25 PM
I think you mean sigle ball screw, also while I understand on your side of the pond that would be the Y axis, on this side it's the X axis, no big deal with that just mentioned it to prevent any confusion.

It's got a single screw and also a single carriage (which is what I think crazydiamond was looking at) on the X axis rails which I guess could be OK for a plasma/laser but not OK for anything else. I wouldn't be too concerned with the non branded rails if this was for DIY home use and not for commercial use as by the time they've worn to any extent that is becoming noticable (assuming that the build has been put together so there's not undue stress on the bearing to start with) the OP will be an OAP (if they're not already :playful:)

What are you looking to use the machnie for Dwayne Dibbley?

Dwayne Dibbley
05-02-2015, 07:49 PM
Hi, i was after some ideas to build a machine approx 3'x2' with the ability to machine aluminium along with MDF acrylic etc. Only saw this design as it looked fairly easy to build using the ali extrusion with some mods. But maybe it will still be too flimsy for my needs ( only home diy ).

Thanks