Thank you, so much for this suggestion! I was looking at videos which show you needed to do complex formula's! Mach3 settings makes this a very easy procedure with digital calipers to measure distance moved!

 

Thank you Dave. It feels great when you see it move for the first time. But still so much to learn... In the end I decided to make X axis 24" 610mm. In my opinion the X beam 750mm will be fine if you drill and screw the beams together, this really, really helps reduce flex in addition to using the aluminium side plates.

 

Thank you Tweakie it's been a real fun adventure.

Next part of the project is to make a custom bracket for my router. I have a spare Dewalt DWP611 1 1/4 hp whicj I'm going to try.

My Z axis has a nema 23 so I'm assuming to will lift this small router with no problem.

 

That's great... They look so small and compact I had to ask!
I have another newbie question. When I turn the machine on and it's not moving the motors quietly buzz when not moving, I assume this is perfectly normal?

 

The Power supply is 48volts, 12.5amps, 600 watts. Each motor has a slightly different hum sound when not turning. They appear to run fine..

Cncrouterparts does not mention the need for resistors with the cables you buy from them? I assumed this was part of the cable?
http://www.cncrouterparts.com/g540-nema-23-wiring-instructions-p-144.html

Curious how did you install resistor? Did you cut the end off or add a mini cable between with D9 connectors.

 

Thank you Rick, now I feel better!

 

Hi Lew, I'm currently running on an old dell workstation running windows xp. I still need to strip it down to the basics...

 

Curious has anyone tried one of these usb to lpt devices?
http://www.cnc4pc.com/Store/osc/product_info.php?products_id=481

Can you explain more about your smooth stepper setup please? When I look at these circuits I don't understand who they would work with the grecko g540?

 

Hi Nick, I'm happy to make another one. My version will be cut this week when I know everything is perfect I will contact you.

 

Thank you for your help & support Gerald. Seeing it move under it's own power is really great, seeing it cut something real will be even better.
My limit switches should be here soon, the soft limits in Mach3 at least provide some level of safety confidence.

I have been watching various training videos about Mach3... It has lots & lots of options & parameters.

Still lots of learning about LPT ports, pins, Bobs, smooth steppers, etc:-}

 

I decided I want to try linear bearing on the X axis, with the intention to remove ALL flex and provide strong smooth movement.

I'm planing to bolt a 1/4" * 4" * 24" plate to my X rail. Then mount two SBR16 linear rails which will also be attached to two new gantry plates. The Z axis plate mounted to the bearings is the same physical size as the original with the same mounting holes, I may change this design later but want to focus on one improvement at a time.

See below early concept design ideas...

 

Thank you. The round rails are mounted and fully support along the length on an aluminium rail with bolts.


I'm thinking about using the same concept for the Z axis but smaller versions.

My logic was the original beams bolted together, 1/4" plate & these beams bolted through both was over engineered... But physical testing will provide the honest answer.

Your 100% correct the cost difference would be small to go from 1/4" to 1/2", plus I could then add cross bolts to the gantry plates. The is in addition to the cross bolts which go into the end of the rails.

Your guessing right, X axis is step one in multiple re-design approach. But that one I think will be rack & pinion like you approach.

I originally started the project to cut carbon fiber & G10 sheets, now I'm thinking why not make it strong enough to accurately cut aluminium. Motors & electronics are the same... The machine just needs to be stiffened up... Which is a fun design challenge!

 

I have to wait for the parts from China... In the mean time I can complete the original design and start cutting.
When you consider $45 ish for extreme wheels VS $86 for two rails & 4 bearings it was worth a try!

 

I have been adjusting the Z axis wheels to try to remove the flex on the Z axis. Have other people found that the Z axis has a good amount of flex even when light pressure is applied?

I have redesigned Z axis with linear bearings SBR-12's, 1/2" 5 start thread. I ordered some good quality pillow block bearings for the threaded rod.

 

Hi Dave, I honestly don't think the flex in the original design is the aluminium extrusion in the Z axis or X axis. I think the flex comes from the wheels in the V channel. Plus the front & rear Z axis plates only have 5mm bolts holding the whole carriage together. When I first assembled the X carriage I put the wrong size spacers in the center and was shocked to see how much the 5mm bolts bowed!

Many CNC machines use the round rail system and linear bearings. My gut feeling was linear reals which are mounted along the full length would be even stronger when mounted to a 5" tall plate.

The X axis still has the original 20 * 60 double beam which is bolted together, so when you combine this with an aluminium plate & these linear rails which are also bolted along the length, I don't imagine seeing the X flex or twist. But we will see!

If I do then I will replace the two 20 * 60 beams with something much beefier.

The original design is not bad, I'm just having fun doing the mod's and design work.