X2 CNC Fusion - Replace Lovejoy Connectors?

[Clot]

Hi All,

I completed my CNC Fusion conversion a couple of months back and have machined a few parts. I noticed that I had X Axis gib adjustment issues recently and was getting noise from my X axis when I would rapid from one end to the other. Thought there might be some misalignment issues and I messed around with the mounting screws and some shims but had no luck. However, tonight I spotted that the X lovejoy connector that came with the kit has some play - I can slop the X screw side to side (radial movement, not axial movement). I bashed up a U shaped shim to remove the slop and the noise has massively reduced. The fix is rough to say the least but it got me wondering, should I replace the lovejoy connector with something like Hoss used in his conversion? The machine hasn't done many hours but it seems this are might be a weak area. However, I'd be surprised if the rubber has given out so soon.

Thoughts?

[Crevice Reamer]

Lovejoys are not the best connectors. A solid helical connector would be way better. I have the optional CncFusion helicals on my SX3 and they are Great!

CR.

[Regnar]

I have the Heli-Cals from CNCFusion for my X2 and they are Money! Sorry heard the term at work the other day. To get these for the X2 you need to email him and then go to the X3 area of his website, buy 3 and in the comments let them know its for a X2. I tried for while to find these but because the all the screws are different sizes it makes it difficult to find all of them. So I just went with his. I should also mention that this took my backlash that was around .008 and brought it down to .001 on x and y and .002 on the z axis.

[Al_The_Man]

For Stepper/Servo make sure you get Stainless Helical, not the aluminum version.
HeliCal make both.
BTW Lovejoy is not a type, it is a Manufacturer, they make many types of couplers.
Lovejoy call them Jaw coupling, otherwise known as spider type.
Al.

[cyclestart]

Originally Posted by Al_The_Man For Stepper/Servo make sure you get Stainless Helical, not the aluminum version.

Ok, I've got to ask why. The ones from cncfusion are listed as aluminum.

[DogWood]

Regnar, what is the outside diameter of the helicals you got from CNCFusion?

[Al_The_Man]

Personally I have never found aluminum stand up to long term use in servo use, they usually end up fracturing.
The aluminum I use for encoder coupling.
You can initially save a few $$s by going cheap but often end up paying for it in the long run.
Al.

[Clot]

Thanks all for the advice. Tonight I put two U shaped pieces of 0.35mm shim into the connector rubber (one on each side and sitting against the "teeth" on the ball screw side of the connector). This has really improved the feed and removed the slop that had appeared. I'll definitely look at a better fix long term. Is there ary reason not to just machine up a solid tube with grub screws and rigidly couple the motor to the X screw?

[LeeWay]

If you have a good way to adjust for alignment, then solid couplings work well. I initially tried the spider couplings on my router. After awhile, I could look and see that the rubber had weakened and actually changed shape. You can't drive a 150 pound axis with rubber and expect it to stay in shape.

I went straight into solid couplers and have had no trouble with it.
The X axis on my mill has a nice SS helical coupler that is the clamp on type. Now that is one fine coupler. It came on the screw though from Ebay.

[Crevice Reamer]

If your alignment is exactly perfect, then you COULD use a solid coupler. But you have a Chinese mill. These are not known for perfection. Chances are that you need some flex--Bite the bullet and get the Helical couplers.

CR.

[LeeWay]

I agree.
If it's off even a little, it will transfer this even to the cut. Not only that, but with motors that have the smaller shafts, like 1/4", you run the risk of either snapping the shaft or destroying the bearing eventually.

Solid couplers are cheaper. It does take more work to design in alignment though. Not too difficult when you have plenty of room, but when space is lacking like on a small mill, it's best to go with a better coupling.

[tooManyHobbies]

Originally Posted by Regnar To get these for the X2 you need to email him and then go to the X3 area of his website, buy 3 and in the comments let them know its for a X2.

Looks like you guys influenced CNCFusion!

They now list Heli-Cals as an option on their X2 page.

tom