[kolias]

Last February I posted a similar post here "How to select a 4th Axis" but due to other priorities the project was canceled. Now I started again and have these questions:

My existing CNC has 3 axis with 4 NEMA 23 270oz/in 2.8A motors (Y is slaved to A), 4 KL-5056E motor drivers, C11G-r9 BOB and is connected to my Windows11 laptop with ESS. The tabletop is 36”x25”, approx. cutting area 32"x22",

The attached pictures indicate sample sets I would like to order. Since this is a hobby CNC, speed and torque are not that important.

Since the 4th axis will have a Nema23 motor is there a problem to connect this motor to my BOB? I do have spare pins on the BOB for extra motors but not sure if I will be able to use the same BOB

Is it better to select Belt Driven or Direct Driven set ?

Is it better to select 3 or 4 jaws chuck ?

When I buy the 4th axis, most likely I will have more questions regarding how to configure Mach3.

Thanks

[awerby]

Both those things are junk. The belt drive one doesn't have enough rigidity, and the direct drive one doesn't have enough torque. You need a rotary table with a gear drive, the higher the ratio the better. The easiest one to retrofit on that machine would be a Sherline, which accepts Sherline 3 and 4-jaw chucks: https://www.sherline.com/product/873...r/#description

[pippin88]

Awerby - the direct drive one is a harmonic gearbox (strain wave) with 50:1 or 100:1 ratio

The harmonic one will have enough torque. Will be slow.

Difficult and expensive to have a rotary axis that is fast and has high torque.

[kolias]

Thanks for the help. I know about the Sherline, a good choice but expensive. Adding a chuck + tailstock + shipping/duties we are talking close to CAD$900.00. The 4th axis is intended for a hobby/occasional use which doesn't justify the cost. However its something to consider Sherline vs the Harmonic at half cost.

[joeavaerage]

Hi,

https://www.ebay.com/itm/20230179089...3ABFBM0v7mqsNi

19.5:1 reduction, less than 2 arc min lash, 130Nm rated output....brand new albeit old stock for $150USD. If you bought new direct you'd pay over $1500USD. Whats not to like.

Craig

[kolias]

Looks good Craig, thanks but have a few questions since I didn't find anything in the link..

I have no idea how big it is
Does it have a motor and if yes where do I find the power requirements (volts + Amps)

Price looks very good at first but at US$300 shipping included I still have to add duties and taxes + find a chuck to fit + a tailstock.

And as I have mentioned I still like to have a complete 4th axis set, trying to find a chuck to fit and a tailstock the right height would be a problem for me.

[joeavaerage]

Hi,
the part no. breaks down like this:
58 =Hi Performance series <2arc min lash
44= 63 mm between centre of the worm gear to the crown gear, keyway output. The actual device is about 9 inches square and 4.5 wide, weighs about 7kg.

Fit your own motor, up to 3.8kW.
These things are heavy duty and superbly made gear reducers. Cheapest way to make a good fourth axis as I could find.

Craig

[kolias]

I must say it looks like an excellent part Craig but not for my needs. In addition finding a motor for it will be another headache and extra $$$. I'm sure the units shown in my first post or similar will be more than enough for my hobby needs.

[againstallodds1]

Hi,
the part no. breaks down like this:
58 =Hi Performance series <2arc min lash
44= 63 mm between centre of the worm gear to the crown gear, keyway output. The actual device is about 9 inches square and 4.5 wide, weighs about 7kg.

Fit your own motor, up to 3.8kW.
These things are heavy duty and superbly made gear reducers. Cheapest way to make a good fourth axis as I could find.

Craig

That looks very interesting. How is the chuck mounted inside? Tapered tailstock backplate? Couldnt find size to fit.