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Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Wed Oct 10, 2012 1:19 am
by Todd Bailey
Just order the ACME screw upgrade for Shapeoko Z-axis!!! Looking forward to the upgrade!

Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Wed Oct 10, 2012 11:15 pm
by Improbable Construct
Update:
I only have a couple more kits left in stock right now.
Once they sell out it will be about 2-3 weeks before I have more ready to go.

Todd,
I sent yours out today. Hopefully it will not take to long to cross the border.

Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Thu Oct 11, 2012 11:22 am
by Todd Bailey
I'll let you know when it arrives!!!!

Thanks for getting it out so fast!

This is going to be great.

Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Mon Oct 15, 2012 7:06 pm
by Improbable Construct
There is only one kit still available from the first batch!
Second batch ETA 2-3 weeks.
Thank you for your support.

Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Tue Oct 16, 2012 3:07 pm
by CptanPanic
I will get one of the next batch if you can test out the 2 nut idea.

Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Thu Oct 18, 2012 1:08 pm
by northbear
How does the standard nema 17 motor hold up with the ACME screw and a large spindle (ie DW660 or a trim router). What I am wondering is if there were no other tradeoffs (price was no object, mounting the different size motor was not an issue, etc) would it be better to have a more powerful nema 23 motor? Or would it not gain you anything by doing this change?

Another way to ask my question is if there was some mythical nema 17 motor that was exactly the same in every way but twice the amount of torque (for example), would it practically make any difference in the performance with a larger then standard spindle (ie DW660)?

Thanks!

Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Thu Oct 18, 2012 4:16 pm
by Improbable Construct
My machine is 1000 mm X 1200 mm with all NEMA 17 69 oz/in motors and I am using a DW660 for the spindle.
So pretty much the scenario you describe.
As far as I can tell a larger motor would not offer any real world performance gains.
I have pushed my Shapeoko to the limits many times and the ACME Z-Axis has never been the limiting factor.
The weak points in my setup are the flex/bounce/twist in the X axis, followed by lack of torque from the DW660.
During testing I was running ramp cuts with a 1/4" 4 flute end mill into 3/4 MDF.
There was no problem with the Z axis plunging into the stock but the DW660 bogged down severely.
So you could use a bigger motor but I don't see it as necessary.

Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Thu Oct 18, 2012 11:15 pm
by Todd Bailey
Just got my upgrade in the mail today!!!! Thanks!

Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Fri Oct 19, 2012 2:43 am
by northbear
Thanks for the reply IC!

I had done a rough calculation with numbers from an equivalent Nook ACME screw and plastic nut and it seemed like there should be **plenty** of force with the standard NEMA 17 motor, but I thought I may be missing something. Thanks so much for giving a "Real World" experience!

Out of curiosity, could you expound on what you found were the limits on your system? Was it the flex/twist in the x-axis makerslide itself, in the aluminum carriage plate or something else, (or maybe unknown)?

Thanks again!

Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Sun Oct 21, 2012 3:19 am
by Improbable Construct
I have found that there is flex/twist in the X to Z Axis in four places.
1. The X-axis makerslide.
2. The V wheels.
3. The universal plate.
4. The spacers on the Z-axis V wheels.

Solutions:
1. Double X-axis makerslide - helps a lot, but not a comprehinsive solution.
2. V-wheels - some of them are bad - out of round or out of spec - dont roll smoothly or bearings don't fit tightly.
3. The universal plate has some flex - I tried double universal plates - did not seem to make a difference.
4. The nylon spacers on the Z-Axis can flex - replaced with aluminum spacers - recomended upgrade.

I still have flex in the X to Z axis but with careful settings in your CAM program most backlash can be eliminated.