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ACME screw upgrade for Shapeoko Z-Axis

Posted: Sun Sep 30, 2012 3:48 pm
by Improbable Construct
I am pleased to announce an ACME screw upgrade kit to replace the stock M8 threaded rod.

$75.00 with free domestic shipping

http://www.shapeoko.com/acme_upgrade

Wiki Page:
http://www.shapeoko.com/wiki/index.php/ACME_Z-axis

Top video is the stock Z-axis, bottom video is the ACME screw Z-axis.
Play both videos at the same time to see the difference.



Benefits:
1. Increased speed, 12 TPI vs. 20.32 TPI.
2. Increased strength, threads are broader and squarer than M8 threads.
3. Increased accuracy, ACME screws are made to tighter tolerances than threaded rod.
4. Better support, Z-Axis supported by the bearing blocks, not the motor.


The kit contains:
1. 1x 3/8-12 Acme screw 200mm of threads turned down to 8mm on both ends.
2. 1x Delrin ACME nut
3. 2x Bearing Blocks / Motor Mounts
4. 2x 608 Bearings
5. 4x M5x20 socket head cap screws
6. 4x M5 washers
7. 1x 8mm shim washer
ACME_parts (Medium).JPG
ACME_parts (Medium).JPG (157.83 KiB) Viewed 10519 times
ACME_exploded (Medium).JPG
ACME_exploded (Medium).JPG (133.23 KiB) Viewed 10519 times
Makerslide Not Included!
ACME_assembled (Medium).JPG
ACME_assembled (Medium).JPG (152.83 KiB) Viewed 10519 times
http://www.shapeoko.com/acme_upgrade

Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Sun Sep 30, 2012 6:12 pm
by jzatopa
I would be interested in this if my shapeoko would just get here. Any chance this could be made to increase the range on the Z axis?

Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Sun Sep 30, 2012 10:09 pm
by Improbable Construct
There is the possibility of an increased range Z-axis but I am not sure it is necessary.
Unless you plan on raising the machine way up in the air the standard travel should be more than enough.
Do you have a specific need for more travel?

Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Mon Oct 01, 2012 12:00 am
by cvoinescu
This is a great idea, and the kit looks really nice!

I'm already thinking of how to use this upgrade, or something similar, with my kit (the eShapeOko), but without the need for 250mm of threads for only 100mm of travel. It's a problem specific to my machine, because of its taller Z-wheel plate replacing the 90mm standard carriage plate. With a leadscrew mounted in the same way, it would not be able to use the bottom 130mm of thread; the ShapeOko can use all but the bottom 70mm, so it gets 110mm of travel out of 200mm of threads (the lead nut is 20mm tall). If I can design a mount for the bottom end of the screw that fits within the 13mm clearance behind the Z rail, and is adjustable with the Z axis assembled, I could then use a shorter leadscrew. I have a few ideas, two of them fairly promising.

Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Mon Oct 01, 2012 6:38 am
by SnapFracturePop
Glad to see some of these upgrades being offered as packages - sometimes I end up stalled trying to find that one screw/spacer/connector that I can't source locally. Since GRBL limits the max speed to the max any axis can take, this should provide some additional zip in all directions.

Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Mon Oct 01, 2012 1:05 pm
by edwardrford
SnapFracturePop wrote:...Since GRBL limits the max speed to the max any axis can take, this should provide some additional zip in all directions.

That is exactly correct. As IC said, this upgrade reduces the number of rotations required to move a specified distance, which should allow for the total machine speed to be significantly faster as you're no longer constrained to the max z-axis speed of the standard build.

I'd be interested to see how fast you can run the machine with the new setup through grbl. With Mach3 (and linuxcnc) one can specify speeds for each axis individually, so it won't be an apples to apples comparison. IC sent me one of these upgrades which I'm planning to mount sometime this week. I'll post back when I have an answer.

-Edward

Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Mon Oct 01, 2012 1:34 pm
by zimmer62
I'd like this upgrade if the motor block had holes for both the nema 17 and the nema 23

I suppose I can just build my own nema23 block.

Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Wed Oct 03, 2012 5:37 am
by dointhangs
I've just got mine in and ran a few little pen jobs and of course ran it up and down a bunch. As background I have pretty much been struggling with z axis stuff since my shapeoko hello world. At one point I got a new threaded rod installed and I was planning on doing the mod of turning down the threaded rod to fit into a smaller coupler, just hoping that a better seat for the little coupler allen bolts would help. So long story short even at its best behaved my z-axis wobble was worse than IC's "before" video above. And some of you may have seen a video of mine with a pretty downright horrible wobble where it looks like the machine was going to self destruct haha.
So I am not going to post a video or a picture of this tonight but please understand that it seems all of my tears are washed away with this new z-axis kit. You may need a hacksaw (I used a band saw) to trim 5-10cm off the turned down portion of the acme that fits into the coupler - my stepper had a pretty long 25cm shaft and the 50 mm long 3mm bolts werent reaching up into the stepper. Other than that installation was straightforward... I did not need the little included washer to take up any play in the top/bottom plates, it was money as is. Hey the thing just flat out moves and moves straight as an arrow. Any other developments in upcoming days I will update you here but thats what it looks like right now. I'm happy to keep looking at this with a critical eye but right now just to say cheers on the solid work.

Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Wed Oct 03, 2012 4:04 pm
by Improbable Construct

Re: ACME screw upgrade for Shapeoko Z-Axis

Posted: Wed Oct 03, 2012 7:30 pm
by potatotron
IC - thanks for coming up with this, I just ordered mine. Great timing, I've been really busy with my day job for the last few months and am just getting back to my ShapeOko pick and place machine. One big outstanding problem has been the speed of the Z axis; it limits how fast I can place components. I am looking forward to seeing the improvements from this.