Inexpensive add-ons for z-axis slack imprecision

GardenRobot · June 26, 2018, 9:04pm

This is a companion discussion topic for the original entry at http://maslowcommunitygarden.org/Inexpensive-add-ons-for-z-axis-slack-imprecision.html

geeklimit · June 27, 2018, 3:19pm

Initial post to forums has been migrated to github / community garden.

Text is too long for a forum post, linking github:

github.com

MaslowCommunityGarden/Inexpensive-add-ons-for-z-axis-slack-imprecision/blob/master/INSTRUCTIONS.md

# THE SITUATION

The router motor is inside of a metal sleeve, and the sleeve has a wide slot cut out of the side. There is a rectangular cutout in the router motor body that travels up and down, visible in this cutout. A spring-loaded clip pushes a rectangular-shaped tab into the rectangular-shaped cutout in the motor body. This clip is what the z-axis adjustment screw (technically a 'worm') pushes up and down when the screw rotates.

# THE PROBLEM

These are not precision-machined parts, and either the cutout in the motor body is too big, the tab on the clip is too small, the hole in the clip has problems, the worm can slide up and down parallel to the router body - or a combination of all four.
![](https://raw.githubusercontent.com/MaslowCommunityGarden/Inexpensive-add-ons-for-z-axis-slack-imprecision/master/2018-05-12%2017.20.11.jpg)

## TESTING

With my Ridgid R22002, the problem was the hole in the clip used by the worm. In testing, here's what happens when we zero the bit and drill two 10mm holes: (numbers rounded for illustration)

### ZEROING ERROR

1. The bit is 10mm above the surface, The clip is perfectly perpendicular to the router body (level).
2. The z-axis is told to move 5mm down. The worm side of the clip moves 5mm down while the router body doesn't move.
3. The clip is now tilted "down", with the worm side 5mm lower than the router side.
4. The z-axis is told to move 10mm down. The bit is now zeroed, just grazing the surface. The clip is still angled 5mm down, lower on the worm side.
5. The z-axis is told to rise to its traverse height of 5mm. The worm side of the clip is raised 5mm, and the clip is now level. The bit is still zeroed on the surface of the wood.

This file has been truncated. show original

geeklimit · June 27, 2018, 3:20pm

added text and picture for using a bolt & nut to hold parts in place while bushing glue dries, thanks @ChuckC!

Sreenigne · August 17, 2018, 4:03pm

Be warned that you need to use a strong adhesive to connect the bushing or it will fail. I used 2P-10 (a type of wood super glue) and it failed after about a week). I had to break it down and redo it. The second time I used a $2 two part epoxy from Harbor Freight. This seems to be holding well.

Note: 2P-10 is amazing for holding wood parts together when assembling. It is not cheap, but holds wood great and sets in seconds.

9/18/18 Update:

My “Z” axis came apart. I have re-done it again. If it comes apart again, I am going to make new one piece one design replacement (stainless steel).

I recommend that everyone perform a pre-flight safety check of their Maslow before EVERY use. Here is what I try to do every time:

Check to ensure cables are securely connected and the power cord is not wrapped around the “Z” axis cabling.
Check the bottom of the sled to make certain it is smooth and has no obstructions.
Verify software updates have been performed.
Verify motors are working and verify “Z” is correct.
Exercise the system by moving sled to be certain all is OK.
Inspect your tool bit for wear and/or damage and confirm it is tightened properly into the collet .
Verify your vacuum system is cleaned out and ready for use.
Check that the “Z” axis upgrade is still firmly attached.
Put on hearing protection (recommended)
Confirm “Home” position and the “zero” height position of the Z axis.

Please feel free to add your own checklist items and possible add to the index for the Maslow. I am sure that there are a number of good practices and safety related things that we can address with this.

Cbolt360 · August 17, 2018, 6:46pm

Yeah I had the clear super glue from gorilla fail quickly. Ended up using jbweld a few weeks ago and so far so good.

iceblu3710 · September 4, 2018, 2:40am

I am waiting on one of these to help solve my slop problem. I will remove the orange pin, glue and put one anchor screw through the existing piece.

Anybody else tried this?

ShadyG · September 4, 2018, 2:56am

Looks like a good tool, be aware it will severly impact your range of motion. Watch out for the safety height in your gcode after you install it or it may run your shiny new nut into the top of the screw support.

johnboiles · September 5, 2018, 2:55am

Do you think it’d make sense to 3d print parts for any of these fixes?

I bet using a strong-ish material like PETG could be used for the washer at least. Potentially saves a trip to the store.

Maybe it could also work to make a piece that wraps around the clip and allows some straightening from both sides of the clip (with a look that looks more like @arnoldcp’s version in his post Z axis only moving the router some of the time)

Just wanted to put that out there in case anyone has thought about it

arnoldcp · September 5, 2018, 10:43am

I think a 3D printer part could absolutely be useful here. You could print a “stubby” anti-backlash nut with guide tubes extending upward and downward for support that fits in the lock tab exactly.

theHipNerd · September 5, 2018, 11:39pm

I took that dang clip and bent it into a more conical shape. That did the trick. I’m trying it without the metal sleeve modification, will see how it goes.

theHipNerd · September 6, 2018, 1:15am

It worked! I might still go back and add the collar mod, but this is good enough for now.

theHipNerd · September 17, 2018, 8:33pm

For completeness: In the long run, this did not work, and the clip flattened itself out. I went and got a washer of the right thickness, and a collar as recommended.

Brent_Becker · April 6, 2020, 7:17pm

For clarification, is the washer you use 5/16" ID or 3/4"ID? The Lowes item # 58125 is described as “Hillman 12 Count x 3/4-in Zinc-Plated Standard (SAE) Flat Washer”. The instructions say to use a 5/16" ID washer. Lowes Item #41574 is described as “Hillman 25-Count 5/16-in Galvanized/Uncoated Standard (SAE) Flat Washer”.

CoJo · April 24, 2020, 1:56pm

Just wanted to put my 2 cents in. Rather than using glue or epoxy, I tapped the mechanical fuse and bolted the bushing on. It was really easy. I used a half inch dowel to keep everything aligned while drilling the holes. You can see the spacing washer below too.

Another thing, sprayed all the parts, and the inside of the router base with dry-moly.

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Inexpensive add-ons for z-axis slack imprecision

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