Two Trees 3018S CNC Router 500w Spindle Upgrade Kit

NOTE: The big hole for the anti-backlash nut that has the 4 pilot holes for screws goes down. Don't put this side up because there will not be clearance for the stepper motor coupler.

Warning: Version 1.2 has motor to spindle clearance problems. Use Version 1.3

This is for a Two Trees 3018S CNC Router upgrade to a 500W spindle using Two Trees 500W spindle upgrade kit intended for a different model.

Use this at your own risk, or don't use it at all. By “at your own risk”, I mean damage, injury, or anything at all for that matter, as a result from you using this design is your responsibility if you choose to use this design. Strapping a 500W motor spinning a sharp tool at 11,000+ RPM to a hunk of plastic that may have structural, material, or design flaws in order to get more power on a machine that was not designed for it… I put that risk on the end user. You should think: enclosure, PPE, add an E-Stop, etc… Again, end user responsible. No warranty or promise made.

I am releasing this as public domain. If someone else has already published something similar enough to this, and it is indeed original, prior to my publication and there is some requirement not met… I made no intention of violating any laws, plagiarizing, or causing any harm and will attempt to make reasonable corrections. If they just copied the basic design of a commercially made product, made some dimensional changes, and printed it out of plastic, I don't believe that should or could be protected.

Features:

The carriage has a very tight tolerance edge going across the top and bottom to position the spindle mount perfectly horizontal. This is meant to fit the Two Trees mount provided in their kit. Other mounts may require adaptation, but maybe not.

The mount was not created as part of the print due to concerns the heat from the spindle would cause excessive thermal expansion and softening of 3d filament material. Any effects from this heat source will be minimized by this decision in at least these two ways: 1) allowing the heat to dissipate more before reaching the filament material than direct contact would. 2) the area where the filament is used, even if subjected to the same thermal changes as if the mount were being printed, is all in a less critical area with features preventing catastrophic events(ex: dropping the spindle because it loses grip)

Efforts were made in the design to keep the center of the larger motor to as close to the original center of the smaller motor as possible to reduce the effects of additional torque on the z and x axes due to the effective lever arm length being increased.

The spacing of the z-axis bearings (38mm center to center) is spaced for the z-axis of a Two Trees 3018S. Other variations of the 3018 might have different spacing, but maybe not.

This design creates NO change in the x-axis available travel. However, it does lessen the amount of travel in the z-axis as a result from utilizing a longer bearing. This design could have been made to use the original shorter bearings and maintain the z-axis length, but the longer bearing offers more support, more stability and accuracy, and this should help with the increase in weight and leverage in the area.

You will need the following parts:

1. A Two Trees 3018S CNC Router. You can find them for ~$130 on Temu.
2. Anti-Backlash nut for acme lead screw. T8. 2 start, 2mm pitch. Available on Amazon: https://a.co/d/hpeaXFx
3. 2 Bearings for the rods. LM8LUU 8x15x45. Temu has these. https://share.temu.com/6CoSlsX3YHC
4. 4 thread forming screws to mount the Anti-Backlash Nut size 4-20x1/2. Hillman 38135: https://shop.hillmangroup.com/ccrz__ProductDetails?sku=38135&cclcl=en_US you might find these at your local hardware store. Might not.
5. 4 Allen Socket Drive M6-1.0x70mm cap screws with Nuts, Washers, and Lock Washers. The Allen Cap Screws included in the Two Trees kit are not long enough. They also don't include the nuts or washers because the screws are meant to screw into a plate.
6. Two Trees 500W Spindle kit. This was designed specifically for this kit, but you might be able to get by using something else as long as the aluminum mount is the same size and bolt pattern… or…  I've included the CAD files so this could be adjusted for other CNC machines and kits.
7. OPTIONAL PART: bearing for the lower end of acme screw stability. MR128-2RS Deep Groove Ball Bearings 8mm Inner Dia 12mm OD. You only need one, but you can get 10 on Amazon: https://a.co/d/jgiHQrJ It's odd how Two Trees left the end of the acme lead screw just hanging loose with no guidance. Glue/epoxy/???  a bearing in there and it's fixed.

Disassembly: You can actually do this without too much tear down.

1. Remove stepper motor and associated hardware. Loosen Coupler on the motor side and leave coupler attached to the screw(do not loosen this end of the coupler), remove 4 mounts, unplug, etc. etc. This is actually the biggest PITA of the whole thing.
2. Use an Allen Key or punch that fits into the hole under the two rods and tap them up and out enough to remove the old z axis carriage, they don't need to come out all the way, you don't need to pull the side off the CNC. You may need to position things a little to do this, but I like this better than taking the sides off and the whole thing apart. The L shape of the Allen key allows low profile way of getting a tool in there. Use your head and stabilize parts and to smack things too hard.
3. Now that the carriage is out… you need a new one. You will reuse the acme screw with the attached coupler, so save those.

Printing the New Carriage:

Use the 3mf file. Use ASA CF 50% infill in the gyroid pattern with supports and print it upright. Be sure to dry this filament thoroughly. ASA handles more heat than PLA and the CF adds a bit of strength, stability, and is just cool to say there's carbon fiber in there. CLEAN UP all remaining support material and defects.

Installation: 

Install optional bearing if you wish.

The Bearings: These will press in with a vise and some wood to protect it. It seems like it's going to break, and maybe if you're really being reckless it will. Go straight. It makes noises and complains, but a tight fit is a good thing.

The Anti-Backlash Nut:

It is tricky to get the anti-backlash nut installed on the acme screw properly. It's unfortunately necessary to be this way, see my note at the bottom if you're curious. First attach the one side of the nut to the carriage with the 4 screws so it doesn't move. (flat side to the outside)

Drop the other side into the opposite end without the spring first just to get it seated in place and coupled where the two halves link. There should be about 18mm from the face of the carriage to the face of the nut, then you'll know it's in the correct spot. Make a mark on the loose nut with a sharpie so you know how to orient it to put it back in this position because you can't see what you're doing otherwise.

Take the loose half of the nut back out, put the spring in, barely screw the acme screw into the loose half of the nut as few threads as possible and push it down and align things until in place being careful not to screw it in any more and then HOLD IT IN place while you start screwing the acme screw in more until it's through both nut halves. Measure. If it's not around 18mm, it's not right, try again. The idea is to have the spring compressed as much as possible and it coupled. If it's not coupled, very bad things will happen if installed that way. If it's coupled but loose, it won't anti-backlash very well.

Putting the carriage in:

Tilt it, make sure you don't put it in backwards or upside down. Look at photo. Slide the acme coupler into the hole, slide the carriage bearings onto the part of the rod which should be sticking out a bit because you were only supposed to push it up enough to get the carriage out. Then push the rods back down into their seats. Screw the acme screw down a bit. Make sure the screw fits the optional bearing if you installed it…

The rest is up to you:

Okay, you should be able to handle the rest. Share your success, failures and mods with this. Hope this helped someone else upgrade.

NOTE: Making the hole in the middle bigger so the anti-backlash nut could just drop in would remove where the screws go. The nut would need to be epoxied in because screws wouldn't work. So. it's possible, but at a cost… CAD files are here if you want/need them.