Low Cost Linear Actuator for Cnc Xy Table and Alike!

If you are interested in 3D printing, you might also want to check out my other instructable for a revolutionarily cheap DIY SLS 3D printer

Creating a good linear actuator for your personal 3D printer or cnc machine is never easy. Either you try to incorporate lucky eBay finds in your design, which isn’t very dependable as a source for your parts. Or you come up with a solution that works in your case, but may be complex and yet is not very flexible when it comes to changing your design later on. The industry has solved this problem by creating systems that are build modular as well as allowing different usages of the linear actuator.

My take on trying to create something that is rather close to the performance of an industrial system was using 3d printed parts. Also the system allows for direct mounting of either on or two NEMA 17 motors per axis as well as mounting any motor using an adapter which is to be 3d printed.

I have uploaded two designs, one is using laser cut parts, the other one can be compleatly 3D printed.

for the Linear actuator with laser cut parts, use: "endblock.stl","schlitten.stl" and "seitenteil.stl"

For the Linear actuator that is 3d printed, use: "Endblock 3d print.stl" "seitenteil.3d print.stl" and "schlitten.stl"

(I am sorry about the german names, i will fix it when i have the time)

if you are capable of reading german, pleas contact me for a more complete documentation of this assembly.

I may soon upload the pulley as printable file, so that you dont need to buy those as well

Step 1: Versions

Before building one of these you want to consider wherever you want to only use 3D printed parts, or you have access to a laser cutter. even though the laser cut design looks a lot neater, you will find that i have made a little mistake, wich results in a verry hard to reach screw... this is not tragic at all, but i have changed the 3d printed design so that this mistakte does not show up. also in the 3d printed model, there is no gap between the motor and the panel.

Step 2: Parts

The key ideas behind this project were using as many parts that you can get anywhere and reduce the number of custom made parts. In fact only the linear guides and bearings are of a specific brand, all the other bits are available around the world. These linear actuators are not only very precise, they also allow easy mounting to itself and to other aluminum extrusions. The current design uses 3d printed parts as well as laser cut parts. As many people don’t have a laser cutter available and online services may be expensive I am soon going to upload a design which only uses 3d printed parts

Parts:

1 Piece of 30x30 Aluminium Extrusion with Bosh/Rexroth Profile. 8 Piece T-nuts with M4 thread

1 Piece linear rail (Igus NS-01-27.)

2 piece linear bearing Igus NW-02-27. GT2 timing belt (6mm width)

2 Piece 40 tooth pulleys for GT2 belts 4 Piece ball bearings 16*8*2mm.

2 Piece *20*9 mm. A bunch of metric screws.

2 Piece 37*20*9mm bearings

4 Piece 16*5*5 bearings

And not to forget about your 3d printed and laser cut parts. To save material and money, the Pulley housings are hollow, but even made in PLA, they are strong enough.

Step 3: Assembly

Start by making the idler

pulley assembly.

To do this, attach the pulley to the 5mm shaft. This is not entirely nesseresary, as the big bearing ist holding quite well. Also you may consider putting a washer in the to take the last millimeter of play. Next insert both of the smaller bearings into corresponding hole in the mounting block. Finally insert the big bearing and attach both of the laser cut mounting plates using four 3mm wood screws each.

Before you mount the motor to one of the laser cut plates (make sure your cable goes the way you want it…) you should put in the 4 screws for mounting the plate to the 3d printed part. If you miss this you may want to glue the plate and the 3d printed block together as the screwing will be rather fiddly. After you have mounted the motor, it is time to put the pulley on the driveshaft. Make sure the belt can go right through the middle of the block after your pulley is in place. Then attach the plate with the motor to the 3d printed block.

Next you can just put the other plate on to the same block, just as you did on the other idler assembly.

Next attach your linear bearings to the 3d printed “table”.

Then attach the linear rail to the aluminum extrusion, by using t-nuts and flathead screws. Now it’s time to slide in your “table” assembly. Next get the belt untwisted through the hole in your extrusion (really, make sure it isn’t twisted).

Also slide 4 t-nuts in each sideway facing slot of the extrusion. These will allow you to attach both “pulley assemblies”.

Carefully slide the belt through the pulley assemblies, so that it won’t get twisted, and then slide the assemblies on, so that they are flus against the sides of the profile.

Now it’s time to attach the belt to the table. Do so, by bending the tip of your belt up, and then compress it underneath the table. Once it comes out the top of the assembly just bend it over so that the toothed sides are facing to each other. Push it back inside the table’s assembly and insert the 2mm screw that goes across the assembly. Make sure the connection is strong, for extra security, you may put a screw in the remaining hole in the front.

Repeat this on the other side. If the belt isn’t tight right away, don’t worry about that. We will fix it in a minute.

In order to tighten your belt, loosen your idler assembly from the extrusion, this will allow you to pull out the assembly and thereby tighten up the belt. Once your belt is tight, just tighten the screws again.

And there you go, a perfectly fine linear module for less than a 100 bucks. I hope this will help you in making your own 3d printer, CNC mill, laser cutter or other invention.

I am currently working on a sls 3d printer, have the option of laser cutting a vast amout of parts with your own laser cutter would be incredible. thank you for considering

Step 4: Endstops!

after the requests i have addet an endstop mounting plate to the files. it is suitable for the huse of the common reprap enstops (either hall effect or mechanical).the mounting plate attaches to one of the side panels. if you come up with a better solution feel free to contact me, if you are not familiar with cad just do a small drwaing of it. i will integrate your solution. have a great day!