Coasty Source Files

A lot of people have asked about building their own Coasty Laser Cutter. It takes a lot of work to get the files ready for release. I will release the source files in stages as they are ready so people can get started. Watch this post for updates. Subscribing to this blog or following me on Twitter (@buildlog) is a good way to keep up.

When everything is ready, I’ll probably also post on Thingiverse.

3D Printed Parts

Here are the STL files for the 3D printed parts. The parts are generally pretty easy to print. They require no support and can be printed in low resolution. I print at 0.28mm layer height. You need to watch out for warping on the chassis and front door. If the chassis warps it will stress the PCB and could damage some parts. The door needs to be flat in order to close properly.

I printed my parts in generic PLA. They printed fine, but if you have some crappier PLA or if you don’t have a heated bed, you should probably print with a brim. I would suggest printing the chassis first. If you can print that, the other parts are easier. I have some PETG on order to test. That supposedly warps less that PLA.

The holes used for the 8mm rods are designed to be a press fit. If the rods are hard to install, try cleaning the holes up a little by hand with a 5/16 or 8mm drill. The drive shaft bearing is also a tight fit. Try using a vise or clamp to press it into the chassis.

Zip File containing the STL files.

Mechanical BOM


Part DescriptionQtySupplierSupplier P/N
3mm Smooth Pulley (16T equiv dia.) 6mm Wide1
Bearing 3mm x 10mm x 4mm2Generic623-2RS
BEARING 5mm 16mm 5mm1Generic625-2RS
Bearing Shaft 8mm2
Butoon Head Screw M3 x 302
Button Head Screw M3 x 121
Button Head Screw M5 x 201
Coasty Chassis13D Print
Coasty Controller Assy1Buildlog.netCoasty Controller
Coasty Drive Shaft13D Printed Part
Coasty Final Assembly1---
Coasty Laser Carriage13D Printed Part
Coasty Laser Carriage Assy1User Assembly
Coasty X Motor Cover13D Printed Part
Dual Fan Cover13D Printed Part
Flat Head Screw M3 x 64
GT2 Belt 6mm Wide cut to 385mm1GenericGT2 6mm
Hex Nut M33
Laser Module 3.5W 450nm1EleksmakerLA03-3500
Linear Shaft Bearing 8mm Dual2GenericLM8LUU
NEMA14 Stepper Motor2Generic
Nylock Locking Nut M22
Nylon Locking Nut M33
Pan Head Screw M2 x 122
Silicon Oring #9052McMaster Carr1283N428
Socket Head Screw M3 x 820
Socket Head Screw M3 x 162
Socket Head Screw M3 x 203
Timing Pulley GT2 18T 6mm Wide 5mm Bore1
Wiring Cover13D Printed Part
Coasty Window149mm x 76mmJ Tech PhotonicsRating: OD+4 @ 445nm
Coasty Door13D Printed Part
Beam Stop (Metal Strip)170mm x 9mm x (0.5mm - 1.5mm)Fabricated


PCB Source Files

See this blog post


Coming Soon

Build Instructions

Assembly Drawing

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38 Responses to “Coasty Source Files”

  1. Bob

    Bart — Can’t thank you enough. Preparing these things for release is definitely a lot of work (more than some may realize), so I once again just thank you for doing it.

  2. bdring

    I added the basic BOM.

  3. Cameron

    This is awesome! I’ve been reading your posts on “coasty”, and I really want to build one! The proper release of the design is greatly appreciated, especially knowing the work required. Thanks!

  4. Bob

    @bdring — Is it possible to run Coasty using a Cohesion3D Mini? It’s made to run GRBL-LPC. I ask because I already own one, and it costs less than the Coasty controller (though admittedly it’s not purpose-built for Coasty). If I can save the money by reusing the C3D Mini, that would be awesome. 🙂

    Product —
    Firmware KB —

  5. bdring

    I would assume so. My first version had a solid back and ran external electronics. The wiring was a scary mess. The goal was to have something look as clean as possible and be portable without worrying about loose connections.

    You would need to add fans and redo the switches. The laser module I have fires the beam when there is no direct control of the PWM, so you would want a decent pull down on that.

  6. Bob

    Thanks, Bart. You’ve convinced me to bite the bullet and buy the purpose-built controller. 🙂

  7. Bob

    @bdring — Does the BOM include the hardware to mount the laser module to the linear shafts and the belt? Closest mention I can find is the Laser Carriage Assembly but you note in the BOM that it’s a 3D printed part which I don’t see in the STL zip file. Am I just missing or overlooking something?

  8. bdring

    Sorry about that

    I forgot to add that STL to the zip file. I uploaded a new zip file, so please download that one.

    I also added a assembly drawing that should show you how the laser mounts.

  9. Bob

    Thanks, Bart! 🙂 FYI — I think the Assembly Drawing link is pointing to the STL zip file.

  10. bdring

    Thanks, should work now.

  11. Bob

    I thought I’d share this interactive BOM status tracker I built in Google Sheets. Feel free to copy it for your own personal use:

    It uses some conditional formatting rules to color code the rows according to what’s set in the Order Status column.

  12. Bob

    After reviewing the assembly drawing, I think the only thing that’s still a little unclear is how the bearings that sit under the roller shaft are mounted to the chassis. You say to use the nylon locknuts, but which type of screw is needed there, and is there a specific way they should attach?

  13. Bob

    Question: In the BOM, you call for a GT2 18T 6mm Wide 5mm Bore Timing Pulley. I’m having trouble sourcing an 18T, and I’m curious if a 16T or 20T would also work? There are bundles like this readily available online, which is why I ask:

    Also: Some belts have steel bands in them to improve their strength and reduce stretch. Given that the length needed for Coasty is so short, is that a concern here? Replacing the belt every so often is easy enough, so I doubt it. But I thought I’d ask.

  14. bdring


    Assembly Drawing: I added a section view that will help show that bearing screw. I also used a thinner “pen” to make the PDF that should help.

    Pulley: I think this one should work.

    Belts: Do not get the steel bands. I tried them on other projects and the belt is thicker, so it has issues with the fit on standard parts.

  15. Bob

    Great! thank you, Bart! 🙂

  16. Bob

    Oh. My apologies for any confusion. The parts I’m confused about are the 18T timing pulley (the one with grooves for the belt teeth), and the belt itself. The problem I’m running into is finding an 18T pulley. I can easily find 16T and 20T, but not 18T for some reason.


  17. bdring


    It is not very obvious, but you can change the “color” of this pulley to 18T.

    That is common with some mechatronics stuff on eBay and Amazon.

  18. Bob

    Ahh. Thanks! Not sure how I missed that.

  19. Bob

    BOM is missing a line for the 3D printed door.

  20. Bob

    A few interesting facts after running the numbers (see my BOM calculator link above for details):

    1. Total build cost: $275
    2. Total investment (retail parts bundles): $408
    3. Controller and Laser module account for 53% of the cost

    Given that Coasty’s design and functionality meets my specific maker needs so well, I personally feel that the build cost is reasonable. It’s encouraging also that factoring in wholesale pricing for parts quantities, and the elegance of the build’s design making for a fairly simple assembly procedure, one could probably reduce the per-unit cost pretty significantly at-scale.

  21. Bob

    Correction on #3 above:

    Controller and Laser module account for 68% of the total build cost.

  22. Bob

    What’s the thickest material that can be fed through Coasty? The CAD drawings show the opening is 2.75mm, but I imagine with the O-rings on top and the bearings on the bottom that the actual max feed size would be smaller. 2mm max, perhaps?

  23. Bob

    Quick update: Just plugged real gram counts for printing the parts using a 20% in-fill and no supports into my BOM cost calculator.

    The parts require 28% of a 1KG spool of PLA to print, and the filament I ordered was $30 a spool (because Hatchbox has an inventory shortage right now). These figures drop the overall build cost to $253. The Laser and the controller now account for 74% of the total build cost.

  24. Bob

    Bart — I think the BOM and Assembly Guide are both missing the strip of metal on the bottom of the chassis to shield the beam. Yes?

  25. bdring


    Correct on the strip. That was a part I just trimmed from a piece of metal. I had and did not model it. I fixed that and it is on the BOM now. The strip can be made out of virtually any metal off any thickness that fits. The beam won’t cut metal and it is not very focused there anyway.

  26. Bob

    Thanks, Bart. I figured, but thought I’d raise it for the sake of completeness and ambiguity avoidance. 🙂

    I’m having trouble finding stuff that is ~16 Gauge and less than half an inch wide. Since the width of the slot (10mm) on the Coasty is pretty well constrained in both directions, widening doesn’t seem too possible.

    Here’s the best I’ve found so far. Any suggestions?:

  27. bdring

    I would suggest going to a home depot type place. You might find something like roof flashing. You could even fold over some aluminum foil and fold it a few times.

    The laser probably won’t pierce any metal. It just reflects and scatters.

  28. Bob

    Good point. I’ll improvise something.

    Oh, also, while I’m thinking about it: Does the 12v 5A power adapter need to be added to the BOM, or is that considered outside of the mechanical build?

  29. Bob

    Does anyone happen to have a better source for these 4-pin JST connectors? My NEMA14s didn’t come with terminals attached, and so now I need to figure out a solution:

    Any help would be appreciated.

  30. bdring


    That is a good source for the motor connectors. I have a similar kit and use it all the time. You can manually crimp with needle nose pliers if you don’t want to buy a crimper.

    Those are not typically called JST connectors. Most people call them 0.1″ header connectors.

  31. Bob

    Thanks, Bart. After posting that, I also figured out another common name for them is Dupont connectors. Using that search phrase returned the most consistent results so far. In any event, I’m glad I found the right thing.

    Do you solder them too, or just make sure you get a nice, tight crimp?

  32. Bob

    Quick update on my Coasty build: I’ve sourced and acquired all the necessary components. I’ve manually added Dupont (0.1″) connectors to both NEMA14 motors, and I’m currently waiting for a friend to upgrade their 3D printer to a heated glass bed so they can print the custom parts.

    For anyone looking to build their own Coasty, I recommend solving the 3D printing requirement early, as it has the longest lead time if you don’t own your own printer.

    Along those lines, if anyone happens to have an economical printing solution, I’m all ears. The print on demand shops I’ve found so far are exorbitantly priced.

    I’m thinking I might live stream the assembly itself. Which should be equal parts interesting and terrifying. 🙂

  33. Maks Surguy


    I’m building one of these and am wondering if there’s a simple tweak I can do to make the biggest part fit on 200×200 mm bed and perhaps make it a bit more modular so that multiple printers could be used. Do you guys have any thoughts around that?

  34. Bob

    Hi Maks. I think the chassis and door are both about 170mm on their longest sides. So both parts should fit on a 200x200mm print bed. Unless I’m missing something? What problems are you encountering?

  35. Maks Surguy

    @Bob, it looks like the chassis is 212 mm on the longest size, here’s a screenshot : so I was not sure how to fit it into 200mm bed

  36. Bob

    Hi Maks,

    Ahh yes. I’d forgotten about the motor mount. You might try trimming it out in such a way as to ensure you can epoxy it back on accurately as a separate print. For example, if you cut the piece out of the model so that it carries through the main chassis wall, then you’d merely need to insert the piece into its own slot.


  37. Bob

    Hey Bart,

    I’m still not able to build a Coasty despite having all the electronic and mechanical parts now on hand, because unfortunately, print-on-demand services want $170 just to build the chassis, let alone the rest. Do you have any thoughts on ways to solve this roadblock?

    What about a chassis and lid that can be assembled rather than printed whole? Not sure what else to do…

  38. bdring

    I’ll contact you off-line with some suggestions.