3D Printer to Laser Cutter

For no particularly good reason I have decided that I need a laser cutter.  I already have the basics that are needed in that I have a 3D Printer for the mechanicals so what I really need to add is the laser and some additional logic.

The laser kit that I have purchased is the JTechPhotonics - 2.8W Laser engraving & cutting Kit.  This comes with both a laser and the power supply with some control electronics.

My goal in driving this laser is to be able to use as much of my current workflow as possible (e.g. Sketchup and Simplify3D), without making any firmware changes on the printer, and with a minimum of hardware intrusion.

The first thing that this means is that I need a way of telling when the laser should be firing and then I need to be able to fire it from GCode.   Telling when the laser should be on and off is relatively easy assuming that I write a preprocessor that can scan and regurgitate GCode.

Driving the laser from GCode is a little harder.  This is where the power supply and control electronics come in from JTechPhotonics.  It can take as input either the LCD or the FAN PWM signal from the printer,  both of which are controllable via GCode, and use that signal for turning the laser on and off.

Raspberry Pi Zero PoV Wireless Camera

This is one more project in the long list of projects that may not actually meet a need but was fun to build.

The "requirement" that this solution meets is to provide a wireless Point of View camera that can be used to photograph dioramas, model railroad layouts, or for Line of Sight previews when playing a tabletop game such as Flames of War.

The solution is a 3D Printed case that encloses a Raspberry Pi Zero that is attached to a Pi Camera. The Pi Camera is in a mount that can slide up and down a track to match a PoV elevation. The Pi supports a wireless dongle that can either attach to a network or provide one of its own (Adhoc or Otherwise). Power is supplied by a portable mini charger.

There are examples of each possible usage above. The first photo is showing a PoV looking down an N-Scale Drawbridge, the second two are showing a picture being taken of a small diorama, and the third is a representation of what a Flames of War usage might entail.

Models are here and there is an Instructable here.

Some Considerations for Building the Bascule Drawbridge

This is a bit of a catch-all post in support of a project to build my N-Scale Bascule Style Drawbridge.  The various model files are here and the instructables are here.

Dimensions

The smallest bridge is four sections with each section being 19 full scale feet or 37mm at scale.  I can also do five or six sections just as easily.  Clearance side to side is 28mm and from the road bed to the stringers is 40mm (which, with track laid, is too short for some cars).  The operating part of the bridge is 140mm long, 55mm wide, and stands 120mm high.  Below the table there is another 90mm needed for the motor assembly.

Power for the Bridge

The electronics stack needs 5v and the stepper motor needs 12v (though you can get one of the right form factor that will work with 5v).  You can also drive signal lights from a relay as part of the configuration and for my demo these were 12v.  In my demo configuration I took a single 12v supply and used a little voltage regulator to provide the 5v supply.  Decision Needed:  Provide both 5v and 12v to the bridge or just provide 12v.  If you just provide 12v there are a variety of voltage regulators that you can use.  If you want to trigger signal lights then you will need relays that can be actuated by the Arduino.

Options for Mounting the Electronics

My demo, as described above had the PCB, a relay that drove the signal lights, and a little voltage regulator all attached to a tray that was designed to hold the pcb and allow the other components to be tied down.  There was also another printed part for a control panel.  My assumption was that the tray would be secured somewhere with wire run to the bridge, the control panel, and to power.  The other option is a new one and that rendered the tray as a drawer that slides into two printed guides that would be mounted behind a cutout on the side of the frame the layout sits on.  The control panel becomes the front of this drawer.   What approach works best for your layout?

Configuration One

Configuration Two - Front and Parts

Configuration Two - Back

Stepper Motor Specifications

DC 5 or 12V 2 Phase 4 Wire 35mm Stepper Motor .  The under structure mount is designed for this specific motor (35mm deep).  The electronics would handle a lot of different motors but the mount would need rework (though the 42mm motor may fit).

Parts Needed for the PCB

• Arduino Nano V3
• Easy Driver - Gold Version - Cloned Version
• Screw Terminals - 5mm Pitch - 10x 2 connector, 3x3 connector, 1x4 connector
• Resistors for the LEDs - 4 x 30 ohm
• Headers - 3 x 2 pin

Other Parts Needed

• 4 x LEDs, 2 x RED, 2 x GREEN
• Push Button (SPST momentary) to fit 16mm Cutout
• Switch (SPST) to fit 9mm x 14mm Cutout
• Micro Switch Endstop x 2

Final Note

You may have noticed that my links take you to eBay UK.  I live there so that makes sense!  Simply take the verbiage from the search box and plug it into eBay US (or wherever you live).

3D Printing Challenge

Every once in awhile something stumps me with my printers.  This is a test print of some tiny little reinforcing panels for one of my bridge designs.  The little dots are meant to be bolts or rivets.  The print is done using a 250 micron nozzle and 125 micron layers in PLA.

The panels printed at top, in normal orientation are fine, but the ones that are rotated by 45 degrees are not.  I suspect this is a belt tension issue but am not sure!

Bowden Tube Friction

The bowden tube I mention is the teflon tube that moves filament from the extruder to the nozzle.  The use of a bowden tube, with the stepper motor on the back of the printer, helps make the Ultimaker 2 more accurate and speedy as it takes weight out of the moving print assembly.

I have two Ultimaker 2's upgraded this summer to 2+'s.   The + upgrade, and its new feeder, has really helped with my extrusion reliability but I am struggling at the moment with one of the printers and during debugging I observed a distinct difference in material flow between the front right and left rear of the build platform.

The below chart shows weights for a small test object printed on two locations of the build platform with #1 being the right side closest to the door and #2 being the back left.

With two out of two printers behaving this way, and some other posts on the same topic seemingly reporting similar things, it would seem this is not an unusual behaviour?   What percentage difference is tolerable?   I have not noticed an issue with a print but may need to watch more carefully!

Need a Custom Designed, 3D Printed, Model for your N-Scale Layout?

If you live in the UK and are actively building or upgrading an N-Scale model railroad layout, AND, you are interested in having some custom designed, 3D Printed, structures for that layout, please reach out to me either here or on Facebook.

My rates are very reasonable...just your time integrating my work into your layout and providing me feedback on the designs along with some photos of the finished product (and ideally the work in progress).  I am retired and do 3D design and printing for kicks but since I do not have the space for a layout of my own I am hoping to see my work on your layout...and I like getting ideas and seeing if I can turn the idea into a model.  My idea project idea would be for an animated structure but any other creative thoughts for things not readily available will be considered!

Below are images of some of the work that I have done.   All of these designs are in the public domain on Thingiverse for folks that have their own 3D Printer:

Parts of a Bascule Style Drawbridge

Design Rendering

Instructables for the Bascule Style Drawbridge: One, Two, Three, and Four

A Truss Railroad Bridge

Instructable for a Truss Railroad Bridge

Plate and Girder Railroad Bridge

Instructable for the Plate and Girder Railroad Bridge

Windmill

Instructable for the Windmill

Bailey Bridge (1:100 Scale)

Instructable for the Bailey Bridge

Field Wagon (1:100 Scale)

Instructable for the Field Wagon

Best Approach for an Entry Level Printer

This is a follow-on to the article that I wrote a while ago in regards to what 3D Printer I would recommend.   I had a question about an entry level printer, in particular regarding kits, and thought I would add to my previous article.

My first recommendation would be that if you are going to build a kit...build a Prusa I3.   This is by far the most popular type of kit and there will be a lot of support from other users.

The kit that I originally assembled is still available from 3D Printer Czar in China but the price ($499) is certainly not the lowest that can be found for a kit.  In fact, and more on this in a bit, there are ready assembled I3's for that price.   I am not sure what the "best" kit is at this point but if I were looking for the lowest cost Prusa I3 printer I would go to eBay and do a search for "Prusa I3 3D Printer Kit".  I filtered the list by value to 100-500 quid to get rid of kit parts and checked the box for UK only stock.   This yielded a list of printers from just over 100 GBP to the top end of 279 GBP.

I am not familiar with any of these kits but would advise spending some time reading the listing carefully and looking at customer reviews.  I would recommend an aluminum frame for the extra sturdiness though my printer and its plastic frame worked just fine.   I would probably not go with one of the very cheapest kits but if you are really strapped for cash it could be worth the risk.  The worst case is that you may have to source an additional part or two from a range of readily available stock.  I suspect, though I am not completely sure of this, but you are going to be on your own when it comes to doing the build in any case of these kits!

Building one of these inexpensive kits is going to be somewhat of a challenge and it is going to be a while before you print your first object.   When you are finally printing it is going to take another chunk of time to get the printer tuned and calibrated so that prints are of good quality and can be done reliably.  On the plus side...you will have learned a lot.

I am not sure that I would do it differently but there are some entry level printers out there now that I think would be worth considering.   My particular favorite is the Wanhao Duplicator I3.  This is a ready built Prusa I3 and while I do not have experience with it directly I did have a Wanhao Duplicator D4S and thought it was pretty well done.  A ready to go printer, with the glass bed and a can of print bonding spray, will cost you 309 GBP.   This is 100-150 quid more than a kit (with a metal frame) but you will be printing from day one.

There are some other entry level printers in a similar price range to the Wanhao that I describe above but I like the idea of the Prusa I3 as it is open source...if you want to upgrade it you will be able to do so.  Some of the other entry level printers will not allow this as an option.

That is my two cents.