Actually printing.

September 13th, 2016

I spent all weekend and nights after work fiddling with the printer. I added the limit switches. The Z axis switch mounts to the motor which is at the positive end of the travel. The X and Y are both on the negative ends (i.e. at 0,0). This is all configurable in software but you do have to be aware of what it means for your home position, the position the machine goes to to know where it is. With the Z on positive it means my home position is (0, 0, whatever I tell it maximum Z is!).

IMG_0309 IMG_0376 IMG_0310

The Z axis switch is triggered by a small bent piece of metal attached to the top of the Z base, currently with masking tape but soon to be screwed in place. The X and Y switches bolt to the frame between one of the guide rails and the lead screw. They are pressed by small discs I machined up in the lathe. They have an off centre hole so the disc can be rotated and operate the switch like a cam. That gives me very fine adjustment of the switching position by rotating the little disc then tightening the screw.

For now all the wiring it temporary and taped in place. Cable management will need to be carefully though out so the wires aren’t caught in any of the moving parts, get in the way fo prints and they also need to be run so they cables aren’t strained. I have ordered connectors so I can make longer leads to the motors and sensors as well as some drag chain to help route it all nicely.

With the cabling in place I was able to test things out. I ended up changing the firmware I was running from Marlin to Repetier as I am also running Repetier as the PC host to talk to the printer. I set everything up with guessed values I figured out from a lot of reading online. The problem is not many people make 3D printers using screws on the X and Y axes. Most seems to be belt drives so the settings are not the same. Where lead screws are used it is usually for the Z axis which tend to be run much slower than the X and Y.

I cobbled together some values that worked, set my limits and tested the switches. They need some careful configuration to get right. I also played about with the microstepping on the motors, eventually settling on 1/16th microsteps. Any bigger and the machine was noisy and any smaller (1/32) sometimes the steppers missed steps.

With all that done I was able to control the machine to move!

So the next thing I did was try it out as a plotter. This takes a little fiddling with configuration but I got that going. You also need something to plot with so I drew up and laser cut this pen holder at work.

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It has a sprung attachment that bolts to the Z axis that the pen rides on. This is so I can use a constant pressure on the pen. I used a piece of MDF as a flat plotting base and managed to draw this on it. The screws that hold it to the machine are effectively captive behind the sliding arm. The holes allow an allen key through so the thing can be screwed in place.


My little table made from an old stool base comes in handy for working on the machine. It rotates and you can adjust the height! It makes a very good laptop stand too.

I was able to plot a larger version of the test file I made for my little laser cutter.


With the plotter I was able to fine tune my speed and acceleration values (down) until I could accurately draw the logo multiple times over the exact same lines.

Since I knew all that worked I looked at attaching the plastic extruder. I am using what’s called a J head extruder. First I made the heated base mount because I needed to know the height of that to know what height I would need for the extruder.

The base is another piece of scrap MDF (cut at work now I have been trained am allowed to use the table saw). That attaches to the base plate with 8mm bolts that fit into the mounting holes. The top of the bolts were machined flat and drilled and tapped for 3mm screws.


The holes allow the heated bed to be screwed down to the bolts on the base plate. The heated bed sits on screws so you can adjust the level of it. On top of it goes a flat piece of glass held with binder clips. This is to provide a perfectly flat surface to print on. The surface can be leveled by adjusting the screws. The springs ensure the level stays set. They also allow the bed to move sideways slightly which is important as it expands and contracts slightly as it heats and cools. If you screwed the corners down hard, as the bed heats it would expand and bow.

I am also using a piece of cork tile under the bed as insulation.


The original idea was the bed could be bolted to the Y axis base with 8mm nuts under the plate (remember the cut outs in the frame rails to allow for this) but so far that hasn’t been necessary as there is enough weight to hold things still and the holes are drilled to a close enough tolerance to not allow any movement.

I will make a similar, larger base for plotting/laser cutting on but with a flat, sheet steel top. The steel means you can hold things onto it with magnets.

With the bed done I knew the height I needed for the extruder. The J head uses an aluminium body with a round head that has a slot in it for attaching to the machine. I expect you can buy brackets for these (or 3D print them) but I made my own.

A small piece of L angle has a slot cut into it to match the groove in the extruder. Another small plate had a hole drilled in it the same diameter as the groove. This was then cut in two. One plate is screwed to the angle bracket. The other has over sized holes allowing it to be pushed hard up against the extruder then hold it in place.

IMG_0323 IMG_0321 IMG_0322

This works very well.


With that in place I was able to try the machine again but I hit a snag. The Z axis wasn’t working very well. The stepper was skipping steps!

It turns out the carriage was binding slightly on the guide rails and was too still for the motor to move. That turned out to be because of an ‘improvement” I had made to the machine. I originally used button head screws to attach the plate to the carriages. I then changed to countersunk screws so I counter sunk all the holes.


There is one small problem with doing this. The countersink forces the screw into one position, even if the hole is oversized to allow for some wiggle. Since this machine is hand made my drilling wasn’t precise enough and when countersunk screws were used it forced the carriages into a position that made them still on the rails.


The solution was to go back to the original screws. I just turned the plate over so the screws had a flat surface to sit on. That allows a bit of wiggle in the positioning before the screws are done up hard. This solved the problem. Note the taped on Z axis limit switch actuator!

Steed looks on.


With that fixed I was able to start squirting plastic. The first thing I tried printing was the 3DBenchy boat. This is meant to be a good test for 3D printers. The first couple of attempts didn’t go so well. It seemed the machine was going too fast so I lowered the feed rate each time.

IMG_0357 IMG_0359

At 50% speed things started going better. I got my first actual print! This took about 1h 45 minutes. Apparently this print should normally take about an hour so my printer is slow but then it was never built with speed in mind. The first print was rough but recognisable.


One of the parts of the process of 3D printing is called slicing. This is where you take your 3D model and run some software on it that that works out the commands to actually drive the printer, this is the slicer. It spits out G-code commands which is what the firmware running on the printer used to know how to control the machine. The Repetier software I am using comes with two different slicers, Slic3r and Cura.

I had been using Slic3r (this is what I used to do the plotting too) but I thought I should give Cura a try too. Both pieces of software have many settings to fiddle with but I am using defaults for my setup. In Cura this is a 0.2mm print using a 0.4mm nozzle.

My Cura print came out much nicer.

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I was quite pleased with that! Not bad for an untuned home-hand made printer. That print I actually left running by itself while I went to bed. It seems the way with 3D printing that everything takes forever. I have noticed this at work too. It’s quite a slow process, even on fancy printers.

Today I was working from home (I needed quiet to concentrate ) but I couldn’t use the printer as all the software is on my laptop and I was using that for work. I really must get a dedicated machine built and running. I did fire up the rescued thrown out PC from work and that works so I will build that up soon.

This evening, after work, I did some more playing with the printer and settings. I tried speeding things up again and had problems. I also played with the filament temperature. Then it occurred to me I had never calibrated my extruder. You need to tell the software how many steps it must drive the feeder to extrude a given length of plastic. I hadn’t set that up. It was set to 50 steps per mm but after doing some tests I found it should have been 88 steps. I hadn’t been extruding enough plastic!


During the tests the machine printed that by itself.


With the extruder set correctly I printed another boat! The base was immediately better. I also changed the settings to print more of a border. I think this is just to mark around the outline of the print you are doing but it also gets the plastic flowing nicely before you start printing your object.

That boat came out better than the last!

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The blue tape, by the way, is there to provide a nice surface for the first layers of the model to stick to. You don’t want your print moving while printing it! Apparently 3D printing enthusiasts spent a great deal of time experimenting with anything they could print on to come up with the best surface. Blue painters tape works very well. Kapton tape also works well apparently but it is much more expensive.

That’s one of the great things about 3D printing. Hobbyists have done so much work and experimentation into making all this work. It makes it much easier for me to come along later and read what they have done and make my own.

Still lots to do. Play with all the settings. Speeds, accelerations, temperatures, nozzles, layer heights, all kinds of things. Best to change one thing at a time though! I need to sort out the wiring and a housing. As well as cooling. I am currently using the print cooling fan to cool the electronics! I need a permanent fan blowing air over the drivers to keep them cool. I also need to look at mounting a small cooling fan on the extruder head to help cool the print although I am not sure how necessary that actually is yet.

My power supply is having regulation issues. The 12 volt rail wobbles about a bit. This is a known issue with PC supplies where the 12 volt regulation is not very good without a 5 volt load. I might add some 6 volt car laps as a load and to provide lighting around the printer. Hopefully this helps. I could also run a small 5 volt cooling fan as well.

I also need to print something other than boats so I started something tonight. Have to wait till morning to see what it is!


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CNC Y axis.

September 5th, 2016

This weekend I finished (mostly) the Y axis and base of the CNC machine. This is again made from L section aluminium extrusion. I really had to scrounge about at work to find enough bits to make it. I cut the angles on the drop saw again one lunchtime. I did the same as on the gantry and used angle pieces and small square plates in the corners to hold it all together.


One thing that is really handy when working with aluminium like this is a very coarse file. I used the file I use when I do lead work on the car. The name of the file totally escapes me but it has a very coarse pattern, one side a curved cut. It works great on aluminium and doesn’t clog like a normal file.


After bolting it together I made the base plate and the two lots of spacers that go between that and the linear bearings. The spacers are needed to lift the base plate above the edges of the extrusion used to make the base. After doing all that I drilled the holes for the rails and screw mounting again using a laser cut card template to mark where the holes went. It was only when I went to assemble things I found the template was wrong! I am not sure what happened but the spacing of the rails didn’t match the spacing of the moving bed.


I suspect the issue happened when I drew the templates. I probably accidentally stretched something. Since the holes were only just off I couldn’t drill new holes and I didn’t want to drill or file the existing ones bigger so in the end I remade the base plate that mounted on the rails so I could use the slightly off rail holes. Instead of remaking the two spacers I just cut them up to make 3 sets of smaller spacers. I had been thinking about doing that anyway to help save weight so that worked out fine.


The base plate is mounted with countersunk screws that sit just below the surface so that the top face of the bed is totally flat. I drilled six 8mm holes in it to be used as mounting points. The idea is to use MDF sheets with mounts that match the 8mm holes as changeable bases depending on if the machine is being used for laser cutting or 3D printing or milling.

The holes match the holes in the corners of the 3D printing heated base so my idea is to use 8mm bolts through a piece of MDF. The bolts go through the 8mm holes and are secured with nuts underneath. The tops of the bolts, where they come though the MDF, will be drilled and tapped for 3mm screws. The heated bed will then sit on springs sitting on top of the bolts with 3mm screws holding it down. That allows for height adjustment to level the printing base. It should become clearer when I make it I hope. I am rather making this up as I go along!

Since the base goes past the edges of the frame I needed to make cutouts to leave space for the nuts that hold my bases on. These were marked, then cut with a hacksaw and the bottom of the slot drilled so a piece could be broken out using pliers. The edges were then filed smooth.

IMG_0292 IMG_0291

I also files grooves in the X axis to allow for the bolts heads there that hold the Z axis in place where they pass the edges of the frame. Having the axes go past the edges of the frame make the machines footprint smaller while still allowing full travel on the lead screws I have.

IMG_0304 IMG_0305

It only occurred to me later that I could have used countersunk head screws there too and removed the need for the grooves!

I also bolted the gantry with the X and Z axes to the base. When I cut the base I deliberately made it fractionally wider than the width between the gantry uprights. This was to allow for any small variations in measurements. I wanted the base to be wider so there was a gap between the base and the gantry. If wider you can add in shims. But if the base had been narrower it would have been very hard to fix!


I made the shims to fill the gap each side from some 1.2mm aluminium sheet.

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They filled the gaps perfectly. I still need to make another bracket that fits behind the vertical so that the gantry is held to the base in two planes and not just on the side. The extra mounting holes for that are seen above.

I also spent some time this week getting the electronics done. The thermistor for the heated bed arrived so I fitted that and I have had the bed and the extruder successfully heating. I even managed to squirt out some plastic but not very well as the bowden cable was all curled up and the filament was in a huge tangle on the desk. The feeder motor would skip sometimes. But I was able to extrude nice, even spurts of plastic. I also cut some glass to go over the heater. Really I should use borosilicate glass as it has the lowest coefficient of expansion. That’s hard to find here so I am just using ordinary thin glass. At least it is a flat surface to print on and the glass stops any damage to the heater itself.


I need to get more of the metal clips to holds the glass to the heater.

I will need to measure the temperature of the actual glass I think. The bed thermistor is in the middle of the heater so the reading you get there isn’t necessarily the actual temperature of the bed. The temperature of the bed may not also be even, it is likely to be cooler in the corners. When everything is properly set up I will measure actual temperatures so I know how the shown value compares to the real world values. I plan to use a layer of cork under the heater to help insulate the base of it.

On both the bed and the extruder the electronics seem to maintain the shown temperature quite well, to within a degree or so. When it is all set up I can fiddle with the PID values (used by the software to maintain the temperature)  to try to make things as accurate as possible.

I still need to make a small power breakout board for running the various fans needed. The extruder has a fan that runs all the time. As do the electronics. You can also use a fan on the parts you are printing I gather but I am not certain of the details on that yet. It depends on what plastic you are extruding.

I have had all three axes moving but they need some adjustment, both mechanical and electrical (motor currents). I need to extend some of the motor wires too as the ones on them are too short. I bought some cable to do that today. I might see if we have the correct crimp pins at work for the motor connectors then I can make entirely new cables instead of splicing in new cable to the existing ones. It would be much neater. I also ordered some drag chain to help make the wiring neat. It is mainly needed on the Z axis as all the wires to that need to move.


The above shot gives some idea of the size. The heated bed is a standard 200mm by 200mm one. I also drilled four 8mm holes in the base to work as feet and/or mounting points. Currently I have four 8mm bolts through the holes to act as feet but I am wondering if I shouldn’t bolt the whole base to some MDF to increase the stiffness of it. I don’t think that is necessary as there is movement in the bearings/rails way before the base ever twists.

Still to do is the limit/homing switches. I will probably mount them near the motors so I can keep all the wiring neat. This means the Z and X axes will have the limits on the positive end but the Y axis will be on the negative end. I am sure this is all configurable in software (I hope anyway!). I have an idea for making some off centre cams as adjustable microswitch triggers but I need to work out the mechanics of that first. Whatever I do they is plenty of room for mounting things.


The other thing I did today was buy a new Dremel.


These are very cheap at only $60NZ, I think because they only have two speeds rather than the multiple speeds of the other models. I am hoping I can use this as a spindle for light CNC work and PCB milling on my machine. I am not sure it’s going to be rigid enough for that (8mm rods actually flex a lot!) but as my old Dremel was starting to play up it was worth getting anyway. The first thing I 3D print, if this even works, might have to be mounting brackets so I can attach the Dremel to the machine!

It is mains operated but I think I can use a relay to switch the Dremel on and off based on the extruder signal.

All of this will become much clearer when I can make a small film of the machine hopefully working!

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CNC Electronics.

August 28th, 2016

This weekend I worked some more on the CNC machine. It’s really meant to be for laser cutting but seems to have become more of a 3D printer. Mainly since there is more involved in getting that to work. It is easier to stick a laser on a 3D printer than stick a 3D print head on a laser cutter! During the week my electronics and extra linear bearings arrived. I spent a bit of free time on Friday getting the RAMPS board fired up.  It took me a little while to get things actually working, mainly due to a string of silly but easy to make mistakes.

First I needed to get the firmware on the board. I am using the latest stable version of Marlin (1.0.2-1 at time of writing). Marlin needs configuring before you install it and the way this is done is by changing #defines in a couple of header files. Being an old computer geek this isn’t too hard. Where I did go wonky though was when the code wouldn’t build.  That turned out to be and error in one of the header files, dogm_font_marlin.h. Inside there the include path to the library used by the LCD I have was wrong. It should read #include <clib/u8g.h> but the path was originally wrong. The thing that threw me was for some reason that include is in the file twice, once at the top and again half way down. I had changed it in one place and not the other. The IDE was telling me why it wasn’t building, I just wasn’t reading the error carefully enough and assumed I had fixed it!

Most people probably won’t know what I am on about there. It’s probably enough to say if you are building a machine yourself there are quite a few fiddly little things you need to do to get everything working. There is documentation out there but it is all over the place. It takes a bit of digging to figure out what is the best way to do things sometimes. With the software building and uploaded to the Arduino Mega I finally got the screen and controller working. But with the motors connected I couldn’t get anything to move.

One issue was when I plugged the RAMPS board onto the Arduino Mega some of the pins were misaligned and they didn’t go into the sockets correctly. I removed the board, straightened the pins and reconnected everything. Still the motors wouldn’t work. Then I realised I had made a truly daft mistake. I had followed some instructions I had found online for plugging in the stepper driver boards. I am using the DRV8825 stepper driver boards (well Chinese copies anyway). The instructions I found showed an earlier type of driver board so when I plugged mine in I plugged them in the same was as in those instructions. I should have actually looked at the boards and worked out which pin was which. Of course I had them in backwards!

Luckily this didn’t damage anything. With them installed the right way around I finally got stepper motors stepping. So far so good.

In the weekend I spent Saturday morning finally organising the computer wing. It’s been bugging me it was still as it was when I moved in and now I actually want to be doing electronics and making things in here so it needed a tidy up. I was also looking for some things I knew I had for the CNC machine at the same time. After organising things I find what I was looking for. An old ATX power supply out an old PC. I knew I had one floating about but couldn’t remember if it worked.

It didn’t.

But then I remembered I had another in an old working PC. So I pulled that apart.


Some people reading this might recognise the old Intel Home PC from way back in the day when Intel decided every employee should be given a free computer! It’s the original box (was a nice HP machine with a great modular case) but had long since had the motherboard, drives, power supply, etc upgraded before finally being retired to the cupboard’o’crap in my spare room. I pulled out the supply (and also a 120Gb drive and 1GB of RAM I didn’t know it had in it) as well as the CPU and case fans.

It’s an old 450W ATX supply. Not exactly a well known brand I think but it worked fine in my old machine so it should be good.


The RAMPS boards needs a 12 volt supply at quite high current, 5A for the motors and extruder and 11A for the heated bed. All of this is explained (not very clearly) here. An ATX supply can easily supply the right current. There are some traps though. Some ATX supplies won’t supply a well regulated 12 volt line unless there is some load on the 5 volt line. There are tons of sites about talking about this, it’s called ATX balancing, so I won’t repeat it here. My supply seems to work ok so far but I will see when things are actually running.

Converting an ATX power supply is also well documented out there. I will briefly mention what I did. First I opened it up.

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I gave it a good clean as these things are always dust magnets. Then I unsoldered all the wires after taking note of which colours when where. Black wires are grounds, red are +5 volts, yellows are +12 volts. There are three other wires I was interested in, the green PS_ON, the purple +5VSB and the grey PWR_OK.

The green wire is used to turn the supply on and off. If you short this to ground the power supply will turn on. The purple wire supplies 5 volts all the time (when the mains switch is on) even if the green wire hasn’t been grounded. The grey wire will show 5 volts when the power supply has turned on after the green wire has been grounded.

I left two yellow 12 volt wires and grounds for the two 12 volt inputs into the RAMPS board. I also pulled out a red +5 volt wire and ground wire in case I need it (perhaps for balancing later or to run 5 volt fans). I connected the grey PWR_ON lead to a 220R resistor and a red LED to provide a visual indicator that the power supply is on. I also added a toggle switch to the PS_ON line. The switch either connects the wire straight to ground, turning the supply on, or to an external green wire so the RAMPS board itself can control it. The switch let me test everything was working with some load, in my case two old car headlights.

IMG_0265 IMG_0266

The next bit about how you get RAMPS to control the switching all gets a bit confusing and the documentation isn’t very clear. How I understand it works is this.

The Arduino is powered either from the 12 volt supply feed into the RAMPS board or via the USB connection to the computer. The ATX supply can supply 12 volts and can be controlled via the green PS_ON green. So you can plug this wire into the RAMPS board on the provided connector and switch the 12 volt supply on and off as needed (there is an M code to do this). This works fine if the Arduino is connected via USB and getting it’s power via that. Then you can switch the 12 volt lines from the ATX supply on and off easily.

The problem is if you don’t have the USB connected. If the Arduino is being powered via the 12 volt in this of course this won’t work. The ATX won’t switch on unless the Arduino tells it to but the Arduino won’t be running until the ATX supply is turned on! So we’re deadlocked.

The way around this is to use the purple +5VSB wire. Since this is powered all the time we can use that to power the Arduino and then that can turn on the main 12 volt supply when needed. The RAMPS board provides a connector for this.

What you need to do is wire the +5VSB from the supply into the VCC pin on the header near the RAMPS reset button. That is the top pin. The green PS_ON wire goes into the bottom pin. The middle 5 volt pin is left unconnected. That is only there to power the servo headers to the right of the reset switch.


The one other VERY important thing to do is remove diode D1. This diode is what feeds 12 volt power to the Arduino. We don’t need that as we are now supplying the Arduino with 5 volt directly via that VCC pin above. It is bad to try to do both at the same time. So we disconnect D1. This is a little tricky as it is hard to reach. The tweezers point to where it was on my board.


So now we have the Arduino powered directly by the 5 volt stand by signal from the supply which means it can turn on and start up. It can then tell the ATX supply when to turn on and off the main 12 volt supply. All this works with no USB connection which is handy since my controller also has an SD card slot so it can run without a PC at all.

With this working I was able to hook up the supply, motors, extruder, extruder thermocouple and heatbed and test it out. Unfortunately the heated bed that came in my kit didn’t have a thermistor! I have ordered one separately but until that comes I can’t test the heated bed. I was able to test the stepper motors and that the extruder heats up and the temperature reading of that works. I haven’t actually tried melting plastic yet though as I only went up to 60 degrees C. One thing I do need to do is provide wiring for the extruder fan and for fans to cool the electronics (using one of the case fans I pulled from the old PC).


So, having gone as far as I could with that, I then went out to the garage to work on the X axis gantry. This was more simple metalwork. I used my laser cut templates to mark where to drill the holes for the mounting points. I ran out of time so haven’t actually bolted everything together yet but it is coming together.

IMG_0273 IMG_0276 IMG_0277

I can do more on that tomorrow evening I hope. The whole thing is rather heavy. I am not even sure it will work as a 3D printer at all. It might be too slow although I think slow isn’t a problem except it means printing anything will take forever! The problem isn’t the speed but accelerating everything up to that speed. It’s going to be interesting to see!

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More CNC progress.

August 24th, 2016

I’ve been coming home and working on the CNC machine as well as at work in breaks. I am still waiting for parts to arrive from China before I can do too much more though.

I spent an evening making motor mounting brackets then when I was done realised I had made them all too small! I also realised I had made one part backwards so I redrilled some holes in the Z axis plate to make things right again. If anyone asks the holes are too add lightness like we do on old racing cars.

Today I cut up some angle aluminium (40 x 40 x 4mm) to make the gantry/X axis frame. I used the metal saw at work to cut the 45 degree angles and it works extremely well. I did the straight cuts at home by hand. This is them laid out to see how things will fit. I cut small brackets to bolt the corners together when the time comes. The gantry is just under 600mm high and I get 207mm of usable Z axis. That will be the absolute tallest thing I can 3D print.

IMG_0252 IMG_0255

I laid the Z axis on top of the rails to check the motion and found a problem. Although everything moves smoothly I messed up some measurements and the X axis plate just hits the top of the frame at the sides so I will need to take them back to work and mill 10mm or so off the top of the angle that makes up the sides of the gantry. The X platform base needs to go over the top of the frame to get full sideways travel. If the base hits the frame the tool can’t get to the extremes of the X travel. I am using two bearings side by side to give me a wider base (at the expense of less travel) and am still waiting for the extra bearings to arrive.


You can see above how the top of the platform is flush with the top of the frame instead of running just over it.

My colleague Rod didn’t believe me you can drill through aluminium with a normal spade bit. I manage it fine. I just use a very slow speed in the drill press and lots of cutting fluid. Lately I have been using Inox as a cutting fluid (since I ran out of other stuff). It actually works very well. It has the advantage of being clear so you can see through it and see what you are drilling. It also smells nice!

IMG_0247 IMG_0248

That was the hole in my new motor mount for the Z axis. I need shorter screws to mount the motor and also need to make a spacer to go between the plate and the bracket to get the motor height correct. The top of the gantry frame will need to be milled down a little to provide clearance for this bracket.

IMG_0257 IMG_0258 IMG_0259

You can see above the flexible coupling that links the stepper motor to the lead screw. The X and Y axis motor brackets will be the same. They are held by the same bolts that hold the lead screw bearing in place.

You can see my planning wasn’t precise. My drawings allowed me to see the basics would work and I knew I would have some tweaks to do as I actually started building. But I am trying to keep the design as simple as possible. I am confident the basic design is going to work now though. Lots of little things to work out still like where to mount limit switches and exactly the best way to make the base plate so it can be changed from 3D printing (which needs a heated bed) to laser cutting to machining.

Long overdue update.

August 18th, 2016

Well, it’s been a while since I wrote anything here. Not from lack of anything happening though! Lets see, I am still at Weta and still loving it. The things I get to work on and see are amazing. And mostly secret a lot of the time! Not sure what I am allowed to say I have worked on. Animatronics for films and various other things. I have to wait until these things come out then I can say what I did I guess. It’s great fun though and the stuff I am doing is a perfect match for my skill set. We do a lot of microcontroller stuff so I still do a lot of coding. Lots of hand making of things too. I knew one day all my silly projects over the years would be useful for something!

It’s going so well I have decided to give up on IT and just keep doing the animatronics thing for as long as that lasts. I sold my house in Auckland and bought a house here in Wellington in Miramar, close to work. Finally no mortgage which is great but I am on way less income so not a lot of money either! So much for my dream, no mortgage Orient Express trip (for now at least). But I earn enough to live comfortably so that’s all fine.

Been in my new house for about 4 months now and am just getting settled. I made this film to show people my new place in the world.

Sorry for the croaky voice, I had a bad cold.

So now I am almost settled I am thinking about getting back into my car projects. I have the Austin body to finish and the engine to build. And I would like to start on the Brooklands. I am now in contact with someone who has an original Brooklands and he is happy to help me with pictures and measurements of parts I am missing.  Mainly the engine/steering mounting brackets and some of the spring mounts and hangers. Will be good to get started on that. I have a parts list (for a Riley Nine, not a Brooklands) that I will go through and mark off what I have an figure out what I am missing.

I have the fireplace I am making but I will talk about that later. This post is about a new project, a laser cutter/3D printer/CNC type machine I am building.

In the film you can see a little project I was doing at work in my breaks and spare time. IT were throwing out a bunch of old PCs and parts. I managed to get a bunch of old DVD burners and pulled out the mechanisms and lasers. In a DVD burner the red laser is powerful to engrave things. This instructable inspired me and I basically did the same thing myself and made my own tiny laser engraver. I don’t have any need for one, we have several laser cutters at work I can use (we use them all the time) but I wanted to know how the machine worked. We also have at work a number of CNC machines they use for milling materials. They cut wood, metal and have an industrial robot arm used for cutting large blocks of polystyrene. I find them fascinating. I figured it would be fun to build my tiny machine to see how they work as the principles are the same as on a ‘real’ machine.


In the end I kept blowing up the red lasers from the DVD drives. They are very finicky and even with the correct current limited driver for some reason mine kept dying on me. In the end I bought a 500mW blue laser module from Aliexpress. It is more powerful and comes complete with driver, heatsink, fan and so on. Given how well that tiny machine (working area of 36mm by 36mm!) works I thought why not build a bigger machine. What I really want to make is a laser cutter that I can use to cut out paper gaskets for my vintage cars. My plan is to build up a library of gaskets that I can then cut out as needed. So I started thinking about a bigger machine, something that can cut a A4 sized sheet (210mm x 297 mm).

There a lot of machines and designs about online if you look. Or complete kits you can buy and build. I prefer working things out for myself. In the end I decided on a machine build from aluminium using lead screws to move the axes. These you can find on Aliexpress such as these ones. You can find everything on Aliexpress. I’ve been using it a lot lately!

As well as laser cutting I was thinking it would be interesting to see if I could mount a small spindle on it and do light CNC type things. Mainly engraving PCBs. That would be very handy. Failing that just being able to plot resist onto boards, manually etch them but then use the machine to drill the holes would be good. To do that you need a Z axis as well as X and Y. You need to be able to lift and lower the cutting tool or drill or pen or whatever it is you have mounted on the machine. Since I was starting to think about adding a Z axis I began to think well, why not add a decent height Z axis and add an extruder and use the machine as a 3D printer. Feature creep, it’s not just for software!

So my simple laser cutter has become something of a multipurpose machine. In the end I got two sets of 400mm rails/screws for the X and Y axis and a 300mm set for the Z. That gives me a useable area of just over an A4 sheet in X and Y and with about 200mm of Z. That is comparable (actually a little larger) than most of the DIY 3D printers around.

I drew up my design in Inkscape. Now Inkscape is a 2D drawing program. I guess really I should be learning how to use a 3D program which I will need to design 3D printed parts! I have started playing with DesignSpark which you can get free from RS. Inkscape works great for doing any 2D designs for laser cutting though. But I designed the machine in 2D using old fashioned 3 view plans. By grouping parts of the drawing I can shift the moving parts around to check the limits of the machine and so on. That actually worked rather well.

laser cutter zx axis template

To test parts of the design I laser cut some of the parts from 3mm scraps of MDF. That allowed me to see how things could all fit together. I was able to power up the stepper motor to see how well things would move. I did notice a little problem with the design but I will come back to that in a minute.


The main frame of the machine will be aluminium L section 40mm wide and 4mm thick. That will all be bolted together. The Y axis moves under a fixed gantry that holds the X axis. On the moving X axis is mounted the Z axis that moves up and down. The moving platforms for the axes are made from 3mm thick aluminium plate I scrounged from the scrap piles at work. One problem was how to cut it. To get it all nice I really should CNC cut it all. But I decided to do it all by hand. I cut the plate with a special blade in my jigsaw by hand. That worked very well. These days people are so quick to go for the modern ways but with patience and practice you can still do a lot of things by hand if you’re careful. After cutting I then linish the edges on my little home made linishing disc.

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The design problem I had was that there is a little unwanted movement in the platforms that run on the rails. This comes from two places, the lead screw nut and the rails and bearings themselves. The rail sets from Aliexpress come with one brass nut per screw. With the nut mounted into it’s aluminium block and that all threaded onto the screw there was a little bit of movement in it. I fixed this by ordering extra nuts and making what’s called an anti-backlash nut. Instead of one nut you have two nuts separated by a spring. I simply added extra threaded holes for the second nut on the aluminium mounting block and inserted a spring into the middle of the block around the lead screw that pushes against the second nut. The screws holding this nut on are not done up tight but instead are left with a gap so the nut can move a little. I loctite the screws in place.

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This seems to work very well although it adds extra friction to the whole mechanism. The stepper seems to easily overcome that though.

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The other source of movement is the bearing blocks that run on the rails. They are not very wide so I found you could get some movement on the rail. In practice this would show up as twist on the moving platform. To counter this I have ordered extra bearings and will double them up. This helps a lot although you do lose a little travel (the same amount as the width of the bearing) on the axes. Having the rails spaced as far apart as possible will also help eliminate twist.

This twisting is what I think will prevent the machine being a good CNC cutting machine. With laser cutting and 3D printing there is no side loading on the moving bits as the tool (i.e the laser or the extruder) isn’t actually touching the workpiece. As soon as you have a spinning cutting tool you are trying to move into a material you are adding a lot of extra force to the bits you are trying to move. I think this is when you’ll start noticing deficiencies in the machine. I think drilling will be possible as the force is all up and down but I am not sure how well it will go when sideways cutting. I can only try and see!

To help with making the aluminium parts I laser cut cardboard templates and used them as cutting and drilling guides. I hand drilled all the holes on the drill press.

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That last plate is the one on the Z axis. Since I want to mount different things on it (laser, extruder, pen, spindle, etc) I am putting in many threaded holes so I can attach whatever I like. I will talk very nicely to Jordan at work and see if I can use his parallel arm air driven tapping machine to tap all the holes. These machines are brilliant and I wish I could have had one when I was drilling my Austin 7 crankcase to helicoil the studs into it!

Once those are done I can start assembling the Z and X axis parts and it should start making more sense how this machine will work. I am very new to this and I am sure I am making mistakes and there are better ways to build such a machine but this is a learning exercise so that’s OK.

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I random orbit sand the plates after drilling rather than countersinking the holes. I prefer the clean, sharp look it gives and countersinking also reduces the thickness available to put threads into.

The electronics for the machine are on the way. The mini laser engraver uses an Arduino running GRBL. That works great and allowed me to get my head around G-Code and how all that works. Not to be confused with G-Spots, something most engineers never have to deal with.

I already have an extruder (the bit that melts the plastic filament for 3D printing) as well as a feeder that forces the filament into the extruder. These I got off eBay along with extra nozzles in different sizes.

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Still coming are the main electronics, which consists of an Arduino Mega and a RAMPS board, as well as limit switches, cables and also a heated bed. 3D printing is much harder than laser cutting hence the need for upgraded electronics and all sorts of other paraphenalia. A laser just needs simple on/off commands which you can do in G-Code. The 3D printer has extruders to control with heaters and temperature feedback as well as feeders and heated beds and goodness knows what else.

I should say here I have never actually used a 3D printer or had any interest in them. I am a metalworker really. I prefer making things by hand in real materials! But working where I do I can see the uses of 3D printing. We use it all the time. So understanding how that all works is a good idea I think and for me the best way to learn is to do things for myself. I don’t know what I will actually use it for when I have it! Maybe I can 3D print small patterns to then cast in aluminium? 3D printed christmas presents for everyone this year?

The laser cutting should be much more useful. I could buy a bigger laser although I have successfully cut gaskets with the 500mW one I have. Oh, that’s one thing to note. In NZ there are now restrictions on high powered laser pointers. You can’t easily buy them and if you try to import one you need special permission and a valid reason. This is due to idiots pointing them at planes and so on. So before I bought my burning laser I contacted the Ministry of Health(!) to make sure it was OK for me to import a laser module. Apparently it only applies to laser pointers specifically. Actual high powered laser modules are no problem whatsoever!

Anyway, that’s where I am up to at the moment. It’s a bit rambling sorry, am out of practice with this blogging business. I will keep documenting the machine as I go. It could be a total failure but it is good to be out in the garage again making things. I am just starting to settle again. It was quite a move!


Oh, and apologies for the bad photos. My old Canon Ixus camera died and I got a new one, a later model Canon thinking I could reuse the battery. But the bastards change the battery form factor between models so the batteries, even though they are actually the same, won’t fit the new model. And the new camera, an Ixus 175, is rubbish. The auto focus is really bad. Hence all the slightly out of focus photos. Next camera won’t be a Canon I think.

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