Printing update.

September 15th, 2016

A quick update on my printing efforts the other night. It fell over!

Well, not the print itself. This is what I got up to the point it went wrong.

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It’s upside down in that first picture. The second one gives a good view of the infill, the pattern inside the printed object so it is not totally solid.

The reason ti fell over was simple. My laptops power settings kicked in and it went to sleep! I am sure I had fixed that. So far my biggest issues 3D printing have been caused by the computer side of things. I forgot to mention I spent hours in the weekend not able to upload new firmware to the printer. It keys getting write errors. The simple blink program would upload fine, but not the 3D printer code.

In the end my friend Mike had the answer, try a different USB cable. That was it. A new cable fixed it.

I redid the print the other night. It took 7 hours! This is how it came out.

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This is the Pink Panther Woman off Thingiverse. I wanted to print something other than a boat and try a longer, and bigger, print.


It is 150mm high so took up 3/4 of the build height I have available. I print at 50% feedrate so my prints take about twice as long as ‘normal’ printers.

I started experimenting with that. I printed another 3D Benchy boat at 70% speed to compare to my best print at 50%.


This is the 50% print on the left and the 70% on the right. You can see how the faster print isn’t quite as good.

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I still need to play with the speed and acceleration values in the firmware itself. Currently I have them set to 1000 acceleration for X and Y and 100 for Z. Speed (feedrate) is set to 200 for X, Y and Z and Jerk is set to 20. I think my issue is going to be acceleration, there is just a bunch of weight to be getting up to speed (and stopping).

I started putting together a Linux box as a dedicated printing machine. I am running Xubuntu on it on the advice of Dave. I still need to sort out wiring on the machine and a balancing load for the 5 volt rail. I can see if we have any old, high powered resistors in the junk at work.

I also want to start 3D modelling my own designs. I did start with DesignSpark a while back so need to get back into that. I was trying to model up my TARDIS!

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!).

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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.

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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.

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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!


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.

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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.

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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!

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.

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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.

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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!

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.

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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!

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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.

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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.

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