Sunday 26 September 2010

More Pictures.....

My Extruder Cogs. I just hope they survive. The quality is VERY poor.
 Spot the Crack in the end plate. There is a steel plate holding it together.
 More repairs - they don't show up well.....


Images of the Final build.

My Machine in all it's Glory :)
The filament is1.7 mm Dia.
The Extruder has been modified to cope with the smaller filament.
 The back of the machine.
You can see the "Dust covers"  over the Motor Spindles.

 









Hot End / extruder.
Notice I recessed all the Bolt heads.

2 LED's to indicate the heater is on.
I made a small cable clip to prevent srtess on the motor wires.
Y Axis drive.
Spot the missing Lock Nut !

Tuesday 21 September 2010

Heater Update

I have been working on a circuit board design for a RepRap heated bed. Far tidier than mk1.
The maths really did my head in I tell you !

I have made circuits in the past with Toner transferr, but only small ones.
Trying to do 200 x 200 mm just don't happen.
The Thermal expansion pulls the tracks off the paper :(

This is the best image I managed after 4 attempts.

Thursday 16 September 2010

Heated bed: Update

Hi All

I got a bit of 5 mm aluminium sheet today. It's a little rough but it did come out of a skip !
I coated the heater Side in Kapton Tape to provide the electrical insulation.

The heater mat remains unchanged with a resistance of 1 ohm.

My Type K thermiter registered 5 mv after 10 or so mins and water boils away furiously.


My Type K thermiter registered 5 mv after 10 or so mins and water boils away furiously.
I call this viable :)
Next question is how do I mount this on my reprap.

I'm also working on a PCB based heater.


Saturday 11 September 2010

2 great sites that have helped me with the Heater

Maths is not exactly my strongest point.
I did the maths to work out the resistances i needed but then found an Ohms Law calculator
Type in what you know or want and you get the answer.

Another site I used has a Paralell Resistor calculator.

Thnaks to both the authors for taking the time to put these sites up.

Heated bed:

I dropped the cheap n nasty Thermostat out of the circuit and wired the heater Direct.

I got the bed to 120 C in Still air - that may just be enough to hold 110 C

Then there was a Ping and the Glass cracked.

I'll put this idea on the shelf and revisit another time for now.

Heated bed: Result.

This Method is NOT Suitable for ABS.

However for PLA running at 50 - 60 C this method will work reasonably well.

The big issus is that 12 Volts is simply not enough to generate the heat output required at any reasonable current to power the bed above about 90 C.

Note:
The Voltages, Currents and Heat Outputs we are talking about here are more than enough to Burn your House / Shed down as well as burn your fingers.
If you do try this be VERY CAREFULL !

Heated Bed Update.

Well this is not going to get any where near hot enough for ABS if people are saying 110 C
After 30 mins it got to 76 C 

I also checked the Voltage on the 12 Volt rail - 10 Volts with the heater connected. That about 75 watts. 

My PC Power Supply is simply not up to the job :(

Friday 10 September 2010

Heated Bed: ParCan Style

With all this talk of Heated Beds, I decided i'd jump on the Band waggon cos i like a nice warm bed !

The design brief is simple: easy and low cost.

1 reel resistance wire from Maplin: £6.49
1 Plumbers heat risistant Matt from plubing Shop: £2.00
1 Bit of 4 mm Plate galss 200mm X 200mm  from the glass shop: £1.00

This is not yet tested in real life but is working (The Glass gets hot)

Maplin resistance wire runs at about 1 ohm every 200 mm.

Draw around your glass amd measure 4 mm in from 1 side.
Then mark 8mm Intervals and put lines 8 mm apart. use a light coloured Pencil.
You should end up with 24 or so lines and about 4 mm at the other end.
Now draw another line 6 mm from the other side.
Cut 8 X 800 mm lengths of resistance wire.

With a needle sew the wires onto the surface of the Heat Matt.
Each wire makes 3 passes over the mat along the lines you marked.

To connect this up:
Solder all the ends along 1 side to a bit of a bit of 22 swg copper wire so that the glass plate buts up aginst it.
(You can solder Constantine wire but NOT Nichrome)

Along the other edge you need about 2 mm space for the glass to expand. I used my Ruler.
Solder the other ends in 2 sets of 4.
That will give you about 1.5 Ohm resistance or about 100 w at 12 V

I then covered one side of the glass in kapton tape so that if it cracked it won't shatter everywhere.

 The completed bed .
It's drawing 7.7 amps at 12 volts.
That's 92 watts.

Thursday 2 September 2010

Reprap build Notes: Part 5. Belts, Wiring and the Extruder.

The Belt Runners on the X and Z axis seemed somewhat ineffective. I was not happy that the M5 large washers I had were only slightly bigger then the bearing.
The M8 Washers I have are 0.75 x the thickness of the M4 washers.
So from the end I have:

M4 Screw | M5 LG Washer |  2x M4 washer. | 1 X M8 Washer | Bearing M4 Washer

The M8 Washers spin on the M4 washers and are approx 2 mm larger than the Bearing.

Extruder Manufacture and Assembly: (Adrians)

Brass Nozzle.

The Rod came from the arm off an old Ball Valve which was 7mm dia. (many people have said that M6 is to small and fragile) 
I ran an M7 x1 die down the rod to put a thread on it.

To make the Nozzle on a lathe:
I faced the end off, centered it, and drilled it 28 mm deep at 3 mm then ran a 3.5 mm drill down to 30 mm deep. 
Use the scale on the tail Stock to get the correct depth.
The drills were all flatted off for drilling brass.
I then parted it off and turned it round.
Center drilled it and put in the 0.5 mm hole before putting the 45 deg angle on the end.
I left the hole recessed by about 0.25 mm.


PTFE Insulator.

I turned that on a Lathe from 20 mm dia rod.
Faced it off and drilled it through with the small hole.
Turned the end down to 16 mm and used the parting tool to put 2 X 2 mm deep groves in. That should give the glue plenty to get hold of.
I parted it off then drilled the large hole 1.5 mm under size then tapped it with a sharp tap to 7 mm to suite my Nozzles.

2 further nozzles and PTFE insulators were made to suite the 1.7 mm filament I have. They were drilled to 2 mm with 0.5 mm in the end of the Nozzle.


Extruder Assembly:

I didn’t have the correct length screws to assemble the extruder so bought some M4 studding and Thread Locked nuts on 1 end.
The large cog is assembled as per the instructions but with NyLoc nuts.

I held the Brass Nozzle in a drill chuck and screwed on the PTFE with some Plumbers tape to provide a good seal.

The Ni Chrome Wire I have is Insulated. 
I wound that on the threads of the M7 Nozzle. The 28 cm required to get 6 ohms is the perfic length for the M7 nozzle.
1 Winding then back to the top.
The Nozzle was covered in Kapton tape and the Thermister installed.

I used Brass Tube to make the crimps and insulated them with silicon sleeving.

The wiring: ( Still work in progress )

Power Supply.

That was made from an old PC Power Supply. See the instructions on the wiki.
I added several big red LED’s so you can see if it’s on.

Need to add a BIG “Time to Panic” button !


Electrical headers and Wiring:

Most of the connectors were provided by the Power supply.

The 4 Pin PCB headers got salvaged from old floppy drives.

Ribbon Cables are old IDE and SCSI Drive cables split down.
10 way IDC Headers are from the Serial Connections on old PC’s.
10 way IDC Header sockets were salvaged from old Motherboards.

Other connectors are from various bits of old PC parts.

Reprap build Notes: Part 4. Getting the whole thing together.

Now you can complete the assembly.

Remember the Back Left corner is your Datum / Home point.

The Rods for the Z Axis must be perfectly vertical.
Make sure your frame is flat both ways with a spirit level.
Start with a Plumb Line, get the rods in place then use a spirit level to make sure the rods are vertical then remove the rods.

Now you can add in the X Axis assembly. Take care not to twist it on the lead screws
Make sure cogs and bearing are centred on the lead screws, Do them up tight and add some Thread Lock. You really don’t want these coming lose.

Now put the Z Axis Rods back in place and re-check them with a level.

Tighten up the bed and check that the bed runs free and square.
Do Not tip your frame with the bed running free. I locked mine in place with a rubber band

Check and adjust all the bearings. 
The bearings should all touch the rods and you should be able to turn the bearing with your fingers against the friction on the rod.
Check the X carrage and Y bed run free and true.
Add in the Belts, and motors and adjust. The belts should not rub on the washer or reprap parts either side of the bearings in a perfect world. Reality however makes this somewhat impossible to achieve.


Once the motors are fitted the bearings looked a bit exposed. I fitted an M5 washers and a small grommet over the shafts to stop dust getting in.

I made the flags from the case of a dead CD Player.
Thick enough to work, Easy to cut with Snips.

The Motor wires looked a bit exposed. I stripped the insulation off a bit of coax cable and ratted the wires through with a paper clip tied to some cotton thread.

With a bit of luck it shold look something like this:

Reprap build Notes: Part 3. A few hints and Tips on the Build process.

Gather the parts you require and check them.
Remove any Burrs, sharp edges and rough bits.
Check every hole size and drill as required.

CLEAN UP Dust and swarf before you start each section of the build.

Use parts Bins for all your fixings. Lay them out the way you like – you will soon memorise what is in each parts bin.
Have a “Dump” parts bin to put extras in and the stuff you drop on the floor etc.
Use NyLoc Nuts wherever reasonable.
Many of my fasteners were done up with Std Nuts then a Nyloc was added as a lock nut.

Once a section is complete Check it. Then check it again. 
It's far easier to make adjustment when the parts are small and managable.

I started with the X Axis, as per the Build Instructions.
No real issues other than the parts I bought needed a lot of finishing work.
The Bearings on the end plates I used m8 washers with m4 washers inside for the belt guides. This allows the Belt Guides to rotate with the bearings.
Store your X axis assembly somewhere clean.

The Z Axis was straight forwards.
Make sure the 4 large Blocks are drilled so that the studding holes overlap slightly.
Check the teeth on the Lead screw cogs are good. 
I used large support washers and shakeproof washers either side of the cogs.
Make sure nothing protrudes to far down or you will scratch your work bench.

The Y Axis and Bed was more challenging to get nice.
This was mainly due to the poor quality parts I bought.
Get the bearing Blocks built and done up tight.
Assemble the base Lose, then tighten up with the 8mm rods in place.
I made the belt clamp nuts Captive. Far easier to tighten later.

The Frame:

The M8 nuts on the end of the rods are all NyLoc.
I tried twice to get my fame square using the method described in the build Instructions.
On the 3rd Attempt:
To get the Triangles square I used 8mm rod offcuts in the horizontal holes. I then measured the frames with a vernier to get them within 0.1 mm and built the 2nd exactly the same.
Once the triangles were built I used the uprights to get the widths correct.

If you have them, put a ½ nut and washers between the Z axis blocks.

Once your frame is assembled check it for squareness before you add any extra parts. It should sit flat on all 3 sides.
Double check all the measuremants.
Lock any plain nuts in place with a dab of Locktite or nail varnish.

Add in the Z axis support rods and check the blocks are square and level.
Loosely put the bed in place and check that the bed does not catch on any of the rods underneath.

Reprap build Notes: Part 2. What you need to get started.

You will also need the following Consumables:

Selection of Heat shrink tubing.
Selection of Cable Ties.
Selection of Glue ( Cyanocrylate, Epoxy, UHU)
Electrical tape, kapton Tape, PTFE Plumbers tape.
Some Coax cable ( great for sleeving, De Solder brade and copper wire )
Selection of Grometts.

Space:
You need a bench at comfortable working height with Power, Lighting and ventilation. Minimum 2 M wide and 600 mm deep.
Try and organise a clean area and a dirty area in your Build space.

General hints and Tips.

Gather the parts you require and check them.
Remove any Burrs, sharp edges and rough bits.
Check every hole size and drill as required.

CLEAN UP Dust and swarf before you start each section of the build.

Use parts Bins for all your fixings. Lay them out the way you like – you will soon memorise what is in each parts bin.
Have a parts bin to put extras in, stuff you drop on the floor etc.

Use NyLoc Nuts wherever reasonable.
Many of my fasteners were done up with Std Nuts then a Nyloc was added as a lock nut.

Reprap build Notes: Part 1. What you need to get started.

This is probably going to turn out a rather long and Listy blog. bear with me - it will be worth it....

To build a Reprap you will need the following tools.

A Drill and Drill set covering at the minimum 2 mm to 8 mm in 0.5 mm sizes.
Small drills: 1.5 mm, 1 mm, 0.5 mm for PCB work and the nozzle.

Selection of Allen keys, Spanners, Screwdrivers, Nut Spinners to suite your fixings.
A selection of Pliers and Cutters.
Crimp Tools to suite your electrical connections.

Exacto Knife, Stanley Knife and SHARP Blades + A Cutting mat.
Tweezers: Needle Nose, Screw catcher and curved.
Files and a selection of Needle Files.
Small Bench Vice.
Junior hacksaw and good blades.
Good quality Soldering irons and soldering Kit.
Test Meter and selection of leads.
Vernier calliper (digital makes life easy)
Engineers Ruler

Tools that will make your life much easier.

A Pillar Drill + Accessories to go with the drill.
Dremell + good selection of tools.
Access to a Lathe.
Parts Bin stack.
“Helping Hands”
Magnifier
Small Vacuum Cleaner