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Fabrication

In order to assist students, researchers and academics a number of pieces of equipment have been acquired and systems put in place, at present these are:

Use of these facilities and methods is encouraged, however some restrictions are in place and you should read the relevant section and/or speak to the responsible member of technical staff before commencing any work that will make use of them.

Enclosures

If you are considering making an enclosure for an item then please see here for advice.


3d Printer

Status - OPERATIONAL and AVAILABLE.

Queue:

At present we have a MakerBot Replicator 2X, an experimental 3d printer capable of dual filament printing, however due to time constraints and equipment issues only single extrusion is available. We currently are only able to offer ABS. If you wish to make use of this facility please, in the first instance read the guidance below, and then contact Bill Backhouse to arrange a meeting to discuss your requirements.

Rules

  1. The 3d printer is primarily for the use of the undergraduates. If you are a non-taught student or staff then any use will be at the discretion of the technical staff.
  2. The 3d printer will be operated by the technical staff unless they decide otherwise.
  3. We will only accept single extrusion jobs.
  4. If your job is deemed too complex or unlikely to succeed then you will be recommended to re-design your build, use an external supplier or try an alternative approach.
  5. The 3d printer is operated on a first come, first served basis. To join the queue you need to provide an STL file as outlined below. If your design is found to have flaws then it can be re-designed but you may lose your place in the queue.
  6. The queue is shown above.

Instructions (to be done in order)

  1. Discuss needs with Bill to determine if your use of the machine is sensible.
  2. Design object to be printed, a variety of CAD software is available, and provided it is capable of exporting as an .STL then most would be suitable. If you have never used any 3d design software then you should consider SketchUp*, this has a smooth learning curve but is not as powerful as other tools. Free alternatives can be found online, for instance.
  3. Provide a .STL file to Bill (one file per item), either by email or USB stick. You should also confirm the following details:
    1. Who you are? What level/year you are? What group you are associated with (if any)?
    2. Contact details.
    3. Colour of the print required. At present we have: Black, White, Magenta, Blue, Grey and Natural (off-white).
    4. Print quality: Low, Medium or High. Unless specified we will assue Medium. #
  4. Once received you will be added to the queue.
  5. The file will be checked for potential problems and if any are found you will be notified and recommendations of amendments will be made. If no problems then your item will be printed when your turn arises.
  6. You will be notified by email once the jobs are completed or should there be any problems with your prints or the printer itself.

* SketchUp has (had?) a significant issue when generating STL files for 3d printing, in that some files do not appear as watertight objects. See Recommendations below for advice.

# If you intend drilling, sanding or otherwise modifying the final item please confirm this fact as settings will need to be adjusted to account for the loss of the outer layer and consequent need to increase the strength of the object.

Recommendations

Issue Problem Description Resolution
Avoid overhangs 3d print overhang catastrophe Arches and overhangs are a problem for 3d printing and if larger than a few millimetres will necessitate the use of supports.$

If you have an overhanging piece try to avoid angles from the vertical over 30° which may droop, or over 45°which are very unlikely to succeed.

Overhang with supports

Use of supports can reduce the problem (above).

Include curved edges on base if possible If there is a right angle at the base then it is frequently very hard to remove the piece from the surface material. This can lead to damage of the surface covering when removing the piece which delays future prints, or damage to the piece itself which may necessitate re-printing of the piece. By including a curved base it is, in general, possible to lever the piece off with minimal fuss.
Shrinkages ABS can shrink 1-2% as it cools. Consequently if you are attaching other pieces to a 3d printed piece care may need to be taken to ensure that some scope for this shrinkage is present. As the shrinkage depends on the thickness, in-fill and general structure it is impossible to precisely determine the shrinkage without a test print. Therefore whenever possible other pieces should be shaped about the 3d printed piece.

Alternatively it may be possible to use a blanket scale increment of say 2%, i.e. x1.02. However this has been known to cause issues with holes on the surface.

Watertight On some objects, usually from SketchUp, joins were not made fully when combining surfaces, this meant that rather than being a solid object with a thickness it appeared to be a very thin sheet folded around but not connected. This problem is described as the object not being 'watertight' Occasionally this can be fixed by use of software such as Netfabb whose free Basic version allows some fixes to take place.

$ Supports are strong by minimal parts added in by the printing software to provide structural integrity for some pieces. In general they are snapped off by hand, however there may be a need to clean up the contact points with a scalpel or sandpaper.


Laser Cutter

Status - Operational, turnaround time ~2 days.

We have a Trotec Speedy 300, this is capable of cutting a variety of materials up to about 20mm, specific details are below. If you wish to make use of the Laser cutter please contact Bill Backhouse.

Material Supplier Cutting Etching Note
ABS ~ Aquarius, = Yes - confirmed up to 2mm. * Yes. *
Acrylic - cast Aquarius Yes - up to 20mm. Yes - up to 1mm depth.
Acrylic - extruded Aquarius Very badly. 1-2mm max. Badly. More melt than etch. Avoid if possible.
Carbon fibre N/A No. No. Will damage machine.
Glass Addison No. Yes. *
Metal Smiths No. No. +
Metal (anodised) Smiths No. Yes.
Nylon Aquarius Yes - confirmed up to 2mm. Unknown.
Paper/card Yes - confirmed up to 20pp. Yes.
Phenolic board (Tufnol) Yes - confirmed up to 3mm. Yes. At 3mm cuts start to be charred.
Plywood Champion Yes - up to 12mm. Yes. #
Polyester - HDPE (High Density Polyester) Aquarius Yes Yes
Polystyrene - HIPS (High Impact Polystyrene) Aquarius Yes - confirmed up to 2mm. Unknown. Probably melts more than etch.
PTFE (Teflon) N/A No. No. Will damage machine.
PVC N/A No. No. Will damage machine.
Rubber Yes - confirmed up to 1.5mm. Unknown.

~ Most standard plastic enclosures are made of ABS and these can therefore be cut. It should be noted that these frequently have sloped edges and therefore aligning can be an issue.

= Also standard suppliers Rapid, OneCall or RS.

* Cover material with damp paper to assist in cutting/etching.

+ CerMark is a range of materials that can be applied to metal and will be bonded to the surface by the laser action. We have an aerosol of black that can be utilised.

# Lasercuttable plywood is sold by a number of suppliers. This gives a superior finish and should be considered if appearances are of paramount importance. Normal plywood is adequate for most uses.


IR rework station

We have a PDR Rework Station, this allows for the video alignment of SMD, BGA and similar components. If you wish to make use of this please speak to John Mouat.


Fabrication room (room 6a AB 04)

The fabrication room is stocked with most basic tools that should be needed for the work of students.

Only trained users can make use of the room, undergraduates undertake this in the 1st year in the weeks before Christmas break in experiment C4, if this is completed satisfactorily then you may make use of it during your usual lab times and Wednesday afternoons if appropriate. If the C4 assessment is failed or missed then the 1st year lab technician will be in touch to organise a further session to provide you the opportunity to pass again. Direct entry students will be contacted by the 1st year lab technician to arrange a session after Christmas.

We should emphasise that we expect basic rules to be followed:


Printed Circuit Board manufacture

We can manufacture PCBs in-house. A summary is on the home page, and additional detailed information is provided by Technical Services Unit. The cost calculator is here (only available on campus). Boards for 1st years are manufactured by the 1st year lab technician, for 2nd years the 2nd year technician, and all others are prepared by Raphael Sutcliffe.