Boxford offer a taster day which introduces the Scalextric 4 Schools project to both pupils and teachers.
I was pleased to deliver the first of these to the year 9 pupils from Bradford Grammar.
Whilst I was there Mike McKay the current head of department introduced me to this elastomer project for which I instantly requested permission to plagiaries.
I have added very little to the basic project and as such must pass all the kudos back to Mike.
Once I saw this material and it's characteristics then gave me the idea of making a number of projects out of this compound one of them being the Scalextric Wheels, I also tried to come up with as many projects for it as possible which would make a whole school solution for the one material and could negate the need to change the material in the injection moulder.
We will come back to the Scalextric Tyres and Other projects in pages to come.
In the mean time.
The elastomer know as - TPE TES A5005 BASI MULTIFLEX
It is available in 10kg bags from Azelis Plastics UK
www.azelisplastics.co.uk
At a cost of about £85
As most projects only weigh a few grams the whole thing should last quite well.
The concept is brilliant, pupils are given a small piece of MDF that fits perfectly into one half of the injection mould.
They take this away and either with a coping saw, Hegner, Laser Cutter or CNC router cut a silhouette of the pupils choice.
The MDF is then sealed to stop the elastomer sticking to it, we used cellulose sanding sealer and just before injection dabbed the mould with french chalk to act as a release agent.
When the silhouette is ready the MDF is placed in the mould in the injection machine.
CR Clarke Injection Moulder In our workshop.
Mould prior to the insertion of the MDF
Mould with MDF Inserted
(We use a CR Clarke machine) and the elastomer is side injected into the void.
Moulding With Spru.
On cooling the Eraser is removed from the mould and trimmed . Approximately 5 to 6 Erasers can be easily made without undue wear on the mould.
Sea Horse Mould with finished example and empty mould.
Sea Horse Mould - Download
Sea Horse Mould (DXF) - Download
Dog Mould (DXF) - Download
Head Mould (DXF)- Download
MDF Blank (DXF) - Download
Making the Injection Mould Blank.
The Boxford moulds are made from free cutting aluminium. The blank is - 76 mm diameter by 30mm thick
The additional thickness allows for the re-machining of a second or possible third mould project after the first becomes obsolete or worn.
Using the Boxford 190 / 300 with the 3 jaw vice fitted.
First skim the block to ensure it is flat and level.
Skim File - Download
Then run the following drawing
with these settings.
Based on the tooling being :-
Tool 01 - 2mm Slot Drill
Tool 02 - 3mm Slot Drill
Tool 03 - 4mm Slot Drill
Tool 04 - 8mm Slot Drill
Tool 05 - 10mm Drill with 45 Degree Rake
Tool 06 - 25mm Tipped facing cutter.
Injection Mould Back - Download
Finished Cutting.
Machining the second side of the blank.
When fitting the job back to the 3 jaw chuck it is necessary that the four holes are positioned so that when the blank is placed into the injection moulder the entry point is correctly located at the top.
To achieve this we need a jig which locates into the four holes and uses the jaws to lock the position front to back.
Jig File - Download
Jig File (DXF) - Download
Pins File - Download
The second side needs to be skimmed and then machined with the following settings.
When finished it should look like this
Top
Back
Using the Boxford A3 "M"
It must be an M model to machine metal other models may suffer damage if this type of machining is undertaken.
The first part of the machining can take place using the bracket with offset nut position.
The drawings and settings remain the same as on the 190.
To help with the machining of moulds Boxford has created a jig to hold part machined blanks.
CR Clarke also sell ready to finish blanks that follow the same profile. These will also fit the jig and can be machined in the same manner.
CR Clarke Blank
Making The MDF Mould Half.
The MDF piece is in mould terms a relatively simple piece of machining.
The depths are.
6mm for Pink
5mm for Red.
Making The Side Injection Half.
The Side Injection is also in mould terms a relatively simple piece of machining.
The depths are.
6mm for Pink
4mm for Blue.
Finished Moulds
F
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