I’m not sure how widely known it is, but the main part of a fibreglass control stake is actually an electric fence post and, while a single glass fibre stake from SportIdent UK costs £14.40 inc. VAT (discounted), ten fibreglass electric fence posts can be bought from electric-fence.co.uk for £17.20 + £5.99 carriage (inc. VAT).
So, what are the differences? There are only two – the electric fence post is longer at 112 cm compared to 85 cm, so will need to be shortened and the SportIdent control stake is supplied with a moulded plastic top piece to which the plastic control plate / mount (purchased separately) is fastened. Basically, this little piece of moulded plastic is costing over £12.00! As you need quite a few control stakes for an event, this can add up to quite a tidy sum.
Over lockdown, one of my non-orienteering projects resulted in me both designing and having made a number of 3D-printed items. As my club is now looking to increase our number of fibreglass control stakes, I’ve designed 3D-printable top pieces for the fibreglass electric fence posts to cater for different control arrangements.
Three designs have been uploaded to Thingiverse and are available to be downloaded and used for free. All designs have a top plate and an oval stem with an oval central hole to accommodate the 10 mm x 8 mm section of the fibreglass electric fence post. So far, I’ve had a prototype top piece printed by one of our club members and will be having a quantity printed shortly. This prototype has confirmed the dimensions of the most critical part, the oval hole down the centre of the stem. The three designs produced so far are:
Thing:4859025. This design has an elongated top plate with two 4.5 mm diameter holes at 40 mm apart. This design is for use with the narrow plastic mounting plates that are bought undrilled. The design should be used with M4 countersink screws, washers (preferably larger Form ‘G’) and Nylok nuts. My preference is for stainless steel fasteners.
Thing:4913218. This design has been produced for use with the full base moulded plastic holders with mounting holes and has two 4.5 mm holes at 20 mm apart. Due to the constraint that this small distance produces, the design includes hexagonal recesses to accept M4 nuts. Two different options for this have been produced, one with a circular top plate and the other with an elongated one. Both have ribs to provide extra strength. Note that the distance of 20 mm between fastenings has been estimated as I’ve not had a full base plate to hand to take dimensions from. If the fastening distance is different, then let me know and I’ll update the design accordingly.
Thing:4918589. This design is the most speculative, as it doesn’t replace something currently available, rather it is extending the utility of the fibreglass stake. I’ve designed this top to be used with a length of 30 mm x 30 mm x 3 mm aluminium angle allowing any number of configurations to be produced, such as a control stake with both an Si control and a pin punch in the form more often used for higher level and international events. I’ve designed this top to be more robust due to the offset loads involved with punching and the stories of competitors hitting the controls. The two top holes are again 4.5 mm diameter, this time 45 mm apart and slightly offset. There are also indents to allow the drilling of horizontal holes to give a 4-point fastening as horizontal holes don’t print very well. I've designed two variants, the second with end plates to make the design even more robust. Again, these designs can be amended and updated to use different aluminium sections, for example, or add additional features.
The most common filament used for 3D printing is PLA and this should be suitable for the purpose, but PETG is more UV-resistant and a better choice. Both PLA and PETG filaments come in a multitude of colours, so you could make your controls stand out from those of other clubs in your region, for example, if you regularly share equipment for higher level events.
As I said at the start, these designs are free to download and use. Also, I’m happy to alter or update a design to meet specific requirements or to design a new top piece from scratch if necessary
Control stakes
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Re: Control stakes
Good stuff. How do we cut the fiberglass rod to length without leaving spiky bits and then what adehisive do we use to stick post to mounting plate ? Cheers.
- Davy
- white
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Re: Control stakes
The fibreglass stake is solid and cuts like a solid rod with a hacksaw, no loose fibres. It just needs a quick smoothing with wet and dry or a file.
Use Gorilla glue or epoxy. Put a small bit into the oval hole in the stem. This ensures that the adhesive flows up the joint. There's a hole in the centre of the top plate that joins to the oval hole to let air and any excess glue out. The stake goes in part way through the top plate to ensure no stress-raiser at the top of the stake.
Use Gorilla glue or epoxy. Put a small bit into the oval hole in the stem. This ensures that the adhesive flows up the joint. There's a hole in the centre of the top plate that joins to the oval hole to let air and any excess glue out. The stake goes in part way through the top plate to ensure no stress-raiser at the top of the stake.
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Wayward-O - light green
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Re: Control stakes
Looks good. Roughly how much do your designs weigh, i.e. how much filament is needed to produce them? I presume this gives an indication of cost - or is there some waste involved?
- Snail
- diehard
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Re: Control stakes
Note that the distance of 20 mm between fastenings has been estimated as I’ve not had a full base plate to hand to take dimensions from.
I have just measured a plate using a Vernier gauge and I think the distance is 21.5mm. Maybe somebody else can verify that ?
- Davy
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Re: Control stakes
Snail wrote:Looks good. Roughly how much do your designs weigh, i.e. how much filament is needed to produce them? I presume this gives an indication of cost - or is there some waste involved?
I've weighed the prototype, a photograph of which is included on Thing:4859025 and it weighs 10 g. The item was printed by a club member and I don't know how much the filament cost. I don't think there will be any waste with a design like this, nor any scaffolding required.
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Wayward-O - light green
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Re: Control stakes
Davy wrote:I have just measured a plate using a Vernier gauge and I think the distance is 21.5mm. Maybe somebody else can verify that ?
Thanks Davy, that is useful. I now know that the distance is more than 20 mm so will wait until I can measure one or someone can verify your measurement. Measuring edge-to-edge rather than hole centre-to-hole centre is usually more accurate.
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Wayward-O - light green
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