Pierburg 2E3 choke

[CJH]

I wonder if this is a 'standard' type of rivet that you can buy off the shelf.



If not, it might be worth trying to model one for printing in Nylon 12. Modelling an internal screw thread in AutoCAD seems a bit beyond me, but I could at least model an internal hole that could easily be tapped. I wonder if it would be strong enough - a full length internal bolt might give it enough of a backbone.

[itchyfeet]

shoulder rivet

[CJH]

shoulder rivet

Thank you - probably best to source a direct replacement then.

[CJH]

The geometry of the other lever seems to be more complex than it needs to be as far as I can see. The important aspect seems to be the left and right sides of the lobe that sit between the metal U-bracket. Provided these limit the movement of the whole part in the same way as the original, without fouling anything, I would say the geometry can be simplified somewhat. What do you think about this?




In particular I can't see why the original part has this lobe above the plane of the rest of the part - since the arms of the U-bracket are (almost) parallel and there's nothing below this lobe, I don't see why the top of this lobe can't be flush with the top of the other lobe. This would seem to make it stronger - it'll also make it easier to do a test print in the blue plastic, as there'll be no overhanging bits if I print it upside down, so there'll be no support structures.

Here's my earlier photo again for reference.

[CJH]

shoulder rivet

Thank you - probably best to source a direct replacement then.

Ebay just brings up a load of handbags if I search on 'shoulder rivet'!

[itchyfeet]

Have you heard of google?
http://www.valleyfastener.com/shoulder-rivets.html" onclick="window.open(this.href);return false;

thats merican, here is a uk company
http://www.hamptonworks.co.uk/rivfastrivets.html" onclick="window.open(this.href);return false;

[CJH]

Have you heard of google?

I was getting there

[itchyfeet]

Only jokin'
what size is the hole in the centre or the diameter of ths rivet?
Measuring mine it looks like 8 or 8.5 mm on the shoulder.
You can also get shoulder bolts/screws and it looks to me like you could easily get a nut on the back, head needs to be slim at 2mm thick but you could probably file it down.

http://www.ebay.co.uk/itm/M4-x-8mm-Sock ... Sw~gRVrj2n" onclick="window.open(this.href);return false;

[CJH]

It's ok - none taken

The rivet I've removed measures as follows:
Shoulder: 8.3mm long x 5.1mm diameter
Head: 9mm diameter x 1.1mm thickness
Tail (not sure what to call it - the threaded bit on those shoulder screws):~3mm

I quite like the idea of a shoulder screw. The M4 x 8 version you linked to is perhaps a bit big - in particular the head length of 4mm is too big to fit under the pushrod socket. But the M3 x 5 version has a head length of 3mm and a shoulder length of 5mm, so if I was to recess the head into the plastic part to suit then the head would end up flush with the top of the part. The threaded section is a fraction short though at 4mm - there'd be only 2mm protruding to take a nut.

So perhaps a good compromise is this M4 x 6 version. Head length of 4mm and shoulder length of 6mm, so if I recess the head then there'll be 2mm above the piece, and the threaded part is 5mm long so there'll be 3mm for a nut. The hole in the bracket on the spindle will need to be opened up to 4mm but that's easy enough.

Thread Size (T) M4
Head Length (H) 4mm
Head Diameter (∅D) 8mm
Manufacturing Standard ISO 7379
Shoulder Length (L) 6mm
Shoulder Diameter (∅d) 5mm
Thread Length (E) 5mm
Hexagon A/F (J) 2.5mm
Thread Size M4
Material A2 Stainless Steel
Material Specification A2-70 Stainless Steel
Screw Thread Pitch 0.7mm

[CJH]

Here it is with an 8mm diameter x 2mm recess to take the head of the bolt. Could work.

[itchyfeet]

you can get thin head shoulder screws, not on ebay but worth looking into

[itchyfeet]

You can also consider shoulder washers or a standard screw, nut and washer with a spacer.

http://www.ebay.co.uk/itm/10pc-M3x8-M3x ... AsWdKkqD8w" onclick="window.open(this.href);return false;

[CJH]

Ooh I like those M3 x 8 threaded spacers - just need a flat M3 bolt at each end.

[itchyfeet]

Ooh I like those M3 x 8 threaded spacers - just need a flat M3 bolt at each end.

or one right through because m3x6 is the shortest you will get, nut on the other end
head diameter of an M3 cheese head is 5mm, not enough, add a flat washer at 7mm diameter gives 2.4 mm head thickness.

M3x16 cheese head with washer in pic below, head maybe too thick with washer at 2.4mm and foul the push rod I think, If you could get a 6mm spacer and reduce plastic part then it would work but you can't get 14mm screws so you need to cut one down if a 12mm is not long enough.

[Mocki]

yeah, there isnt much room for a nut, my m3 cabinet screw was tricky to get in .......