Pierburg 2E3 choke

[CJH]

This is going to be tiny - probably too tiny to read, but worth a go.

[CJH]

Version 2 is much closer. There's enough of a gap between the socket pillar and the plastic part now, and the flat on the face of the second arm creates the right amount of swivel.

Lesson learned about the recess in the top though - 0.5mm is too much as it allows the part to ride up the spindle so that the bottom coil of the spring gets trapped under the part. I'll cut that right back to 0.1mm, which should still ensure that the part rotates freely.

The tiny logo was completely overlooked by the Ultimaker 2 - no sign of it whatsoever. The SLS powder process might just show an impression of the logo I think. I costs nothing to have it there.

[Mocki]

i was kidding about the logo..... lol!!

[CJH]

i was kidding about the logo..... lol!!

Yeah, I know, but I fancied the challenge. It'll be interesting to see what it comes out like in the SLS.

[Mocki]

hehehe..... nice touch tho.... if it shows up in the process....

[CJH]

The spacers arrived today - they're definitely a bit smaller than 3.2mm inside diameter, so a 3.2mm rivet doesn't fit. If I drill one through with a 3.2mm bit then the rivets fit nicely. I think I'll do that rather than going up a size in the spacers, partly because Farnell don't stock the next size up in 8mm, and partly because I don't want to increase the size of the hole through the middle of the piece.

I also discovered that it's a devil of a job trying to get the spring assembled without trapping the bottom coil under the piece - it needs a bit more room to sit over the lower spindle part of the piece, so I've lifted everything around the central spindle section by 1mm, while keeping the spindle height to 8mm (7.9mm in fact), and I kept the lower face of the curved arm in the same place, so that the throttle cam bears centrally on the end of this arm.

Thank goodness for trial runs with the Ultimaker 2.

[CJH]

I printed the revised design today, and since my rivets arrived too I did a trial assembly. The wide flange of the rivets works well.

I think it's just about there. Unfortunately I broke the small lever arm off the sample by not supporting the bracket when tightening the nut on the other end of the throttle spindle. It's glued back on with super glue for the photos. That's something to watch out for during assembly I guess. I'll also beef up the connection between the lever arm and the centre section to try and combat this. And the spring looks a touch close to the plastic socket above it - I think I'll recess it just a fraction, but again that could be something to be aware of during assembly - perhaps squeeze the hook on the spring a bit first.




And the nice man at Digits2Widgets said the logo wouldn't show at all at that size, so I'll reluctantly smooth that over.

[Dazco]

Great bit of work there , im well impressed

[itchyfeet]

[kevtherev]

Awesome work CJ

[CJH]

The choke parts arrived today, a day earlier than Digits2Widgets promised. I like that in a company - under promise and over deliver.



It's an ingenious system they have. They print a mesh box, complete with customer details, around the parts. Even the perforated seal along the edge of the lid is unbroken. Their other container sizes are multiples of this smallest size, so I guess they've designed them to pack tightly into the volume that one of their printers can cope with. Instead of having to fish out hundreds of small pieces from the powder bed and pack them up for different customers, they simply retrieve each mesh container, blow it clean with compressed air, and then stick it in a jiffy bag.



So the moment of truth - do the choke parts fit?!



They do! In fact I suspect the tolerances of this commercial system are even better than the SLS samples I had done locally, as the two holes that I opened up a fraction are slightly looser than I was expecting. I'll have to compare the printed parts to the model I sent them. For this particular part this isn't a problem. The circular hole needs to be loose as any friction would restrict the choke flap movement. Where the slotted hole fits over the spindle, the piece is captive inside the carb housing so it can't slide off. Nevertheless, I may tweak the design if ever another batch is needed, and I'll bear this in mind for the throttle part design.

[itchyfeet]

Cost, and paypal address please CJH?
Don't be shy stick a bit of for the hassle factor
I have a carb waiting.

[Mocki]

Good man !
Impressive that in just a few days form being talked about , it's been designed ( well re designed ) , delivered and ready to go .

How much will they be , I think I need at least 3 for my own fleet

[CJH]

No charge for this batch to members of the forum. All I need is a PM with a postal address and the number that you want. If ever we get through this batch and I have to make some more then I'll do them at cost.

I'll stick them in the van when I go to Dubfreeze this weekend too.

Good man !
Impressive that in just a few days form being talked about , it's been designed ( well re designed ) , delivered and ready to go .

How much will they be , I think I need at least 3 for my own fleet

This is just the choke flap part at the moment. The throttle lever thingy isn't quite there yet. For either part, the raw cost of the printed part is under a pound. I've got rivets and spacers here to make up a little kit for the throttle part, but they're only pennies. With postage and packing materials I'll cover my costs with about £2.50 + £1 for each extra choke flap part or £1.50 for each extra throttle part.

[itchyfeet]

Ah I get it, we all give you an address and you pop round and nick our vans, if it's too good to be true...











Only jokin' Pm sent