Alfa 8C wire wheels anyone?

[nick]

So was it worth the effort then?

 

This is only white primer, but I absolutely love the look. IMHO this has made the model.

 

 

 

Nick

[albergman]

You are too clever by half Nick!!   Just lovely.   My son who has my old filament printer is now intrigued by your results and is starting to stroke his chin and think about resin.   He's working on larger production parts (not models) and just can't get the dimensional accuracy he needs.   Is there a noticeable shrinkage at all in any of the larger parts ... say the rim diameter?

[nick]

2 minutes ago, albergman said:

You are too clever by half Nick!!   Just lovely.   My son who has my old filament printer is now intrigued by your results and is starting to stroke his chin and think about resin.   He's working on larger production parts (not models) and just can't get the dimensional accuracy he needs.   Is there a noticeable shrinkage at all in any of the larger parts ... say the rim diameter?

Thanks Frank. Printer accuracy is pretty good in fairness in my opinion.

 

As it happens, and as you might expect !  I've been reading up on this, take a look at this:-

 

https://blog.honzamrazek.cz/2019/08/testing-the-precision-of-elegoo-mars-volume-2-xy-plane/

 

The biggest issue is printing small holes (like in wire wheels!) I'm pretty sure they print accurately, but it's very difficult to ensure they are always clear of uncured resin no matter how much cleaning you do.

 

 

[nick]

And paint

 

here’s the real one

 

 

Nick

[albergman]

As a builder of wire wheels the old fashioned way and someone who doesn't really care how many spokes I end up with far be it from me to critique your results ... they're outstanding!    I'm comparing yours to the "real" one you posted and I'm wondering if you have the wiring pattern correct.    The "real" one seems to have "clusters" of 4 spokes with more open space between them.    No doubt you have the correct number of spokes (I didn't count them) so maybe it's a matter of just realigning them?

 

Frank

[Bandsaw Steve]

Ingenious work on a very tricky problem.

 

Awesome final model! 
 

Love it! 

[nick]

5 hours ago, albergman said:

As a builder of wire wheels the old fashioned way and someone who doesn't really care how many spokes I end up with far be it from me to critique your results ... they're outstanding!    I'm comparing yours to the "real" one you posted and I'm wondering if you have the wiring pattern correct.    The "real" one seems to have "clusters" of 4 spokes with more open space between them.    No doubt you have the correct number of spokes (I didn't count them) so maybe it's a matter of just realigning them?

 

Frank

Frank, I think you’re right, I’ll take another look. There’s something going on with the rear spokes I think, I suspect one set is 90° ‘out of phase’ ie slanting left, where it should be right or vice versa. 
 

I should be able to stack and align the two images in photoshop and it will jump out then with 50% transparency on the top one.

 

 Good spot though, I must have gone blind looking at it, as one often does with these things!

 

Nick

[galaxyg]

Very cool. What is the 3D Printer you're using?

[albergman]

Glad you're OK with me mentioning it.    Believe me there are rivet counters out there!    Pity though, your arrangement actually looks better and more robust.

[Mumbly]

Any chance of a side by side of the original and the printed version?  Just to show the improvement.  

 

Tony

[Sabrejet]

Wowzers. Truly the way forward. Mind you I still fancy hand-spoking

[dnl42]

Those look outstanding! 

 

I have some printed wire wheels for a 1/25 DB4, and the problems are all in the spokes. Your use of wire for the spokes completely avoids this--brilliant observation!

 

Hm, hubs, rims, jig, and two-eared knock-off nuts and I'd be set...

 

 

[colin]

Are you planning on making these for sale Nick

[nick]

9 minutes ago, colin said:

Are you planning on making these for sale Nick

Funny you should say this. Yes. 

[nick]

54 minutes ago, Sabrejet said:

Wowzers. Truly the way forward. Mind you I still fancy hand-spoking

They are hand spoked? Printed everything else. 

[colin]

1 hour ago, nick said:

Funny you should say this. Yes. 

PM sent

[nick]

15 hours ago, nick said:

Frank, I think you’re right, I’ll take another look. There’s something going on with the rear spokes I think, I suspect one set is 90° ‘out of phase’ ie slanting left, where it should be right or vice versa. 
 

I should be able to stack and align the two images in photoshop and it will jump out then with 50% transparency on the top one.

 

 Good spot though, I must have gone blind looking at it, as one often does with these things!

 

Nick

Frank,

          you had me for a while there. My wheels don't match the ones in the image you're right, and I found a bunch of errors when comparing them - most notably, I have 24 spokes on the rear set and the image has 12? I was scratching my head for a while and I thought how could have I got it this wrong? and the answer is simple.

 

The image is an 8C road car (as you can see by the cycle wings) the track car, like modern day race cars has different wheels to the road it turns out, like these:-

 

 

Although it's harder to see on this image, this car does have the same stringing pattern as mine (honest!) and that's what I based mine on. I didn't realise they were different until Frank pointed it out.

 

Regards,

 

Nick

[nick]

4 hours ago, Mumbly said:

Any chance of a side by side of the original and the printed version?  Just to show the improvement.  

 

Tony

Like this?

 

 

An earlier prototype version, but you get the idea.

 

Nick

[Nick Belbin]

This is seriously impressive stuff - love it!

 

Nick

[albergman]

14 hours ago, nick said:

Frank,

          you had me for a while there. My wheels don't match the ones in the image you're right, and I found a bunch of errors when comparing them - most notably, I have 24 spokes on the rear set and the image has 12? I was scratching my head for a while and I thought how could have I got it this wrong? and the answer is simple.

 

The image is an 8C road car (as you can see by the cycle wings) the track car, like modern day race cars has different wheels to the road it turns out, like these:-

 

 

Although it's harder to see on this image, this car does have the same stringing pattern as mine (honest!) and that's what I based mine on. I didn't realise they were different until Frank pointed it out.

 

Regards,

 

Nick

 

HA!   I'm so glad you sussed that one.   I knew you couldn't have made a mistake.   As I said before your own arrangement looks better anyway.

[nick]

Two major improvements today;

1. Steel wire for the spokes. This isn’t super-springy piano wire, just florists wire and it’s just stiff enough to still be easy to bend as well as run straight. 
the only down side is that it isn’t round for some reason, but has a flattened profile, hopefully this won’t be noticeable.

2. The biggest breakthrough is reliably printing everything in such a way that it no longer requires drilling. This was a show stopper really as the spoke nipples required a very fragile .3 drill and their wall thickness is extremely thin so failure rates were very high, even more so after a few days curing, to the point where it wasn’t really viable even with loads of spares.
 

 

when I analysed the problem properly it wasn’t that the printer couldn’t print holes that small (it can it turns out!) it was that they weren’t draining of uncured resin properly as they look like tiny syringes so hold liquid resin with suction. 
 

I’ve designed a tiny, flared support structure for each with a cruciform cutout at the base which it seems works perfectly, admittedly at about the 5th attempt, buy hey I’ve cracked it!

 

I’ll print to a few more to ensure it’s reliable, but looking good I think!

 

Nick

[albergman]

These are wonderful and just begging for a nice chromed rim!

[Jo NZ]

Nick, you have really encouraged me to design and print things instead of laboriously machining them. Starting point is a 19" Rudge Whitworth wire wheel.

On the subject of spokes, soft stainless steel wire is available from the Chinese website. I have reels in 0.3mm and 0.4mm. If pulled gently in a vice it straightens nicely.

 

And next... has anyone used flexible resin to print tyres?

[nick]

4 hours ago, Jo NZ said:

 

And next... has anyone used flexible resin to print tyres?

Unsurprisingly I’ve been thinking about tyres. I can’t see how they could be supported without scarring at the moment, but I’m still pondering. 
 

I’m currently thinking either print them in two halves OR print a mould for latex/silicon.

 

if I go down the print in two halves route, then they don’t actually need to flexible either. It would be straightforward to have a complex split point, for example following the tread pattern, watch this space!
 

Nick

[nick]

This is what caused all the trouble, tiny as they are!

 

 

As I've become a bit more involved with all this stuff, it's allowed me to understand what's going on a bit better, especially during the stages where the resin is still liquid.

 

This was an interesting one because the hole had to be .35 to take a .3 wire, the wall thickness had to be as it is for scale, they needed to naturally snap or separate from the carrier at the right place, they needed to drain when printing and be mechanically attached to the build plate so as not to pull off during printing.

 

And all this is going on at about the limit of what the printer is capable of producing.

 

If this hadn't worked, I was going to print a manifold/matrix type affair in the support plate that would connect to an airline to blow the uncured resin out before curing. 

 

I got the idea from my Honda exhausts that I have been doing that with - ooh, I let that slip out didn't I Tony

 

Anyway got another set of wheels coming off now and seems to be printing reliably and doesn't need drilling - so far so good! 

 

Nick