Volvo G990 Grader

[doodlebug]

I see problem's with the quality of there sand, I see gas problem's, and I don't think they understand how to vent the mold properly! They need to pay attention to what temperature they pour at.
Yes, I understand your frustration!

Cheer's, Neil.

[Stefan]

I´ve found another foundry to entrust with the next, much beefier part(s). Hope they´ll do better.

In the meantime I´ve started making cylinders. They come in two rather small sizes, namely 10 and 13 mm inside dia., respectively.

This is my CAD drawing of the the circle turn cylinder. The piston rod is a mere 4 mm in diameter, even in 1/8. The cylinder piston is the 10 mm one. The stroke is 39 mm.


This is, obviously , the real one:


The tubes here are just pre-cut.




The cylinder heads are at a 14.4 and 17.4 mm outside diameter, respectively.


Stefan

[Madda]

What is that green part next to the O-ring in your Cad drawing?

Great build, always gives me so much ideas and inspiraion! Keep posting!

[Stefan]

Thanks Madda! The green part is supposed to symbolize a wiper and support for the O-ring.

Stefan

[JAMMER]

That is some very nice machining on those caps, Ed

[Madda]

Wiper, okay, what is the material you use to make this?

[tc1cat]

That is some outstanding machining!! What are you using to be able to thread that close to the bottom of the caps??

[Stefan]

Thanks! Well, I too thought that would be a problem, but luckily I found out there are tools like this:

[Stefan]

Originally Posted by Madda

Wiper, okay, what is the material you use to make this?

For the wiper I expect some experimentation to be necessary (since plastic kind of yields to the cutting tool). I´ll start with PTFE and hope that I can somehow produce a working wiping lip.

[Trackerman]

Stefan,
when you make up the wipers for the cylinders can you provide photos and description of how you make them as well as what material you use apart from the PTFE please. Learning a lot from builds like yours and appreciate any detailed information that helps to make the parts in the home workshop.

Cheers

Paul

[Stefan]

Paul,
Sure! When I know what works I´ll show you.

Stefan

[ihbuilder]

OK , now where did you find that id threading bar ? been looking forever OTOH , the grader is coming along nicely

[dabears]

Your cylinders are off to a great start!! You have some major talent with those machines

[Stefan]

@Steve: The threading bar is a SIR S16x07 M08 from AKKO. Needs a minimum 11 mm id hole. They also sell on eBay (Germany). The insert is a 08 IR 0,5 ISO BMA from www.bachgmbh.de.

Another german supplier (they don't seem to have any englich page, am sorry) sell threading bars for holes down to 6.2 mm (1/4").

Stefan

[Trackerman]

Stefan,
thankyou for the reply I look forward to following the rest of your build.

Cheers

Paul

[Espeefan]

Wow, the attention to detail! Incredible. You are very talented. It's just amazing to me, to see this project, and others like it, come together.

[Stefan]

Thanks Nathan! Despite all intentions to plan well ahead I run out of brass for the cylinders build and have to put it on hold for a while. But thanks to that I had time to prepare some pics from the circle build.

The basis is this 210 mm (over the tips) toothed wheel, which was laser cut from 6 mm (1/4") stainless. Here with an MDF fixture for centering the ring (see further down).





Here you see the shaping of said ring from a 4 mm x 19 mm bar in a simple bending device. If you wonder what the black dots at the edge are, here´s the story: As I milled away 1 mm along the edge from a 4x20 bar I must have released some surface tension having the effect of bending the whole bar in its main plane, the milled surface being convex by about 2 mm in the middle portion . Trying to straight that out in the vice in a controlled way I imagined to be rather frustrating if not infeasible , but I remembered that there´s always this problem with contraction with welding. So I made all these welding spots with the TIG, starting sparsely and adding more until the bar was back to straight. I´ll tell you it was a good feeling turning that problem to my advantage and watching the bar returning to straight almost effortlessly.




Due to the elasticity (you see the spring back two pics above) the bending core is this small and makes an overlap necessary. I reckoned a coiling overlap to be less detrimental to the end result than a layer on layer kind of winding. In any case, it allowed the forming wheel (the ball bearings) to be closer to the core.


The ends stay straight or become bent with the wrong radius, so have to be cut away.


Attaching the ring to the cog wheel.


Then the bearing surface was ground.




The resulting surface compared to the raw laser cut to the right.



The edge if the ring is internally reinforced by this narrower ring.






Thanks for looking.

Stefan

[Finster]

WOW! Just wow! Amazing work on your models, I really wish I had your talent. I love the wooden bending jig too.

[Stefan]

Glad you like it, Brian . The fork portion of the circle is now ready. Final fixing to the gear and ring portion to follow when I have tested the circle turning drive.









Stefan

[9W Monighan]

Pretty tricky work cutting that ring to fit inside of the circle. I do that alot at my work on some of the products we build.