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Author Topic: 1:35 Bucket chain excavator Ertmer KB 1  (Read 59576 times)
Ray Dunakin
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« Reply #240 on: March 31, 2020, 05:09:28 PM »

I would never have guessed that anyone else had also built a model of that excavator.
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Visit my website to see pics of the rugged and rocky In-ko-pah Railroad!

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Bernhard
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« Reply #241 on: April 01, 2020, 02:43:23 AM »

Thank you guys for your interest.

Russ, thanks so much for posting. I also have quite a collection of pictures, but I've never seen this before. Definitely an excellent model. It's always inspiring to see things like this.

Nick, if I were to get a model like that paid by the hour, you'd probably have to rob a bank. Besides, I just don't have the time because I've got so many projects in the drawer.

Stay healthy

Bernhard
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shropshire lad
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« Reply #242 on: April 01, 2020, 07:27:34 AM »

Thank you guys for your interest.

Russ, thanks so much for posting. I also have quite a collection of pictures, but I've never seen this before. Definitely an excellent model. It's always inspiring to see things like this.

Nick, if I were to get a model like that paid by the hour, you'd probably have to rob a bank. Besides, I just don't have the time because I've got so many projects in the drawer.

Stay healthy

Bernhard

   

    Bernhard,

     I have been looking to move on some of the money I got when me and the gang hijacked the armoured payroll truck the other year and one of your machines would fit the bill nicely . Just let me know when it is done and I will forward the cash to you . Rubles OK for you ?!

     Here is one in action that I think I saw at a show in Germany a few years ago . Obviously not as good as yours , but not bad all the same . https://m.youtube.com/watch?v=LIgKT05FDl4.

    I look forward to seeing what else you have got in the drawer , other than your socks !

   Keep up the exceptional work,

    Nick

     
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Bernhard
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« Reply #243 on: April 01, 2020, 09:32:56 AM »

Nick, we'd better talk about those rubles in private.
Nice video. The model may be a little rough, but at least it runs. I'd be amazed at the scale it's built to.
I will report on my other projects in due course. Stay curious.

Bernard
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Bernhard
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« Reply #244 on: May 02, 2020, 02:23:38 AM »

I hope you are all healthy and in good spirits despite the lockdown.

The last big challenge before painting and assembly is the assembly of the chain with the buckets.
The chain consists of
282 links, the inner ones with a thickness of 0.5 mm, the outer ones with 0.3 mm
188 rivets
16 spacers
16 buckets
This means a total of 502 parts, which now have to be assembled.
The stretched length of a chain strand is 601.6 mm.

It's gonna be a real patience job. So here we go.


* KB1 184.JPG (219.88 KB, 539x540 - viewed 252 times.)

* KB1 185.JPG (80.52 KB, 1170x792 - viewed 260 times.)
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Bernhard
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« Reply #245 on: May 02, 2020, 02:24:17 AM »

For a long time I have been thinking about how I can produce so many chain links rationally. Finally I decided to have them etched from nickel silver.
The etched plates looked good so far.


* KB1 186.JPG (227.46 KB, 765x515 - viewed 227 times.)
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Bernhard
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« Reply #246 on: May 02, 2020, 02:29:11 AM »

On closer inspection, however, a few serious problems became apparent:
  • Seen with a magnifying glass, the edges of the parts look like in the sketch below. This is actually normal, and is neither noticeable nor significant for other parts. With the links, however, it can be seen with the naked eye, and the contact area of the chain is reduced by 2/3 of the thickness.
  • But the more serious problem is that the parts were slightly too big. I had considered the undercutting in the drawing, but apparently the effect cannot be quantified exactly. Unfortunately, the masses were different for the two sheet thicknesses.
  • The holes were too small in the 0.3 mm links and not properly etched through in the 0.5 mm links.
Conclusion: normally I have made good experiences with etched parts. In this case, however, the whole production is sent to the bin as unusable.


* KB1 187.JPG (152.38 KB, 850x638 - viewed 237 times.)
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Bernhard
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« Reply #247 on: May 02, 2020, 02:30:00 AM »

After a lot of thought I decided to try laser cutting.
When I showed the parts to a sheet metal processing company near us, they just laughed. Their laser cutter has a working range of 3 x 4 m and can cut sheets up to 25 mm.
Finally I found a supplier in Germany who made the links for me, for a however sinful price.
The pleasing result: the parts are absolutely accurate to size. The rivets and the spacers fit into the holes without rework.
However, all 282 parts have a fine cinder burr on the underside, which I have to remove on a whetstone.


* KB1 188.JPG (207.16 KB, 703x459 - viewed 256 times.)

* KB1 189.JPG (191.86 KB, 935x700 - viewed 267 times.)
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Bernhard
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« Reply #248 on: May 02, 2020, 02:30:33 AM »

After the tip of my right index finger has grown back, all parts are now ready for the assembly of the chain.


* KB1 190.JPG (227.54 KB, 646x644 - viewed 267 times.)
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Bernhard
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« Reply #249 on: May 02, 2020, 02:30:59 AM »

I start the assembly by assembling chain sections with 6 links.
For this I have milled a gauge from Pertinax again.
The outer and middle links are inserted into it. I painted the ends of the links with a felt pen. This is to prevent that solder flows into the chain when the rivet is soldered and the links are soldered as well.


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Bernhard
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« Reply #250 on: May 02, 2020, 02:32:09 AM »

Now a layer of cigarette paper is inserted to ensure minimal play between the links.


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Bernhard
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« Reply #251 on: May 02, 2020, 02:32:37 AM »

Then the inner links are put on and the rivets are soldered to them.


* KB1 193.JPG (225.53 KB, 992x725 - viewed 277 times.)
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Bernhard
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« Reply #252 on: May 02, 2020, 02:33:03 AM »

The first of 32 sections is ready. The rivets still have to be shortened and sanded.


* KB1 194.JPG (227.33 KB, 737x520 - viewed 243 times.)
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Bernhard
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« Reply #253 on: May 02, 2020, 02:33:49 AM »

Now the complete chain is assembled step by step from the parts. For this purpose I have made another jig from Pertinax.


* KB1 195.JPG (224.16 KB, 765x587 - viewed 239 times.)
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Bernhard
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« Reply #254 on: May 02, 2020, 02:34:20 AM »

Two sections are added to the chain. Then the spacer is soldered in.


* KB1 196.JPG (229.15 KB, 822x551 - viewed 245 times.)
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