Cromwell Track links, A big thanks to Adrian for his help!!

[Old Git]

I recently asked for some help with 14" Cromwell track links and Adrian Barrell came through with some great pics of an unused track link. So I just wanted to publically thank him and post a few images of what that information was used for. Using Adrian's pictures and some drawings from the Tank Museum I was able to make up a CAD file for these track links, here's a couple of renderings of what they look like on the screen...

 

 

 

 

 

Last Friday I sent this CAD file off to a 3D printers in Holland and today they sent me these, see pics below. Now, I know these are only 1/6th scale of the original size but the great thing about a CAD file is that it is so easily scalable. Once you have the file it's a simple case of either making it bigger or smaller. And if you wanted a mold making so you can cast new track links at a 'proper' casting firm then you'd have to start with a CAD file!

 

 

 

 

 

Edited March 7, 2013 by Old Git
fixed picture links

[paul_bish]

amazing. I love 3D printers and shows how useful this forum is.

[David Herbert]

That is pretty impressive. I wish I was that good with autocad! Did you include the tapers that allow the pattern to be removed from the mould? If you plan to make them in metal, full size or 1/6, it will be much easier if there is draw as in the real ones. I expect you know that there was an earlier version of that track with the three recesses in the road face of the grouser joined up to form a deep slightly wiggly groove all the way accross the running face. This gave more grip and was lighter but wore down quicker and rapidly gave way to the pattern you have made.

 

Please tell us how the 3D printing works and how you will translate this into metal.

 

David

[Rick W]

Very nice.

[Pzkpfw-e]

Please tell us how the 3D printing works and how you will translate this into metal.

David

 

I'm guessing that a 1:1 resin version could be produced & either used as-is for a static restoration, or used as a pattern to produce a mould to make steel ones from.

They're thought to be going to produce a bit of a revolution in the model making world, here's one for a mere £1500

http://www.coolcomponents.co.uk/catalog/plus-personal-portable-printer-p-644.html

They work by literally printing the design, building up layers of material.

[sirhc]

I've done some work with a company who can produce a rapid prototype in wax and then use it to produce an investment casting. We've also had laser sintered stainless steel rapid prototypes produced.. But it's not cheap!

 

Chris

[Caddy]

So what CAD programme do you use? I've used Rhino and am thinking about getting a into it. Have you any thoughts or tips?

[Old Git]

3D printing has been around for a while now, it's also know by the term rapid prototyper or additive manufacturing. It's a simple process really. You take a spool of ABS plastic and feed it as a filament into the head of the printer where it is liquefied as it is laid down. As someone said earlier it builds up the component, micro-layer by micro-layer and it cools quickly as it's laid down; in so doing it can build quite complex shapes. In fact it can be used to build a solid housing with a working spur gear mechanism inside, like a ship in a bottle, only everything is made in situ and works as it should do. It's because it layers the component from the bottom up that it is called 'additive manufacturing' as opposed to traditional technologies such as machining which 'removes' waste material to make the component.

 

At the moment the high-end machines cost in the region of $6,000 to $10,000. The $1500 machines are cheap and dirty hobby machines and they're pretty much defined by the slowness of their printing process and the roughness of the finished article. However, they will improve and soon 3D printers will be something everyone has at home, much like everyone has inkjet printers at home today.

 

To give you an idea you have to look back to the early days of desktop printing. Anyone who worked in an office enviroment in the 70's/80's will remember the large, heavy iron, dot matrix printers that we first had. These things were massive and pounded out their print jobs. They were so noisy we had to keep them in sound proof boxes, in separate rooms. And this was before the madness of health and safety...we put them in sound proof boxes because we HAD too! The Dot marix printers got smaller but they we're still very basic and we needed a break through the first came with the Lasert printer and the first of those, released commercially about 1981, cost in the region of $17,000. By 1984 HP were making the Laserjet desktop printer for sub-$5,000 and today you can have one at home for a couple hundred quid. It, took more than 20 years for the tech to filter down but then the computer industry was still in it's infancy and the desktop PC hadn't really taken off. By the time the desktop PC takes off it took the printers with it and they, inevitably, became cheaper. I was involved in writing printer drivers for very many printers that appeared throughout the 90's and the work my colleagues and I did helped to pull the complexity out of the printers and thus make them even cheaper. We wrote printer drivers for HP, Xerox, Canon, Microsoft, Compaq, Samsung, Oce, Man Tally, Olivetti, and Epson! Remember those fantastic Epson Stylus printers which produced stunning colour pictures...we did that! They made the piezoelectric inkjet heads but we got the absolute best out of them, that was our thing and we did it spectacularly well for Epson. If you looked in the 'About Box' of any of their printer drivers back then you'd have seen the name of "Software 2000, Oxford, England"! In fact it's probably still there in the current crop of drivers as I'm sure they're still using our code. Anyway the point is that once the pressure built up the behind the printer, the need to own a printer started to drive resources and ideas to solving the practical problems and..., the prices came down. The same is happening with 3D printers right now, there's an Israeli compnay making sub-$6,000 3D printers and the low-end hobby machines are improving all the time. The pressure is building up behind them and now all that's needed is for someone to invent a type of piezoelectric head for the 3D printer. It will not be long before everyone will have one in their homes(Think Star Trek replicator, to go with the communication devices (mobile phones) and the Powderject hypodermic).

 

The tricky bit about 3D printers is the need to master a 3D CAD program such as AutoCAD, Solidworks or Solid Edge (which the part above was first designed on). These are very high-end packages and as someone I wa talking to recently said, "cost more than my blimmin house!". But, I'm not sure that everyone will need to learn CAD. What I believe will happen to 3D printers is that we'll use them to replace broken parts on items we own. For instance if you break the tray on something like a Blueray player then you simply go to the manufactures website and type in your serial number. If you're still within warranty then you get the CAD file for free, if you're out of warranty then you pay for it. To protect the copyright you won't get the CAD file to download instead it'll be delivered direct to your printer and once printed the file is deleted from the printer and you're left with the part you need. Simple! This will revolutionise a lot of things in as much folks will throw away less stuff when it can be so easily repaired and firms will slim their overheads because they won't have to keep stocks of spare parts to service their products in the field! I see Women sitting at home designing new shoes for themselves by combining pre-existing CAD designs for soles, heels, uppers, straps and buckles etc. When they're done they send it to the Printer and go to bed, when they wake the next morning the shoes are sitting on the printer waiting to be worn. Your own magic elves! Your Kids will never be able to play a computer game again, because when your wife can design her own shoes no-one else is going to have a chance of getting on the family PC!:nut:

 

A lot of people find CAD programs very difficult to deal with, for some the concept of working in a 3D landscape on a computer screen is too much to take-in, especially when their whole computer experience has been 2D. However, once you get past the shock of that CAD programs become easier to use and I predict that the CAD programmer of the future is where the money will be. But right now it's very cheap to hire a CAD programmer, about $50 - $80 will get you an experienced professional who will take your drawings and turn them into a working CAD file of a relatively complex component. The price varies between CAD programmers and based upon how complex the item is to lay down in CAD. And whilst some my balk at that price remember that's the whole price and the CAD design and the copyright all belongs to you when he's done! Also, it's cheap compared with teaching yourself something as complex as CAD. CAD programmers can be found advertising their services in the forum attached to the Dutch 3D printing company who did these parts for me. They're called Shapeways and they can be found at www.shapeways.com, just browse to the website and look for the link to their forum. Somewhere in the forum will be an area where these guys adverise themselve and you'll also find a review and feedback area so you can see who is good and who is less good.

 

If you want to learn a CAD program I'd recommend going to your local FE and signing up for a class; very many FE's and Universities offer these course as either p/t evening course or extra-mural course respectively. If you wanted to play with CAD now, then you can download Google Sketchup, which comes with a tutorial program. But give yourself plenty of time to sit and learn, you're not going to pick it up in one evening. Of-course all the whizzy stuff comes in Sketch-up Pro which you have to pay for and I'm not sure what that runs at these days but it is substantially less than the price of Solidworks, AutoCAD or Soild Edge. Also, there's TurboCAD which claims to be a low-end price (about $300) with high end features. It comes with a tutorial CD as well I believe.

 

In the vehicle arena 3D printing is being used to prototype replacement parts and it's conceivable that, in the future, you restorer chappies can print as many extra track links as you need to hang off the front of your Sherman. Not today though as it can still be expensive to print stuff. It's good if you're planning of going into production or plan to make many copies of something but if I was to print all the track links I need to make a 1/6th Cromwell it would cost me over £1400 and then I couldn't RC it! They charge by the Sq-cm at the moment but soon enough Shapeways and the other boutique 3D printers will get serious competition and then you'll see prices coming down. In fact, I believe that there's a 3D printing outfit who recently opened it's door down in either Essex or Kent! All you vehicle restorers are going to be using this technology in the not too distant future and the copyright of the CAD files is going to be key so if you do get a programmer to make you up some CAD files make sure you're both agreed up front that copyright rests with you and you alone!

 

OH, and btw, I had help with getting my files done. I know enough to make wheels and stuff but I'm still teaching myself the more complicated stuff and sometimes it's better to simply get help than it is to beat your head against a brick wall!

 

Pete