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4 hours ago, Giles said:

Thank you Gents.... i'm very fortunate in the tools I've acquired over time! 

I must say this has taken some persistence. I finally managed to work out how to do it 'properly' from an stl 3D model, but it broke yet another tool within the first second, so I guess doing it the long way is better.... I also had problems doing this job in Nickel Silver, and for some reason that was breaking cutters left right and centre. So I have gone back to brass with a 0.8mm cutter going slowly.

This is the first 'production' one, and it took 50 minutes cutting time, but came out really nicely.

 

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CNC cylinder end cover by giles favell, on Flickr

 

 

If you can deal with the Canadian foul language, look up AvE on Youtube.  He's playing with a Hass mill in full size, and also breaking the occasional thing.  (not so much for you Giles, but for the rest of your followers...I think you have probably passed most of the little hints he's been dropping via experience)   You know how you get experience right?  By doing things the wrong way...   Another person I am aware of doing small scale work is Richard Trounce in Toronto, he is slowly working on finishing a UP Big Boy in 3.5" gauge.  Mostly it's the details that he is puttering with.  (also CNC in small scale work).  RET posts on Chaski home machinist & Live Steam boards, and he may be of more use for you.  He's using a Shereline Mill, with their CNC pack on it.

 

James

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Whichever you use you need free machining. Anything with higher copper content will snag and snap tools. There is a special oil used in taping brass, which is also good for small machining jobs. (Sorry can't remember it's name). It's very much like coloured water but does evaporate off leaving it dry. Cranking work. Wish I had the computer skill to do this.

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  • 2 weeks later...

Thank you.. 

 

I'm now having an experiment with another idea, a little different, but it's a bit of a tall order, mechanically. Before I go too far I want to prove the techniques as it were....

 

These gears (and the rest that mesh to them) are drawn up on CAD and laser cut, and the gearbox plates are cut out on my Stepcraft.

 

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2019-05-14_06-18-04 by giles favell, on Flickr

 

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2019-05-14_06-21-05 by giles favell, on Flickr

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Or paint black latex onto the wheels?

 

or rubber bands of “just the right size”?

 

you do only have one rear wheel driving?

 

atb

simon

Edited by Simond
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Thats very nice Giles, I am jealous. A traction engine has been on my to do list for ages, but I havent got around to it.

It has a nice speed to it.

 

To Simond's suggestions: Plasti Dip silicone paint works well to add grip. But is difficult to get a smooth coating. My current project I have been making rubber tyres from square section drive bands, sold for repairing cassette players and dvd drives. I cut them down and glued to shorten them, although it has proved tricky to get a good joint, once acheived it seems to be stable. I used specialist rubber cyanacrylate.

I havent got the truck running yet, so I cant vouch for the durability. Maybe larger Xsection belts or rubber sheet could serve your larger scale requirements.

_20190518_102904.JPG

_20190518_102935.JPG

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Certainly it is possible to make o-rings to any desired size, as the rubber extrusions are available, and there is a glue to suit.  Never done it personally, but it would certainly support the approach OtherPlanet is taking.

 

watching with interest

Simon

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1 hour ago, Simond said:

Certainly it is possible to make o-rings to any desired size, as the rubber extrusions are available, and there is a glue to suit.  Never done it personally, but it would certainly support the approach OtherPlanet is taking.

 

watching with interest

Simon

 

I get to use lots of sizes of o-ring for work. A friend found me a great supplier in Chichester who will sell online. So I would not bother to make them.

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Looking good Giles, you going to use a steering servo to turn the bar that controls the steering chains to mimic the full scale ones?
You may be able to get square profile O rings like the ones used for pneumatic cylinders to use as scale vulcanised tyres ?

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Thank you Gents....

 

First lesson is that proper rubber tyres are an absolute necessity. I therefore bought a 300 x 300 square of 1mm neoprene on Amazon for about 3 quid, from which I could cut strips of whatever width. I had  to machine down all the wheels by 2mm over the diameter, and then superglue the neoprene on  - all of which went well.....

Servo is fitted. Work has in fact started on the cylinder and crank-shaft

 

 

 

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