1/32 A Loco for the Garden

Discussion in 'G1/32' started by JimG, 28 August 2015.

  1. richard carr

    richard carr Western Thunderer

    Thanks Jim

    I like Mach3 software I haven't tried cut2d before. I have a sherline based system but the Z axis isn't accurate it can drop suddenly due to the weight of the motor being attached to it.

    Richard
     
  2. JimG

    JimG Western Thunderer

    I find that the Mach3 works well. I haven't delved into all the operations you can do with it but I find that it always seems to do what you expect it to. I got the Cut2D bundled with the KX1 and I find it to be an excellent 2.5D program. I've only just upgraded to the Cut2D desktop version with a load of additional bits and pieces like more CAD facilities so I'm still apraising these at the moment.

    I have to confess that the Z axis on the KX1 is the one area where I'm not too happy. The KX1 suffers from a problem on all Seig mills where the Z leadscrew is behind the column. When you reverse direction of the leadscrew, the head "nods" and the head assembly pivots on the guides on the column. So if your head is descending and you reverse direction, the head continues down for a small distance then starts to rise, and the reverse happens when changing from rising to descending. So you get an effect which looks like backlash at first, but isn't. You can minimise it by tightening up the taper gib on the head guides, but then you run into the problem of the head sticking if the gib is too tight. I can get round it to a certain extent by using the backlash facility in Mach3 but that only partially gets round the nod excursion and I still get problems like witness marks when cutting pockets when the cutter/head dips slightly when the head is lifted out of the pocket. But the advantages of using the machine far outweigh this drawback and I am finding ways to minimise the problem.

    Jim.
     
    Steve Cook and Dog Star like this.
  3. john lewsey

    john lewsey Western Thunderer

    Some people are just so clever great thread
    John
     
  4. JimG

    JimG Western Thunderer

    After attending to other things, the wheels came back out on the bench over the weekend.

    G1loco-07.jpg
    At the moment I'm still scraping the spokes to get rid of the square edges. The two on the left were done last year and I've been working on the four on the left. The wheel centre at lower centre has been scraped and the one on the lower right has half of its spokes treated. The centres on the upper right have still to be worked on. After scraping to get the main amount of metal off, I use thin strips of wet and dry sandpaper to get a smooth finish on the spokes.

    All this work was being done while the milling machine was churning out the S scale sleepers mentioned in another thread - one of the advantages of a CNC mill - doing productive work with no human intervention to adversely affect it. :)

    Jim.
     
  5. JimG

    JimG Western Thunderer

    I can't believe it's been a year and a half since I last contributed to this thread. :) But I was thinking that that there was a danger of a bit of track getting laid in the garden some time soon and it might help it I had something to run on it. :) The spoke centres and the steel tyres had been maturing so it was maybe time to put them together.

    Cal782Pug-017.jpg

    The first job was to open out the steel tyres to the required inside diameter - a scale 3' 10". I opted to try doing this work on the Cowells rather than the Myford. It would take a bit longer but it meant that I could do the work indoors rather than in the garage at the bottom of the garden. The Cowells worked quite well in the fastest backgear speed with up to 15 thou cuts. I also had to remember how to set the reversible jaws on the Cowells three jaw - I'm used to the Burnerd three jaw on the Myford with separate sets of jaws. :) The tyres were spaced out from the chuck jaws with a styrene washer so that i could cut right through without damaging the jaws.

    Cal782Pug-018.jpg

    The next job was to cut the seat for the spoke centre. First I took a light across the faces of the tyre to true it up. There was now no need for the styrene washer to hold the tyre off the jaws so the tyre could be located against the face of the chuck jaws and a light cut across the face would true up any discrepancies caused by the styrene washer. After that I cut a recess to take the spoke centre leaving a lip at the front of the tyre which the spoke centre would butt against. I wanted the spoke centre to be a press fit in the tyre so it was a case of opening out the recess until close to the finished size, then opening out just the first millimetre of the recess until the spoke centre was an easy push fit, set back about one thou/0.25mm and finish the recess off to this reduced size to give a press fit.

    Cal782Pug-019.jpg

    The spoke centre was then located in the first 1mm which had been opened out to be an easy push fit and the pad in the tailstock was used to push the spoke centre into the press fit.

    Cal782Pug-020.jpg
    The spoke centre almost fully pressed home. It is handy that the Cowells tailstock pad is a nice size for 1:32 scale driving wheels. :)

    Cal782Pug-021.jpg
    The next job is to open out the 6mm hole in the spoke centre to 1/4" and provide a bit of taper to allow a press fit. The reamer is a hand reamer with an end taper so it is possible to enter the reamer such that there is a short section of 1/4" parallel bore with the remainder of the bore having a reducing taper to give a press fit. The small brass collar sets the depth of cut to achieve the amount of parallel and taper bores. This position is found by advancing the reamer by about a millimetre at a time and testing with a piece of the axle material then the collar is locked with the 8BA screw.

    Cal782Pug-022.jpg

    The tapered hole has been reamed and a test piece has been entered to check it. The nice thing about this method is that the wheels can locate on the axle ends and be held reasonably square. For adjusting quartering, the wheel can be pressed lightly until the taper starts to bite. This allows quartering to be checked and adjusted by twisting against the taper until all is well when the wheel can then be pressed fully on to the taper.

    Cal782Pug-023.jpg
    The six wheels so far. The next job is to make up a holder to hold the wheel face out on a true mandrel and finish off the face of the tyre to width, then turn the tyre down to diameter. Th e slightly different tyre top right was made from a left over from the slicing operation. I messed up on the internal diameter on one of the tyres and the leftover was pressed into service. I think there is just enough meat to provide a full diameter tyre but if not, then the six of them will be representing a reduced diameter set. :)

    Jim.