Jump to content

andypugh

Members
  • Posts

    797
  • Joined

  • Last visited

  • Days Won

    10

Posts posted by andypugh

  1. When I was a mechanic all we had was a steel sheet offcut that we kept well greased so we could place it on the ground under the hub, rolled the wheel onto it and the slid the wheel onto the hub.

     

    But I imagine you were doing this in the era of detachable wheels and pneumatic tyres?

     

    I wouldn't want to bet that a double solid-tyred wheel weighs more than a modern truck wheel (I can imagine that those are very heavy) but the game here is sliding the wheel onto the bearing without damaging the bearing.

    And they are certainly quite heavy enough in the case of a Sankey disc wheel. :-)

  2. The only proper course of action is to make up some patterns and make up new tanks. However, I really don't want to do that at the moment as there is so much else to be going on with so I need a solution that will last just one more season.

     

    I wonder if building up on the inside with metal-spray would be any help?

     

    Ben?

  3. You are not the only one with this problem in trying to store larger vehicles.

    Aside from have another set of smaller diameter wheels to soley move the vehicle into a low building, I have looked over the idea of altering the spring mounts to enable the chassis to be lowered on to the axle. What ever way it still requires some time in undoing bolts, moving hangers etc, then a re-assembly. Otherwise a re-design to the top of the framing over the door.

    Doug

     

    From the drawing it looks like ballast tanks in the back of the truck might be a solution for Ben.

     

    Or, just make the truck a little shorter than original. I doubt that anyone would every guess. It isn't like you will ever park next to another one.

  4. I think only a carbide tipped 'Rotabroach' would have been suitable for this job!

     

    I don't think that it would need to be carbide.

    I have used ordinary HSS Rotabroach cutters for birds-mouthing thick-walled tubes, so I am pretty sure that one woud have worked here.

     

    With that job to do I would have relished the opportunity to realise a long-held ambition to own a mag-base drill.

     

    But, failing that, with the guide plate I am sure that a Rotabroach cutter held in a normal drill would have worked.

     

    http://www.ebay.co.uk/itm/Rotabroach-Type-Mag-Base-Cutter-Hole-Cutters-Annular-1-50mm-LOC-/262241740348

     

    If there is any likelyhood that you will be wanting to drill in-situ holes in chassis frames on an ongoing basis then I would strongly suggest keeping an eye out for a nice little mag-base drill.

  5. If there is no phase change, how does the annealing change the aluminium ?

     

    The hardening of aluminium is caused either by work hardening (dislocations in the crystal structure start interfering with each other) or precipitation hardening (https://en.wikipedia.org/wiki/Precipitation_hardening)

    Softening a precipitaion hardening alloy requires quite complex heat-treatment, and it seems fair to assume that this isn't what we are doing with soap and a blowlamp.

     

    Instead the heat allows the atoms to move enough to "repair" dislocations and/or for tangled dislocations to combine into less-tangled ones.

     

    At least this is my understanding, I confess that whilst I am a metallurgist, I am a ferrous metallurgist :-)

  6. Tony, I spoke to Father yesterday, yes he did quench it after heating.

     

    I don't think that it is "quenching" in the traditional sense of the term in the case of aluminium or copper alloys. There is no phase change, so you can cool in water or not as the mood takes you. The part will stay hot longer and might end up slightly softer if left to cool naturally, but you can handle the workpiece and get on with the job quicker if you cool it.

  7. Andy, that seems quite reasonable. Do they charge by weight? Is there any extra charge for intricate components that require a lot of setting up?

     

    I don't know how the pricing is derived, but simple parts with no core seem to be about £25 and then it costs more if he has to make a core, and as more iron is used (and more fuel is used to melt the iron).

     

    As a guide, the parts here:

    https://picasaweb.google.com/108164504656404380542/Holbrook#6230479127730875154

     

    Were priced at £10 each for the rectangular strips, £150 for the big hollow box, £100 for the smaller hollow box, £25 for the chain covers (which did have a core) and £20 for the toolpost boss. Not shown is a simple flat plate that was £10.

  8. I have annealed both copper and brass in the past but have never tried annealing aluminium. I guess there is a danger of melting aluminium and I am curious to know how your father did it. Propane? - and what sort of temperature - and what colour did he take it to

     

    With aluminium, if you can see a colour, it has already melted.

     

    What has worked for me is to scribble over it with marker pen, then heat until the ink loses its colour.

     

    This is rather the same idea as the soap, but easier.

     

    I don't know if it matters, but I used green pen.

     

    First picture here: http://bodgesoc.blogspot.co.uk/search/label/Neracar11%20The%20Eyes%20Have%20It

  9. Neither option of fabrication, casting or machining from a billet is particularly easy.

     

    Once you find a helpful foundry, castings can be moderately easy and rather less expensive than you might guess. I recently spent £350 on 8 cast iron castings weighing about 80kg total. (To patterns I supplied)

  10. When broken down into individual steps it is possible to see how a miraculous result can be achieved from a number of merely impressive sub-steps. Apart from:

     

    The welds were then filed and polished up

     

    I can't imagine the skill it takes to file those radii correctly without accidentally gouging other parts. And I consider myself pretty handy with a file.

  11. Actually 20,000 does sound an awfull lot, is that really the right number ?

     

    I suspect that is is one of those things you get when you keep multiplying numbers together

     

    8 per inch

    x 30 inches of tube

    x 4 tubes deep

    x 15 tubes wide

    x 3 radiators = 43,000...

     

    So, I must have over-estimated some numbers, but it's easy to get there.

  12. We shall make the core ourselves – but this will be an expensive job. We shall need about 20,000 Gills to be thread on the tubes – these are available commercially and cost about £30 per thousand – you work out the cost of those!

     

    I can imagine that it would be possible to make a press-punch to make these yourself with a hand press. I also imagine that after the first few thousand £30/1000 would start to look very cheap indeed.

  13. The front pair will be much more of a challenge. There is a reasonable amount of the nearside mount remaining but the offside one is completely missing. This will probably involve fabricating a copy of the missing mounting, then trying to weld it to the existing casing. For this brace I think I will resort to bolts through the case to the inside of the gearbox as well (making sure I position them to miss the gears).

     

    It might be better to leave it as an "honest repair" with just the steel frame not disguised by aluminium (which is unlikely to be particularly structural, even if welded on)

  14. 1/16" seems about right I'd say. You'd need to be sure the axle end nut was pinned or locked so it wouldn't self-tighten though.

     

    I think the place to start is that you always want some tiny float even in the worst case scenario.

    So work out how far differential thermal expansion could make things go wrong at the melting point of brass, and you need no more than that.

     

    I would guess we are talking about 50 thou.

×
×
  • Create New...