Here is a list of all the postings Dusty has made in our forums. Click on a thread name to jump to the thread.
|Thread: Chronos silver steel, water or oil quench?|
The oil and water trick is good and works, but it will not harden and temper in one go. The oil which should be about 6/8mm thick is to help prevent cracking the shock of plunging small sections into cold water can cause stress cracks to appear. Usually the first you know about them is when the component falls apart. For most items I use a jar of about 500grams capacity. The glass jar allows you to drop the item to be hardened into the jar and being glass you can see it to recover it.
|Thread: Boring problems|
I have sussed out how to add photos, sorry about the quality, the rule is a 6". I will now have to learn how to take decent photo's.
To prove to myself that I was not talking a load of b******s, I have just spent 40mins in my workshop and created your component from scratch. Using my method above. If I knew how to put photo's on the system I would show you. I used a 3/32" long series drill followed by 1/8" long series the lathe was run at 1600rpm for the drilling and the turning
It does work! And for information the 3/32" hole was only 2 1/2 thou off centre.
Edited By Dusty on 30/09/2010 17:49:14
Having re-read your original post I notice that you have had several attempts at this component. You are obviously not using the original material, what are you using? If you are using brass bar and drilling the hole from scratch this may be part of your problem. Drilling long thin holes in the lathe is problematic in as much as the drill has a tendency to wander. This has something to do with rotating the work round the drill. I did know all the reasons why this happens, but the passage of time has dulled my memory. If I were doing this job I would start with a bar of say 1/4" dia and about 3/4" longer than the finished job. Drill the hole, if using 60/40 brass then yes negative rake the drill, use a new good quality drill and as big as you dare, 3mm? and finish to size. Reaming from both ends is not good engineering practice, if you are going to ream do it from one end only. Now mount the job between centres and turn the outside to size. Screwcut the first end and remove. cut to length + allowance for cleaning up. You can now put a short length of 1/8" dia into the hole and mount in the 3 jaw or collet, make sure that it is running true screw cut the other end having finished to length you can just run a die down the thread to finish it. Reverse and die the other end if required. Job done.
Whilst I will not take issue with you on the fact that a reamer cuts. Unless you have a machine reamer long enough to pass through the job (I doubt most model engineers will have) a hand reamer cuts on such a wide front that the forces involved are such that you would never hold a thin walled tube, except in a collet , without it collapsing, tight enough to stop it turning. A 'D' bit is another proposition.
With care my method will work.
I am going to fly in the face of everything that has been suggested so far. The biggest problem is crushing the tube in the chuck jaws, if you have a collet this will overcome to a degree that problem.As this appears to be brass tube it is not going to be the usual 60/40 brass and therefore I would not negative rake the drill. Negative raking the drill in this type of brass will cause the drill to try and push the metal rather than cutting it, that will increase the problems you are experiencing. I would not tighten everything up but allow it to float, this way the drill will guide itself, yes do lock the tailstock but do not lock the barrel. First use a 3mm drill (best if this is a new drill) followed by a 3.2mm drill, this drill should be doctored by grinding a small radius on the two corners of the drill, this can be done freehand. If you feed this fairly slowly you will get a good finish, generally better than a reamer as the drill will cut as opposed to scrape. You will still need to be aware of the drill snatching but it is far less likely than with 60/40 brass.
|Thread: New Machines|
I do not know if you are a member of a Model Engineering Club or not, if not I strongly recommend that you join your local Club if possible. Here you will find like minded men and sometimes ladies who will be only to willing to let you have a go on their machines. The older members of the club will also offer advice. This is very often a help in deciding what to buy. Biggest is best is not a view I subscribe to. What many who advocate this are really saying is you want a heavy rigid machine, this will help in the accuracy of the machine, generally. Having said that it is advisable to buy a machine that is capable of work larger than you anticipate doing. I do not mean a 6" lathe to do what you have indicated you wish to make. This brings me back to my first point, if you do not want to do that, being a member of a club you will generally find someone with a machine big enough to cope with your job. Both Warco and Chesters sell machines that many Model Engineers use. I have a Warco lathe and a Chester milling machine and as you say" you gets what you pay for" If you can get to one of the Model Engineering shows where both these companies exhibit they will demonstrate their offerings and often do show deals.
|Thread: Angled HSS toolholder and tool sharpening angles|
These tool holders are best used in a 'boat type' tool post. This allows the top rake and tool height to be adjusted farly simply by rocking the tool on the 'boat' before tightening the clamp bolt. the other adcantage of this type of tool holder is economy of tool steel. generally they use smaller section tool steel and you can use up to the last half inch or 12mm if you prefer.
|Thread: help with seeing|
One of my local pound shops sells glasses(spectacles) for yes £1. They are available from many outlets for just a little more. You can try before you buy and they are ideal in the workshop. If you scratch em, bin em you wont break the bank. I have a couple of pairs that live in the workshop in cases. I like many spectacle wearers have a large collection of redundant glasses cases. Why do we get rid of the glasses and keep the cases?
|Thread: Is this hobby dying?|
|Thread: BMS angle not 90 deg|
You could try putting your angle in the domestic oven (when the catering manageress is not looking) and leaving it there for a week or two. While the heat is not really high enough to give a complete stress relief the heating and cooling will have some effect. It is no good just heating it once. Do not be tempted to remove it from the oven while warm, allow to cool completely. Domestic godesses sometimes need bribing when attempting to use their appliances, it could be a small price to pay. If it works it will improve your language and you should be a better person to live with.
|Thread: Die Filer files|
You will not get a very sharp corner with machine filing. In use a toomaker would file out his die with a die filer and finish to within a couple of thou by hand. The punch would then be sheared into the die to produce the finished die. I say finished but that is not quite true.
The die would be backed off and the clearance filed into the die, then it was finished. I know not where you might obtain machine files, sorry.
|Thread: darjeeling locomotive|
Yes that would be sensible. I must admit that I had not thought along those lines. Bit of tunnel vision on my part I fear.
I do not agree, my sizes have come from the works drawing which shows 3/8" thick by 3" wide for this spring. This makes the model spring 0.054 thick by 7/16 wide. The drawing in M.E. is 7/16 wide but .78 thick. This would then make the full size spring 17/32" thick if the dimension should be 0.078 on the model. I doubt that they would have made the spring such a bastard size, especially with a stack of leaves underneath it.
If you look at album 5 of David Clarkes photo's a very good view of the springs is available the top leaf is not massivly thicker than the lower leaves, this I think supports my argument.
Edited By Dusty on 27/08/2010 16:41:23
Having just read the latest instalment of this series I have noticed that the drawing for the main spring shows the thickness as 0.78. Ray says that it is masive and would be rigid in the model, that is an understatement. By my calculation the thickness of this spring should be 0.054. How did I arrive at that, The spring on the original is 3/8" or .375, if you use a divisor of 6.85 this will give you 0.054. Why 6.85, this is arrived at by dividing 24" (the gauge of the original loco) by 3 1/2" (the gauge of the model). By the way the remaining springs in the stack are 5/16" thick or 0.045 in model terms.
|Thread: Darjeeling photos uploaded|
Yes, I aknowledge that I am a bit thick, but how do I access these photo's. Can someone direct me on the right path please.
|Thread: Centring a rotary table horizontally on a mill table.|
I agree in some part with Bogs assesment of your problem. I think the problem is with your gibs, I believe that your gibs are set too slack. You can check the play in the table by locking everything up lashing up a clock on the end of the table and giving the opposite end of the table a bit of a push and shove having slackened the lock. This should show how much slack is in your gibs. Theoretically if you removed the leadscrew and pushed the table up and down you should feel resistance, it should feel quite stiff. When applying the locks you do not need to torque wrench them up, just a nip should suffice. This will also help with your ordinary milling. Locking everything up and then tapping the rotary table into position is making hard work of a simple task.
|Thread: repeated postings|
What you are seeing is contributors adding to your original post. When this happens the forum is showing the date and time of that posting. As you are well aware we do not own the thread that we create, and it can be hijacked. This means that it can, and often does go off at a tangent to the original posting. As far as I can see there is nothing that can, or should be done to alter this. This is after all a forum for the exchange of ideas,and a point where help from more knowlegable members can benifit us all. We can all learn, even from the newest beginer. See I have hijacked the thread and gone on a rant
|Thread: darjeeling locomotive|
I am afraid that a lot of you seem to be missing the point. In effect the back to back dimension means nothing, it is the thickness of the flange and the measurment over the flanges that is important. This measurement has to be less than 3 1/2" by, I would say 1/16". This is to allow the loco to run on the tread of the wheel as oposed to tight on the flanges. The larger the radius between the flange and the tread then the nominal 1/16" needs to be larger. In essence the thicker the flanges the smaller the back to back dimension needs to be.
Playing the devils addvocate, if for instance we had a back to back dimension as per Martin Evans of 3 9/32" and flanges of 5/32" The loco would not sit on the track. I am afraid I cannot advance this any further. Everything in life is a comprimise especially Model Engineering.
I forgot to say that the wheels of my Loco are in fact 43/64 wide, even wider than Darjeeling Loco
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