Machining a Dart by a hobbiest

Discussion in 'Tools of the Trade' started by kennyg, Apr 11, 2019.

  1. kennyg

    kennyg Member

    So when trying to create something as a hobby, machinist always finds one lacking tools and or knowledge of how to do some operation. As you may know I am collaborating with VanO making a design of his. I ran into some problems with tooling and accessories so I made an order,while waiting for the stuff I realized that I didn’t have a set of steel tips of my own. So I guess you can see where this is going. Yep made a set .



    These are made form steel just some off the shelf variety and are patterned after the Bottlesen GT in that they are a full length taper. The taper isn’t as radical as the GT’s mainly due to the trying to achieve a weight suitable for steel tips and that the nominal shaft size is a 2BA. I also wanted some aggressive grip so added groves for 2/3 of the length. All steel darts like this come in a about 14-15 grams for the 50mm length that I used, too light for good steel tips. VanO (Dutch)turned me onto the Unicorn darts that use tungsten inserts for weight and balance control (Unicorn Ultra core darts). The Unicorns work on the basis of turning heavier darts into lighter darts or changing the balance points. I took it the other direction to turn light darts into heavier darts. (MORE TO COME)
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    Erik, Squiggle and VanO like this.
  2. zeeple

    zeeple Member

    Sweet! I have been reading through some of my old blog posts about working with Jeff Pickup on my own designs. I am jonesing bad for a lathe of my own. I have absolutely no idea how to work one tho.
     
  3. kennyg

    kennyg Member

    zeeple I'm glad you chimed in on this . I gave you a somewhat vague answer about the need for a CNC lathe to make a perfect set of darts. Here are my thoughts. A CNC lathe is not necessary to make a perfectly matched set of darts but there are caveats . With some of the Chinese lathes on the market, those referred to as mini lathes one can make just as perfect a set as you can on a CNC lathe but this assumes that one is experienced enough to know how to make all the adjustments to the lathe to make it preform adequately. Having all the necessary tooling to create the design features or the ability to make your own tooling, which in turn usually means having a mill also. Now to make a thousand sets of darts to within a certain tolerance is probably best left to the robot(CNC) as a person trying to do mass quantities would probably get tired, bored and sloppy after a certain amount. CNC lathes require the same type of diligence to be properly adjusted, after a while all machines work out of adjustment and will result in products out of tolerance. I am sure that in the Dart industry there are certain tolerances used, for instance they may say that a perfect match of diameter for length may be .005 inches from one end to another for say 5 inches or .001 inches per inch.
    Some may disagree with me but darts are not rocket science. All kinds of factors are involved that are not related to the dart itself. You may know or have heard of the guy that can take a broom handle, stick a nail in it and shoot trip 20's all day. I think I'd be safe to say that there is no perfectly matched set of darts once you add the shafts, flights, and tips.
    So now for a disclaimer. I am only a hobbyist, I am 72yrs young and have only been doing this about 2years, these are strictly my opinions based on what I have read and learned on my own, no formal education in machining. I have only recently even had steel tips to ply with and most of my experience with darts was probably twenty years ago with a little ten years ago.
    If you or anyone else has any questions about getting started with machining just ask here or give me a PM I'll be glade to share what I know about it.
     
  4. VanO

    VanO Moderator Site Moderator

    This is a story my dad told me about the engineer on the tugboat he sailed on. Pete Monk was an old school Norwegian immigrant machinist and it was the early 1970’s. The boat was out of commission due to a single part and it would be weeks before the company could get them a replacement. The 2 crews were facing those weeks off without pay. Apparently Pete called the home office and spoke to the President of the company and said that he could go home and make the part over the weekend. When he came back and replaced the engine part the President called him(before they started the 6500hp Diesel engine)and asked if the part would work. Pete’s answer in his Norway accent “It might be off by a tausend oov an inch but it’ll werk fine”. Pete died in the 1980’s but my dad didn’t retire until 1996 and he never remembers that part ever being replaced again.
     
  5. zeeple

    zeeple Member

    Love this story. Thanks for sharing!
     
  6. zeeple

    zeeple Member

    It'll be a while before I ever have my own lathe. But in the meantime, I am curious, what do you use for "practice" billets? Is there a super cheap material like aluminum or something that you use just for experimenting, etc? Where do you get your raw materials?
     
  7. VanO

    VanO Moderator Site Moderator

    I love it too. And others of my dad’s. He passed away almost 2 years ago. I miss him but he’s here every time I recall these stories. A bit more on Pete. The machining tools he used he had to make first. Made them from components picked in the dump, washing machine motors and such. What my dad did with wood Pete was able to do with metal. He built my dad’s first wood lathe and it was probably the best one dad owned.
     
  8. kennyg

    kennyg Member

    There are dirt cheap things like free, but most of the time they will be less than easy machinable stock. You can take a piece of rusted scrap steel and use it. You can check with a local metal fabricator and ask for any drops they may have, they may just say knock yourself out or volunteer to give them a few bucks. The easiest way is to go to a local metal supply business for instance I use Pacifice Steel and Recycling they are located in Tacoma FWIW, but living in a metro area there are more business like them. There are many online sellers but local is better because the shipping can kill you.

    As far as what to use for practice the above darts are just made from mild steel round bar from ACE hardware Mild steel like this is less than optimal for machining but it will give you practice at taking a sows ear and turning it into a silk well maybe nylon purse. There are also certain steel alloys that are machinable but cost a little more.
     

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