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Trouble with drills/alignment

Discussion in 'General Pinewood Derby Discussion' started by Brian Stanley, Jul 27, 2019.

  1. Brian Stanley

    Brian Stanley Pinewood Ninja

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    I’ve been trying to perfect my drilling process and I’m having trouble. Have probably attempted over 50 drills by now and I just can’t achieve repeatable results. I’ve been able to drill only a handful of holes that are approaching what I would think is acceptable, none of them are perfect.

    Here is some basic info:

    1) Have both the clear jig and the silver bullet extreme (SBE)
    2) Have pin gages and 123 blocks to check alignment
    3) I’ve rolled the pin gages on the 123 blocks and they appear to be straight
    4) I’ve inserted the pin gages into the SBE and checked against the 123 blocks and they are straight, so I think the bushings in the SBE are straight
    5) I’ve watched Lighting Boy’s video on alignment several times as well as John’s video on using the SBE.
    6) Using basswood, grain running along the length of the car and oriented perpendicular to the holes
    7) I’ve tried two separate cordless drills, a drill press and a pin vise on the SBE. So far the best and most consistent results have been with the pin vise

    I believe I have good tools, so the problem must be me. Or, am I expecting too much precision given the material and tools?

    I certainly open to any suggestions.

    Here is a sampling of the results, it moves from tow in to toe out between drills, not really any consistency.

    The set up to check alignment:
    IMG_6043.png

    Here are two different drills:
    IMG_6044.png

    IMG_6057.png
     
  2. Charles Studer

    Charles Studer Workshop Leader Pro Racer

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    Are you using new drill bits? Locking down the the blanks? And stuffing the drilled hole with a pin guage before starting the other side drill? Those things helped me become more consistent.
     
  3. Charles Studer

    Charles Studer Workshop Leader Pro Racer

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    One more thing....keep the 1-2-3 blocks thight and square to the blanks when checking the drill
     
  4. HurriCrane Racing

    HurriCrane Racing PWD Royalty Pro Racer 25+ Pro Race Wins! National Champion

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    It may also be your drill bits. I would normally order 5 or 6, hoping to get one that would fit the bushings.
    Like CC mentioned, inserting a pin gauge or a drill bit into a finished axle hole while drilling the opposite side will help.

    Last is the amount of pressure you use to clamp the block in the drill jig. Too much and the block will flex, too little and it will slip.

    Good luck
     
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  5. Brian Stanley

    Brian Stanley Pinewood Ninja

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    Charles/Crane,

    To answer your questions:

    - Yes, using new bits I purchased from John
    - Yes, clamping the blanks
    - Yes, inserting a pin gauge into the just drilled side
    - 123 blocks are tight against the straight edge

    I have been using a fair amount of clamping pressure on the jig, so I'll back that off a bit and see where that gets me.

    This morning I was checking the SBE closely with the 123 blocks and the pin gauges, it's actually indicating that the SBE is off a bit, which I'm thinking is unlikely. I have two sets of 123 blocks and they're both showing the same thing. However, I only have one set of pin gages and while they appear straight, they could be off. I'll order a new set and see.

    Thanks for the advice!
     
  6. HurriCrane Racing

    HurriCrane Racing PWD Royalty Pro Racer 25+ Pro Race Wins! National Champion

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    Check how well the bit fits in the bushings. If you feel any slop, then the drill can be influenced by the direction you apply the pressure. If you are consistently getting toe in our out on a side of the drill, you can apply pressure in the opposite direction to offset the situation.
     
  7. flockshot

    flockshot Pinewood Ninja

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    I use the SBE and had a similar experience. When you put a drill bit into the SBE there is 'wiggle room' for the bit (not in the bushing, but with the butt end of the bit). You can see it and feel it. Your drill bit may move to slightly tow-in or tow-out before you even start the drill motor. As long as you allow that 'flexibility' you will get flexible results. The drill bit must be stable at both ends IMHO.

    I have been working on how to do that, and am confident I am barking up the right tree. I have only drilled a couple blocks with my new set up and cant find a flaw with the 3-2-1 blocks, or the tuning table.

    I am a scout car rookie, so the machinists here on the site can do much better than what I think up, but if the bit is in the correct position throughout the drilling process I believe the results will follow.
     
    Last edited: Jul 28, 2019
  8. Brian Stanley

    Brian Stanley Pinewood Ninja

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    I've spent a few more hours today trying to sort this out. I've probably done 75 more drills, and have not had one yet that is perfect. I'm now starting to worry that I'm going to wear out the bushings in the SB.

    I have had a few drills that are close, but to get those I've had to vary the direction and amount of pressure I apply to the drill as its going in. If I do stumble upon the right combination, its probably going to be difficult to repeat it.

    I can reasonably consistently get them to slight toe out on both sides. I'm guessing that is the next best option if you can't get them straight?
     
  9. Gso125 Racing

    Gso125 Racing District Champion

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    Have you tested both your jigs yet with the pin gauges and blocks? If they are off contact who you bought them from to see if they can fix/replace them.
     
  10. aircooled

    aircooled National Contender

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    Times have changed some, when I received my Goat Boy Jig in Jun of 2015 it came with a drill which was sized for the bushings. I think the current Drill Jigs being sold should include a drill bit which has been sized for the bushings they are installing without increasing the price. Doing this would give the buyers a complete tool as far as the drill jigs go.
     
    Last edited: Jul 29, 2019
  11. Loud2ns

    Loud2ns Pinewood Ninja

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    Bottom of your blank totally flat? If not that will skew your test.
     
  12. flockshot

    flockshot Pinewood Ninja

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    When you slide a drill bit through one of the bushings on the jig and wiggle the sharp end, you can see the range of movement that the jig allows. With mine you can both feel and see it. In my limited experience I doubt that a single bushing jig can do any better than the SBE.

    I consider the jig to be a tool, not a stand alone solution.
     
  13. Brian Stanley

    Brian Stanley Pinewood Ninja

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    What drill bits are you folks using with the SBE? I'm using the HSS bits from DD4H. I wonder if they're walking/shifting a bit on me. I think I'll try a carbide bit this evening and see what happens.
     
  14. Charles Studer

    Charles Studer Workshop Leader Pro Racer

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    A carbide will cut your bushings
     
  15. Brian Stanley

    Brian Stanley Pinewood Ninja

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    Ok, I tried the carbide bit, not really any improvement, however, I'll lay off it so I won't risk the bushings.

    I have some other #43 bits but they're a little too big and won't fit. What is the best practice here? Just don't try them? Sand the bits a little to get them to fit?
     
  16. HurriCrane Racing

    HurriCrane Racing PWD Royalty Pro Racer 25+ Pro Race Wins! National Champion

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    I generally will look for a bit that is very snug in the bushing. There is some variations in the manufacturing tolerances of the bits. Once I find a bit that will drill accurate axles I'll mark it and only use it for drilling blocks. I prefer the pin vise over the power drill but that is just a personal preference. I know some racers like to use a power drill.
     
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  17. flockshot

    flockshot Pinewood Ninja

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    The bushings for drilling the front holes in my jig are significantly tighter than the bushings for drilling the rear axle holes. It is not that I have worn out the rear bushings, because two of those bushings have never been used to drill a block. So it appears that there are a lot of manufacturing tolerance levels that can come into play.
     
  18. DerbyDad4Hire

    DerbyDad4Hire Administrator Staff Member 25+ Pro Race Wins! National Champion

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    If they are #43 and snug you can drill with them. Try multiple bits. the ones I sell are the ones I use.
     
  19. Brian Stanley

    Brian Stanley Pinewood Ninja

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    John, I just sent you an email.
     

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