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Weight relieving the base cup?

Discussion in 'The Lumber Yard' started by Stuart Barron, Dec 27, 2016.

  1. Stuart Barron

    Stuart Barron Slayer

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    Obviously Musous have the base cup hole and now also the Krom Birthday model and I think there is a Yancy custom with a base cup hole. But does anyone drill their base cups to attain better balance on some of their setups? And If so what sort of hole diameter drill and depth are you going for?


    I ask as I am sure I'm seeing edits pop up now and again where the kendamas being slayed have some base cup mods going on!


    Also I have a base heavy setup that I may modify:).
     
    Dec 27, 2016
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  2. James Hoang

    James Hoang Slayer

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    I have honestly never tried out a kendama with a drilled out base cup hole, but after watching some reviews of the Mugen Musou, I've heard that it makes the area near the base cup a bit easier to flips. I'm probably not going to custom drill my own balance hole, but I may buy some damas with a pre-drilled base cup hole like the Catchy street.
     
    Dec 27, 2016
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  3. Aloysius_hung_

    Aloysius_hung_ Honed Member

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    The lighter basecup helps in lunars because that way the big cup portion will be heavier than the basecup, helping in loons, if im not wrong
     
    Dec 27, 2016
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  4. htimSxelA

    htimSxelA Moderator Staff Member

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    I've never drilled one out, personally I find it makes the ken feel less 'solid', but many players do like the mod.

    As for the hold diameter/size, I think that the musou hole is likely around 0.45" diameter, considering that the spike can fit into it. Not sure about the depth, but you could always drill a bit, test play, and then drill deeper if you think it needs more weight removed.
    Worth experimenting if you have a ken to do so with!
     
    Dec 27, 2016
  5. Steezdiaz

    Steezdiaz Slayer

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    I just bought a BDAY slaydawg with the base cup hole and honestly love it.

    I have one other setup I drilled myself and that's a Krom Viking. That thing was so base-heavy that it balanced it out a little. I started with a very small drill bit to get it centered and then worked my way up from there.
     
    Dec 27, 2016
  6. Stuart Barron

    Stuart Barron Slayer

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    Yeah I think it would definitely help with lunars, although they are far from impossible with the setup I have.
    I've heard people say that a heavier base cup helps with slingers, but I am not finding that to be the case.

    I like the look of the Birthday 'dawg but also the Iji prodawg has my attention. I have wondered why only the Bday version has the base cup hole though.

    Yeah around 11-12mm (1/2") is what I am getting on my musou and the whole depth seems to be about slip grip area deep.

    If I go ahead with the mod I will try and remember to weigh the sword before and after and post the results here. If!
     
    Dec 28, 2016
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  7. htimSxelA

    htimSxelA Moderator Staff Member

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    Nice, I was thinking 1/2" might have been it, but since the spike fits in snug from what I remember, I thought it was maybe a little smaller (avg spike is 0.39" to 0.41" at the very tip, but musous are a little larger). Would definitely be interesting to hear how the weight changes, I've been thinking of writing some analytical blog-style posts on the Terra site, doing a bunch of tests like that and running stats on the results.
    I had an excel spreadsheet with a TON of ken/tama weights recorded, many hundreds of pieces, from a bunch of different brands (Terra, Terra LBB, Ozora, KUSA, etc). Backed that file up onto a hard drive, and then had both my laptop AND that hard drive stolen. So I had to restart that experiment :(
     
    Dec 28, 2016
  8. Steezdiaz

    Steezdiaz Slayer

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    Noooo :(
     
    Dec 28, 2016
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  9. Nick Lectura

    Nick Lectura Moderator Staff Member

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    I do not drill my own holes, but I do own a ken that sort of has a hole in the basecup. It's a GT-1.5, so it's basically the GT-1 shape except with a deeper basecup. It's not a straight up hole like the musou ken though. I'm not quite sure how to describe it, but just picture a basecup with an opening in the hole deep enough to fit part of your pinky in it. I find that it helps with lunars a bit, I'm still breaking it in so I can't say for sure.

    Generally speaking, a ken with heavier cups than the sword will be good for lunars and a ken with a heavier sword than cups will be better for slingers.

    Take off the string (optional) and try slinging the ken around your fingers. If you've ever spun something around your finger, like a hanger or some other circular object, it's the same thing. You just gotta get the motion down.
     
    Dec 29, 2016
  10. NicholasPereira

    NicholasPereira Honed Member

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    Not completely true. Most of the people you're seeing are just that good at Lunars.
     
    Dec 29, 2016
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  11. Stuart Barron

    Stuart Barron Slayer

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    Dec 31, 2016
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  12. Stuart Barron

    Stuart Barron Slayer

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    This is probably sacrilege but the kendama I butchered is a Maple RWB OG shape. In my defence my next kendama will almost certainly be a Classic shape RWB (and I wont do it again. Honest.)

    Sword 41.9g
    Sarado 34.5g

    I drilled a hole using an 11mm drill however I didn't go too deep with the first pass (.800”) re strung and tested it. I then thought Id round up to 1” deep. Unfortunatly re centring on the lathe wasn't overly accurate so the hole opened up a little and is now closer to 12mm.

    The sword now weighs 40g. Hole depth is approx 1” and close to 12mm (.472”) diameter (sorry for jumping between imperial and metric)

    Obviously just shy of 2g is not a huge difference but ken flips and whirlwinds feel a bit better to me aswell as 1 and 2 turn pull up tricks (spins more to my liking). The lunar balance of this dama is never going to be amazing, but removing some weight from the bottom has stopped the need for shoving the tama into the back of the cup to get the front to settle as much.Slingers are still ok!

    Comparison pic:-

    IMG_5092.JPG

    Judging from this picture the Musou hole is more like 13/14mm.

    @htimSxelA
     
    Jan 10, 2017
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  13. htimSxelA

    htimSxelA Moderator Staff Member

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    @Stuart Barron right on! Good reporting, and I see no sacrilege commited haha. If you were drilling a hole in an OG mugen or something I think that would raise some eyebrows, but thats another story.

    I just realized I don't know the (avg) ratio of ken volume : sarado volume... I wonder what it looks like. I would imagine a ken with a weight ratio that matches the volume ratio would be a sort of ideal 'all around' setup. From my experience just weighing pieces it seems like the ratio should be close to 1:1.
     
    Jan 10, 2017
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  14. Stuart Barron

    Stuart Barron Slayer

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    Yeah that would be interesting to find out the volume of sword and sarado and if the ratio is the same. If you look on kendama cz Frankendama section Mirek weighs all sword and sarados and there can be lots of variance obviously due to the wood density.

    I see @htimSxelA you mention you have some Alu kendamas. Are the sword and sarado machined and welded or bolted together? or is it cast?

    Aluminium density should be consistent especialy if turned and would maybe give you an easier way to see how the weights match. Instead of working out the volume that is.
     
    Jan 11, 2017
  15. htimSxelA

    htimSxelA Moderator Staff Member

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    Good thinking on the alu density, I have a kendalex massive alu and plastic, so I could check them both. They're basically Ozora clones so it'll be a good look at the ratio. They're turned on a CNC metal lathe, so they still fit together 'traditional style'.
     
    Jan 11, 2017
  16. azleonhart

    azleonhart Moderator Staff Member

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    Does anyone have pointers to someone who does not have a lathe?

    I have a g-clamp and an electric drill, but i would like to relieve some weight off the base cup of some of my kens.
     
    Mar 13, 2017
  17. htimSxelA

    htimSxelA Moderator Staff Member

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    Hmm I assume you're mostly concerned with drilling centre, and not ending up with a misaligned hole.

    It should be simple enough to mark the very centre of the bottom cup, beyond that I would say start with a smaller diameter drill bit, as it's easier to get a small bit tracking centre than a large one. Once you have a 'pilot hole' drilled, you can go up to the full size bit.
    That'll ensure the opening of the hole is centre, keeping the hole 'straight' is another issue though. You could probably clamp and jig up some sort of setup to track centre perfectly, but honestly I bet if you carefully align things and visually check from a couple of angles before sending it, you could get some decent results.
    You prob won't hit exact centre, but that won't matter much once you're finished.
     
    Mar 13, 2017
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  18. Ben Lowe

    Ben Lowe Slayer

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    Okay so I went for it and did this. My Sweets Prime was actually not as solid for lunars as I'd hoped, and upon weighing, lo and behold the sarado was ~37g and the sword ~41. I figured that was in the range that I could get it pretty close and the hole drilling made sense. Plus it is the cheapest kendama I've ever purchased, so I thought what the heck.

    I drilled with a 1/2" bit and took off enough to get the sword to 37-38g! The lunars are definitely more stable/solid, which is great. The rest of the play doesn't really seem affected as far as I can tell. There is no noticeable difference, at least to me, but I've only played it a little just tonight, so I'll wait to play it more for the final verdict.

    If/when I do it again I will get a better drill bit (spade or whatever). I used a metal drill bit which is all I had, and my guide hole was crooked to boot. So double whammy there. Not good, ha! Hole looks terrible, but I cleaned up the edges a bit with the dremel so as long as you don't look inside you can't tell too bad except for the fact that it is off-center. Anyway, glad I did it on the Prime, and I think the end result is net positive!
     
    Mar 14, 2017
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  19. Stuart Barron

    Stuart Barron Slayer

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    Sounds good @Ben Lowe

    I've also drilled a base cup out with a regular high speed metal drill with good results. However a wood drill (spade type) will definitely cut better, with less chance of snagging and ripping the base cup a new one!!
    Also as @htimSxelA says get your pilot hole straight and then I'd advise going with the biggest diameter drill you want to use. This is because you can always go deeper but moving up drill sizes will tend to rip into the wood, and more than likely destroy the base cup.
     
    Mar 15, 2017
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  20. Stuart Barron

    Stuart Barron Slayer

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    @Nicksaw1

    I started this thread a while back on the same thing, and put what info I could about the process I used and how much weight drilling removed from the sword. Hope it helps.
     
    Nov 9, 2017
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