Thrumming Bow???

[paulc]

So after years of hanging on these boards I might finally have a bow I made and 3 or 4 arrows I made that I'm comfortable shooting at a living target. Only today the bow was "thrumming" with each shot. Definitely the bow, not the arrows. I've never noticed it before but I've also never succeeded in making an arrow to shoot thru the bow. I've shot lots of crappy fiberglass shaft arrows thru this bow in the past w no sounds from the bow. I don't have any silencers on the string as it was never needed before.

Hickory bow, about 45lbs or so. Crepe myrtle shafts, river cane shafts w trade point or obsidian. Turkey feathers fletch. I did put a piece of bamboo onto a fiberglass shaft so I could mount a trade point on it...Frankenstein for sure but my best arrow :-)

Any thoughts on the noise coming from the bow?

Thanks, Paul

[Hamish]

If the "thrumming" hasn't happened with the bow in the past I would carefully look it(and the string) over for damage. Do it whilst strung and unstrung. Look for cracks at the nocks.

It may not be the issue, but best to check.

 I would also check the brace height, and arrow weight. Your arrows could be too light, the excess energy staying in the limbs, showing up as noise

 I was shooting a long self bow at an archery club. They used these steel rebar, ground quivers. Basically the bar stuck in the ground with a loop at the top to hold your arrows together at the shooting line. Lots of people shooting at the same time, people were crowded in side by side, not much room to move. All the modern bows, glass or compound were shorter and cleared quivers but my bow tips slapped it when I loosed the arrow. Only happened twice, before I started to notice the bow shooting differently.

I thought I might have damaged the limbs, but they were fine, no dent's bruises or even a scrape in the finish. The spliced handle was out of line though. The shock had travelled up the limb, into the splice, and the billets were tearing apart along the glue line. Caught it early enough and no permanent damage done, able to be repaired.

[bownarra]

Eiter arrows too light - unlikely if you are using glass arrows.
Bows limbs are out of balance, one relative to the other
Or tiller is out of whack.

[ShorterJ]

Is the bow making this “thrumming” noise with the same arrows that were quiet before?  I have more noise with my homemade arrows. 

When you say it’s “definitely the bow not the arrows” do you mean it’s definitely the bow making the sound (could still be arrow/string issues), or that it’s definitely the bow itself that’s causing the noise problems (the bows fault only not arrow/string)?  If it’s the latter then all I can think of is some sort of unknown alteration/damage to the bow itself.  Otherwise all I can think of is arrow/string tuning issues. 

Hopefully you can locate the issue.  One of mine has quite the “thrumming” sound that I would like to get rid of as well.

[Eric Krewson]

Raise your brace height, that should take care of it, your string may have stretched.

[gutpile]

agree with Eric thats probably all it is.. gut

[paulc]

First pic is of some fiber "texture" that has appeared on the back of the lower limb.  I don't shoot like most y'all do as far as I can tell so it isn't like I have handled this bow 3 or 4 times a week for the last 6 months or a year or whatever...But I certainly didn't make the bow and leave that lifted grain on the belly.  I guess the compression on the belly could cause some splinters to lift...?  Is that a thing?  The stave had dried for years inside before I finally worked on it so I doubt its a moisture content issue when the bow was made.  And I made this bow years ago...stored safely in a home with humidity around 50%.  We like it dry...

Brace height-if anything is too high right?  The string was slapping my wrist a couple weeks ago so I twisted it tighter and restrung the bow.  It seemed to shoot better so I left it. 

And the fraying on the bow string...too much so as to be dangerous?

And braced-I don't see anything alarming but I know enough to hurt myself :-)

Thanks so much.

Paul

[WhistlingBadger]

Pretty bow!

I'm not sure, but that grain lifting just looks to me like your bow surface got a little moisture on it.  Give it a light sanding and seal it with something (I like grease/beeswax/pine pitch, but there are other ways) and you shouldn't have that again.  Your string looks like it could use a good coat of wax, but I don't see anything super scary.

As for the noise, I'd throw in my guess for arrow weight.  I didn't completely understand your first post, but it sounded like you went from fiberglass shafts to myrtle or river cane.  If so, you're dropping a lot of weight.  That can make a bow louder.  Either use a heavier arrow, mess around with brace height, or put on string silencers.  My solution would be all of the above. 

[bradsmith2010]

I think it is the string touching the recurves,,

[bownarra]

Like I said it is a tiller issue - lower limb is weak.
Regarding the fibers - your bow has simply had some moisture on it. This is a non-issue....

[George Tsoukalas]

That  noise you heard  is usually a sign of stiff arrows or too low a brace height. The brace height seems good.  You may have lost some  bow weight from the moisture. Try a lighter spine or a heavier point. Jawge

[paulc]

thanks all for the input...gotta love archery.  Multiple answers all of which probably have some truth in them :-(  I did just the other day tighten the string which changed the brace height which would have changed the relationship of the sting to the recurves.  So that makes sense.  I shot the same arrows yesterday after work out of an osage bow (purchased).  No noise but the bow pulls a bit more than the hickory.  And no recurves.  So maybe the arrows match the bow better maybe the lack of recurves is the answer...And yeah, the limbs may just be out of balance.  But I swear it didn't use to make noise.

Thanks WB on the compliment-the handle is too long but it is my first successful bow so it is "special".

I will shoot some more with the osage and if I can hit consistently maybe I take that into the woods this fall.  Not sure a thrumming bow will help me make a clean shot.

Thanks, Paul

[bradsmith2010]

you could put some fur silencers where the string is hitting the bow, the strumming will stop.. but then the music will stop..

[bownarra]

thanks all for the input...gotta love archery.  Multiple answers all of which probably have some truth in them :-(  I did just the other day tighten the string which changed the brace height which would have changed the relationship of the sting to the recurves.  So that makes sense.  I shot the same arrows yesterday after work out of an osage bow (purchased).  No noise but the bow pulls a bit more than the hickory.  And no recurves.  So maybe the arrows match the bow better maybe the lack of recurves is the answer...And yeah, the limbs may just be out of balance.  But I swear it didn't use to make noise.

Thanks WB on the compliment-the handle is too long but it is my first successful bow so it is "special".

I will shoot some more with the osage and if I can hit consistently maybe I take that into the woods this fall.  Not sure a thrumming bow will help me make a clean shot.

Thanks, Paul

That is what happens when the bow isn't 'bedded in' properly. it can be fine for 50 shots then drift out of tiller. I've been doing this a long time. Nothing to do with recurves. Highly unlikey to be the arrows making a thrumming noise...arrows are either silent or if they are far too stiff you will hear a crack/whack/thwack noise when it hits the side of the bow. there would also be a mark at the arrowpass. Shooting heavy arrows will quiet the bow down, too light an arrow is obvious....but all that stuff is bandaid. Sort the tiller out. To confirm wether it is a tiller issue - post a photo of it unstrung, one braced and one at full draw. Even with the limited info going for the diagnosis I'd put money on your lower 'coming around' with shooting ' settling it in'.

[George Tsoukalas]

bownarra, good point. The stave should be exercised 10 times or so after wood removal to register the changes.

You say there is a difference between a thrumming noise and a thwacking noise (stiff arrows, low brace). If yes, I've never heard it and I've had bows change tiller.

Jawge