Base failures

TheMadScientist
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Base failures

Post by TheMadScientist »

Our boomilever team has tested three boomilevers and all of them have been failing at the base. We have been gluing 1/4 inch dowels to the tension members with gorilla glue. We also glued pieces of balsa wood over and around the dowel to increase surface area. Every time we test the dowel is ripped off the tension member but the tension member itself is not damaged. How do we strengthen the connection?
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Re: Base failures

Post by MadCow2357 »

1. Are you using a square 1/4" dowel?
2. How long are you letting the glue dry
3. What weights are your boomilevers failing at?
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Re: Base failures

Post by TheMadScientist »

We are using round dowels.

We are letting the glue dry overnight.

Our boomilevers are failing at ~5 kg.

Thanks.
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Re: Base failures

Post by TheSquaad »

TheMadScientist wrote:We are using round dowels.

We are letting the glue dry overnight.

Our boomilevers are failing at ~5 kg.

Thanks.
Add pieces to gusset the tension member. Have additional balsa chunks on the end of the dowel surrounding the tension member. Also try adding a stick to the inside of the tension member so you can glue it to the round side of your dowel.
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Re: Base failures

Post by arshah2 »

One thing that worked for us was to cut a little rectangular 1/16 bass piece and poke holes in them for the tension members to go through. we gorilla glued that overnight. Then it was just a matter of gluing the dowel on to the basswood piece and gluing the sides to the tension members. This method held 44 kgs, when tension was applied, just under the 47.4 kg tension force applied with 15 kgs hanging off of the loading block. Thus, we can assume that with a perfect boomilever, the max load will be around 14 kgs.
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Re: Base failures

Post by jinhusong »

Setup tested:
glue 1/16 X 1/16 basswood as tension member to base, glued length 1/2. It was in slot with laminate. So all 4 sides of the tension member are glued to the base. It can hold more than 40 Kg.

We also tried drill a hole. Still 1/2 length glued. Hold 40Kg too.
All Gorilla Glue.

The base we are testing is 1/4 X 1/2 X 1 basswood block.

Hope these can give some hints.

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Re: Base failures

Post by MadCow2357 »

1. Try using a square 1/4" dowel. It has more surface area than a 1/4" round one, and it is easier to attach other pieces to strengthen the base-tension connection.
2. Gorilla Glue reaches full strength over a period of 24 hours.
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Re: Base failures

Post by stevepilot »

Make sure the gorilla glue is clamped. Also, consider drilling holes inside the dowel so the tension members are actually seated inside.
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Re: Base failures

Post by Atlanta »

Hi,
Does the 1/16 *1/16 Bass work as good tension chords ? As of now I used 1/8 * 3/16 Bass as tension chords but the weight of the boomilever is on the higher side.
The 1/16 * 1/16 looks very very thin. Will it work good. Please suggest.

Thanks.
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Re: Base failures

Post by MadCow2357 »

Atlanta wrote:Hi,
Does the 1/16 *1/16 Bass work as good tension chords ? As of now I used 1/8 * 3/16 Bass as tension chords but the weight of the boomilever is on the higher side.
The 1/16 * 1/16 looks very very thin. Will it work good. Please suggest.

Thanks.
I'd go with 3/32" square.
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