Post by: tippit on April 11, 2020, 01:36:50 PM
Now 68" 38#@28 in nice tiller and shooting again after 40 years...tippit
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Post by: slowbowjoe on April 11, 2020, 02:13:18 PM
Post by: wapitishooter on April 11, 2020, 03:16:02 PM
Post by: Bob D on April 11, 2020, 03:23:54 PM
I was always under the impression that 10 lbs was the most that one could expect but then I saw where Chris Unger at Bearpaw in Germany took a recurve from 55 lbs to 22 lbs. Thats the reduction I need.
Post by: tippit on April 11, 2020, 04:55:46 PM
Now if you tried this by hand, you wind up at the doctor's office getting a cortisone shot in your elbow or wrist...I know as I started that way :)
Disclaimer: I only do this on my bows, they are never sold, and I don't do it for anyone else. Too much liability even though I never broken a bow. I do pull all the reduced bows on my tillering tree beyond 32 inches and I pull 27 1/2 to 28 inches on these lighter bows...tippit
Post by: Bob D on April 12, 2020, 09:38:14 AM
Post by: The Whittler on April 12, 2020, 10:03:42 AM
Post by: Gordon Jabben on April 12, 2020, 10:05:55 AM
Post by: Crooked Stic on April 13, 2020, 09:45:24 AM
. 30 lbs. on my bows would be quite a bit reduction in stack.
Post by: tippit on April 13, 2020, 11:49:52 AM
You're right taking that much weight leaves very little glass...but the bow that is left has significantly less stress with the weight reduction. Again for me and only me... they shoot incredibly well and I try to break them on my tillering tree before I even start to shoot them.
The Whittler,
As to where I start and finish grinding, I go from the riser fades to about 6 inches from the tips. Most importantly any transition areas from thin glass to thicker glass has to to feathered so you Don't feel that transition which would cause a hinge effect. It is important to feel the entire length of the limb for any irregular areas. When I grind a knife, I can feel any uneven areas with my fingers better than looking for them.
You would need to have a tillering set up to be able to pull your reduced bow to make sure your tiller is good and to check your weight reduction. Mine is just a 2x4 with a holding area for the bow with scale attached at the string and pulling from the base of the 2x4....
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Two ways to visualize your tiller is to 1) hold your bow with the string up and with the other hand either push the limb tip up or pull it down. Then look at the opposite limb how it reacts. By pulling or pushing on one limb tip you make the other limb react to being either week or strong. Try it on any of your bows and you'll see the reaction.
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2) The other way to visualize your tiller is to hang the bow by the string on a wall with horizonal boards or a lay it on a tile floor to see the evenness of the limbs.
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Post by: Overspined on April 13, 2020, 01:18:20 PM
Also, you can knock off a lot of pounds just by taking 150 then 220 and rounding the corners of the bow but just make sure you’re liking what you’re doing. And again be consistent.
One of the keys to all of this is to keep it all moving. Don’t let any tool sanding stay in one spot. The consequences will be a ruined bow.
Post by: tippit on April 13, 2020, 01:45:01 PM
I agree with the palm sander and 120 to 150...but be careful when approaching an inward curved area that you don't dig a grove in glass there...tippit
Post by: HornHunter on April 13, 2020, 06:21:34 PM
Ive taken weight off by sanding down the edges of recurve limbs but 5-7 lbs is the max
palm sander I would be afraid of creating a weak spot
Post by: tippit on April 13, 2020, 08:32:30 PM
Post by: Overspined on April 17, 2020, 06:18:49 PM
Post by: tippit on April 17, 2020, 08:23:21 PM
Post by: pdk25 on April 17, 2020, 10:45:29 PM
Post by: Kelly on April 20, 2020, 10:23:44 AM
I now reduce 95% of the weight by taking glass off the Belly & Back. Rarely do I trap the sides as you don't take much weight off there. I use my KMG knife grinder with the rotary platin attachment. It supports the 72X2 inch grinding belt with a rubber belt. I will grind with a worn out 220 grit belt so I don't gouge the glass. With that I can skim/feather off glass very thinly. The process is multiple passes on each limb on both sides. I'm continually checking weight and tiller. I takes me about a half hour to reduce a bow. Also I'm a pretty good grinder from forging knives for the past 15+ years.
Now if you tried this by hand, you wind up at the doctor's office getting a cortisone shot in your elbow or wrist...I know as I started that way :)
Disclaimer: I only do this on my bows, they are never sold, and I don't do it for anyone else. Too much liability even though I never broken a bow. I do pull all the reduced bows on my tillering tree beyond 32 inches and I pull 27 1/2 to 28 inches on these lighter bows...tippit
Jeff, do you have a picture of your knife grinder with rotary platinum attachment to see how you reduce the glass? I have some bows in my pile that I’d like to try to reduce. Thanks!
Post by: tippit on April 20, 2020, 11:05:05 AM
You don't want my KMG grinder unless you are into grinding knife blades...cost a few thousand dollars. For just doing a few bows use a palm sander or a spinal sander what the bowyers use. Anyway here is my KMG with rubber backed rotary platin. To reduce glass I feather off the edge of the platin... but the learning curve to grind steel smoothly is Long & Hard! tippit
Post by: Kelly on April 20, 2020, 11:34:24 AM
Are the oscillating ones ok or just straight spining?
Post by: Kelly on April 20, 2020, 11:36:08 AM
Post by: tippit on April 20, 2020, 11:42:53 AM
The biggest thing to remember no mater what you use is don't stop...smooth sweeps with light pressure.
Post by: Kelly on April 20, 2020, 12:13:38 PM
Post by: tippit on April 20, 2020, 12:39:58 PM
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Post by: Bob D on April 20, 2020, 03:37:39 PM
My belt sander is loaned out at the moment, but would a setup like this work? Like the red arrows show, pulling the bow towards you with the belt rotating away from you.
It seems like the bow limb slides real flat against the aerosol cans which are about the same size as the rolls on my sander.
You have a nice setup there, but I feel if I went horizontally like you show without a nice polly-v belt backing, my steel platin would make gouges in the glass.
As always, your advice in greatly appreciated.
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Post by: tippit on April 20, 2020, 04:14:48 PM
That looks like it will work fine.
PS: For me going perpendicular is more like grinding a knife which I'm way more comfortable doing.
Post by: Hud on April 23, 2020, 12:49:31 AM
Post by: tippit on April 23, 2020, 07:54:49 AM