My Record for Weight Loss on a Bow

[tippit]

Spending a lot of time in my shop...reducing weight on my older bows and forging knives.  I started shooting traditional bows in 1980.  For several years I just shot Robertson Stykbows and Great Northerns.  This Robertson Heritage longbow was one of my first real custom bows (even though it was used when I bought it).  Robertson Heritage Stykbow 68" 68#@28...Reduced weight by 30#.
Now 68" 38#@28 in nice tiller and shooting again after 40 years...tippit

[slowbowjoe]

That's quite a feat! I'm wondering how in the world you can reduce that much and still have a shootable bow (purely curiosity). Do you take down mostly the thickness, the width, or I'd guess both? Remove then replace laminations?

[wapitishooter]

I would like to know the process of reducing weight. If you would, like to know how you do it.

[Bob D]

I would also like to know how to do that properly. I have a whole wall of bows I couldn’t pull to save my life. Any knowledge about your methods you would be willing to pass on to an old crippled dub like me would be appreciated.
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.

[tippit]

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

[Bob D]

Thanks Tippit, I have never tillered a bow either so I have a whole lot of learning to do. I better get started...

[The Whittler]

Tippit, how far down the limbs do you grind/sand to take the weight off, 13"-14" or more. Thank you.

[Gordon Jabben]

   Thanks for the information.

[Crooked Stic]

Man that bow must have had .050 glass on both sides
. 30 lbs. on my bows would be quite a bit reduction in stack.

[tippit]

Crooked Stic
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....

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. 

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.

[Overspined]

You can do this with a palm sander too, probably easier for most people to do those belts take a special talent!!  If you are not using too heavy of an abrasive, 220 would take forever so I’d probably go 120, 150, and then finish with 220. Unless you just want to remove a little then go 150 or 220.  Go evenly, replace the sanding pad pretty often, and check your work. Count your passes and be consistent.

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.

[tippit]

Overspined,
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

[HornHunter]

hmmm sounds like a good excuse to make a jig for table top belt sander that only allows you to take off so much?

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

[tippit]

Well this is as good a time to try reducing an old bow that you never shoot and are not likely to sell due to how heavy it is.  Not much to lose and a lot to gain plus most of us have a bunch of free time on our hands.  Enjoy...tippit

[Overspined]

Yeah the palm sander works great and like any tool, you get better with practice. I would not be pressing into riser curves and the like with a palm sander, you arent affecting weight there either..

[tippit]

I think I've reduced 30 bows in the last couple of months all between 40-35#.  I'm really enjoying shooting them again plus it's keeping me busy and on the farm away from people...tippit

[pdk25]

Wish I had the skill for this. I am not getting any younger.

[Kelly]

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!

[tippit]

Kelly,
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

[Kelly]

Thanks Jeff, did you mean “spindle” ?

Are the oscillating ones ok or just straight spining?