Post by: Bryan Adolphe on December 05, 2022, 01:05:17 PM
I glued on a piece for my riser I think too early anyways, I profiled the limbs. I’ve double checked, and they’re both very close to being similar all the way to the tips I measured tiller at the end of the fades ? and my top limb measures 6 5/16 my bottom limb measures 6 9/16 so if I read that right, I’m a quarter inch negative on the top ? The bow is braced at 8 inches. As you can see in the pictures, my lower limb tip which is on the left now that I glued that riser piece in. :deadhorse: It’s about 3/4 of an inch short to be in balanced with the top limb tip. I have block sanded the lower limb on the back a fair bit, but it has not moved yet. I would like to hear your thoughts honest, you won’t hurt my feelings. :biglaugh: Bryan
Post by: Kirkll on December 05, 2022, 02:26:11 PM
best way to balance the limbs is putting an 18" stick on the bow that holds it at about half draw, then put it on your bench on some butcher paper and trace out the back of the limbs, then flip the bow over.... That will tell you the story on limb balance right now....
Also..... Tiller measurements, and Tillering a bow is 2 different things.... On glass bows with precise lamination grinding, its typically close to even tiller.... But after balancing the limbs it can easily be a positive or negative tiller measurement...... Ya gotta thump the string and check for vibration... Pull it back an inch or so and drop the string.... Listen to it... feel it.... Shoot it.... You get the feel of a good tiller more than measurements... .02 cents... Kirk
Post by: Bryan Adolphe on December 05, 2022, 03:59:10 PM
Also thanks Roy for the picture fix 👍
Post by: Roy from Pa on December 05, 2022, 05:17:25 PM
:thumbsup:
Post by: kennym on December 05, 2022, 06:47:40 PM
Did your riser move a little maybe during glue up?
Those bows are a little sensitive to tiller.
Post by: Bryan Adolphe on December 05, 2022, 07:54:39 PM
Post by: Kirkll on December 05, 2022, 09:17:04 PM
Kirk has good info there.
Did your riser move a little maybe during glue up?
Those bows are a little sensitive to tiller.
Hey Kenny.... What is the length of this design, forward taper rate on lams, and how is the vertical stability?
I played with a design similar to this years ago in a 52-54" length, and it got great performance, but mine had very poor vertical stability. I messed with taper rates and width profile, but still couldn't get what i was looking for. i finally ended up changing the limb shape in the form and added a flat section in the working section.
This is what mine came out like in the end..... This one was a prototype i hunted with for two years before i had it start to come loose at the fades. She's a wall hanger now..... After this one i used longer fades and a power lam to solve that problem. I haven't built one in years. I called it the "Yeti".
Sorry for the hi jack on your thread here....
Post by: Crooked Stic on December 05, 2022, 10:52:44 PM
Post by: kennym on December 06, 2022, 07:40:41 AM
Post by: Kirkll on December 06, 2022, 12:58:00 PM
Post by: kennym on December 06, 2022, 02:36:14 PM
.001 taper only in that one- you know , testing... :)
Post by: Bryan Adolphe on December 06, 2022, 08:33:43 PM
Post by: Kirkll on December 09, 2022, 07:00:41 PM
Post by: Bryan Adolphe on December 09, 2022, 09:50:44 PM
Post by: Bryan Adolphe on December 09, 2022, 09:52:00 PM
Post by: Crooked Stic on December 09, 2022, 10:45:11 PM
Post by: kennym on December 10, 2022, 01:07:11 PM
Post by: Bryan Adolphe on December 10, 2022, 02:22:05 PM
Post by: Bryan Adolphe on December 11, 2022, 06:37:59 PM
[ You are not allowed to view attachments ] This is starting to look not right to me.
[ You are not allowed to view attachments ] So i havnt touched my upper limb but it seems the more i screw with a lower limb its crazy but It looks like it’s changing the shape of the upper limb. :dunno: i may surrender while it’s still shoots :biglaugh: not bad for my first bow had a ton of fun, learned what I shouldn’t do , and it shoots not bad, considering I’m sure it could be improved by someone that knows what they’re doing . :bigsmyl: heres a couple pics of the riser before finish sanding.
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Post by: Kirkll on December 11, 2022, 07:41:13 PM
The unstrung brace looked very similar to your bow, and it had a fast taper rate.... I did get it balanced out.
https://youtu.be/sEOF6eCD-Mc
There has been a debate about this particular limb design for as long as I have been building bows. Some guys like em... some guys don't...........Trust me....I'm not bad mouthing the design here.... I just do not care for the floppy limbs. These things can really fling an arrow once you get em dialed in....
Zipper Bows had a design just like this and he sold em like hot cakes! :dunno: :dunno:
You are doing great being patient, and did a great job on shaping the riser... Kirk
Post by: Kirkll on December 11, 2022, 08:12:03 PM
BUT..... When you use a power sander on glass with aggressive grit paper, you can screw up a limb REAL quickly trying to shorten your sanding time, and i screwed a few up learning the tricks too. I use a very stiff backing pad with hook and loop paper, on a very well balanced palm sander.... that ..... and i have about 30 years of experience running these things, and there is a feel to it you learn.
Here is a video explaining this better...... https://youtu.be/-LMg3D3kQSM
Post by: Bryan Adolphe on December 11, 2022, 09:21:33 PM
Post by: Kirkll on December 12, 2022, 11:44:22 AM
Good example.... i just laid up a bow that i have literally built hundreds of this same design , and the tiller was off by an inch.... :o :o :o Precession lam grinding was done with veneers belly and back, that i ground myself. I used book matched core lams, & I double checked the stack thickness too.... I also double checked the limb lengths from riser to tip notch's, and had my limb profile the same.... I use a pattern for that, and spray paint the outline on the limbs.....
There is absolutely no reason at all these limbs should be so different...... But they are.... :dunno: :dunno:
Saving grace is that i ALWAYS bring these things in 5-7 #'s over my target draw weight so i have room for adjustment. This one came in about 8-9 pounds over on the rough profile. I always leave the limbs an 1/8" wide all the way through the limb on rough profile. This gives me a bit of room for adjusting alignment , tiller , and draw weight. On long bow limbs you can often adjust these things a lot more than you think by just reducing width and trapping the belly side...... I've got this one within 3# of my target draw weight now
and haven't even sanded glass yet....... I gotta admit... The stiff limb was a bit wider through the fades than the lighter limb, so that helped with my excessive tiller difference quandary. It's manageable now with sanding and trapping.
Bottom line is some of these go smooth as silk, and others fight you every inch of the way, and leave you scratching your head on why..... But that's what makes you a good bowyer. Learning the tricks to balancing things out, and knowing how far you can take it. Sometimes you get da lion.... Sometimes da lion get you... Keep after it bro............ Kirk
Post by: Bryan Adolphe on December 12, 2022, 12:52:43 PM
Post by: Kirkll on December 12, 2022, 01:38:15 PM
Personally... i just use enough masking tape on the limb butts to lay out my drilling AFTER the limbs come out of the form. I never lay up limbs with tape on them.... It's too hard to get off after cooking that tape to the glass. Sometimes i use a bit of tape on the limb tips for a center line reference and tip notch location, and razor knife it after i clamp the pattern on.
Using a formica pattern works well. I Just clamp it on the limb and use some primer or spray paint..... Bingo! the finished limb shape is right there.... Easy to sand on the edge sander without having tape curling up too.....
https://photos.app.goo.gl/QZ1pQGPLxtgRYJUp6
Here is another little trick that works well on getting your centerline established on recurve limbs if you do not have a machinist table that would work well on that limb design you are building now. This is another reason you want a wider width on rough profile, so you can adjust the tracking of the limbs.
https://photos.app.goo.gl/S5pZf5LkezQwmpqT6
Post by: Buemaker on December 12, 2022, 02:54:57 PM
Post by: Kirkll on December 12, 2022, 07:59:17 PM
Post by: Buggs on December 13, 2022, 11:25:07 AM
How much glass are you removing? I don't think I am brave enough to power sand finish side glass :scared:
Post by: Kirkll on December 13, 2022, 03:33:19 PM
I’ve taken it down to .030 many times on mid 40# bows and they have been shooting for many, many years heavily.
Now you start getting up around 55-60# you want to keep your glass above .035.
60-70# range, or higher it’s best to start out with .050 glass. I’ve built them up to 70# with .040 , but I had minimal glass sanding. I Mostly used trapping and profile adjustment for balancing limbs that heavy with.040.
Now when I get orders for 60-80# bows I just order .050 glass so I have some room to adjust and sand my limbs. Kirk
Post by: kennym on December 13, 2022, 07:00:51 PM
Post by: Crooked Stic on December 13, 2022, 09:45:17 PM
Post by: Bryan Adolphe on December 14, 2022, 08:18:44 AM
#1 My question is when you first get the limbs profiled and a string on it and you put it up on the Tiller tree the riser itself should be level?
#2 when it’s on the tree and it’s at brace The limb tips should be relatively level also ?
#3 when you go to exercise the limbs, do you draw the bow on the tree from the centre of the bow or from where you would normally draw from with your fingers slightly off-center ?
Post by: Buggs on December 14, 2022, 11:41:21 AM
#2 yes
#3 lots of different methods. I do this; [ You are not allowed to view attachments ]
Post by: Bryan Adolphe on December 14, 2022, 04:31:32 PM
Post by: Kelly on December 14, 2022, 07:53:54 PM
Couple of questions from my observations here. 1. Shouldn’t the center of the handle be on the tillering tree? Looks to me like your handle is more on the top limb than the bottom.
2. If the the bottom limb is positive tiller measurement over the upper which you stated in the very first post, shouldn’t one be trying to weaken the upper limb?
This is not a critic just trying to learn for the day when I try building my own.
By the way, I like this design but have not shot one shorter than 60”, I sure would like to tho.
Post by: Kirkll on December 14, 2022, 08:48:59 PM
Keeping the riser block flat and level, and hooking to center to start out, lets you see the limb balance easier. I put the deepest part of the grip centered on the bow for an ergonomic grip shape with a thumb ledge.....
For ASL style risers (Straight & dished shape grip) A lot of long bow guys heel down pressure on the grip, and the limb balance should be done from the pressure point applied to the riser.
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Post by: Bryan Adolphe on December 15, 2022, 08:59:26 AM
:thumbsup: onto the next one. Bryan