Setting height of spring blade rest on compound

[KidCurry]

I would set up for centre shot and ignore tail left/right for now as the paper tear will be extremely sensitive to bow torque. The blades are available in 0.008", 0.010" and 0.012" depending on arrow weight. Before switching to the resin fibre blades, which I really like, I used to stick a layer of PVC tape to the underside of a 0.010 blade to dampen the oscillations. From memory 0.010 take you up to 350grain arrow but check this out as I may be way out here.
Oh... centre shot on a compound can be tricky to find. Modified french tune is a simple way to set this.

 

[ThomVis]

The blades are available in 0.008", 0.010" and 0.012" depending on arrow weight.

Or take two 0.008" blades, cut 1 in half halfway and mount it below the other to get a "thicker" blade than the 0.012" for heavy arrow.

 

[geoffretired]

I would check for contact with lipstick or similar, just to find out where the contact is being made.
Sometimes bullet holes are possible with the odd clearance issue. A slight lowering of the rest can give equally good bullet holes and very few,if any, contacts.
The tail of the arrow just needs to lift 1mm or so to get clear.
I like KidCurry's idea of the tape. ThomVis' idea is good, too.
With a shorter blade ( or equivalent) above instead of below you can reduce the amount of upward bounce of the proper blade.

 

[chuffalump]

@KidCurry - yes. The modified French tune would be my ideal next step. We can set two ranges up at the club so I might be able to try next weekend. My arrows are 28 grams which is 432 grains. I'll see if this elicits better info from the net or manufacturer.

@Thom/Geoff - hmmm. I can check for contact on the vanes I think (no lipstick but might be able to improvise) but not enough blades to experiment with. Might try the tape idea to damp vibration.

Overall, I'm not sure how much torque I might be applying but hopefully I'm a lot closer to correct set up than I was yesterday. As an engineer this is quite entertaining. If only it was more convenient.

 

[geoffretired]

Hi Chuffalump, another blade isn't really necessary; any thing that can be placed above, and fitted to the blade support, to resist the bounce back will work. I have some thin sheets of spring steel, I make the blades and a support if necessary.
I find the paper test can be very helpful to discover whether or not I am applying bow hand torque. I can deliberately add some and watch the tear change shape. I can relax my hand and see if the tear goes back to a bullet hole; or at least no left/right rip.

 

[chuffalump]

Might be able to try some shim steel from work, although a cut down second blade would be easier to fit. I have a 0.3T blade as well so could possibly cut it or just fit it but not both . I have no idea what 0.3T represents. Thought it might be thickness in mm but need a vernier to check.

 

[geoffretired]

According to Google 0.3 T = 0.3 Tonne
Should be Ok at holding up an arrow unless you use Tungsten points.heehee

 

[chuffalump]

According to Google 0.3 T = 0.3 Tonne
Should be Ok at holding up an arrow unless you use Tungsten points.heehee

Turns out it is the thickness. Vernier shows exactly 0.3mm thick at tip.

 

[bimble]

See, I just use a 10 or a 12 blade* for everything, from 300gr 3D arrows, to +600gr indoor arrows.

* - depending on what I find first in my box

 

[chuffalump]

The 0.25T I have fitted is the same as the 10 whilst the 0.3T is the same as the 12.

However, sounds like it shouldn't matter. Might try the 0.3T in case my blades are more springy due to being from a cheaper rest. Vane contact test probably the first step though.

If grip torque can cause left/right tears then maybe heeling the bow can cause up/down tears too.

EDIT - finally found something. Abbey Archery has a page suggesting arrows over 425 grains use the thickest std blade. So maybe another paper tune during the week with the 0.3T blade as a trial.

 

[geoffretired]

Torquing a compound left to right is easy as the string is under low tension and the limb tips are short and not that far back from the bow grip. A little torque moves the limb tips by a small amount and against a low tension.
Compare that with recurve where the draw weight is much higher at full draw and the limb tips are a fair way back from the grip. A little torque would require a lot of limb tip movement and against a high tension in the string.
Heeling the compound is not so easy as the bow becomes a rigid system at full draw, as the limbs are almost impossible to bend. With recurve heeling can tilt the riser back at the top as the limbs flex in opposite directions.
I might be wrong, but I think the flex in the blade shouldn't make so much difference to the launch of the arrow as far as the pile end is concerned. What can happen, is the flex rate may bring the V back in contact with the fletchings or back end of the shaft. Softer blades will flex more slowly; that might mean it doesn't get back soon enough to contact the back of the arrow. It will flex further though, so if its timing is bad it can require a higher nock point for clearance. Kid Curry's tape can help slow the return and reduce the amount of flex.

 

[chuffalump]

Aye, I think I'll set up again in the garage tomorrow. Try tape first as the easiest, then vane contact test and maybe the stiffer rest blade depending on time.

You're bow heeling comment makes sense. I'm not fully comfortable with a compound grip yet. It strikes me that pressure square to the flat surface should be more stable but sometimes just tucking into the pivot works just as well. I wrapped the old bow grip in handlebar tape but felt it made it too imprecise.

I think I'm enjoying it because it feels like starting out in recurve did. Only without the 'you should have this sorted by now' feeling.

 

[geoffretired]

I had to leave recurve because of a damaged second finger. In a way, compound was my only option apart from leaving archery. I was lucky to be near a guy who was years ahead of his time. He designed and had built a compound that was just as they are today; long risers, short near parallel limbs,; and that was in 1985!! The bow I bought from him was a superb piece of kit and I never wanted to go back to recuve after that.
They offer me the chance to make all sorts of bits for the bow.And fiddle/ make with all the different components.
The compound bow grip can be narrow as the load on the hand is slight at full draw. Having a flat surface facing the archer , means that any pressure put on one side (and not both equally), is easy to feel. T have fairly sharp edges on mine as it makes detection easier.
Usually the slope is very steep( very low grip) and that, I feel, makes it less likely that heeling will happen.
I never wrapped my grips as i always thought it disguised what might be happening rather than giving clear feedback.Too comfortable, even if you move the hand deliberately.( I know that is a generalisation.)
Well, after 28 years on compound, I am still sorting things out. Something new to look forward to; whether it is form; or settings; or items.

 

[chuffalump]

In this thrilling episode!!! I learn some stuff. Some success is achieved and more puzzlement is created.

Ok. Spent the morning in the garage with the paper tuning box. Tried using deodorant to check for contact but the results were inconclusive. Need to order the spray. Tried the thicker rest but no obvious differences so went back to the mid thickness. Haven't tried taping the blade yet as I only had sellotape. Insulating tape has gone walkabout.

After a bunch of random results (good to tail up), eventually I got fed up and moved the rest upwards by a large amount. The principle being to swap the tail high for a tail low result and then work back down. However, it actually produced a good result. Several ends later I was still getting random results. Not massively wrong but not bullet holes either. Then I was convinced that my sight dropped on the paper at release so I swapped to a thumb trigger release (instead of the hinge). No risk of punching when aiming at a blank piece of paper. The next nine arrows produced at least six bullet holes and three with a slight tail left (could be the arrow).

So, Top Tech Tip - use a trigger release unless you are absolutely sure of your hinge technique.

The upshot of all this is that my sight pin is now almost bang on the bow centre as judged by aligning string with stabiliser holes. However, the arrow is pointing quite a long way to the right when compared in the same way. I haven't checked to see if the cam spacing puts the string at limb centre yet. I also haven't shot with the string away from the face to eliminate potential sideways oscillation caused by face pressure. My 2016s are probably a little underspined, should probably set up the 3-39 ACCs instead but, as far as I am aware, using a release aid and no button should prevent the recurve type left/right issues of arrow spine.

 

[geoffretired]

Nice post. Like the intro!
The raised arrow rest seems like it could explain the low sight marks...good news!
One way to check for straight ahead is to look down from above the limbs. Look through the gap between the split limbs and there arrow should be facing parallel to the gap. I did make a jig that looked like a H which fitted against the top and bottom limbs at the riser end and the cam end. That had a straight rod facing towards the sight so was indicating parallel to straight ahead. With an arrow in place I could measure arrow to rod are each end to check for parallel.
After the work was done I found eyeballing worked equally well.
The release aid is an experience like no other! One that uses the index finger seems so natural as we have all mimed shooting by imitating the trigger action.
A hinge can be bliss or mind blistering. Thumbs are safer in the security they seem to offer. Avoiding punching the trigger is a lesson worth giving time to.
You are sounding much happier....... good!

 

[chuffalump]

I think it's a nice demonstration that a bow's setup is a dynamic system rather than a static. There is no way a rigid rest should work at this height so the blade must be acting like a button on a recurve. On release it must flex down bringing the arrow level followed by the arrow flexing over the moving rest in a vertical movement paralleling the horizontal movement of a recurve launched arrow.

 

[KidCurry]

...On release it must flex down bringing the arrow level followed by the arrow flexing over the moving rest in a vertical movement paralleling the horizontal movement of a recurve launched arrow.

https://www.youtube.com/watch?time_continue=72&v=2qDdAzw_vY0

from 0.23

 

[chuffalump]

Well, that was interesting. The vertical movement doesn't match what I imagine. In the video the blade seems to remain mostly steady at the start before gradually building up vibration towards the back end of the arrow. I wonder if my vertical setting is basically compensating for some other problem. I guess watching an arrow in flight will tell me if I have just managed to tune for perfect arrow orientation at 3m. Back to ordering the spray for contact checking.

What I liked was the shot of side to side string movement. This would explain my horizontal rest positioning, as the string cycle must hit arrow separation a few mm to the right of centre.

EDIT - blue lipstick ordered. Should contrast well enough and a lot cheaper than spray.

 

[chuffalump]

......and I'm going to have to do it all again soon. A combination of a wet day, with no chance to practice and the internet, means a set of X7s have been deducted from my bank account.

 

[chuffalump]

First time shoot since the garage paper tuning today.

At first I thought it was a disaster. Arrows massively tail left in target at 20yds. Bow didn't sound the same. Everything felt wrong. I put the rest horizontal movement and sightings back to original and it still felt wrong. Then had a little sit down and contemplated life. There was a fair cross wind so maybe it was all related to conditions.

Put all settings back to post paper tuning places and shot again. Gradually it started to come together. I decided that the arrows were biased left at 20 yds so moved the rest one more mark to the right (closest I could get to walk back tuning). Then moved into 30 yds. Arrows mostly still central. 40 yds and the arrows were fairly random. At which point I realised that my bow or my set up was punishing me badly for mistakes. A firm grip on the hinge release improved things and I realised that anything loosed slightly off bubble flew like it was p###ed. I have a tendency to stoop and this makes it very difficult to avoid canting the bow (I think).

So 40 yds, consciously upright stance, firm grip on the release. Suddenly much easier to aim and release without disturbance. Arrows clustered around the centre of a small field target we found a bunch of at the back of the lockup.

Even better, the differences between sight marks was less than ten points on the sight tape. 3.3 for 20 yds, 4.1 for 30 yds and 4.9 for 40 yds. I've no idea why it works but it looks like it does.