Author Topic: #s of air pressure for riser overlays?  (Read 3031 times)

Online Bryan Adolphe

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#s of air pressure for riser overlays?
« on: January 21, 2024, 02:52:54 PM »
So I glued this up this morning was too sure how many pounds of air pressure for these back overlays ? I ended up putting 50 pounds  :dunno: four laminations with EA 40. Any insight on that is that too much air?

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Re: #s of air pressure for riser overlays?
« Reply #1 on: January 21, 2024, 04:35:54 PM »
50 good :thumbsup:
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Offline Crooked Stic

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Re: #s of air pressure for riser overlays?
« Reply #2 on: January 21, 2024, 09:11:20 PM »
50 will work if all your tolorencs are good. I do run 70 on everything and have had no problems.
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Re: #s of air pressure for riser overlays?
« Reply #3 on: January 21, 2024, 10:10:40 PM »
A dry run will tell you how many # you need + about 10 more at glueup
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Offline Crooked Stic

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Re: #s of air pressure for riser overlays?
« Reply #4 on: January 22, 2024, 09:31:45 AM »
What I do is act about half. Then wait maybe a minute then add the rest. Some say there is less chance for trapping an air bubble. I have not proof of that but do it anyhow, I keep a regulator to control the pressure. One time I had the regulator out of line to air a tire and forgot to put it back.tank gage showed 120. Filled the hose instantly . That limb had a split veneer, that what I blame it on anyhow  :dunno:
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Online Kirkll

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Re: #s of air pressure for riser overlays?
« Reply #5 on: January 22, 2024, 10:50:53 AM »
Are you using a metal pressure strip on top of those lams?  50# is plenty of pressure…. But distributing it equally is important, and using a pressure strip helps with that, as well as keeping the space between the form and the lams minimal so the hose doesn’t apply more pressure to the center. Too much space , and it can cause cupping with limbs. But your set up looks good to me.

I use a stainless steel strip myself, then hook up my battery charger to it, and it’s cured in 30 - 40 minutes time….
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Re: #s of air pressure for riser overlays?
« Reply #6 on: January 22, 2024, 12:07:58 PM »
[quote author=Bryan Adolphe link=topic=182919
So I glued this up this morning was too sure how many pounds of air pressure for these back overlays ? I ended up putting 50 pounds  :dunno: four laminations with EA 40. Any insight on that is that too much air?[attachment=1,msg3045869]
[/quote]

I think you have to much space between the upper and lower, I like 1" to 1-1/4" with it aired up.
You could get the cupping Kirk is talking about .
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Offline Crooked Stic

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Re: #s of air pressure for riser overlays?
« Reply #7 on: January 22, 2024, 12:53:43 PM »
If you were to be able to cut your fire hose in two with it inflated the end view should be dog bone shaped.  If there is any clearance at all the air pressure will push it apart.
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Re: #s of air pressure for riser overlays?
« Reply #8 on: January 22, 2024, 03:57:57 PM »
When setting up your upper form spacing for the fire hose, you want it so that your hose is pretty flat . Shouldn’t be much more than 7/8” . The best way to get the form together is hooking up a clip on air Chuck that allows you to compress the hose.

Like this one…

https://www.amazon.com/SAFELIFE-Chuck-Inflator-Compressor-Accessories/dp/B0BVFJRGXG/ref=sr_1_3?crid=O26HZ5OBL89L&keywords=clip+on+air+chuck&qid=1705957000&s=automotive&sprefix=Clip+on+air%2Cautomotive%2C148&sr=1-3

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Online Bryan Adolphe

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Re: #s of air pressure for riser overlays?
« Reply #9 on: January 22, 2024, 05:36:31 PM »
I cleaned it up this afternoon and it turned out almost perfect. The space I allowed was 7/8 - 1”  which was pretty much bang on and it came out dead flat except my blocks at the end of the riser to keep the hose running true weren’t quite the same height. They were slightly less than the end of the riser block which produced a little bit of a bulge, so i make sure next time that those blocks are exactly the same height as the riser , the last overlay, which becomes my limb pads is thick enough that I’ll be able to carefully sand out that little bit of bulge on this one, yes, I did have a pressure strip under that fire hose , all in all it was painless  and it turned out pretty darn good.

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Re: #s of air pressure for riser overlays?
« Reply #10 on: January 25, 2024, 09:48:08 AM »
Hey Bryan,  are you going back and checking your limb pads closely for square after doing these overlays?  Might be worth while to do…. Kirk
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Online Bryan Adolphe

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Re: #s of air pressure for riser overlays?
« Reply #11 on: January 25, 2024, 01:05:50 PM »
Hey Bryan,  are you going back and checking your limb pads closely for square after doing these overlays?  Might be worth while to do…. Kirk
Oh yes for sure , throughout the building of the riser, including drilling for the pins and insert i always try and work off of one side at all times to keep things square to each other.

Online Bryan Adolphe

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Re: #s of air pressure for riser overlays?
« Reply #12 on: January 25, 2024, 01:21:52 PM »
What I am still having issues with is those mystery noises coming from the connection between riser and limbs, not all of them do it, but every once in a while, I get one So I’m seriously considering a gasket material and I guess cork is one that appeals to me just not sure how it’ll stand up for longevity , rain, cold, and wear and tear but it’s a product that would do the job well and still look good.

Offline Jon Lipovac

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Re: #s of air pressure for riser overlays?
« Reply #13 on: January 25, 2024, 03:16:08 PM »
What I am still having issues with is those mystery noises coming from the connection between riser and limbs, not all of them do it, but every once in a while, I get one So I’m seriously considering a gasket material and I guess cork is one that appeals to me just not sure how it’ll stand up for longevity , rain, cold, and wear and tear but it’s a product that would do the job well and still look good.

I’ve had the same type of noise you talk about. Typically it’s a single ‘click’ that I hear when I first draw a bow that has been sitting for a a while. Usually only does it once then consecutive shots after you don’t hear it. It’s only after I have finish on them for me. Before I finish them and the surfaces are still ‘raw’ I have zero noise. When I do have a bow that does that, I apply a fair amount of string wax to the pins and limb pads. That has always worked for me.

I have noticed that on my thinner, straight taper butt wedges, the wedge will bend just enough on the riser pad that you can barely see some daylight under it at full draw. Surprised me the first time I saw it. I’m now experimenting with moving the bolt a little closer towards the end of the riser, just 1/4” at a time and seeing how that effects things. Otherwise, I’m gonna start adding a limb pad lam to the finished limb to add stiffness or run a second bolt. I did both of those on this one and it is dead quite, no wax, no gasket.

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Re: #s of air pressure for riser overlays?
« Reply #14 on: January 25, 2024, 03:46:10 PM »
 "I have noticed that on my thinner, straight taper butt wedges"

How thick is the wedge at the end of the riser Kirk?? :dunno:
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Offline Crooked Stic

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Re: #s of air pressure for riser overlays?
« Reply #15 on: January 25, 2024, 04:45:45 PM »
Here is the deal if you got moving parts they need lube. I find a brand new potty ring wax on the pads quite things. And if you got a st. Taper wedge that moves the outer pi hole Ned's to be a bit oblong. It don't take much. Can be accomplished by moving a bit back and forth ln the hole.works for me.
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Re: #s of air pressure for riser overlays?
« Reply #16 on: January 25, 2024, 09:38:28 PM »
Yup… that clicking noise is the outer pin hole in the limb binding up. I use a slot instead of a hole in my limb using a 1/4” mill end our router bit in my mill. I use one pin above the bolt .50” and the other is 2” below and slotted .040 . .020 each way from center….. But Mike is right… you can simply take your drill and rock it back and forth a fuzz from riser to tip direction by hand. But go easy, and go steady with it.

I’ve had some bows that I did everything to, and they still made noise until I covered the limb pads with a soft material. I’ve used mole skin, cork, and thin rubber pads. The rubber pads work the best and don’t wear out, and are unaffected by weather. I bought a 2” wide roll of it about .0625 thick. The .125 thickness was too much.

Yup…. That’s the thing about long lean wedges. If you mount them flat on the limb pad you can get flex in the wedge. What I did was put a very slight reflex in the wedge section of my forms so the air hose actually pushes a bit of reflex in the straight wedge during lay up…. You don’t need much, but it works well.  On my hybrid long bow limbs those limbs don’t even lay flat and touch at the end of the riser until you string them up. This actually does wonderful things for adding preload to your limbs loading up that wedge at brace.

Type of wedge material used can make a big difference too. Heavy limbs need good dense hardwood wedges, or something really stiff. Lighter weight limbs you can use walnut or different woods with less tensile strength. Curly maple is not a good wedge wood. That stuff flexes a lot.

My wedge thickness at the end of my risers run about 3/16” thick and go out there another 6.5”.   About 5/16 to nothing in a 12” wedge when milling. Finished wedges are 11.5 and 10.5” for medium and long limbs,  with a 4.75” limb pad length.  You can do the math if ya want. It works well.   Kirk
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Online Bryan Adolphe

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Re: #s of air pressure for riser overlays?
« Reply #17 on: January 25, 2024, 10:27:17 PM »
 I will look closer into removing a bit of material to Oblong those holes a little,  :thumbsup:

Online Bryan Adolphe

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Re: #s of air pressure for riser overlays?
« Reply #18 on: January 25, 2024, 10:29:27 PM »
 Nice job Jon !

Online Bryan Adolphe

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Re: #s of air pressure for riser overlays?
« Reply #19 on: January 26, 2024, 08:04:23 AM »
I will look closer into removing a bit of material to Oblong those holes a little,  :thumbsup:
Forgot to mention I haven’t sprayed a finish  on these bows yet so I haven’t applied wax to them yet.  :thumbsup:

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