2019 what did ya do today....

[Crooked Stic]

Its green.

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[Flem]

Stic, is that Green Apple or lemon Lime flavor.
To answer your question about the larch, if you like Douglas fir shafts and you got your hand on some Larch,
 you would be giving away the Fir. It's kind of like compressed cedar, great if you like shooting arrows with thumping power.

[Crooked Stic]

Hmmm does kinda look like a Jolly Rancher apple.   

[Roy from Pa]

That larch does look like good arrow wood...

[Shredd]

Sucking up some blanks for forms for experimental limbs to be used on a takedown riser...  Gonna try making a high performance, lightweight, short draw bow for women and youth...

[Flem]

Go Shredd! Love to see a fellow air sucker. I am continuously amazed that more Bowyers don't use this simple, effective method.

[Shredd]

  Flem...  I knew you would go stickin' your nose into this...     

   I am totally with you Bro...  You can glue up a riser in a quarter of the time or less and you don't have to worry about screw placement...   Get with the program Boys...   

[Mad Max]

"blanks for forms"
?????????????????????????????
I guess I'v been gone to long.

[Shredd]

It's just a block of wood until you cut it out into a form... 

[Flem]

  Flem...  I knew you would go stickin' your nose into this...   

   That was like shooting fish in a barrel

[Shredd]

More like you just shot a hole in the bottom of the barrel and let the water out...        

   Well guys  never assume anything...   I assumed that granite top was dead flat...  It's not...  SOB!!!   It's not off by much but it is off...  I guess I will do a little trick with the lam keepers to straighten things out...  It sucks to do all this work and use good material for a sub-par job...

[Mad Max]

This is what you need if you want it to be flat.
I use these all the time back in the day.
see if you can find one local on a auction site.
https://www.mscdirect.com/product/details/00468595

[razorsharptokill]

Made a string jig out of scrap oak.

[Crooked Stic]

I dont understand how a thin plastic bag can bend plywood enough to keep it straight. Even with a vacuum? I suppose the dumbbells do that. AS far as riser blocks go I use C clamps.

[Flem]

I dont understand how a thin plastic bag can bend plywood enough to keep it straight. Even with a vacuum? I suppose the dumbbells do that. AS far as riser blocks go I use C clamps.

Is that a nice way of saying, you don't believe it? Believe it, it works! Obviously you cannot bend 3/4" plywood into a arch, but Shredd was glueing up plywood into a blank form and needed it to be flat and the reference surface he was using, was not. This pic is from a thread back in March. Thats 4-3/16" Maple slats(3/4" total) pulled with 12Hg vacuum, pumps will pull 29Hg at sea level. I didn't get the full bend at the tips because I let the bag pinch together before it could suck onto the form. This was using cheap 4mil LDPE plastic.

[Crooked Stic]

Oh I understand how it would work with thin lams. And with perfectly flat thick pieces just to hold them together tight while glue cures. But you aint bending 3/4 plywood very much with that plastic. Although I may be missing something.

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[Flem]

You are absolutely correct on that account, Stic. But then again you would not be bending 3/4" ply with any method, unless you streamed or soaked it first to make it flexible, in which case you could then vacuum bend it.

[Crooked Stic]

But you can bend it for forms wih screws.

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[Shredd]

Stic we discussed this a few years back with psi in an air hose...  I don't think you grasp how much pressure there is when you spread it out over a larger area...  If done correctly I would think that you could easily snap a piece of 3/4 " plywood under a vacuum...

   Here is an experiment for you to comprehend this chit...  Take two pieces of 2x4's and cut them 10"...  Round all the corners so that they are not sharp...  Stack them on top of one another and put then in a trash bag...  Make sure there are no holes in the bag...  Take your shopvac hose and insert it in the opening of the bag...  Take a zip tie or hose clamp and secure the hose to the bag...  Turn on the shop vac and suck the air out...  Now grasp each 2x4 and try to pull them apart...

   Keep in mind that there is only about 1 to 2 lbs of suction going on which is about 35 to 70 lbs squeezing those blocks together...   Use a real vacuum pump at 8 to 10 psi or more and you will have roughly 280 to 350 lbs squeezing those blocks together...

  Just another note...  If I would have enclosed the granite slab with the wood I was using inside of the bag, I would have not needed the weights to hold things flat...  That bag would have sucked that wood right down to the granite...  Which would actually be more effective...

[Flem]

Here's the way I see it; screw pierces plastic, hydraulic press crushes screw, plastic encapsulates hydraulic press.