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Main Boards => The Bowyer's Bench => Topic started by: Forwardhandle on February 12, 2018, 08:01:00 AM
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Morning Fellas finally getting a chance to do a little bow work been plowing snow for 8 days here, but I noticed this form is about 3/64 off the center line out of alignment, the alignment issue falls right in the riser section how critical is dead strait ? Im going to mill some stiffing strips to see if I can pull it back in before routing the form but how critical is that alignment ? Im thinking if I joint some 2x4s dead flat for each side full length and run bolts threw it should snug it up ? (https://i.imgur.com/qSrySD9.jpg)
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(https://i.imgur.com/V9ubEME.jpg)
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3/64 is not a lot, but if ya aint happy start over. Better safe than sorry.
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I will have to see how the stiffiners work I guess what Im asking is how much if a tolerance if any is acceptible ? If it was a wood bow I wouldnt worry about it but never made a glass form before.
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The straighter you start the better. If the tips of the blank are off you have to allow for that when laying out the limbs. Easier to stay square/straight if you start straight.
I screw angle iron to both sides on the bottom of the form to help keep it from warping. Plus it gives the form a foot and helps keep it standing up. Downfall is it adds weight.
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I was just looking at angle Iron at the big box store man it will add a lot of weight your right about that, but would rather deal with it then be off I think it should pull that little bit in ,I might do it mid form closer to the top leaving room for the templet ! Thanks
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You have to handle extra weight for a minute or two, but how many minutes dealing with a bow prob? LOL
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Yep Im really hopping it sucks it in other wise starting over thats a bad spot to be off , I think it will be ok with the stiffners I can get it to flex a bit when I lay it flat and stand on it ,
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Might have to use some shims with them.
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Thanks I will give it a go next one Im sticking to
Plywood the boards are at dimension and save time there but other issues eat the time , the solid lumber is harder to get strait with out milling !
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I clamp them to a big pc of angle iron and shim as needed to get straight lengthwise and diagonally when glued and screwed before glue sets
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If I'm reading this right, you're off by 3/64" in the riser section over the length of the form. That's about .045" Less than the thickness of a dime.
Obviously, the straighter the better, but I think you'll be fine with it the way it is.
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Yep thats right , but if I can get it dead strait with the stiffiners the better sense its my first glass bow just trying to put every thing in my favor
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Originally posted by Yellowwood:
Yep thats right , but if I can get it dead strait with the stiffiners the better sense its my first glass bow just trying to put every thing in my favor
Absolutely! The closer to perfect you have it, the better off you'll be.
I'm a gunsmith's kid. To him, .045" may as well be greater than the distance to Mars! ;)
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On the other hand, (hey, somebody has to be contrary here :) ) you are talking less than 1/8". How wide do you want the finished bow to be at the fades? Do you have 1/8" to spare in the blank when it comes off the form?
If you have the 1/8" to spare, you can get a straight blank out of the form as long as squirm is controlled.
If you twist the form while trying to get it dead straight then you will have introduced a bigger problem, IMO.
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Originally posted by monterey:
On the other hand, (hey, somebody has to be contrary here :) ) you are talking less than 1/8".
Actually its less than 1/16".
I agree with Monterey. I don't think you'll ever notice it.
I don't have a drum sander or a big edge sander, so I could lose that much just cleaning glue boogers off the blank. The 1/16" should correct itself when you profile the limbs as long as you work off a good centerline
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Get it straight and keep it straight with a fastened strong straight edge, could be steel or doubled up 3/4" ply on bottom part of both forms. Heat from the box over time can compromise the form. The better the form the better the bow. JMHO.
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Thanks Monterey thats why Im waiting to route the form dead square after I have it straitened if there is any change I could always recut it but at 3/64 and Im being generous at that I think its slightly less , Im hopping not to get twist but who knows at least at this point I know I wont have to start over I was just concerned because every book I read taked about the form having to be perfect but I appreciate all the help being a newb glass bowyer wantabee
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I just picked up some 1 1/2 x 1 1/2 x 1/8 angle iron and 3/8 bolts,washers & nuts Im clamping the angle together and drilling the holes so the bolts goes threw the form and will act like a clamp maybe a shim or 2 if that doesent work I would be suprised ! I will let you know when done over the week end.
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Go to the end of your street and pull up the stop sign. Use the pole as a stiff back. Cut the form in half and screw the form to the pole. It has holes every inch and alignment will be easy.
James
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Get some birch ply, laminate it together and start again.
I wouldn't waste time trying to straighten it.....if it already warped ask yourself what is it going to do in the hotbox??? Why did it warp - tension in the wood that is still there to a degree.
Only use the most stable materials you can get for forms.
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Probably preety good advice there Mike but Im taking the problem solving 101 approach on this one , I wish I could blame the wood but it was operator error rushing before glue set , but this one will be a metal/wood composite form when done , I could of just bought blank but would have missed all this fun
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Go figure I brought this form inside sense Monday at 28 % RH and when I measured it this morning before work its dead on the money strait Im going to route it tomorrow and put the angle iron on and leave it inside tell I use it ,I probably should have acclimated the boards inside before cutting maybe Im splitting hairs but at least I know its dead strait now to start !
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sight down your irons--use the straight sides--and gorilla glue and bolt
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JamesV I hope your kidding on the pulling of a stop sign
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We don't have stop signs in Chicago only red light cameras any way
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One thing you can do with a board form like that is wet down the wood on the inside of the bend. It expands the wood on the week side and straightens it.
It won't stay that way in the oven but would be fine in a room temperature cure.
Not suggesting as a way to do things, but just as a remedy. Nothing works better than good materials from the git go.
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I'm with Mark. A responsible person would take a yield sign.
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Thanks Monterey I will put that in my pocket for future use ,I think ones I get the angle Iron on and bolted the wood will have a hard time moving but I should be good to go !
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The farm equipment and mowing machines knock down road signs all the time and my county road agent will bring me all I need. I don't actually have to pull them up myself.
James
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well got the bottom form routed and angle iron stiffeners on its dead square and strait now .I really like that its free standing won't have to clamp in the vice (https://i.imgur.com/9IQBSEC.jpg)
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(https://i.imgur.com/oItUeII.jpg)
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Looks good!